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The synthesis and structures of two polymorphs, A and B, of Co(NCS)2(abpt)2 and Ni(NCS)2(abpt)2 are reported. The polymorph structures of A with CoII or NiII were found to be isostructural, as were the corresponding pair of polymorph B structures with the different metals., The synthesis and structures of bis­[4-amino-3,5-bis­(pyridin-2-yl)-1,2,4-triazole-κ2 N 2,N 3]bis­(thio­cyanato-κN)cobalt(II), [Co(NCS)2(C12H10N6)2] or Co(NCS)2(abpt)2, and bis­[4-amino-3,5-bis­(pyridin-2-yl)-1,2,4-triazole-κ2 N 2,N 3]bis­(thio­cyan­ato-κN)nickel(II), [Ni(NCS)2(C12H10N6)2] or Ni(NCS)2(abpt)2, are reported. In both cases, two polymorphs, A and B, were identified and structurally characterized. For both polymorphs, the structures obtained with the different metals, i.e. CoII or NiII, were found to be isostructural. All of the structures contained an intra­molecular N—H⋯N hydrogen bond, C—H⋯N inter­actions and π–π stacking inter­actions. No structural evidence was observed for a thermal spin crossover for either of the Co(NCS)2(abpt)2 polymorphs between 300 (2) and 120 (2) K.

The crystal structure of the radical ferromagnet 1a at 2 K reveals a contraction in the unit cell c constant which, at the molecular level, translates into a decrease in slippage of the radical π-stacks and an increase in ferromagnetic exchange interactions along the stacking axis. The results of BS-DFT calculations using long-range corrected functionals are consistent with an overall ferromagnetic topology.

Three {[(isoxazol-3-yl)imino]­meth­yl}phenols were synthesized and structurally characterized. All three structures contain an intra­molecular O—H⋯N hydrogen bond and none were found to be strongly thermochromic., The synthesis and structures of three isoxazole-containing Schiff bases are reported, namely, (E)-2-{[(isoxazol-3-yl)imino]­meth­yl}phenol, C10H8N2O2, (E)-2-{[(5-methyl­isoxazol-3-yl)imino]­meth­yl}phenol, C11H10N2O2, and (E)-2,4-di-tert-butyl-6-{[(isoxazol-3-yl)imino]­meth­yl}phenol, C18H24N2O2. All three structures contain an intra­molecular O—H⋯N hydrogen bond, alongside weaker inter­molecular C—H⋯N and C—H⋯O contacts. The C—O(H) and imine C=N bond lengths were consistent with structures existing in the enol rather than the keto form. Despite having dihedral angles

Three di-tert-butyl-substituted N-salicylideneaniline derivatives were synthesized, structurally characterized and their chromic properties investigated. Polymorphism was found to affect the photochromic behaviour of the first com­pound, while the second two com­pounds were found to display a temperature-induced phase transition. All of the structures contained an intra­molecular O—H⋯N hydrogen bond., The synthesis, single-crystal structures and chromic behaviour of three related Schiff bases, namely, (E)-2,4-di-tert-butyl-6-{[(4-fluoro­phen­yl)imino]­meth­yl}phenol, C21H26FNO, 1, (E)-2,4-di-tert-butyl-6-{[(4-chloro­phen­yl)imino]­meth­yl}phenol, C21H26ClNO, 2, and (E)-6-{[(4-bromo­phen­yl)imino]­meth­yl}-2,4-di-tert-butyl­phenol, C21H26BrNO, 3, are reported. Two polymorphs of 1 were obtained, which were found to have different photochromic properties. Schiff bases 2 and 3 were found to be isostructural and underwent a phase transition upon cooling which was attributed to the dynamic disorder in one of the tert-butyl groups resolving at low temperature. All of the structures were found to exist in the enol rather than the keto form based on the C—O(H) and imine C=N bond lengths, and contained an intra­molecular O—H⋯N hydrogen bond alongside weaker inter­molecular C—H⋯O contacts.

A novel poly­morph of (E)-4-bromo-2-[(phenyl­imino)­meth­yl]phenol is reported, with a dihedral angle between the planes of the two aromatic rings of 45.6 (1)°, significantly different to that of the previously published poly­morph. The structure contains an intra­molecular O—H⋯N hydrogen bond forming an S(6) ring., A new poly­morph of (E)-4-bromo-2-[(phenyl­imino)­meth­yl]phenol, C13H10BrNO, is reported, together with a low-temperature structure determination of the previously published poly­morph. Both poly­morphs were found to have an intra­molecular O—H⋯N hydrogen bond between the phenol OH group and the imine N atom, forming an S(6) ring. The crystals were observed to have different colours at room temperature, with the previously published poly­morph being more orange and the new poly­morph more yellow. The planarity of the mol­ecule in the two poly­morphs was found to be significantly different, with dihedral angles (Φ) between the two aromatic rings for the previously published ‘orange’ poly­morph of Φ = 1.8 (2)° at 120 K, while the new ‘yellow’ poly­morph had Φ = 45.6 (1)° at 150 K. It was also observed that both poly­morphs displayed some degree of thermochromism and upon cooling the ‘orange’ poly­morph became more yellow, while the ‘yellow’ poly­morph became paler upon cooling.

Two new coordination polymers [Cu(btzx)2(MeOH)2](NO3)2 (1) and [Cu(btrcy)2(H2O)2](ClO4)2·btrcy (2) have been synthesized by reacting two bis-triazole/tetrazole-ligands namely m-xylylene-bis(tetrazole) (btzx) and bis(1,2,4-triazole)-trans-cyclohexane (btrcy) with Cu(NO3)2 and Cu(ClO4)2 respectively in a 1:3 metal/ligand ratio. These compounds are shown to form X-ray quality single-crystals under different conditions, and the crystal structures have been determined by single-crystal X-ray diffraction (SXRD). The SXRD data analysis revealed that 1 and 2 are 1D looped chain and 2D-square grid coordination polymers, respectively. More interestingly, the 2D-square grid architecture in 2 acts as an excellent host for the large guest ligand molecule btrcy, which is encapsulated within the voids of the 2D coordination polymer., info:eu-repo/semantics/published

The spin crossover behaviour of [Fe(abpt)2(NCSe)2] (abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) polymorph A has been examined using single crystal X-ray diffraction and variable temperature UV-Vis transmission spectroscopy. The crystal structure of A is reported at sixteen temperatures between 30 and 375 K, all of which are in the monoclinic space group P21/n with Z’ = 0.5. Changes in the crystallographic cell parameters, bond lengths, distortion parameters and intra and intermolecular interactions between 375 K and 30 K are discussed. Continuous irradiation with a 670 nm, 5 mW CW laser at 30 K enabled a light induced excited spin state trapping (LIESST) metastable high spin structure, HS*, to be obtained.

1-(3-Ammoniopropyl)-4-[(E)-2-(3,4-dichlorophenyl)vinyl]pyridinium diperchlorate was synthesized and its crystal structure was studied by X-ray diffraction. The photochemical properties of this compound and its complexation with a 18-crown-6-containing derivative of 4-styrylpyridine were studied by electronic spectroscopy. These compounds form a supramolecular complex (logK = 3.89 in MeCN at an ionic strength of 0.01 mol L–1), in which the styryl chromophores are arranged one above another due to stacking interactions. The complexation activates the cross [2+2] photocycloaddition of styrylpyridine derivatives. A procedure is proposed for the global analysis of spectrophotometric data, which takes into account the effect of the ionic strength of the solution on the observed equilibrium reaction.

