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The self-assembly of Pd4L2 metallocylcic and Pd6L3 trigonal prismatic assemblies are described. The selection of one species over the other has been achieved by careful choice of ancilliary ligands, which switch the dynamics of the Pd-pyridine bonds such that a highly unusual and distorted smaller assembly can be kinetically trapped en route to the more energetically favourable larger species. Both assemblies provide promise as easy to access multicavity reaction vessels.

Dissolution of FeBr3 in a mixture of acetonitrile and 3,4-lutidine in the presence of an amine results in the formation of an [Fe30] molecular metal oxide containing alternating layers of tetrahedral and octahedral FeIII ions. Mass spectrometry suggests the cluster is formed quickly and remains stable in solution, while magnetic measurements and DFT calculations reveal competing antiferromagnetic exchange interactions.

Dialumenes are neutral AlI compounds with Al=Al multiple bonds. We report the isolation of an amidophosphine‐supported dialumene. Our X‐ray crystallographic, spectroscopic, and computational DFT analyses reveal a long and extreme trans‐bent Al=Al bond with a low dissociation energy and bond order. In solution, the dialumene can dissociate into monomeric AlI species. Reactivity studies reveal two modes of reaction: as dialumene or as aluminyl monomers., A highly trans‐bent dialumene has marginal Al=Al double‐bond character and, in solution, can dissociate into monomeric aluminyl fragments. Reactivity studies reveal that both the dialuminene and aluminyl monomer can be trapped by varying the reaction partner. DFT calculations elaborate the origins of the extreme trans‐bending, weak Al=Al bond, and define substituent effects in dialumenes.

The combination of two different FeIII salts in a solvothermal reaction with triethanolamine results in the formation of a high symmetry [FeIII15] cluster whose structure conforms to a centred, tetrakis hexahedron., EKB and LC thank U21/EPSRC for funding a studentship (DJC). MKS would like to thank Edinburgh Compute and Data Facility (ECDF), and the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 832488. ME thanks the Spanish Ministry of Science and Innovation (Project RTI2018-098537-B-C22).

Heterolanthanide complexes are difficult to synthesize owing to the similar chemistry of the lanthanide ions. Consequently, very few purely heterolanthanide complexes have been synthesized. This is despite the fact that such complexes hold interesting optical and magnetic properties. To fine-tune these properties, it is important that one can choose complexes with any given combination of lanthanides. Herein we report a synthetic procedure which yields pure heterodinuclear lanthanide cryptates LnLn*LX3 (X = NO3− or OTf−) based on the cryptand H3L = N[(CH2)2N Created by potrace 1.16, written by Peter Selinger 2001-2019 CH–R–CHN–(CH2)2]3N (R = m-C6H2OH-2-Me-5). In the synthesis the choice of counter ion and solvent proves crucial in controlling the Ln–Ln* composition. Choosing the optimal solvent and counter ion afford pure heterodinuclear complexes with any given combination of Gd(iii)–Lu(iii) including Y(iii). To demonstrate the versatility of the synthesis all dinuclear combinations of Y(iii), Gd(iii), Yb(iii) and Lu(iii) were synthesized resulting in 10 novel complexes of the form LnLn*L(OTf)3 with LnLn* = YbGd 1, YbY 2, YbLu 3, YbYb 4, LuGd 5, LuY 6, LuLu 7, YGd 8, YY 9 and GdGd 10. Through the use of 1H, 13C NMR and mass spectrometry the heterodinuclear nature of YbGd, YbY, YbLu, LuGd, LuY and YGd was confirmed. Crystal structures of LnLn*L(NO3)3 reveal short Ln–Ln distances of ∼3.5 Å. Using SQUID magnetometry the exchange coupling between the lanthanide ions was found to be anti-ferromagnetic for GdGd and YbYb while ferromagnetic for YbGd., We present a synthetic strategy to prepare the first heterodinuclear lanthanide(iii) cryptate complexes. The cryptate design ensures that the complexes are stable in solution for days. The exchange coupling in YbYb, GdGd and YbGd is investigated.

