Search

The crystal structure of trans-4-(trifluoromethyl) cinnamic acid (1) has been determined in the triclinic space group P1̄. Differential scanning calorimetry showed that 1 undergoes a single fully reversible temperature induced phase transition at around 132/131 K (cooling/heating). Single crystal structure determinations, carried out at 200, 145 and 120 K, revealed that the volume of the unit cell quadruples as the crystal is cooled through the phase transition with Z′ increasing from 2 to 8. The structures are stabilised by the presence of O–H⋯O hydrogen bonding and C–H⋯O interactions. The results of DSC, single crystal and powder X-ray diffraction studies on 1 are reported. [ABSTRACT FROM AUTHOR]

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/ cin the paraelectric phase to the polar space group Ccin 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. [ABSTRACT FROM AUTHOR]

New transition metal catalysts have been prepared and applied for in situ formation of acyl nitroso dienophiles. [ABSTRACT FROM AUTHOR]

3,4-Pyridinedicarboxylic acid is a compound commonly used as a multifunctional ligand in coordination chemistry. The crystal structure of its orthorhombic Form I has been known for over 30 years, while a new Form II has only been reported recently as crystallizing in the monoclinic space group C2/c. The present work shows that, in its entire temperature stability range, Form II is in fact primitive monoclinic, with space group P21/c. At 120 K, the unit cell parameters are a = 7.594(1) Å, b = 7.332(1) Å, c = 12.113(2) Å, β = 104.339(4)° and V = 653.4(2) Å3. In order to characterize the temperature dependent behaviour of 3,4-pyridinedicarboxylic acid, both polymorphs were studied by single crystal X-ray diffraction at 120 and 400 K, variable temperature powder X-ray diffraction between room temperature and 600 K, solid state NMR and computational methods. Short O–H⋯O hydrogen bonds are found in both forms of 3,4-pyridinedicarboxylic acid, but there appears to be no temperature-induced proton migration along these bonds. [ABSTRACT FROM AUTHOR]

Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by 31P NMR spectroscopy. The crystal and molecular structures of five such derivatives have been ascertained for the first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P–P bond lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium ions, where structural determinations have shown that the P–P bond lengths are intermediate between single and double bonds. [ABSTRACT FROM AUTHOR]

N,N‘-Diisopropylferrocenecarboxamide is utilized for an asymmetric, directed metalation approach to several planar chiral bifunctional ferrocene derivatives. Directed metalation using n-butyllithium-(−)-sparteine on N,N‘-diisopropylferrocenecarboxamide can be achieved to give high yields of the corresponding boronic acid; however, it was found that a sequence involving asymmetric directed metalation−bromination, followed by lithium−halogen exchange, was more convenient to access the same derivatives since this allowed straightforward determination of the enantiomeric excess. (pR)-2-(N,N-Diisopropylamino)methylferrocenylboronic acid and derivatives thereof could be readily accessed with high enantiomeric excess, followed by amide reduction. [ABSTRACT FROM AUTHOR]

PhBrF3, a liquid under ambient conditions, has been crystallised viatwo different methods, resulting in the formation of non-identical solid-state phases with very similar packing efficiencies but markedly different packing motifs, both of which appear to be directed by classically weak intermolecular halogen–halogen interactions. [ABSTRACT FROM AUTHOR]

PhBrF3, a liquid under ambient conditions, has been crystallised viatwo different methods, resulting in the formation of non-identical solid-state phases with very similar packing efficiencies but markedly different packing motifs, both of which appear to be directed by classically weak intermolecular halogen–halogen interactions. [ABSTRACT FROM AUTHOR]

PhBrF3, a liquid under ambient conditions, has been crystallised viatwo different methods, resulting in the formation of non-identical solid-state phases with very similar packing efficiencies but markedly different packing motifs, both of which appear to be directed by classically weak intermolecular halogen–halogen interactions. [ABSTRACT FROM AUTHOR]

PhBrF3, a liquid under ambient conditions, has been crystallised viatwo different methods, resulting in the formation of non-identical solid-state phases with very similar packing efficiencies but markedly different packing motifs, both of which appear to be directed by classically weak intermolecular halogen–halogen interactions. [ABSTRACT FROM AUTHOR]