The work in this report deals with seven compounds of composition {[CuII(dmpn)2]3[FeIII(CN)6]2·6H2O}n (1), {[CuII(dmpn)2]3[CoIII(CN)6]2·6H2O}n (2), {[CuII(dmpn)2]3[CrIII(CN)6]2·4H2O}n (3), {[CuII(dmpn)][NiII(CN)4]·H2O}n (4), [{CuII(dmpn)2Cl}{CuII(dmpn)2(H2O)}][AgI(CN)2]Cl2 (5), [(CuII(dmpn)2(dicyanamide)2] (6) and [(NiII(dmpn)2(dicyanamide)2] (7), where dmpn = 2,2-dimethyl-1,3-diaminopropane. Syntheses, characterization and crystal structures of 1–7 along with variable-temperature (2–300 K) magnetic properties of 1 and 3 are described. Compounds 1–4 are cyanide-bridged two-dimensional coordination polymers. Twelve metal-membered ring is formed in 1–3, while both four and eight metal-membered rings are formed in 4. On the other hand, dicyanoargentate(I) in 5 is noncoordinated and dicyanamide in 6 and 7 behaves as monodentate terminal ligand. The coordination polymers in 1–4 and the discrete systems in 5–7 are self-assembled by hydrogen bonding interactions to generate overall three-dimensional supramolecular topologies. A novel structural aspect, two-dimensional network containing both four and eight metal-membered rings, has been observed in the copper(II)–tetracyanonickelate(II) compound 4. Magnetic studies reveal ferromagnetic interaction between CuII and CrIII in 3. In addition, spin–orbit coupling of low-spin FeIII or weak antiferromagnetic interaction along with intermolecular antiferromagnetic interactions which exist between CuII and FeIII are present in 1.

This paper presents the synthesis, crystal structure, catechol oxidase activity and electrospray ionization mass spectra (ESI-MS positive) of a mixed-valence CoIIICoII compound [CoIIICoIIL(N3)3]· 0.5CH3CN·0.27H2O (1) derived from the Robson type tetraiminodiphenolate macrocyclic ligand H2L, which is the [2 + 2] condensation product of 2,6-diformyl-4-methylphenol and 2,2-dimethyl-1,3-diaminopropane. Compound 1 crystallizes in the monoclinic P21/n space group. The structure consists of two independent units of diphenoxo-bridged CoIIICoII moieties where the CoIII center is hexacoordinated (distorted octahedral) having O(phenoxo)2N(imine)2N(azide)2 environment, while CoII center is pentacoordinated (distorted square pyramidal) having O(phenoxo)2N(imine)2N(azide) environment. Catechol oxidase activity of 1 has been investigated using 3,5-di-tert-butylcatechol (3,5-DTBCH2) as the substrate, revealing that it is an active catalyst with Kcat value 114.24 h–1. Electrospray ionization mass spectra (ESI-MS positive) of 1 and 1 + 3,5-DTBCH2 in acetonitrile have been recorded. No complex⋯substrate aggregate in the spectrum of 1 + 3,5-DTBCH2 has been identified. However, interestingly, two hydrogen bonded metal complex⋯solvent aggregates [{CoII(LH2)(N3)}⋯(CH3CN)]+ and [{CoIII(LH2)(N3)2}⋯(CH3CN)]+ have been identified in the spectrum of 1. Catecholase activity has also been studied with pyrocatechol and tetrachlorocatechol (TCCH2) as substrates. While no activity has been found with TCCH2, weak activity has been observed with pyrocatechol.

The synthesis of three 9-diarylamino-substituted acridines is reported. The compounds of the donor–acceptor type – N,N-diphenylacridin-9-amine (1), 2,7-dimethyl-N,N-bis(4-methylphenyl)acridin-9-amine (2), and 2,7-bis(1-methyl-1-phenylethyl)-N,N-bis[4-(1-methyl-1-phenylethyl)phenyl]acridin-9-amine (3) were characterized by IR, 1H and 13C NMR, mass-spectral and elemental analysis. The crystal structures of compounds 1–3 and their protonated forms were determined by X-ray diffraction analysis. The absorption and fluorescence spectra were measured in various solvents. Solvatochromic shifts and dependence of the fluorescence quantum yields on the solvent polarity and protonation suggest the use of these compounds as chemical sensors. An example of a sensor material based on compound 2 is presented. Density functional theory calculations of the structures and time-dependent density functional theory calculations of the gas-phase excitation and emission energies of 1 were performed at the PBE0/SVP level of theory.

The aluminum(I) compound NacNacAl (1) reacts with diphenyl disulfide and diethyl sulfide to form the respective four-coordinate bis(phenyl sulfide) complex NacNacAl(SPh)2 (2) and alkyl thiolate aluminum complex NacNacAlEt(SEt) (3). As well, reaction of 1 with tetraphenyl diphosphine furnishes the bis(diphenyl phosphido) complex NacNacAl(PPh2)2 (4). Production of 3 and 4 are the first examples of C(sp(3))-S and R2P-PR2 activation by a main-group element complex. All three complexes were characterized by multinuclear NMR spectroscopy and X-ray crystal structure analysis. Furthermore, a variable-temperature NMR spectroscopic study was undertaken on 4 to study its dynamic behavior in solution.

The triple decker dinuclear Cr(ii) salt [(η5-C 5Me5)Cr(μ2:η5-P 5)Cr(η5-C5Me5)]+ (SbF6)- has been structurally characterised by multiple temperature X-ray diffraction experiments from 290 K to 12 K. This material shows changes in its structural features which correlate with its magnetic response, including a structural transition with a change of symmetry from the orthorhombic space group Fddd to the monoclinic I2/a at ∼160 K and an abrupt rearrangement of electron density at ∼23 K This journal is © The Royal Society of Chemistry.

The new compounds [M(η-C7H8)L2Cl2](M = Zr, L = PMe31; M = Hf, L = PMe32; M = Zr, L = PMe2Ph 3; M = Hf, L = PMe2Ph 4; M = Zr, L = PMePh25) have been synthesised by reduction of MCl4 using sodium amalgam in the presence of the tertiary phosphine and cycloheptatriene. Lithium indenide reacts with the triene compounds to give [M(η-C7H7)(η5-C9H7)](M = Zr 6 or Hf 8) which react with trimethylphosphine or 1,2-bis(dimethylphosphino)ethane (dmpe) to form [M(η-C7H7)(η5-C9H7)(PMe3)](M = Zr 7 or Hf 9) and [{Hf(η-C7H7)(η5-C9H7)}2(µ-dmpe)]10 respectively. Treatment of 1 or 2 with sodium cyclopentadienide gives [M(η-C5H5)2{η2-1,2-(or -3,4-) C7H8}(PMe3)][M = Zr 11 or Hf 12). The X-ray crystal structures of 1, 10 and [Zr(η-C5H5)2(η2-3,4-C7H8)(PMe3)]11a have been determined.

Ortho- and para-fluorophenyl 1,2,3,5-dithiadiazolyl (DTDA) radicals were synthesised and structurally characterised in the solid-state. This enables the well-known molecular origins of the electrical conductivity properties in this series of molecules to be studied, specifically S···S conduction pathways. This work includes the first report of monofluorophenyl DTDA crystal structures, filling an important gap in the literature to complement the many structural records of di-, tri-, tetra- and pentafluorophenyl DTDA analogues. This report also overturns previous thinking that monofluoro-substitution in these phenyl DTDA compounds does not influence the supramolecular chemistry; indeed, we demonstrate that singular fluorine is indeed structurally (and therefore property) directing as per their di-, tri-, tetra- and pentafluorinated relatives. In particular, the S···S and S···N interactions that control the electrical conductivity in DTDAs are distinct in these mono-fluorophenyl DTDAs. Hirshfeld surfaces were employed to clarify the nature and extent of these interactions. Their ability to exploit the very sensitive features of surface topologies in order to identify S···S and S···N intermolecular interactions is important since these interactions are much more subtle than, say, classical hydrogen-bonding. Furthermore, we demonstrate that Hirshfeld surfaces can classify the entire set of intermolecular interactions for a compound via a fingerprint plot. This affords the instant recognition of a given type of DTDA supramolecular network. In turn, barcodes can be generated from these fingerprint plots which quantify the percentage contribution of atom pairs that are involved in intermolecular interactions within DTDAs. The predictive potential of such classification within the field of molecular design is shown via a comparison of our fingerprint plots with those of DTDAs from previous studies.