Eight novel manganese carbonyl complexes of the type [Mn(bpy-tBu)(CO)3PR3]+ (bpy-tBu = 4,4'-di-tert-butyl-2,2'-bipyridine; R = Cy, nBu, Me, p-tol, Ph, p-F-Ph, OEt, and OMe), have been synthesized and characterized by 1H NMR, FTIR, UV/Vis, HRMS and CV. X-ray crystallographic structures of [Mn(bpy-tBu)(CO)3(PCy3)]+ and [Mn(bpy-tBu)(CO)3(PPh3)]+ were obtained. The short Mn-P bond length allows for close proximity of the bipyridine ligand and the phosphine R groups, resulting in strong anisotropic shielding of certain bipyridine protons by aryl R groups (reordering the bipyridine 1H NMR pattern in the most extreme case). Electrochemical analysis of the compound series reveals that while each is a competent precatalyst for electrochemical carbon dioxide reduction (to carbon monoxide), the lability of the PR3 ligand results in similar catalytic performance amongst the series.

Reaction of Ni(OTf)2 with the bisbidentate quaterpyridine ligand L results in the self-assembly of a tetrahedral, paramagnetic cage [NiII4L6]8+. By selectively exchanging the bound triflate from [OTf⊂NiII4L6](OTf)7 (1), we have been able to prepare a series of host–guest complexes that feature an encapsulated paramagnetic tetrahalometallate ion inside this paramagnetic host giving [MIIX4⊂NiII4L6](OTf)6, where MIIX42− = MnCl42− (2), CoCl42− (5), CoBr42− (6), NiCl42− (7), and CuBr42− (8) or [MIIIX4⊂NiII4L6](OTf)7, where MIIIX4− = FeCl4− (3) and FeBr4− (4). Triflate-to-tetrahalometallate exchange occurs in solution and can also be accomplished through single-crystal-to-single-crystal transformations. Host–guest complexes 1–8 all crystallise as homochiral racemates in monoclinic space groups, wherein the four {NiN6} vertexes within a single Ni4L6 unit possess the same Δ or Λ stereochemistry. Magnetic susceptibility and magnetisation data show that the magnetic exchange between metal ions in the host [NiII4] complex, and between the host and the MX4n− guest, are of comparable magnitude and antiferromagnetic in nature. Theoretically derived values for the magnetic exchange are in close agreement with experiment, revealing that large spin densities on the electronegative X-atoms of particular MX4n− guest molecules lead to stronger host–guest magnetic exchange interactions., The tetrahedral [NiII4L6]8+ cage can reversibly bind paramagnetic MX41/2− guests, inducing magnetic exchange interactions between host and guest.

Heterometallic Anderson wheels of formula [(VIVO)2MII5(hmp)10Cl2](ClO4)2·2MeOH (M = Ni, 1; Co, 2) have been synthesised from the solvothermal reaction of M(ClO4)2·6H2O and VCl3 with hmpH (2-(hydroxymethyl)pyridine). The metallic skeleton describes a centred hexagon, with the two vanadyl ions sitting on opposing sides of the outer ring. Magnetic susceptibility and magnetisation measurements indicate the presence of both ferromagnetic and antiferromagnetic exchange interactions. Theoretical calculations based on density functional methods reproduce both the sign and strength of the exchange interactions found experimentally, and rationalise the parameters extracted.

Acetate ligand metathesis results in the first hybrid [MIII(Pc)(PW11O39)]6− (M = Y, Dy, Tb) double-decker scaffolds, where a phthalocyanate (Pc2−) and one of the conceptually most simple polyoxotungstates, a monolacunary Keggin cluster, are interlinked via a single rare earth ion. Characterisation includes high-resolution mass spectrometry, synchrotron-based single-crystal X-ray diffraction, various spectroscopic and electrochemical methods, and magnetic studies revealing slow relaxation of the magnetisation for the Dy derivate.