In the presence of SnCl2, a novel cycloaddition of two moles of R'PCl2 (R′ = Et or Ph) to a diphosphane has been achieved, forming a cyclic dication with four linked phosphorus atoms and an organic backbone; two of these species have been characterised by single-crystal X-ray diffraction, and the mechanism of the reaction has been established. [ABSTRACT FROM AUTHOR]

Transition-metal complexes containing (C–C)→M σ-interactions have potential applications in both catalysis and the activation and cleavage of C–C bonds. Fully characterising the bonding and interactions in complexes containing such (C–C)→M σ-interactions is vital to understand their chemical behaviour. As a result a high-resolution experimental X-ray charge density study has been undertaken on [Rh(Binor-S)(PCy3)][HCB11Me11] (Binor-S = 1,2,4,5,6,8-dimetheno-s-indacene) which contains a (C–C)→Rh interaction. The data are analysed using Bader's “Atoms in Molecules” (AIM) approach with particular attention paid to the interactions around the rhodium centre. The results provide clear evidence for the σ(C–C)→Rh interaction in the solid-state which is classified as a weak covalent interaction. These results are supported by theoretical calculations. [ABSTRACT FROM AUTHOR]

Hydrogen bonding interactions with the π-system of thiocarbonyls are evident in the X-ray crystal structures of a range of thiourea derivatives and from an analysis of the CSD. [ABSTRACT FROM AUTHOR]

The structures of various natural amino acid hydrogen peroxide solvates are presented. All “active” hydrogen atoms (amino, hydroxy, peroxy, and water) in the studied amino acid perhydrates are involved in hydrogen bonding. Peroxide molecules form at least two donor hydrogen bonds. In the most common case, the H2O2molecule is engaged in four hydrogen bonds (two donors with –CO2−groups and two acceptors with –NH3+groups). In peroxosolvates of amino acids bearing hydrocarbon side-chains, double layers were observed. These bilayers are hydrophilic inside, while their outer surfaces are hydrophobic. It was found that donor hydrogen bonds formed by hydrogen peroxide in amino acid perhydrates are significantly stronger than those formed by water molecules in amino acid hydrates. [ABSTRACT FROM AUTHOR]

The design and study of organometallic mixed-valence complexes is complicated by the mixing of metal d and bridging ligand π orbitals, which often makes the assignment of metal oxidation states ambiguous. However, in the case of complexes based on the cycloheptatrienyl-ligated molybdenum fragment, Mo(dppe)(η-C7H7), the strong ring to metal π bonding and metal to ring δ back-bonding interactions stabilize four of the metal d orbitals, while the dz2orbital is destabilized by filled−filled interactions with the a-type MO of the C7H7ring. When the Mo(dppe)(η-C7H7) auxiliary is used in conjunction with a 1,12-bis(ethynyl)-1,12-carbaborane-based bridging ligand, a weakly coupled (Robin and Day class II) mixed-valence system, [{Mo(dppe)(η-C7H7)}2{μ-1,12-(CC)2-1,12-C2B10H10}]([2]), with well-defined molybdenum oxidation states can be prepared. The near-IR region of [2]笘扮⭬ three intervalence charge transfer (IVCT) transitions and two lower intensity interconfigurational (or dd) transitions, which have been resolved through spectral deconvolution. The band shape of the lowest energy IVCT transition associated with [2], which arises from electron exchange between the dz2-type orbitals at the two Mo centers, is in excellent agreement with the predictions of the Hush two-state model for weakly coupled mixed-valence complexes. The half-height bandwidths of the higher energy IVCT transitions, which arise from transitions between lower lying metal orbitals that have symmetry properties that permit more significant mixing with the bridging ligand, are in less good agreement with the Hush model, due to the breakdown of the two-state approximation through the greater involvement of the bridge-based orbitals in those transitions. [ABSTRACT FROM AUTHOR]