Novel germanium containing triflates were prepared from the reactions of trifluoromethanesulfonic acid with tetraphenylgermane (1) and digermanes (Ph3GeGeMe3 (4), Ph3GeGePh3 (5)). The improved procedures for synthesis of known organogermanium compounds (Ph4Ge (1), Ph3GeCl (2), Ph3GeGeMe3 (4), Ph3GeGePh3 (5)) were also presented. The crystal structure of Ph3GeOTf (6) and Ph2Ge(OTf)Ge(OTf)Ph2 (7) was studied by X-ray analysis. In 7 each germanium atom is pentacoordinated due to intramolecular interaction with O atom of the neighboring triflate group.

Crystals of molecular complexes of dimethyl sulfoxide with trichloromethane (chloroform), (CH3)2SO·2CHCl3, (I), and dichloromethane, (CH3)2SO·CH2Cl2, (II), have been grownin situ. In both compounds, the components are linked together by (Cl)C—H...O interactions. The dimethyl sulfoxide molecules in (I) are bound into chains by C—H...O interactions. In (II), pairs of the components form centrosymmetric rings, linked into a three-dimensional network by C—H...O contacts and dipole–dipole interactions between dimethyl sulfoxide molecules.

Several alkali metal hydroxoantimonates, K 2 [Sb(O)(OH) 5 ], Na[Sb(OH) 6 ], Cs[Sb(OH) 6 ] and Cs 2 [Sb 2 (μ-O) 2 (OH) 8 ] were isolated from aqueous solutions and characterized by single crystal and powder X-ray diffraction studies and by FTIR and thermal analysis. Crystal structures involving [Sb(O)(OH) 5 ] 2− were never anticipated before, and this is also the first disclosure of a dinuclear antimonate [Sb 2 (μ-O) 2 (OH) 8 ] 2− . Aqueous antimonate solutions of different pH were studied by high resolution electrospray mass spectrometry showing pH indifferent spectra and predominance of the mono and dinuclear antimonate species at pH 4–10.

The synthesis, chemical and structural characterization of a series of pentamethylcyclopentadienyl (Cp*) tantalum imido complexes and aryloxide derivatives are presented. Specifically, the imido complexes Cp*Ta(N t Bu)(CH2 R)2, where R = Ph [dibenzyl(tert-butylamido) (η5-pentamethylcyclopentadienyl)tantalum(IV) (1)], Me2Ph [tert-butylamido)bis(2-methyl-2-phenylpropyl) (η5-pentamethylcyclopentadienyl)tantalum(IV) (2)], CMe3 [(tert-butylamido)bis(2,2-dimethylpropyl) (η5-pentamethylcyclopentadienyl)tantalum(IV) (3)], are reported. The crystal structure of (3) reveals α-agostic interactions with the Ta atom. The resulting increase in the tantalum core coordination improves electronic stability. As such it does not react with pentafluorophenol, in contrast to the other two reported imido complexes [(1) and (2)]. Addition of C6F5OH to (1) yields a dimeric aryl-oxide derivative, [Cp*Ta(CH2Ph)(OC6H5)(μ-O)]2 [di-μ-oxido-bis[benzyl(pentafluorophenolato) (η5-pentamethylcyclopentadienyl)tantalum(V)] (4)]. Its crystal structure reveals long Ta—O(C6H5) bonds but short oxo-bridging Ta—O bonds. This is explained by accounting for the fierce electronic competition for the vacant d π orbitals of the electrophilic TaV centre. Steric congestion around each metal is alleviated by a large twist angle (77.1°) between the benzyl and pentafluorophenyl ligands and the ordering of each of these groups into stacked pairs. The imido complex (2) reacts with C6F5OH to produce a mixture of Cp*Ta(OC6F5)4 [tetrakis(pentafluorophenolato)(η5-pentamethylcyclopentadienyl)tantalum(V) (5)] and [Cp*Ta(OC6F5)2(μ-O)]2 [di-μ-oxido-bis[bis(pentafluorophenolato)(η5-pentamethylcyclopentadienyl)tantalum(V)] (6)]. Steric congestion is offset in both cases by the twisting of its pentafluorophenyl ligands. Particularly strong electronic competition for the empty d π metal orbitals in (6) is reflected in its bond geometry, and owes itself to the more numerous electron-withdrawing pentafluorophenyl ligands. The balance of steric and electronic factors affecting the reactivity of Cp* tantalum imido based complexes with pentafluorophenol is therefore addressed.

A series of 4-styrylpyridine hydroperchlorates were synthesized, and the [2+2] autophotocycloaddition (PCA) reaction in their polycrystalline films and single crystals resulting in the centrosymmetric rctt isomers of 1,2,3,4-tetrasubstituted cyclobutanes was investigated. Unlike neutral styrylpyridines, their protonated forms are better preorganized for the solid-state PCA reaction. According to the X-ray diffraction data, the cations of these compounds, like related styryl dyes, are mainly stacked in crystals in a head-to-head or head-to-tail fashion with equal probability. Only in the latter type of stacks, the PCA reaction is feasible as a single-crystal-to-single-crystal transformation. The crystal packing is stabilized by hydrogen bonds between organic cations and perchlorate anions, as well as by other weak directional interactions, for example, by S…S interactions, thus preventing the atomic displacements in the course of PCA. The completion of the PCA reaction in single crystals without their degradation was observed only for 15-crown-5-containing 4-styrylpyridine hydroperchlorate. The crystals of the latter compound are stabilized not by hydrogen bonds between the cations and anions but by N+-H…O(macrocycle) hydrogen bonds resulting in the formation of head-to-tail stacked dimers. In the crystals, these dimers are surrounded by a soft shell formed by rotationally and translationally mobile anions and benzene solvent molecules, as well as by conformationally flexible crown-ether moieties of adjacent dimer pairs. This leads to a decrease in the steric strain that occurs in the crystals in the course of PCA and prevents the degradation of single crystals. The PCA reaction is accompanied by the reduction in the crystal symmetry due to the doubling of the unit cell.

Syntheses, characterization and crystal structures of heterotetranuclear [2 × 1 + 1 × 2] co-crystals [{CuIILZnII(H2O)2}{CuIIL}2](ClO4)2 (1) and [{CuIILCdII(H2O)2(CH3CN)}{CuIIL}2](ClO4)2 (2), dinuclear compound [CuIILHgII(CH2COCH3)](ClO4) (3) and heterotrinuclear [2 × 1 + 1 × 1] co-crystal [{CuIILAgI(H2O)}{CuIIL}](ClO4) (4) derived from N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L) are reported herein. Compounds 3 and 4 crystallize in the orthorhombic Pbca and monoclinic P21/c systems, respectively, while the space group of compounds 1 and 2 is monoclinic C2/c. The structure of 3 consists of a monophenoxo-bridged CuIIHgII dinuclear core in which the mercury(II) centre is dicoordinated by the bridging phenoxo oxygen atom and the CH2 carbon atom of the mono-deprotonated acetone anion. The coordination environment of HgII in this compound is almost linear. In the CuII2AgI compound 4, one diphenoxo-bridged [CuIILAgI(H2O)]+ cation is co-crystallized with one mononuclear [CuIIL] moieties. On the other hand, the structures of the CuII3MII compounds 1 (M = Zn) and 2 (M = Cd) consist of one diphenoxo-bridged dinuclear CuIIMII unit and two mononuclear [CuIIL] moiety; the composition of the dinuclear unit being [CuIILZnII(H2O)2]2+ and [CuIILCdII(H2O)2(CH3CN)]2+ for 1 and 2, respectively. The AgI (in 4), ZnII (in 1) and CdII (in 2) ions in the diphenoxo-bridged dinuclear cores are tri-, tetra- and heptacoordinated, respectively. The metal ions are coordinated to two bridging phenoxo oxygen atoms, with the silver(I) and zinc(II) centres being additionally coordinated to one and two water molecules, respectively. While in the case of cadmium(II), the additional five coordination positions are occupied by two ethoxy oxygen atoms, two water oxygen atoms and one acetonitrile nitrogen atom. The coordination environment of silver(I) in 4 is pyramidal with a scalene O3 triangle as the base, whereas those of zinc(II) and cadmium(II) in 1 and 2 are distorted tetrahedral and distorted pentagonal bipyramidal, respectively. The coordinated water molecule in 4 and each of the two coordinated water molecules in 1 and 2 are encapsulated into the O4 compartment of a [CuIIL] moiety resulting in the [2 × 1 + 1 × 1] (for 4) or [2 × 1 + 1 × 2] (for 1 and 2) cocrystallization and self-assemblies. Clearly, the encapsulation of the coordinated water molecule(s) is the governing force for the formation of dinuclear-mononuclear co-crystals in 1, 2 and 4. In addition all four compounds 1–4 have π–π stacking interactions which form dimers between pairs of adjacent molecules in the structure of 3 consisting of CuIIHgII dimers, while one-dimensional stacks are formed in the CuII3ZnII (1), CuII3CdII (2) and CuII2AgI (4) complexes. The compositions of the title compounds are compared with the related systems derived from the same ligand. The [2 × 1 + 1 × 1] co-crystal, 4, is a new type of system in terms of the number of components. Again, in spite of the tri-, tetra- and hepta-coordinated nature of the second metal ion in the dinuclear cores, co-crystallization in 1, 2 and 4, respectively, are new observations. The accommodation/coordination of varieties of metal ions by the O4 compartment of H2L has also been highlighted in the present investigation.