The crystallisation of methyl stearate under a range of crystallisation conditions has been studied and three new polymorphs have been identified and structurally characterised. Form III (monoclinic, space group Cc, Z = 8) was obtained at room temperature by slow evaporation of a saturated solution in CS2. Form IV (monoclinic, space group C2/c, Z = 4) was obtained by slow cooling of the melt. Both structures were characterised by single crystal X-ray diffraction. Form V (monoclinic, space group Cc, Z = 4) was obtained from the melt by rapid cooling. X-ray and neutron powder diffraction methods were employed in the determination of this structure. Form V shows highly anisotropic thermal expansion, with expansion along the crystallographic b-axis being substantially greater than along the other two axes.

The dissolution of anhydrous iron bromide in a mixture of pyridine and acetonitrile, in the presence of an organic amine, results in the formation of an [Fe34] metal oxide molecule, structurally characterised by alternate layers of tetrahedral and octahedral FeIII ions connected by oxide and hydroxide ions. The outer shell of the complex is capped by a combination of pyridine molecules and bromide ions. Magnetic data, measured at temperatures as low as 0.4 K and fields up to 35 T, reveal competing antiferromagnetic exchange interactions; DFT calculations showing that the magnitudes of the coupling constants are highly dependent on both the Fe‐O‐Fe angles and Fe−O distances. The simplicity of the synthetic methodology, and the structural similarity between [Fe34], bulk iron oxides, previous FeIII–oxo cages, and polyoxometalates (POMs), hints that much larger molecular FeIII oxides can be made., E.K.B. thanks the EPSRC for funding (grants EP/N01331X/1 and EP/P025986/1). G.R. thanks UGC‐UKIERI grant number 184‐1/2018(lC) and SERB (CRG/2018/000430). S.D. thanks the UGC for an SRF fellowship. M.E. thanks MICINN (RTI2018‐094909‐J‐I00). J.S. thanks the Deutsche Forschungsgemeinschaft DFG (314331397 (SCHN 615/23‐1).

The synthesis and characterization of a series of complexes based upon a central tripalladium ditropylium (Tr) unit [Pd3Tr2]2+ containing different nitrogen-based ligands is reported. The complexes were synthesized in good yield and characterized by multi-nuclei NMR spectroscopy, elemental microanalysis and single-crystal X-ray crystallography. Variation in the equatorial ligand strongly influences Pd N bond distances, but has only a minor effect on Pd Pd distances. These complexes provide insight into the synthesis of materials of higher dimensionality.

A family of heterometallic Anderson-type 'wheels' of general formula [(M2M5II)-M-III(hmp)(12)](4+) (M-III = Cr or Al and M-II = Ni or Zn, Hhmp = 2-pyridinemethanol) has been extended to include M-III = Cr or Al and M-II = Co, Fe, Mn or Cu, affording five new species of formulae [Cr2Co5(hmp)(12)](ClO4)(4) (1), [Cr2Fe5(hmp)(12)](ClO4)(4) (2), [Cr2Mn5(hmp)(12)](ClO4)(4) (3), [Cr2Cu5(hmp)(12)](ClO4)(2)(NO3)(2) (4) and [Al2Co5(hmp)(12)](ClO4)(4) (5). As per previous family members, the metallic skeleton common to the cations of 1-5 describes a centred hexagon with the two M-III sites disordered around the outer wheel, with the exception of compound 4 where the Cu-II sites are localised. A structurally related, but enlarged planar disc possessing a [(M6MII)-M-III] hexagon capped on each edge by a Cu-II ion can be formed, but only when M-III = Al and M-II = Cu. In [(Al6Cu7II)-Cu-III(OH)(12)(hmp)(12)](ClO4)(6)(NO3)(2) (6) the Anderson moiety contains a central, symmetry-imposed octahedral Cu-II ion surrounded by a wheel of Al-III ions. Solid-state dc susceptibility and magnetisation measurements reveal the presence of competing exchange interactions in 1-5, and very weak antiferromagnetic exchange between the Cu-II ions in 6 which may be intra-and/or intermolecular in nature.