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 3and 4crystallize in the orthorhombic Pbcaand monoclinic P21/csystems, respectively, while the space group of compounds 1and 2is monoclinic C2/c. The structure of 3consists of a monophenoxo-bridged CuIIHgIIdinuclear core in which the mercury(ii) centre is dicoordinated by the bridging phenoxo oxygen atom and the CH2carbon atom of the mono-deprotonated acetone anion. The coordination environment of HgIIin this compound is almost linear. In the CuII2AgIcompound 4, one diphenoxo-bridged [CuIILAgI(H2O)]+cation is co-crystallized with one mononuclear [CuIIL] moieties. On the other hand, the structures of the CuII3MIIcompounds 1(M = Zn) and 2(M = Cd) consist of one diphenoxo-bridged dinuclear CuIIMIIunit and two mononuclear [CuIIL] moiety; the composition of the dinuclear unit being [CuIILZnII(H2O)2]2+and [CuIILCdII(H2O)2(CH3CN)]2+for 1and 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 4is pyramidal with a scalene O3triangle as the base, whereas those of zinc(ii) and cadmium(ii) in 1and 2are distorted tetrahedral and distorted pentagonal bipyramidal, respectively. The coordinated water molecule in 4and each of the two coordinated water molecules in 1and 2are encapsulated into the O4compartment of a [CuIIL] moiety resulting in the [2 × 1 + 1 × 1] (for 4) or [2 × 1 + 1 × 2] (for 1and 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, 2and 4. In addition all four compounds 1–4have π–π stacking interactions which form dimers between pairs of adjacent molecules in the structure of 3consisting of CuIIHgIIdimers, 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, 2and 4, respectively, are new observations. The accommodation/coordination of varieties of metal ions by the O4compartment of H2L has also been highlighted in the present investigation. [ABSTRACT FROM AUTHOR]

In the present investigation, various copper(ii)–alkali/alkaline earth metal ion heteronuclear complexes derived from N,N′-ethylenebis(3-ethoxysalicylaldimine) (H2L) have been studied. The syntheses, characterization and crystal structures of three [2 × 1 + 1 × 2] cocrystals [{CuIILLiI(H2O)2}{CuIIL}2](ClO4) (1), [{CuIILNaI(H2O)2}{CuIIL}2](dicyanamide) (2) and [{CuIILMgII(H2O)3}{CuIIL}2](NO3)2·H2O (3), one [3 × 1 + 5 × 1] double-decker–triple-decker cocrystal [{(CuIIL)2KI}(ClO4)]·[{(CuIIL)3KI2(μ-ClO4)}(ClO4)] (4), one dinuclear CuIIKI-based one-dimensional polymer [CuIILKI(μ-PF6)]n(5) and one hexametallic quadruple-decker compound [{(CuIIL)2RbI(μ-H2O)}2](BPh4)2·2CH3COCH3(6) are reported. Compounds 1, 2, 3and 6crystallize in the triclinic crystal system (space group P1), while the crystal systems of 4and 5are monoclinic (space group C2/c) and orthorhombic (space group P212121), respectively. The cocrystallization in 1–3takes place through the encapsulation of coordinated water molecules into the O4compartment of two mononuclear [CuIIL] moieties; both the coordinated water molecules are involved in the case of 1and 2, while 2 of the 3 coordinated water molecules are involved for 3. In 4, the potassium(i) centre in the double-decker moiety is sandwiched in between two mononuclear [CuIIL] moieties, while each of the two potassium(i) centres in the triple-decker moiety are sandwiched in between a pair of two [CuIIL] moieties. The two potassium(i) centres in the triple-decker moiety are bridged by a perchlorate anion. In 5, two cisfluorine atoms from the hexafluorophosphate anion bridge the potassium(i) centres of the neighbouring dinuclear CuIIKIunits to build up a one-dimensional polymer. The quadruple-decker hexanuclear [{(CuIIL)2RbI(μ-H2O)}2]2+dication in 6can be considered to consist of two trinuclear double-decker [(CuIIL)2RbI]+moieties, interlinked by two bridging water molecules. Structural resemblance between the structures formed with LiI, NaIand MgIIand those with 3d metal ions, the anion dependence of the topology of the copper(ii)–potassium(i) complexes, cocrystallization in the presence of the potentially bridging dicyanamide anion, the first report of a one-dimensional polymer derived from H2L and an interesting example of a quadruple-decker complex, are the major outcomes of the present investigation. All in all, structural diversity in the H2L ligand system has been further enriched by some interesting structures in the present investigation. [ABSTRACT FROM AUTHOR]