The syntheses, characterization and crystal structures of four copper(II)/nickel(II)⋯uranyl(VI) self-assemblies of composition [{NiIIL1}2·{(UVIO2)(NO3)2(H2O)2}] (1), [{CuIIL2}2·{(UVIO2)(NO3)2(H2O)2}]·0.68H2O (2), [{NiIIL2}2·{(UVIO2)(NO3)2(H2O)2}] (3) and [{CuIIL3}·{(UVIO2)(NO3)2(H2O)2}]n (4) are described in this investigation (H2L1, H2L2 and H2L3 are the Schiff base ligands obtained on condensing 3-ethoxysalicylaldehyde with ethylenediamine, o-phenylenediamine and trans-1,2-diaminocyclohexane, respectively). Compounds 1 and 4 crystallized in the monoclinic P21/n and C2/c space groups, respectively, while compounds 2 and 3 crystallized in the triclinic space group P. Two water molecules of the [(UVIO2)(NO3)2(H2O)2] moiety in 1–4, have a linear H2O–U–OH2 arrangement. Each of these two water molecules in 1–3 interacts with the O(phenoxo)2O(ethoxy)2 compartment of a mononuclear copper(II) or nickel(II) moiety due to the formation of bifurcated hydrogen bonds between each of the two water hydrogen atoms and a pair of one phenoxo and one ethoxy oxygen atoms resulting in the interlinking of the two mononuclear 3d units by the [(UVIO2)(NO3)2(H2O)2] synthon and therefore these three compounds may be considered as supramolecular dimers. Compounds 1–3 are also two component [1 × 2 + 1 × 1] co-crystals consisting of two mononuclear copper(II) or nickel(II) units and one [(UVIO2)(NO3)2(H2O)2] moiety. On the other hand, in 4, two water molecules, from two different [(UVIO2)(NO3)2(H2O)2] moieties, interact with one O(phenoxo)2O(ethoxy)2 compartment resulting in the formation of a self-assembled one-dimensional topology. Again, since one mononuclear copper(II) unit and one [(UVIO2)(NO3)2(H2O)2] moiety exist in a single crystal in 4, this compound is a two component [1 × 1 + 1 × 1] co-crystal. The outcomes of the present study utilize [(UVIO2)(NO3)2(H2O)2] synthon to derive 3d⋯5f co-crystals, provide the first observation of the interaction of two water molecules with one O(phenoxo)2O(ethoxy)2 compartment, demonstrate the formation of supramolecular dimers and show the first example of a one-dimensional self-assembly resulting from water⋯O4 compartment hydrogen bonds, and the first example of [1 × 2 + 1 × 1] co-crystals in 3-ethoxysalicylaldehyde-diamine ligand system.

Reaction of N-(2′-hydroxyphenyl)-4-R-benzaldimines (L-R, R = OCH3, CH3, H, Cl and NO2) with [Os(PPh3)3Br2] in refluxing 2-methoxyethanol in the presence of triethylamine affords two families of organoosmium complexes (1-R and 2-R). In both 1-R and 2-R complexes a benzaldimine ligand is coordinated to the metal center as tridentate C,N,O-donor. In the 1-R complexes, a bidentate N,O-donor imionsemiquinonate ligand, derived from the hydrolysis of another benzaldimine, and a PPh3 ligand are also coordinated to osmium. In the 2-R complexes, a carbonyl, derived from decarbonylation of 4-R-benzaldehyde (derived from the same hydrolysis stated above), and two PPh3 ligands take up the remaining coordination sites on osmium. Structures of the 1-Cl and 2-OCH3 complexes have been determined by X-ray crystallography. All the 1-R and 2-R complexes are diamagnetic, and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry on the 1-R complexes shows a reversible Os(III)–Os(IV) oxidation within 0.47–0.67 V (vs SCE), followed by an irreversible oxidation of the imionsemiquinonate ligand within 1.10–1.36 V. An irreversible Os(III)–Os(II) reduction is also displayed by the 1-R complexes within −1.02 to −1.14 V. Cyclic voltammetry on the 2-R complexes shows a reversible Os(II)–Os(III) oxidation within 0.29–0.51 V, followed by a quasi-reversible oxidation within 1.04–1.29 V, and an irreversible reduction of the coordinated benzaldimine ligand within −1.16 to −1.31 V.

Syntheses, characterization and crystal structures of four designed host-guest compounds of the compositions [{Cu II L 1 } 2 ⊂(H 3 N(ethylene)NH 3 )](NO 3 ) 2 (1), [{Cu II L 1 } 2 ⊂(H 3 N-(propylene)NH 3 )](NO 3 ) 2 (2), [{Cu II L 1 } 2 ⊂(H 3 N(butylene)-NH 3 )](NO 3 ) 2 (3) and [{Cu II L 2 } 2 ⊂(H 3 N(ethylene)NH 3 )](NO 3 ) 2 (4) are described in this investigation [H 2 L 1 = N,N'-ethylenebis(3-methoxysalicylaldimine); H 2 L 2 = N,N'-ethylenebis(3-ethoxysalicylaldimine); ethylene = (CH 2 ) 2 ; propylene = (CH 2 ) 3 ; butylene = (CH 2 ) 4 ]. Compounds 2 and 3 crystallize in the orthorhombic Pcab and monoclinic C2/c systems, respectively, while the space group of compounds 1 and 4 is triclinic Pi. In all of these four compounds 1-4, the two + NH 3 sites of the [H 3 N(CH 2 ) n NH 3 ] 2+ dication (n = 2-4) behave as guests in the 0 4 compartment of two [Cu II L 1 /L 2 ] moieties through bifurcated N-H···O(phenoxo) and NH···O(methoxy/ethoxy) hydrogen-bonding interactions. Evidently, two mononuclear copper(II) moieties are interlinked by bridging supramolecular synthons, resulting in the formation of a supramolecular dimer in the title compounds. From the extent of displacement of the N atoms of [H 3 N(CH 2 ) n- NH 3 ] 2+ from the least-squares O(phenoxo) 2 O(methoxy/ ethoxy) 2 plane, it is clear that [Cu II L 1 ] is a better host than [Cu II L 2 ] for the diprotonated diamine guests. Comparison of the inclusion of water and diprotonated diamines in [Cu II L 1 / L 2 ] is also described in the present investigation. Interestingly, of the two guest species, water and diprotonated diamines, [Cu II L 2 ] prefers the former and [Cu II L 1 ] prefers the latter.

The crystals of five new low-melting co-crystals of chloroform with organic solvents had been grown in situ and their crystal structures were determined by single-crystal X-ray crystallography. Various aspects of the molecular packing and the role of Cl⋯Cl interactions in these compounds are discussed.