A large family of chromium(iii) dimers has been synthesised and magneto-structurally characterised using a combination of carboxylate and diethanolamine type ligands. The compounds have the general formula [Cr-2(R-1-deaH)(2)(O2CR2)Cl-2]Cl where R-1 = Me and R-2 = H (1), Me (2), CMe3 (3), Ph (4), 3,5-(Cl)(2)Ph (5), (Me)(5)Ph (6), R-1 = Et and R-2 = H (7), Ph (8). The compound [Cr-2(Me-deaH)(2)Cl-4] (9) was synthesised in order to study the effect of removing/adding the carboxylate bridge on the observed magnetic behaviour. Direct current (DC) magnetic susceptibility measurements showed ferromagnetic (FM) exchange interactions between the Cr(iii) centres in the carboxylate bridged family with coupling constants in the range +0.37

A new series of diacetylide-triphenylamine (DATPA) derivatives with five different alkyl chains in the para position, MeO, EtO, nPrO, iPrO and BuO, were synthesised, fully characterised and their function as hole-transport materials in perovskite solar cells (PSC) studied. Their thermal, optical and electrochemical properties were investigated along with their molecular packing and charge transport properties to analyse the influence of different alkyl chains in the solar cell parameters. The shorter alkyl chain facilitates more compact packing structures which enhanced the hole mobilities and reduced recombination. This work suggests that the molecule with the methoxy substituent (MeO) exhibits the best semiconductive properties with a power conversion efficiency of up to 5.63%, an open circuit voltage (Voc) of 0.83 V, a photocurrent density (Jsc) of 10.84 mA cm−2 and a fill factor of 62.3% in perovskite solar cells. Upon replacing the methoxy group with longer alkyl chain substituents without changing the energy levels, there is a decrease in the charge mobility as well as PCE (e.g. 3.29% for BuO-DATPA). The alkyl chain length of semiconductive molecules plays an important role in achieving high performance perovskite solar cells.

A family of heterometallic Anderson-type ‘wheels’ of general formula [MIII2MII5(hmp)12](ClO4)4 (where MIII = Cr or Al and MII = Ni or Zn giving [Cr2Ni5] (1), [Cr2Zn5] (2), [Al2Ni5] (3) and [Al2Zn5] (4); hmpH = 2-pyridinemethanol) have been synthesised solvothermally. The metallic skeleton common to all structures describes a centred hexagon with the MIII sites disordered around the outer wheel. The structural disorder has been characterised via single crystal X-ray crystallography, 1–3D 1H and 13C solution-state NMR spectroscopy of the diamagnetic analogue (4), and solid-state 27Al MAS NMR spectroscopy of compounds (3) and (4). Alongside ESI mass spectrometry, these techniques show that structure is retained in solution, and that the disorder is present in both the solution and solid-state. Solid-state dc susceptibility and magnetisation measurements on (2) and (3) reveal the Cr–Cr and Ni–Ni exchange interactions to be JCr–Cr = −1 cm−1 and JNi–Ni,r = −5 cm−1, JNi–Ni,c = 10 cm−1. Fixing these values allows us to extract JCr–Ni,r = −1.2 cm−1, JCr–Ni,c = 2.6 cm−1 for (1), the exchange between adjacent Ni and Cr ions on the ring is antiferromagnetic and between Cr ions on the ring and the central Ni ion is ferromagnetic., EKB thanks the EPSRC for funding (EP/N01331X/1, EP/P025986/1). UGN acknowledges funding from the Villum Young Investigator (VKR022364) and the Danish Council for Independent Research – Natural Sciences (DFF – 7014-00198). ME thanks MINECO for funding (MAT2015-68204-R)