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 1and 4crystallize in orthorhombic P212121and triclinic P systems, respectively, while the space group of compounds 2and 3is monoclinic P21/c. The structure of 1consists of a diphenoxo-bridged CuIIBiIIIdinuclear core containing three chelating nitrates and a 10-coordinate bismuth(III) centre. The dinuclear cores are self-assembled to two dimensions through intermolecular nitrate oxygencopper(II) semicoordination and weak C–HO hydrogen bonds. Compound 2is a double-decker CuIIBaIICuIIsystem 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 3is 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 4is 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 4are the C–H·π and C–HO 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. [ABSTRACT FROM AUTHOR]

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 4is 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 orthopositions with respect to each other, generate significant regions of negative charge which have a substantial structure-directing influence. [ABSTRACT FROM AUTHOR]

Reactions of a new imido phosphido complex, Cp2Nb(NBut)(PPh2) (1), with olefin complexes of rhodium afford two types of compounds. With [(μ-Cl)Rh(C2H4)2]2, an imido/phosphido-bridged complex, Cp(Cl)Nb(μ-NBut)(μ-PPh2)RhCp (2), characterized by NMR and X-ray diffraction, was prepared. Formation of 2represents a rare example of a Cp/Cl exchange reaction in organometallic chemistry. When 1reacts with [(μ-Cl)Rh(COD)]2, the target phosphido-bridged bimetallic complex Cp2Nb(NBut)(μ-PPh2)Rh(Cl)(COD) (4) is formed. The structure of this product was established by NMR and an X-ray diffraction study. Both 2and 4are catalyst precursors for hydrosilylation of benzaldehyde and acetophenone. The activity of the neutral complex 4exceeds that of the cation [Cp2Nb(NBut)(PPh2)Rh(COD)]+derived from 4by chloride anion abstraction. [ABSTRACT FROM AUTHOR]

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 1and 2crystallize in triclinic P1̅ and monoclinic P21/csystems, respectively. The structure of 1consists 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 O4cavities 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 2is a [3×1+5×1] cocrystal. Structural resemblance of 3d metal ions with Na(I) and a rare example of double-decker−triple-decker cocrystal are the major outcomes of the present investigation. [ABSTRACT FROM AUTHOR]

The reactions of [Ir(PMe3)4]Cl (1) with a variety of substrates (acetonitrile, p-aminobenzonitrile, p-cyanophenol) containing a nitrile group were examined. Cleavage of the X−H bonds occurred selectively over the coordination of the CN moiety in those substrates, and compounds derived from the corresponding X−H (X = C, N, O) oxidative addition reaction, namely, cis-[IrH(CH2CN)(PMe3)4]Cl (2), cis-[IrD(CD2CN)(PMe3)4]Cl (3), cis-[IrH(p-NHC6H4CN)(PMe3)4]Cl (4), and cis-[IrH(p-OC6H4CN)(PMe3)4]Cl (6), were obtained. X-ray diffraction studies have confirmed the structures of 3and 4. In the case of 6, the compound trans-[IrClH(PMe3)4][p-OC6H4CN] (5b), resulting from exchange of Cl and p-OC6H4CN anions between inner and outer sphere, was also formed, and the solid-state structure (5b·HOC6H4CN), obtained by X-ray diffraction, contained the hydrogen-bonded NCC6H4O···H···OC6H4CN anion. The salt [Ir(PMe3)4][BPh4] (7) was also prepared, characterized by X-ray diffraction and reacted with p-HOC6H4CN. Reaction of 1with acetamide, the product of acetonitrile hydration, was undertaken to gain insight into the nitrile hydration process, and the single-crystal structure of the N−H bond cleavage product, cis-[IrH(NHC(O)Me)(PMe3)4]Cl (8), was determined by X-ray diffraction. The peroxo compound derived from reaction of 1with O2, [Ir(O2)(PMe3)4]Cl (9), was prepared, characterized by X-ray diffraction, and used as a catalyst precursor for the hydration of acetonitrile using the protio and deuterio mixtures of substrates, CH3CN/H2O (A), CD3CN/D2O (B), CD3CN/H2O (C), and CH3CN/D2O (D). Catalysis occurred cleanly at 140 °C, giving dn-acetamides; the formation of these was monitored by 1H and 13C{1H} NMR spectroscopy and GC/MS. In situ31P{1H} NMR spectroscopic studies during catalysis confirmed the formation of OPMe3. [ABSTRACT FROM AUTHOR]