The crystal structures of six new partially fluorinated aryl 1,2,3,5-dithiadiazolyls [ArCNSSN]˙ are reported [Ar = 2,6-F2C6H3 (4); Ar = 3,4-F2C6H3 (5); Ar = 3,5-F2C6H3 (6); Ar = 2,3,6-F3C6H2 (9); Ar = 2,4,6-F3C6H2 (11); and Ar = 3,4,5-F3C6H2 (12)] and compared with three previously reported structures in this series (Ar = 2,3-F2C6H3 (1); Ar = 2,5-F2C6H3 (3); Ar = 2,3,4-F3C6H2 (7)]. Radical 4 is shown to be polymorphic. Molecular electrostatic potential maps have been used to rationalise these structures. These reveal that whilst single F atoms appear to have little structure-directing influence, combinations of an ortho-F on the phenyl ring and a heterocyclic ring N, or several F atoms located in mutually ortho positions with respect to each other, generate significant regions of negative charge which have a substantial structure-directing influence.

Syntheses, characterization and structures of heterodinuclear compound [CuIIL1BiIII(NO3)3] (1), sandwich type heterotrinuclear compound [(CuIIL1)2BaII(NO3)2]·0.2H2O (2), heterotetranuclear compound [{CuIIL1PbII(µ-NO3)(NO3)}2] (3) and heterohexanuclear [2 × 1 + 1 × 4] cocrystal [(UVIO2)2(µ-H2O)2(NO3)4]·4[CuIIL1⊂(H2O)] (4) are described in this investigation (H2L1 = N,N′-ethylenebis(3-ethoxysalicylaldiimine)). Compounds 1 and 4 crystallize in orthorhombic P212121 and triclinic Pī systems, respectively, while the space group of compounds 2 and 3 is monoclinic P21/c. The structure of 1 consists of a diphenoxo-bridged CuIIBiIII dinuclear core containing three chelating nitrates and a 10-coordinate bismuth(III) centre. The dinuclear cores are self-assembled to two dimensions through intermolecular nitrate oxygen⋯copper(II) semicoordination and weak C–H⋯O hydrogen bonds. Compound 2 is a double-decker CuIIBaIICuII system in which a barium(II) ion is sandwiched between two mononuclear [CuIIL1] moieties. The barium(II) centre is 11-coordinate, four phenoxo and four ethoxy oxygen atoms and one chelating and one monodentate nitrate ions. Compound 3 is a tetranuclear system (dimer of two dinuclear moieties) in which one nitrate is chelating, while the second nitrate behaves as both a chelating and bridging ligand. The lead(II) centre is 9-coordinate in this compound. Compound 4 is a [2 × 1 + 1 × 4] cocrystal of one diaqua-bridged diuranyl(VI) moiety, containing two chelating nitrates and 8-coordinated hexagonal bipyramidal uranium(VI) centres and four inclusion species [CuIIL1⊂(H2O)]. The governing factor for the self-assembled cocrystallization in 4 are the C–H⋯·π and C–H⋯O hydrogen bonds. The compounds reported in this investigation and other heteronuclear systems derived from N,N′-ethylenebis(3-ethoxysalicylaldiimine) indicate that this ligand system is an important example which gives rise to structurally diverse heteronuclear compounds. In addition to the structural diversity, the structural resemblance of bismuth(III) with lanthanides(III) and utilization of noncovalent interactions to form self-assembly and cocrystals are the major outcomes of the present investigations.

A simple N,N′-diaryl urea derivative was found to form four different anhydrous crystal forms (I−IV°), which can be crystallized in pure form by several techniques from solution as well as from the melt. These polymorphs were characterized by thermomicroscopy, differential scanning calorimetry, Fourier-transform infrared spectroscopy and single crystal and powder X-ray diffraction. The polymorphs were found to be purely monotropically related with large differences in their heats of fusion (11.1 kJ mol−1 for the least stable form I, 34.5 kJ mol−1 for the most stable form IV°). The crystal structures of all forms show the same conformer for forms I−III and a second conformer in form IV°. However, the hydrogen bonding motifs in all of the polymorphs are the same and thus the compound can be seen as a model for the importance of the entire crystal packing arrangement to the overall energy and stability of the crystal form, as opposed to just a few dominant interactions.

The syntheses and structures of a [2×1+1×2] cocrystal [{CuIIL1NaI(H2O)2}{CuIIL1}2](NO3) (1) and [3×1+5×1] cocrystal [{(CuIIL1)2KI}(NO3)]·[{(CuIIL1)3KI2(μ-NO3)}(NO3)]·0.2H2O (2) derived from the hexadentate Schiff base compartmental ligand N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L1) are described. Compounds 1 and 2 crystallize in triclinic P1 and monoclinic P21/c systems, respectively. The structure of 1 consists of the [CuIIL1ΝaI(H2O)3]+ cation and two mononuclear [CuIIL1] moieties. In the dinuclear [CuIIL1ΝaI(H2O)3]+ cation, the metal centers are doubly bridged by the two phenolate oxygen atoms. Each of the two coordinated water molecules of the dinuclear unit is encapsulated in the O4 cavities of the two mononuclear [CuIIL1] moieties resulting in the formation of a [2×1+1×2] cocrystal. In compound 2, one trinuclear double-decker system [{(CuIIL1)2KI}(NO3)] and one pentanuclear triple-decker system [{(CuIIL1)3KI2(μ-NO3)}(NO3)] are cocrystallized. Evidently, compound 2 is a [3×1+5×1] cocrystal. Stru...

Neutral crown-containing and model styrylheterocycles of the 4-pyridine, 4-quinoline, and 9-acridine series were synthesized under acidic catalysis. The influence of the molecular geometry of these compounds, as well as of related styrylheterocycles of the 2-benzothiazole and benzobisthiazole series, on the formation of a particular crystal packing was investigated based on X-ray diffraction data. An extension of the conjugation system in the molecules can result in the sandwich-herringbone packing motif as the only one of the three packing motifs most typical of this class of compounds. This packing provides the preorganization of the structural units for the [2+2] photocycloaddition reaction. The styrylheterocycle containing the bulky 9-acridine moiety is nonplanar due to strong intramolecular steric interactions. The packing motifs formed by nonplanar molecules do not provide the preorganization of the molecules for the [2+2] photocycloaddition. The introduction of the crown ether moiety into the benzene ring of the styrylheterocycle can decrease the predictability of the packing motif as a result of the inclusion of solvent molecules capable of hydrogen bonding with the heteroatoms of the macrocycle in the crystal structure.

A variety of crystal packing motifs for styryl dye Et-Py+-CH=CH-C6H4OMe ClO4− crystallized from solvent mixtures containing different low-molecular aromatic compounds was investigated by X-ray diffraction method. The presence of some of these aromatic compounds was found to affect the mode of the aggregation of the dye structural units in the course of crystal nucleation, regardless of whether these compounds are involved in the growing crystal. The aromatic molecules containing two proton-donating groups can be involved in the crystal packing of the dye as a solvate that forms weak hydrogen bonds with perchlorate anions or other solvate molecules. The aromatic molecules without functional groups (except for benzene) are not involved in the growing crystal as additional building blocks. The syn-head-to-tail stacking with contiguous and antiparallel arrangement of the ethylene bonds is the main packing motif of dye cations in crystals of unsolvated and solvated forms. This is favorable for accomplishing the [2+2]-photocycloaddition (PCA) reaction resulting in the centrosymmetric rctt-isomer of a cyclobutane derivative. In the solvated forms of the crystals, the solvate molecules and perchlorate anions form loose layers between the cation stacks. These layers are capable of leveling internal stresses caused by the PCA reaction, thus promoting this reaction as a single-crystal-to-single-crystal transformation. Other conditions for the PCA reaction to proceed without single crystal degradation are (1) retention of the initial crystal symmetry in the course of the PCA and (2) stack separation into dimeric pairs with d1 < 4.2 A < d2, where d1 and d2 are the distances between the ethylene bonds within the dimeric pairs and between them, respectively. The regularities found for the crystal packing and the PCA reaction in styryl dye single crystals may be used to design information recording and storage cells.