High anion selectivity for PtCl6(2-) over Cl(-) is shown by a series of amidoamines, R(1)R(2)NCOCH2CH2NR(3)R(4) (L1 with R(1) = R(4) = benzyl and R(2) = R(3) = phenyl and L3 with R(1) = H, R(2) = 2-ethylhexyl, R(3) = phenyl and R(4) = methyl), and amidoethers, R(1)R(2)NCOCH2CH2OR(3) (L5 with R(1) = H, R(2) = 2-ethylhexyl and R(3) = phenyl), which provide receptor sites which extract PtCl6(2-) preferentially over Cl(-) in extractions from 6 M HCl solutions. The amidoether receptor L5 was found to be a much weaker extractant for PtCl6(2-) than its amidoamine analogues. Density functional theory calculations indicate that this is due to the difficulty in protonating the amidoether to generate a cationic receptor, LH(+), rather than the latter showing weaker binding to PtCl6(2-). The most stable forms of the receptors, LH(+), contain a tautomer in which the added proton forms an intramolecular hydrogen bond to the amide oxygen atom to give a six-membered proton chelate. Dispersion-corrected DFT calculations appear to suggest a switch in ligand conformation for the amidoamine ligands to an open tautomer state in the complex, such that the cationic N-H or O-H groups are also readily available to form hydrogen bonds to the PtCl6(2-) ion, in addition to the array of polarized C-H bonds. The predicted difference in energies between the proton chelate and nonchelated tautomer states for L1 is small, however, and the former is found in the X-ray crystal structure of the assembly [(L1H)2PtCl6]. The DFT calculations and the X-ray structure indicate that all LH(+) receptors present an array of polarized C-H groups to the large, charge diffuse PtCl6(2-) anion resulting in high selectivity of extraction of PtCl6(2-) over the large excess of chloride.

Three new complexes of the type Mn(NN)(CO)3Br have been synthesized, where NN = 5-substituted-1,10-phenanthroline. The novel compounds have been characterized by 1H NMR, FTIR, CV, HRMS, and UV/Vis, as well as X-ray crystallography in one case. The known NN = phenanthroline compound, and four analogous Re(I) compounds are also presented; their photophysical and electrochemical properties are discussed. A correlation is apparent between the MLCT absorbance bands and the electrochemical reduction of both the Re and Mn series of compounds.

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.-- et al., The reaction of the pro-ligand H4L, which combines the complementary phenolic oxime and diethanolamine moieties within the same organic framework, with Zn(NO3)2·6H2O and Ln(NO3)3·6H2O in a basic methanolic solution generates a family of isostructural heterometallic coordination compounds of general formula [Ln6Zn2(CO3)5(OH)(H2L)4(H3L)2(H4L)]NO3·xMeOH [Ln = Gd, x = 30 (1), Ln = Dy, x = 32 (2), Ln = Sm, x = 31 (3), Ln = Eu, x = 29 (4), Ln = Tb, x = 30 (5)]. The octametallic skeleton of the cage describes a heavily distorted [GdIII6] octahedron capped on two faces by ZnII ions. The metal core is stabilised by a series of μ3- and μ4-CO32− ions, originating from the serendipitous fixation of atmospheric CO2. The magnetic properties of all family members were examined via SQUID magnetometry, with the χMT product and VTVB data of the Gd analogue (1) being independently fitted by numerical diagonalisation to afford the same best-fit parameter JGd–Gd = −0.004 cm−1. The MCE of complex 1 was elucidated from specific heat data, with the magnetic entropy change reaching a value of 22.6 J kg−1 K−1 at T = 1.7 K, close to the maximum entropy value per mole expected from six GdIII spins (SGd = 7/2), 23.7 J kg−1 K−1., S.P. thanks the Danish Ministry of Science, Innovation and Higher Education for a Sapere Aude Fellowship (10-081659), M.E. acknowledges financial support from MINECO through grant MAT2012-38318-C03-01. EKB thanks the EPSRC.

A series of di-alkoxo bridged Cr(III) dimers have been synthesised using pyridine alcohol ligands. The structures fall into four general categories and are of formula: [Cr-2(OMe)(2)(pic)(4)]center dot 1/2 MeOH center dot 1/2 Et2O (1), [Cr-2(hmp)(2)(pic)(2)X-2] (where X = Cl (2), Br (3)), [Cr-2(L)(2)Cl-4(A)(2)]center dot 2S (where L = hmp, A = H2O and S = Et2O (4); L = hmp, A = pyridine and S = pyridine (5); L = hmp, A = 4-picoline and no S (6); L = hep, A = H2O and S = MeCN (7)), and [Cr(hmp)(hmpH) Cl-2] center dot MeCN (8). Direct current (DC) magnetic susceptibility measurements show relatively weak antiferromagnetic exchange interactions between the Cr(III) centres with J values