The reaction of N-methylpyridinium iodide, Mepy+I−, and tetracyanoethylene (TCNE) forms [Mepy]2[TCNE]2, which possesses [TCNE]22−with an intradimer C–C bond distance of 2.806(1) Å at 50 K from X-ray diffraction, and 2.801(4) Å at 50 K from neutron diffraction. In the IR it exhibits νC≡Nabsorptions at 2191, 2174, 2169, 2163 and a νCCabsorption at 1366 cm−1, with UV/Vis absorption bands at 26,880 and 18,520 cm−1. Analysis of the cation-hydrogen to [TCNE]22−interactions do not provide evidence that the cation stabilizes formation of the [TCNE]22−dimer, which is stabilized by the intradimer 2e−-4 center C–C bonding interaction. [ABSTRACT FROM AUTHOR]

Facile acetylide transfer reactions take place between gold(i) complexes Au(CCAr)(PPh3) (Ar = C6H5or C6H4Me-4) and a variety of representative inorganic and organometallic complexes MXLn(M = metal, X = halide, Ln= supporting ligands) featuring metals from groups 8–11, to afford the corresponding metal–alkynyl complexes M(CCR)Lnin modest to good yield. Reaction products have been characterised by spectroscopic methods, and molecular structure determinations are reported for Fe(CCC6H4Me-4)(dppe)Cp, Ru(CCC6H4Me-4)(dppe)Cp*, Ru(CCC6F5)(η2-O2)(PPh3)Cp*, Ir(CCC6H4Me-4)(η2-O2)(CO)(PPh3)2, Ni(CCC6H4Me-4)(PPh3)Cp and trans-Pt(CCAr)2L2(Ar = C6H5, L = PPh3; Ar = C6H4Me-4, L = PPh3, PMe3). [ABSTRACT FROM AUTHOR]

This paper reports preparation of new silyl hydride complexes of ruthenium supported by the Cp/PR3ligand set. It is shown that the easiest and most general route to these complexes is provided by the thermal reaction of [RuCp(PR3)(H)3] with hydrosilanes. Complexes [RuCp(PR3)(H)2(SiMe2Cl)] exhibit Interligand Hypervalent Interactions (IHI) between the hydride and silyl ligands. Comparison of the X-ray structures of complexes [RuCp(PPri3)(H)2(SiMe2Cl)], [RuCp(PPhPri2)(H)2(SiMe2Cl)], and [RuCp(PPh3)(H)2(SiMe2Cl)] shows that the IHI weakens with the decreasing electron-releasing ability of the phosphine. Comparison of the X-ray structure of [RuCp(PPh3)(H)2(SiMe2Cl)] with the structure of the previously reported complex [RuCp*(PPh3)(H)2(SiMe2Cl)] reveals that the lack of IHI in the latter compound is due to unfavourable steric interactions between the bulkier Cp* ring and the SiMe2Cl group. [ABSTRACT FROM AUTHOR]

Six inclusion compounds containing a photoreactive guest molecule, 4-oxo(phenylacetyl)morpholine or 1-(phenylglyoxylyl)piperidine, with different host molecules have been crystallized. The guest molecules underwent photochemical reaction upon irradiation. Examining their structures suggests that γ-hydrogen abstraction by an oxygen, the first step in cyclization of α-oxoamides, should be possible in all cases. In four cases crystallinity was maintained during and at the end of the conversion process i.e. the process was a single-crystal to single-crystal transformation. The crystal structure of the product crystals revealed that in two of the inclusion compounds the product obtained is a result of enclosure to a four-membered ring while in the other two the product obtained results from enclosure to a five-membered ring. The morpholine molecules adopt two different conformations. The photochemical reaction may take different courses either as a result of the different conformation or as a result of the different shapes of the cavities provided by the host molecules. [ABSTRACT FROM AUTHOR]