Reaction of copper(II) acetate, lanthanium(III) or gadolinium(III) nitrate (1/5 equiv.) with pyrazinohydroxamic acid (H2Pyzha) in DMF led to a series of new heterobimetallic 15-metallacrown-5 complexes. In a MeOH/H2O solution the complexes exist as molecular unassociated metallacrowns. In solid state their structures are more complicated as it has been confirmed by X-ray analysis: discrete molecular metallacrowns [Gd(NO3)2{Cu(pyzha)}5(DMF)4(NO3)] · 0.5C6H6 · H2O (1), [Gd(NO3)2{Cu(pyzha)}5(DMF)5](NO3) · 1.5DMF · 0.5H2O (2), [La(NO3)2{Cu(pyzha)}5(DMF)5]NO3 · 1.5DMF · 2C6H6 (3) are solvates, whereas compound [{La(NO3)2{Cu(pyzha)}5(DMF)5}2(μ2-NO3)](NO3) · 3DMF (4) is a dimer, where μ-bridged nitrate links two copper centres of the adjacent metallamacrocycles. Complex [Gd(NO3)2{Cu(pyzha)}5(DMF)2(H2O)(NO3)] · CH2Cl2 · DMF (5) self-associates into a polymer chain by means of one pyrazine moiety and the copper ring atom. Reaction of the molecular metallacrowns with excess of inorganic salts CdBr2 or Cu(OAc)2 proceeds as anion methathesis process affording heteroanionic metallacrowns: molecular [Gd(NO3)2{Cu(pyzha)}5(DMF)5] [Gd(NO3)2{Cu(pyzha)}5(DMF)4(H2O)][CdBr4] · 1.5DMF (6), and 3D hydrogen bonded polymer [La(μ2-OAc)(H2O)3{Cu(pyzha)}5 (H2O)4(NO3)](NO3) · 4H2O (7).

The novel bidentate ligand, C 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 ) ( 3 ), has been prepared and characterized as its lithium salt LiC 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 ) ( 3 – Li ). Cyclopentadiene HC 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 ) ( 3 – H ) has been obtained from 6,6-diphenylfulvene and 1,2-dimethylimidazoline ( 1 ). In THF- d 8 solution in the presence of 1 , (1-methylimidazoline-2-yl)methyllithium ( 2 ) has been proved to undergo gradual conversion into a dilithium derivative of N 1 -methyl- N 2 -[(1 E ,2 E )-1-methyl-2-(1-methylimidazolidine-2-idene)ethylidene]ethane-1,2-diamine ( 2a ). In a solution, cyclopentadiene 3 – H has been shown to undergo isomerization into 3-{ N -[2-( N -methylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene ( 4 ) and, further, into a mixture of 4 and two rotameric 3-[ N -(2-aminoethyl)- N -methylamino]-1,1-diphenyl-1,2-dihydropentalenes ( 5a ) and ( 5b ). Treatment of the lithium salt 3 – Li with Me 3 SiCl has lead to 3-{ N -[2-( N -trimethylsilylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene ( 6 ) as the dominant component in the reaction mixture. In the latter case the expected Me 3 Si–C 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 ) ( 3 – Si ) was not observed. Stannylation of 3 – Li with 1 equiv. of Me 3 SnCl has resulted in formation of a mixture of Me 3 Sn–C 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 ) ( 3 – Sn ), (Me 3 Sn) 2 -C 5 H 3 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 ) ( 3 – Sn 2 ), and cyclopentadiene 3 – H in a ca . 2:1:1 molar ratio. Monocyclopentadienyl complexes {[η 5 :η 1 -κ N -C 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 )]MCl 3 (M = Ti ( 7 ), Zr ( 8 )) have been prepared starting from the organotin and organolithium compounds 3 – Sn and 3 – Li , respectively. The dynamic behavior of complexes 7 and 8 has been investigated by means of variable-temperature NMR spectroscopy in solutions. The molecular structures of the dihydropentalene 4 , binuclear complex {[η 5 :η 1 -κ N -C 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 )]ZrCl 2 } 2 (μ-Cl) 2 8 , and a coordination dimer of the dilithium salt 2a have been established by X-ray diffraction analysis. In the crystal structure of the 2a -dimer, the shortest known Li–Li contact has been found.

Novel half-sandwich [C 9 H 5 (SiMe 3 ) 2 ]ZrCl 3 ( 3 ) and sandwich [C 9 H 5 (SiMe 3 ) 2 ](C 5 Me 4 R)ZrCl 2 (R = CH 3 ( 1) , CH 2 CH 2 NMe 2 ( 2 )) complexes were prepared and characterized. The reduction of 2 by Mg in THF lead to (η 5 -C 9 H 5 (SiMe 3 ) 2 )[η 5 :η 2 ( C , N )-C 5 Me 4 CH 2 CH 2 N(Me)CH 2 ]ZrH ( 7 ). The structure of 7 was proved by NMR spectroscopy data. Hydrolysis of 2 resulted in the binuclear complex ([C 5 Me 4 CH 2 CH 2 NMe 2 ]ZrCl 2 ) 2 O ( 6 ). The crystal structures of 1 and 6 were established by X-ray diffraction analysis.

The crystal packing of a number of styryl dyes of the pyridine series is analyzed. The structures of three dyes and three [2 + 2] photocycloaddition (PCA) products, 1,2,3,4-tetrasubstituted cyclobutanes, obtained in single crystals are determined by X-ray diffraction. Stacks of planar organic cations are characteristic of styryl dye packings. The proceeding of the PCA reaction as a single crystal-to-single crystal transformation in the syn head-to-head stacks is in principle impossible. The syn head-to-tail stacking packings are favorable for the PCA reactions resulting in the centrosymmetric rctt isomers of cyclobutane. The stacking packings, in which molecules are related by the twofold axes (the anti arrangement of molecules), are also favorable for PCA in single crystals. In this case, the products are the rtct isomers of cyclobutane. The presence of the I− counterions in a packing is a factor impeding the PCA reaction, because the secondary I…H-C bonds increase the rigidity of the crystal lattice. The conditions necessary for proceeding the PCA reactions in styryl dyes as single crystal-to-single crystal processes are as follows: (1) the stacks split into pairs of organic cations (dimers) with the d distances within 4.2 A in a dimer and d exceeding 4.2 A between the dimers; and (2) the dimers are surrounded by flexible shells consisting of anions, solvate molecules, or flexible moieties of the organic cations themselves.

The structural ferroelectric phase transition in 2-aminopyridine dihydrogen phosphate (2APP) has been studied by single crystal and powder X-ray diffraction between room temperature and 16 K. It has been shown that α-aminopyridine dihydrogen phosphate (α-2APP) undergoes a transition from the centrosymmetric space group C2/c in the paraelectric phase to the polar space group Cc in the ferroelectric phase. This is a second-order phase transition associated with ordering of protons in short O-H···O hydrogen bonds. This system is found to exhibit rich polymorphism: depending on crystallization conditions, three anhydrate forms and one monohydrate can be isolated. 2APP hydrate and γ-2APP have been identified for the first time, and their structures have been solved from single crystal diffraction data.

Novel substituted 2-[(2-hydroxyethyl)]aminophenols, MeN(CHR1CR2R3OH)(C6H4-o-OH) (2–5), were synthesized by the reaction of 2-methylaminophenol with corresponding oxiranes. Titano-spiro-bis(ocanes) [MeN(CHR1CR2R3O)(C6H4-o-O)]2Ti 6–9 (2, 6, R1 = H, R2 = R3 = Me; 3, 7, R1 = R2 = Ph (treo-), R3 = H; 4, 8, R1 = Ph, R2 = R3 = H; 5, 9, R1 = R2 = H, R3 = Ph) based on [ONO]-ligands have been synthesized. The obtained compounds were characterized by 1H and 13C NMR spectroscopy and elemental analysis data. The complex [Ti(μ2-O){O-o-C6H4}{μ2-CMe2CH2}NMe]6 (10) was obtained by controlled hydrolysis of 6. Molecular structure of 10 was determined by X-ray structure analysis.