Three new complexes of the [Re6(μ3-Se)8]2+ core-containing cluster with isonicotinic acid (INA) were synthesized and characterized by multinuclear NMR (1H and 31P) and high-resolution mass spectrometry. Their molecular and crystal structures were determined by single-crystal X-ray diffraction studies. Unusual degrees of deprotonation of the INA ligand(s) are observed in the crystal structure, possibly due to the activation by the Lewis acidic cluster core. Extensive hydrogen bonding interactions occurring between carboxylate groups of neighboring cluster units as revealed by crystallographic studies lead to the assembly of both linear and zigzag multi-cluster chains in the solid state.

1,4-Piperazine-2,5-diones possessing C2hmolecular symmetry and bearing four methoxy, ethoxy, butoxy, hexyloxy, octyloxy, nonyloxy, dodecyloxy, or octadecyloxy groups weresynthesized from 2-amino-4,7-dialkoxyindan-2-carboxylic acids. Where possible, the piperazinediones were crystallized from appropriate solvents and the supramolecular organizations were determined by X-ray crystallography. In each case so studied, crystal assembly via three mutually orthogonal interactions, namely, R22(8) hydrogen bonding, arene perpendicular edge-to-center interactions, and alkyl chain interdigitation, was observed. The thermochemical properties of these compounds were studied by modulated differential scanning calorimetry. In most cases, one or more reversible thermal events were observed between room temperature and melting to an isotropic liquid. In the cooling cycle, freezing point temperatures were observed to decrease with increasing hydrocarbon chain length. This may be due to greater entropic penalties for hydrog...

The synthesis and characterization of a series of complexes based upon a central triplatinum ditropylium (Tr) unit [Pt 3 Tr 2 ] 2+ containing different halide ligands is reported. The complexes were synthesized in moderate yield and characterized by multi-nuclei NMR spectroscopy, mass spectrometry, microanalysis and X-ray crystallography. In addition it was demonstrated that mixed-metal, palladium–platinum sandwich complexes could also be formed [Pd n Pt 3-n Tr 2 X 3 ][ Y ] ( X = Cl, Br and I, Y = NBu 4 + or PBu 4 + ).

We report the preparation and electrochemical studies of a systematic series of mono- and di-nitro-substituted 2,2'-bipyridine (bipy) compounds [x-NO(2)-bipy (x = 3,4) and x,x'-(NO(2))(2)-bipy (x,x' = 3, 4, 5)] and their complexes with platinum(II), [Pt(x-NO(2)-bipy)Cl(2)] and [Pt(x,x'-(NO(2))(2)-bipy)Cl(2)]. The effect of the number and substitution pattern of the nitro groups on the low-lying acceptor molecular orbitals (involved in charge transfer transitions) is probed by in situ UV/Vis/NIR and EPR spectroelectrochemical methods, supported by DFT calculations. The LUMOs of x-NO(2)-bipy (x = 3-5) are largely localised on the NO(2)-pyridyl moiety; this is also true of their {PtCl(2)} complexes but with a small but significant shift of electron density from the nitro groups. The LUMOs of x,x'-(NO(2))(2)-bipy with x = 3 and 5 are delocalised over both NO(2)-pyridyl rings, but for 4,4'-(NO(2))(2)-bipy is localised on a single NO(2)-pyridyl ring. In all cases the LUMO of the [Pt(x,x'-(NO(2))(2)-bipy)Cl(2)] complexes is delocalised over both nitro-pyridyl rings. For all complexes, the 4(4') derivatives allows greatest overlap with metal valence orbitals in the LUMO.