The syntheses of the cyclic N-phosphino-amidines and -guanidines Ph2PN(Pri)C(NPri2)N(Pri) (1) and Ph2PN(c-Hex)C(R)N(c-Hex) [R = piperazino (2), morpholino (3), Me (4), and Ph (5)] are reported. DFT studies have identified the preferred structures for compounds 1–5 with the E-configuration being the most stable form for the N-phosphino-amidines, while the Z-conformation is preferred for the N-phosphino-guanidines something that highlights the potential of such systems to act as κ2-P,N-chelates. The differences in donor characteristics of 2–5 have been probed through the study of their corresponding P(v) selenide derivatives (6–9) and their complexes with the cis-RhCl(CO) (10–12) and cis-PdCl2 (13–17) fragments. In line with the DFT studies both the amidines and guanidines are found to coordinate as κ2-P,N-chelates, with the latter being moderately weaker donor ligands. The molecular structures of compounds 3 and 4, together with those of the Rh and Pd complexes 10 and 15, respectively, have been determined in the solid state by X-ray crystallography, the latter confirming bidentate κ2-P,N-chelation. [ABSTRACT FROM AUTHOR]

Reactions of half-sandwich ruthenium metal acetylide complexes with 1-cyano-4-dimethylaminopyridinium salts afford complexes containing mono- or di-cyanovinylidene ligands; the procedure can be adapted to permit the simple synthesis of a cyanoacetylide complex, via the in situ deprotonation of a primary cyanovinylidene complex. [ABSTRACT FROM AUTHOR]

Nitrogen donor tetradentate ligands 4,4′-bipyridazine (bpdz) and pyridazino[4,5-d]pyridazine (pp) were prepared by inverse electron demand Diels–Alder cycloaddition reactions of 1,2,4,5-tetrazine. Examination of their behaviour towards silver(i) ions revealed a special potential of the ligands for the design of 3D coordination frameworks involving characteristic polynuclear and polymeric silver(i)–pyridazine motifs and multiple coordination of the ligands. Ag4(pp)5(ClO4)4 and Ag4(pp)5(SiF6)(BF4)2·4H2O adopt a unique 3D trinodal 4,4,5-connected topology based upon five-fold coordination of the metal ions and tetradentate bridging function of the organic modules. Complexes Ag3(L)3(SO3CF3)3·nH2O and Ag4(L)3(X)4·nH2O (L = bpdz, pp; X = BF4−, 0.5SiF62−) illustrate formation of highly-connected frameworks incorporating trinuclear clusters as an origin of the net connectivity. In the carboxylate complexes Ag2(L)(RFCOO)2 (RF = CF3, C2F5, C3F7) the pyridazine and acido ligands act as complementary linkers for generation of 3D frameworks involving helicate motifs. Fused bicyclic pyridazine pp is a unique system combining very efficient σN-donor ability and pronounced π-acidity. The coordination frameworks commonly exhibit strong anion–π interactions, including unprecedented examples of double anion–π,π binding that occur between pyridazino[4,5-d]pyridazine as a double π,π-receptor for geometry complementary SiF62− anions. [ABSTRACT FROM AUTHOR]