New alkali metal hydrogen tellurates have been synthesized, and their structures have been determined by X-ray crystallography. Hydrogen tellurates I–VI contain centrosymmetric binuclear anions [Te2O10H4+x](4−x)−, where x=0, 1, 2. Hydrogen tellurates II and VI contain, in addition to the binuclear anion, mononuclear species [TeO6H4]2− and Te(OH)6, respectively. The CNs of alkali metals vary from 8 to 12. In all structures, the hydrogen atoms (of both the hydroxy groups and water molecules) are involved in hydrogen bonding.

The structures of the reaction products of silver nitrate with monoheterotopic tridentate ligands derived from N-alkyl-3,5-bis(3-pyridylmethylene)piperidin-4-one were studied. The aliphatic nitrogen atoms are involved in the coordination, all three nitrogen atoms of the ligands being coordinated to three different silver atoms. In turn, each silver atom is coordinated by two nitrogen atoms of the pyridine ring and one nitrogen atom of the piperidine ring of different ligands. The crystal structures of the complexes are different. Infinite ladder-like chains consisting of 16-membered metallamacrocycles as monomeric building blocks are present in the structure of the N-methyl derivative, whereas two-dimensional 4.82 nets consisting of 16-and 40-membered metallamacrocycles are observed in the crystal structure of the N-benzyl analog.

Novel titanocanes and spirobititanocanes based on 2,6-bis[hydroxy(diphenyl)methyl]pyridine (1a) and 2,6-di(hydroxymethyl)pyridine (1b) – [2,6-C5H3N(CPh2O)2]Ti(O-i-Pr)2 (2a), [2,6-C5H3N(CPh2O)2]2Ti (3a), [2,6-C5H3N(CH2O)2]2Ti (3b), [2,6-C5H3N(CPh2O)2]TiCl2 (4) – as well as the closely related N-phenyl derivative PhN(CH2CH2O)2Ti(Cl)Cp (5) have been synthesized. Complexes 2–5 were characterized by 1H and 13C NMR spectroscopy and elemental analysis data. The molecular structure of 3a was determined by X-ray structure analysis.

A new series of mono- and diphenylsubstituted silatranes and boratranes N(CH2CH2O)2(CHR3CR1R2O)MZ (M = Si, Z = CH2Cl, C CPh, H, OMenth, R1, R2, R3 = H, Ph; M = B, Z = nothing, R1, R2, R3 = H, Ph) have been synthesized. Both transalkoxylation and stepwise modification of a preformed metallatrane skeleton were used. The chloromethyl derivatives N(CH2CH2O)2(CHRCHRO)SiCH2Cl (R = H, Ph) react with tert-BuOK under intramolecular cycle expansion to give 1-tert-butoxy-2-carba-3-oxahomosilatranes N(CH2CH2O)(CH2CH2OCH2)(CHRCHRO)SiOtBu (R = H, Ph). The treatment of boratranes N(CH2CH2O)2(CH2CR1R2O)B (R1,R2 = H, Ph) with triflic acid and trimethylsilyl triflate results in the products of electrophilic attack at the nitrogen atom. The molecular structures of four silatranes and one boratrane bearing phenyl groups in the atrane skeleton were determined by the X-ray structure analysis.

The crystal structures of two cocrystals composed of 4,4′-(fluorene-9,9-di­yl)diphenol (C25H18O2) and 6-methyl-2H-pyridone (C6H7NO) are reported, namely 4,4′-(fluorene-9,9-di­yl)diphenol–6-methyl-2H-pyridone (1/2), C25H18O2·2C6H7NO, (I), and 4,4′-(fluorene-9,9-di­yl)diphenol–6-methyl-2H-pyridone–water (1/3/3), C25H18O2·3C6H7NO·3H2O, (II). In both cocrystals, the mutual orientation between two 6-methyl-2H-pyridone mol­ecules in principle enables photodimerization, yet in both cases no photodimerization occurs. In cocrystal (I) this is probably due to poor orbital overlap, while in the case of cocrystal (II) it is suggested that the lack of reaction is due to the highly complex hydrogen-bonding network that exists in the structure.

A family of bis-terdentate iridium(III) complexes is reported which contain a cyclometalated, N/\C[wedge]N-coordinating 1,3-di(2-pyridyl)benzene derivative. This coordination mode is favored by blocking competitive cyclometalation at the C4 and C6 positions of the ligand. Thus, 1,3-di(2-pyridyl)-4,6-dimethylbenzene (dpyxH) reacts with IrCl3 x 3H2O to generate a dichlorobridged dimer [Ir(dpyx-N,C,N)Cl(mu-Cl)]2, 1. This dimer is cleaved by DMSO to give [Ir(dpyx)(DMSO)Cl2], the X-ray crystal structure of which is reported here, confirming the N/\C/\N coordination mode of dpyx. The dimer 1 can also be cleaved by a variety of other ligands to generate novel classes of mononuclear complexes. These include charge-neutral bis-terdentate complexes of the form [Ir(N/\C/\N)(C/\N/\C)] and [Ir(N/\C/\N)(C/\N/\O)], by reaction of 1 with C/\N/\C-coordinating ligands (e.g., 2,6-diphenylpyridine and derivatives) and C/\N/\O-coordinating ligands (based on 6-phenylpicolinate), respectively. Treatment of 1 with terpyridines leads to dicationic complexes of the type [Ir(N/\C/\N)(N/\N/\N)]2+, while 2-phenylpyridine gives [Ir(dpyx-N/\C/\N)(ppy-C,N)Cl]. All of the charge-neutral complexes are luminescent in fluid solution at room temperature. Assignment of the emission to charge-transfer excited states with significant MLCT character is supported by DFT calculations. In the [Ir(N/\C/\N)(C/\N/\C)] class, fluorination of the C/\N/\C ligand at the phenyl 2' and 4' positions leads to a blue-shift in the emission and to an increase in the quantum yield (lambda(max) = 547 nm, phi = 0.41 in degassed CH(3)CN at 295 K) compared to the nonfluorinated parent complex (lambda(max) = 585 nm, phi = 0.21), as well as to a stabilization of the compound with respect to photodissociation through cleavage of mutually trans Ir-C bonds. [Ir(dpyx-N/\C/\N)(ppy-C,N)Cl] is an exceptionally bright emitter: phi = 0.76, lambda(max) = 508 nm, in CH(3)CN at 295 K. In contrast, the [Ir(N/\C/\N)(C/\N/\O)] complexes are much less emissive, shown to be due to fast nonradiative decay of the excited state, probably involving reversible Ir-O bond cleavage. The [Ir(N/\C/\N)(N/\N/\N)]2+ complexes are very feeble emitters even at 77 K, probably due to the almost exclusively interligand charge-transfer nature of the lowest-energy excited state in these complexes.

The new side-chain functionalized cyclopentadienyl ligand LiC5H4CPh2CH2R (R is 1-methylimidazol-2-yl) as lithium salt 2, the trimethylsilyl derivative Me3SiC5H4CPh2CH2R (3), and the ligand in the CH form (4) were prepared starting from 6,6-diphenylfulvene and 1,2-dimethylimidazole lithiated at the 2-Me group (1) and then characterized. The half-sandwich complexes (η5:η 1-C5H4CPh2CH2R)TiCl3 (5) and (η5:η 1-C5H4CPh2CH2R)ZrCl3 (6) were synthesized. The molecular structure of complex 5 was established by X-ray diffraction. Complexes 5 and 6 exhibit dynamic behavior in solution associated with degenerate interconversion of the pseudo-six-membered metallacycle. For titanium complex 5 in a solvating solvent, a dynamic process due to intramolecular dissociation—coordination of the imidazole fragment was observed.