The title compounds, C66H46, (I), and C66H42F4, (II), are polyphenylated arylenes synthesized by one-step Diels–Alder cycloaddition reactions. In both structures, all molecules lie on crystallographic inversion centers. In the case of (I), there are two half-molecules present in the asymmetric unit, (IA) and (IB); the geometry of each half-molecule differs principally in the magnitudes of the dihedral angles between mean planes fitted through the central aryl ring and the pendant phenyl rings. The crystal used was a non-merohedral twin, with a refined twin scale factor of 0.460 (8). The dihedral angle between the plane of the central tetrafluorinated ring and the adjacent tetraphenylated ring in (II) is 83.87 (4)°, significantly greater than the dihedral angles of 49.89 (12) and 54.38 (10)° found in the two half-molecules in (IA) and (IB), respectively, and attributed to intermolecular C—H...F hydrogen bonding in (II). Intermolecular C—H...π bonding is found in (I). Two interactions have the C—H bond oriented towards the centroid (Cg) of a butadiene fragment of a phenyl ring; both H...Cgdistances are approximately 2.68 Å and the interactions connect adjacent molecules into stacks in thec-axis direction. The composition of the stacks alternates,i.e.(IA)–(IB)–(IA)–(IB)etc. A third, weaker, C—H...π interaction and a phenyl–phenyl close contact connect each end of the long molecular axes of (IB) with an adjacent molecule of (IA) into chains which run perpendicular to the (140) and (\overline{1}40) planes. C—H...F interactions in (II) have the most profound influence on the molecular and crystal structure, the main effect of which is the above-mentioned increase in the dihedral angle between the plane of the central tetrafluorinated ring and the adjacent tetraphenylated ring. C—H...F interactions have refined H...F distances of 2.572 (15) and 2.642 (16) Å, with approximate C—H...F angles of 123 and 157°, respectively. These form a hydrogen-bonded ribbon structure which propagates in theb-axis direction.

An understanding of the interaction of weakly coordinating ligands with zero-valent palladium complexes is of importance to understanding the potential catalytic mechanisms and properties of these complexes. We have used a combination of multi-nuclei NMR, microanalysis and single crystal X-ray diffraction to characterize a series of tripalladium ditropylium sandwich complexes that possess one or more triflate [CF3SO3]− ligands. The influence of the strong electronic effects on the triflate ligand cause a significant change in the internal bond lengths and angles of the complexes which are coupled to systematic shifts of the tropylium 1H and 13C resonances in the NMR spectra. The use of the Advanced Light Source (ALS) permitted crystallographic characterization of only the third example of a complex containing a Pd–FBF3 bond.

Lanthanide hydroxide cluster complexes with acetylacetonate were synthesized by the hydrolysis of the corresponding hydrated lanthanide acetylacetonates in methanol in the presence of triethylamine. Polymeric lanthanide hydroxide complexes based on diamond-shaped dinuclear repeating units of [Ln(2)(CH(3)CO(3))(2)](4+) (Ln = La, Pr) and discrete complexes featuring a tetranuclear distorted cubane core of [Ln(4)(μ(3)-OH)(2)(μ(3)-OCH(3))(2)](8+) (Ln = Nd, Sm) and a nonanuclear core of [Ln(9)(μ(4)-O)(μ(4)-OH)(μ(3)-OH)(8)](16+) (Ln = Eu-Dy, Er, Yb) were obtained. The dependence of the cluster nuclearity on the identity of the lanthanide ion is rationalized in terms of the influences of a metal ion's Lewis acidity and the sterics about the Ln-OH unit on the kinetics of the assembly process that leads to a particular cluster.

Two Hg(II) complexes with the cluster-complex ligand [Re6(μ3-Se)8(PEt3)5(PTA)](SbF6)2 (PTA = 1,3,5-triaza-7-phosphaadamantane), {[Re6(μ3-Se)8(PEt3)5(PTA)(Hg3I7)](SbF6)}n·(CH3CN)n (1) and {[Re6(μ3-Se)8(PEt3)5(PTA)]2(Hg4I9)}(SbF6)3·2CH3CN (2), were prepared and structurally characterized. The two compounds were obtained from reactions conducted at different temperatures under otherwise identical conditions. Recrystallization of the room-temperature product 2 in a different solvent mixture produced yet another new Hg(II) complex, {[Re6(μ3-Se)8(PEt3)5(PTA)](Hg3I8)}·CH3CN (3) which may be considered as a consequence of the dissociation of the kinetic product 2 in solution and the re-assembly of necessary components to generate the new compound upon crystallization. The solid-state structure of 1 contains polymeric cluster columns, in which the PTA ligand adopts a hitherto unknown coordination mode with simultaneous coordination of all four (one P and three N atoms) potentially coordinating atoms.