A new polydentate ligand 4,4′-bipyridazine (4,4′-bpdz) was prepared by employing inverse electron demand cycloaddition of 1,2,4,5-tetrazine. A unique combination of structural simplicity, ampolydentate character and efficient donor properties towards Cu(i), Cu(ii) and Zn(ii) provide wide new possibilities for the synthesis of coordination polymers incorporating the 4,4′-bpdz module either as a bi-, tri- or tetradentate connector between the metal ions. 1D coordination polymers Cu2(4,4′-bpdz)(CH3CO2)4·4H2O and Zn(4,4′-bpdz)(NO3)2, and interpenetrated (4,4)-nets in [Cu(4,4′-bpdz)2(H2O)2]S2O6 were closely related to 4,4′-bipyridine compounds. 1D “ladder-like” polymer Cu2(4,4′-bpdz)3(CF3CO2)4 and the unprecedented 3D binodal net ({86}{63;83}) in [Cu3(4,4′-bpdz)6(H2O)4](BF4)6·6H2O were based upon a combination of linear and angular organic bridges. Complex [Cu3(OH)2(4,4′-bpdz)3(H2O)2{CF3CO2}2](CF3CO2)2·2H2O has a “NbO-like” 3D topology incorporating discrete dihydroxotricopper(ii) clusters linked by tri- and tetradentate ligands. The tetradentate function of the 4,4′-bpdz ligand was especially relevant for copper(i) complexes, which adopt layered Cu2X2(4,4′-bpdz) (X = Cl, Br) or 3D chiral framework (X = I) structures based upon infinite (CuX)n chains. The electron deficient character of the ligand was manifested by short anion–π interactions (O–π 3.02–3.20; Cl–π 3.35 Å), which may be involved as a factor for controlling the supramolecular structure. [ABSTRACT FROM AUTHOR]

The Sonogashira cross-coupling of two equivalents of para-substituted ethynylbenzenes with 2,5-diiodothiophene provides a simple synthetic route for the preparation of 2,5-bis(para-R-phenylethynyl)thiophenes (R = H, Me, OMe, CF3, NMe2, NO2, CN and CO2Me) (1a–h). Likewise, 2,5-bis(pentafluorophenylethynyl)thiophene (2) was prepared by the coupling of 2,5-diiodothiophene with pentafluorophenylacetylene. All compounds were characterised by NMR, IR, Raman and mass spectroscopy, elemental analysis, and their absorption and emission spectra, quantum yields and lifetimes were also measured. The spectroscopic studies of 1a–h and 2 show that both electron donating and electron withdrawing para-subsituents on the phenyl rings shift the absorption and emission maxima to lower energies, but that acceptors are more efficient in this regard. The short singlet lifetimes and modest fluorescence quantum yields (ca. 0.2–0.3) observed are characteristic of rapid intersystem crossing. The single-crystal structures of 2,5-bis(phenylethynyl)thiophene, 2,5-bis(para-carbomethoxyphenylethynyl)thiophene, 2,5-bis(para-methylphenylethynyl)thiophene and 2,5-bis(pentafluorophenylethynyl)thiophene were determined by X-ray diffraction at 120 K. DFT calculations show that the all-planar form of the compounds is the lowest in energy, although rotation of the phenyl groups about the C≡C bond is facile and TD-DFT calculations suggest that, similar to 1,4-bis(phenylethynyl)benzene analogues, the absorption spectra in solution arise from a variety of rotational conformations. Frequency calculations confirm the assignments of the compounds’ IR and Raman spectra. [ABSTRACT FROM AUTHOR]

Four new (E)-4-styrylquinoline compounds containing two methoxy substituents or an 18-crown-6-ether fragment were synthesized in order to investigate the [2 + 2]-photocycloaddition (PCA) reaction in the solid state. These compounds reveal different abilities to undergo the photoreaction depending on the packing of the quinoline molecules in thin polycrystalline films and single crystals. The only products from the irradiation of (E)-4-styrylquinolines were an rctt isomer of 1,2,3,4-tetrasubstituted cyclobutane and, rarely, a Z isomer of the styrylquinoline. The rctt cyclobutane derivative was formed as a result of the PCA of centrosymmetric syn-‘head-to-tail’ dimeric pairs of the reactant species that are preorganized in such a way as to promote this reaction. Peculiarities in the crystal packing motifs that are typical for single crystals of 4-styrylquinoline compounds are discussed. The solvate molecules can affect significantly the packing of styrylquinolines. Benzene solvate molecules create a soft, flexible, shell about the dimeric pairs that facilitates the PCA in the single crystal without causing degradation of the crystal. In crystal packing that contains CH2Cl2 and H2O solvate molecules, they are prone to form complicated systems of hydrogen bonds with crown-ether oxygen atoms and each other. This results in distorting the organic molecule geometry toward non-planarity and accomplishing a new type of crystal packing uncommon for styrylheterocycles, in which the PCA is impossible. The topochemical single-crystal-to-single-crystal PCA reaction was monitored for one of the species. Two cyclobutane derivatives obtained in single crystals were subjected to recrystallization from a solution. The new single crystals formed belong to different crystal systems, with different unit cell parameters as compared with initial single crystals; significant differences in the geometry of the cyclobutane molecules were also found. This implies that the cyclobutane derivatives obtained in the solid phase have a molecular geometry that is somewhat stressed. [ABSTRACT FROM AUTHOR]