Reaction of the salt [Rh(PMe3)4]Cl (1) with p-F3C–C6H4–C C–C C–C6H4-p-CF3 (2) in THF gives a mixture of two related neutral π-bound diyne complexes of [Rh(PMe3)3Cl], each having two distinct CF3 resonances of equal intensity in the in situ 19F{1H} NMR spectrum. The ratio of the two products can be varied by varying the stoichiometry of the reagents. On the basis of the spectroscopic data and literature precedent, we propose Rh(PMe3)3(Cl)((1,2-η2)-p-F3C–C6H4–C C–C C–C6H4-p-CF3) (3a) and [Rh(PMe3)3(Cl)]2(μ-(1,2-η2):(1,2-η2)-p-F3C–C6H4–C C–C C–C6H4-p-CF3) (3b) as the most likely structures of the species in solution. However, upon standing overnight, single crystals of the unusual, dinuclear complex [Rh(PMe3)3(Cl)]2(μ-(1,2-η2):(3,4-η2)-p-F3C–C6H4–C C–C C–C6H4-p-CF3) (4), an isomer of 3b, form reproducibly and in good yield as two different solvates from THF/C6D6 solution. The centrosymmetric structure of 4, obtained from single-crystal X-ray diffraction data, displays a transoid orientation of the bridging diarylbutadiyne ligand.

(P)-(+)-Hexaspiro[2.0.0.0. 0.0.2.1.1.1.1.1]pentadecane [(P)-17] as well as (M)-(-)- and (P)-(+)-octaspiro[2.0.0.0.0.0.0.0.2.1.1.1.1.1.1.1]nonadecanes [(M)- and (P)-25]-enantiomerically pure unbranched [7]- and [9]triangulanes-have been prepared starting from racemic THP-protected (methylenecyclopropyl)methanol 6. The relative configurations of all important intermediates as well as the absolute configurations of the key intermediates were established by X-ray crystal structure analyses. This new convergent approach to enantiomerically pure linear [n]triangulanes for n=7, 9 was also tested in two variants towards [15]triangulane. Some of the most prominent and unexpected features of the newly prepared compounds are the remarkable modes of self-assembly of the diols (P)-14, (E)-(3S,3'S,4S,4'S,5R,5'R)-21, (P)-(+)-22, and (E)-31 in the solid state through frameworks of intermolecular hydrogen bonds leading to, depending on the respective structure, nanotube- [(P)-14, (P)-(+)-22, and (E)-31], honeycomb-like structures [(E)-(3S,3'S,4S,4'S,5R,5'R)-21] or a supramolecular double helix [(P)-(+)- and (M)-(-)-22]. Liquid crystalline properties of the esters and ethers of the diols (P)-14, (P)-, and (M)-22 have also been tested. Although all of these [n]triangulanes have no chromophore which would lead to significant absorptions above 200 nm, they exhibit surprisingly high specific rotations even at 589 nm with [alpha](20)(D)=+672.9 (c=0.814 in CHCl(3)) for (P)-(+)-17, +909.9 (c=0.96 in CHCl(3)) for (P)-(+)-25, -890.5 (c=1.01 in CHCl(3)) for (M)-(-)-25, and -1302.5 (c=0.36 in CHCl(3)) for (M)-(-)-39, and the specific rotations increase drastically on going to shorter wavelengths. This outstanding rotatory power is in line with their rather rigid helical arrangement of sigma bonds, and accordingly these helically shaped unbranched [n]triangulanes may be termed "sigma-[n]helicenes", as they represent the sigma-bond analogues of the aromatic pi-[n]helicenes. Density functional theory (DFT) computations at the B3 LYP/6-31+G(d,p) level of theory for the geometry optimization and time-dependent DFT for determining optical rotations with a triplet-zeta basis set (B3 LYP/TZVP) reproduce the optical rotatory dispersions (ORD) very well for the lower members (n=4, 5) of the sigma-[n]helicenes. For the higher ones (n=7, 9, 15) the computed specific rotations turn out increasingly larger than the experimental values. The remarkable increase of the specific rotation with an increasing number of three-membered rings is proportional neither to the molecular weight nor to the number of cyclopropane rings in these sigma-[n]helicenes.

Epoxidation of barrelene (3) with a neutralized solution of Oxone® gave the barrelene trisepoxide 6 in 82 % isolated yield, while lead tetraacetate promoted aziridination of 3 with two equiv. of N-aminophthalimide gave a mixture of mono-7 and bis(aziridine) endo,exo-8, which were isolated in 67 and 8 % yield, respectively. Fourfold repetition of this aziridination gave the bis(aziridines) exo,exo- and endo,exo-8 along with the trisaziridine 9 in 21, 8 and 19 % yield, respectively. Epoxidation of 7 and endo,exo-8 with buffered m-chloroperbenzoic acid furnished the dioxaazatrishomobarrelene 10 and oxadiazatrishomobarrelene 11 in 36 and 62 % yield, respectively. The structures of triheteratrishomobarrelenes 6 and 9 were established by X-ray crystallography. Upon treatment with BF3·Et2O at –20 °C (for 6) or with the strongly acidic ion exchange resin Amberlyst 15 at ambient or elevated temperatures (for 9–11), these triheteratrishomobarrelenes rearrange to give the triheteratrishomocubanes rac-12 to rac-15, as proved by X-ray crystal structure analysis of rac-13, in 75–100 % yield. The enantiomeric pairs of trioxa- 12 and triazatrishomocubane 13 were separated by preparative HPLC on a chiral column. 12 exhibited specific rotationsof [α]D25 = +196 and [α]36525 = +652 (c = 0.497, CHCl3) for the firstly eluted and [α]D25 = –173 and [α]36525 = –608 (c = 0.503, CHCl3) for the secondly eluted enantiomer; 13 had [α]D25 = +30 and [α]43525 = +501 (c = 0.490, CHCl3) for the firstly as well as [α]D25 = –28 and [α]43525 = –475 (c = 0.501, CHCl3) for the secondly eluted enantiomer. The geometry of rac-13 and the absolute configurations of (–)-12 and (+)-13 were determined by X-ray crystal structure analyses. According to this, (–)-12 and (+)-13 possess the same (1R,3R,5R,6R,8R,10R)-configuration. Theabsolute configuration of the former was also confirmed byDFT computations at the TD-B3LYP/6-31+G(d,p)//B3LYP/6-31+G(d) level of theory; the computed specific rotation for (–)-12 was –178. Computations for the elusive (all-R)-triazatrishomocubane (all-R)-13-H without phthalimidyl substituents on the nitrogen atoms disclosed that the sign of rotation is the same for the parent (all-R)-13-H and (all-R)-trioxatrishomocubane (all-R)-12 with the same absolute configuration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Terminal alkynes (R–C C–H, R = 1-naphthyl, 9-anthryl, 4-Me2N–C6H4–, or the longer analogue, 4-(4-Me2N–C6H4–C C–)–C6H4–) react with [Rh(PMe3)4Me] at ambient temperature, with loss of methane and one PMe3 ligand, to form the corresponding mer,trans-[(PMe3)3Rh(C CR)2H] compounds in excellent yield. In this preliminary study, the synthesis and spectroscopic characterization of the four new compounds are reported, along with the single-crystal structure of the R = 4-Me2N–C6H4 derivative.

Analysis of crystal packing of related compounds is a necessary ingredient of crystal engineering. We report here the crystal structures of 14 cyclic and fused ring gem-alkynols, compounds that are known for their supramolecular inconsistency because of the juxtaposition of two hydrogen-bond donors (O−H, C⋮C−H) and two hydrogen-bond acceptors (O−H, C⋮C−H) in the molecules. Because of the competition between these hydrogen-bond donors, or hydrogen-bond acceptors, the packing pattern in any particular crystal structure is highly sensitive to substitution by functional groups. The compounds studied here are methyl and chloro derivatives of the parent compounds 1a (benzo series, 1b−1f), 2a (naphtha series, 2b−2f), 3a and 4a (anthra series, 3b, 4b−4d). Structures 2a and 4a are prototypes because the O−H···O, C−H···O, O−H···π, and C−H···π hydrogen bonds form sheets in these cases with the interdigitating hydrocarbon residues perpendicular to the sheets. The hydrogen bonds are arranged to give centrosymmetric sy...