As part of a study into new Fentanyl-derived opioid compounds with potent analgesic activity and reduced side effects the starting material title compound, C14H21N3O (1), was synthesized and characterized by NMR spectroscopy and single-crystal X-ray diffraction. The crystal structure is monoclinic Cc with unit cell parameters a = 14.1480(3) A, b = 14.1720(4) A, c = 27.6701(7) A, β = 96.956(1)°, α = γ = 90°. The compound has crystallized with four crystallographically unique molecules in the asymmetric unit; each molecule has a very similar conformation and an analysis of the structure shows that although all four unique molecules overlay very well there is no evidence of pseudo-symmetry which would relate the molecules in the higher symmetry space group C2/c. The crystal packing consists of two separate hydrogen bonded chains which are linked together to form a thick 2D structure in the ab plane. The compound N′-(1-benzylpiperidin-4-yl)acetohydrazide crystallizes with four crystallographically unique molecules in the asymmetric unit; each molecule has a very similar conformation but there is no evidence of pseudo-symmetry.

A combination of multinuclei NMR, UV-vis spectroscopy, and single crystal X-ray diffraction was used to characterize a new series of tripalladium ditropylium sandwich complexes [Pd(3)Tr(2)(E)(3)][BF(4)](2) (E = PPh(3), AsPh(3), and SbPh(3) and PEt(3)). Ligand substitution leads to a systematic shift of the (1)H and (13)C NMR tropylium resonances and is correlated with the electron donating properties of the substituent group. Replacement of the ligand increases the palladium-pnictogen bond length in the order PAsSb; however, this only slightly alters the internal Pd-Pd bond lengths, supporting the hypothesis that there are only weak Pd-Pd bonding interactions.

The N-functionalized macrocyclic ligand 2,13-bis(1-naphthalenylmethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo(14,4,01.18,07.12)docosane (L3) and its copper(II) complex were prepared. The crystal structure of [Cu(L3)](ClO4)2·2CH3CN was determined by single-crystal X-ray diffraction at 150 K. The copper atom, which lies on an inversion centre, has a square planar arrangement and the complex adopts a stable trans-III configuration. The longer distance [2.081(2) A] for Cu–N(tertiary) compared to 2.030(3) A for Cu–N(secondary) may be due to the steric effect of the attached naphthalenylmethyl group on the tertiary nitrogen atom. Two perchlorate ions are weakly attached to copper in axial sites and are further connected to the ligand of the cation through NH···O hydrogen bonds [N···O 3.098 A]. IR and UV/Vis spectroscopic properties are also described.

A crystallographic investigation of the title compound, C22H28Cl2N4O4, using crystals obtained under different crystallization conditions, revealed the presence of two distinct polymorphic forms. The mol­ecular conformation in the two polymorphs is very different: one adopts a ‘C’ shape, whereas the other adopts an ‘S’ shape. In the latter, the molecule lies across a crystallographic twofold axis. The ‘S’-shaped polymorph undergoes a reversible ortho­rhom­bic-to-monoclinic phase transition on cooling, whereas the structure of the ‘C’-shaped polymorph is temperature insensitive.

Reaction of 4,4′-bipyridine (4,4′-bipy) with barbituric (BAH), orotic (ORH), and uracil-5-carboxylic acids (U5CAH) yielded three new products, which have been characterized by single-crystal X-ray diffraction. The products include a co-crystal of neutral species with Z′ = 2 (4,4′-bipy/BAH), an organic complex ion pair (4,4′-bipy/ORH) and a compound containing both ionic and hydrogen-bonded neutral species (4,4′-bipy/U5CAH). Partial proton transfer is observed in both of the ionic cases, and in all three structures the crystal packing arrangement is such that weak hydrogen bonding, π···π and molecular dipole interactions are optimized.