One-pot reactions of [WCp2(H)2] and [WCp2(H)(SnMe3)] with nBuLi followed by an equivalent of GeMe2Cl2 afford mono(germyl) substituted tungstenocenes [WCp2(H)(GeMe2Cl)] (1) and [WCp2(SnMe3)(GeMe2Cl)] (7). Reactions of the products with tin halides in the presence NEt3 afford the mixed complexes [WCp2(SnR2X)(GeMe2Y)] (X, Y = Cl, Br, R=Me, Et), which were further converted to moderately stable compounds [WCp2(SnR2H)(GeMe2H)] (R = Me (10), Et (11)). A number of asymmetric mono(halo)-substituted germyl/stannyl tungstenocenes [WCp2(SnMe2X)(GeMe2H)] (X = Cl (12), Br (13)) and [WCp2(SnEt2Y)(GeMe2H)] (Y = Br (14), I (15)) were prepared by selective halogenation of the Sn–H bond in 10 and 11. X-Ray studies of [WCp2(H)(GeMe2Cl)] (1), [WCp2(SnEt2Br)(GeMe2Cl)] (4), and [WCp2(SnEt2Br)(GeMe2H)] (14) established classical structures of these compounds. X-Ray study of complex [WCp2(SnMe2Cl)(GeMe2Cl)] (3) revealed the presence of interligand Ge–Cl⋯Sn–Cl interactions in a highly Ge/Sn disordered structure. Analyses of molecular parameters of 1, 4, and 14 suggest the presence of a negative hyperconjugation between metal lone pairs and the σ*-orbital of the E–X bond, which is stronger in bromo substituted complexes in comparison with chloro substituted ones. [ABSTRACT FROM AUTHOR]

The structure of the first tetrameric -lithiated N-phenylphosphazene has been determined in the solid state and shown to persist in toluene solution, an observation that gives insight into the variation in stereoselectivity found for reactions of -lithiated phosphazenes with aldehydes. [ABSTRACT FROM AUTHOR]

The Cp ring is found to exert a primarily electronic effect on the strength of Si−H interaction in silane σ-complexes Cp(Pri3P)RuCl(η2-HSiClR2). Complexation of chlorosilanes HSiClR2is supported by an additional RuCl···SiCl interaction. [ABSTRACT FROM AUTHOR]

A well-characterised 14-electron rhodium phosphine complex, [Rh(PiPr3)3][BArF4], which contains a β-CH agostic interaction, is observed to undergo spontaneous dehydrogenation to afford [Rh(PiPr3)2(PiPr2(C3H5))][BArF4]; calculations on a model system show that while C–H activation is equally accessible from the β-CH agostic species or an alternative γ-CH agostic isomer, subsequent β-H-transfer can only be achieved along pathways originating from the β-CH agostic form. [ABSTRACT FROM AUTHOR]

Photoinduced Fe-to-bpy charge transfer in [{Cp(dppe)Fe}(μ-CCCN){Re(CO)3(bpy)}]PF6has been observed by ps-TRIR spectroscopy, supported by UV-Vis/IR spectroelectrochemistry and DFT calculations. [ABSTRACT FROM AUTHOR]

Interaction of Pd-clusters [Pd(CO)(OCOR)]n with NO was investigated, these Pd-clusters were found to promote the NO disproportionation into N2 and NO2− in mild conditions; an eight-nuclear palladium cluster Pd8(μ-CO)4(μ-OOCCMe3)8(μ-NO2)4 with a new type of structure and an uncommon set of ligands was characterized by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The first member of a novel class of chemoselective reagents, glycosyl methanedithiosulfonates, has been synthesized, identified and employed in the first examples of chemical, site-selective construction of a trisulfide-modified protein with complete conversion. [ABSTRACT FROM AUTHOR]