Di-μ-chlorido-bis­[dichlorido(3,3′,5,5′-tetra­methyl-4,4′-bipyrazol-1-ium-κN 2′)copper(II)] dihydrate

The structure of the centrosymmetric title compound, [Cu2Cl6(C10H15N4)2]·2H2O, consists of a dimeric [{(HMe4bpz)CuCl3}2] unit (HMe4bpz is 3,3′,5,5′-tetra­methyl-4,4′-bipyrazol-1-ium) with two solvent water molecules. Each [HMe4bpz]+ cation is bonded to a CuCl3 unit through a Cu—N dative bond, effectively making square-planar geometry at the Cu atom. Two of these units then undergo a face-to-face dimerization so that the Cu atoms have a Jahn–Teller distorted square-pyramidal geometry with three chlorides and an N atom in the basal plane and one chloride weakly bound in the apical position. Several N—H⋯Cl, O—H⋯Cl and N—H⋯O hydrogen bonds form a three-dimensional network

2,2′-Biimidazolium hexa­aqua­manganese(II) bis­(sulfate)

The title compound, (C6H8N4)[Mn(H2O)6](SO4)2, was obtained by cocrystallization of 2,2′-biimidazolium sulfate and bis­(tetra­butyl­ammonium) tetra­chlorido­manganate(II). The asymmetric unit contains one isolated (SO4)2− anion, one half of an octa­hedral [Mn(H2O)6]2+ dication and one half of a 2,2′-biimidazolium dication, each of which lies on an inversion centre. Mol­ecules are connected by a three-dimensional N—H⋯O and O—H⋯O hydrogen-bond network

2-Oxo-1,2-dihydro­pyrimidin-3-ium di-μ-chlorido-bis­{dichloridobis[pyrimidin-2(1H)-one-κN 3]cuprate(II)} dihydrate

The asymmetric unit of the title compound, (C4H5N2O)2[Cu2Cl6(C4H4N2O)2]·2H2O, consists of one cation, one half of a centrosymmetric dianion and one water mol­ecule. The centrosymmetric dianion formed by dimerization in the crystal structure has neutral pyrimidin-2-one ligands coordinated to each copper(II) centre through Cu—N bonds. The Cu atoms each have a distorted trigonal bipyramidal geometry, with the N atom of the pyrimidin-2-one ligand in an axial position, and dimerize by sharing two equatorial Cl atoms. N—H⋯Cl, O—H⋯Cl and N—H⋯O hydrogen bonds connect the anions, cations and water mol­ecules, forming a three-dimensional network

Innovation in crystal engineering

The first CrystEngComm discussion meeting on crystal engineering has demonstrated that the field has reached maturity in some areas (for example: design strategies, characterization of solid compounds, topological analysis of weak and strong non-covalent interactions), while the quest for novel properties engineered at molecular and supramolecular levels has only recently begun and the need for further research efforts is strongly felt. This Highlight article aims to provide a forward look and a constructive discussion of the prospects for future developments of crystal engineering as a bridge between supramolecular and molecular materials chemistry

Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)

[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372–1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties

The co-ordination chemistry of tris(3,5-dimethylpyrazolyl) methane manganese carbonyl complexes: Synthetic, electrochemical and DFT studies

The tricarbonyl [Mn(CO)3{HC(pz′)3}][PF6] 1+[PF6]− (pz′ = 3,5-dimethylpyrazolyl) reacts with a range of P-, N- and C-donor ligands, L, in the presence of trimethylamine oxide to give [Mn(CO)2L{HC(pz′)3}]+ {L = PEt33+, P(OEt)34+, P(OCH2)3CEt 5+, py 6+, MeCN 7+, CNBut8+ and CNXyl 9+}. The complex [Mn(CO)2(PMe3){HC(pz′)3}]+2+ is formed by reaction of 7+ with PMe3. Complexes 2+ and 6+ were structurally characterised by X-ray diffraction methods. Reaction of 7+ with half a molar equivalent of 4,4′-bipyridine gives a purple compound assumed to be the bridged dimer [{HC(pz′)3}Mn(CO)2(μ-4,4′-bipy)Mn(CO)2{HC(pz′)3}]2+102+. The relative electron donating ability of HC(pz′)3 has been established by comparison with the cyclopentadienyl and tris(pyrazolyl)borate analogues. Cyclic voltammetry shows that each of the complexes undergoes an irreversible oxidation. The correlation between the average carbonyl stretching frequency and the oxidation potential for complexes of P- and C-donor ligands is coincident with the correlation observed for [Mn(CO)3−mLm(η-C5H5−nMen)]. The data for complexes of N-donor ligands, however, are not coincident due to the presence of a node (and phase change) between the metal and the N-donor in the HOMO of the complex as suggested by preliminary DFT calculations

Two-step solid-state synthesis of PEPPSI-type compounds

peer-reviewedThe two-step mechanochemical preparation of carbene–pyridine complexes of palladium and platinum is reported. The organometallic products, which represent a class of commercially available catalysts, are rapidly formed in excellent yield proving solvent-free synthesis to be a viable synthetic alternative even in the case of NHC-containing compounds

Unexpectedly high barriers to M–P rotation in tertiary phobane complexes : PhobPR behavior that is commensurate with tBu2PR

The four isomers of 9-butylphosphabicyclo[3.3.1]nonane, s-PhobPBu, where Bu = n-butyl, sec-butyl, isobutyl, tert-butyl, have been prepared. Seven isomers of 9-butylphosphabicyclo[4.2.1]nonane (a5-PhobPBu, where Bu = n-butyl, sec-butyl, isobutyl, tert-butyl; a7-PhobPBu, where Bu = n-butyl, isobutyl, tert-butyl) have been identified in solution; isomerically pure a5-PhobPBu and a7-PhobPBu, where Bu = n-butyl, isobutyl, have been isolated. The σ-donor properties of the PhobPBu ligands have been compared using the JPSe values for the PhobP(═Se)Bu derivatives. The following complexes have been prepared: trans-[PtCl2(s-PhobPR)2] (R = nBu (1a), iBu (1b), sBu (1c), tBu (1d)); trans-[PtCl2(a5-PhobPR)2] (R = nBu (2a), iBu (2b)); trans-[PtCl2(a7-PhobPR)2] (R = nBu (3a), iBu (3b)); trans-[PdCl2(s-PhobPR)2] (R = nBu (4a), iBu (4b)); trans-[PdCl2(a5-PhobPR)2] (R = nBu (5a), iBu (5b)); trans-[PdCl2(a7-PhobPR)2] (R = nBu (6a), iBu (6b)). The crystal structures of 1a–4a and 1b–6b have been determined, and of the ten structures, eight show an anti conformation with respect to the position of the ligand R groups and two show a syn conformation. Solution variable-temperature 31P NMR studies reveal that all of the Pt and Pd complexes are fluxional on the NMR time scale. In each case, two species are present (assigned to be the syn and anti conformers) which interconvert with kinetic barriers in the range 9 to >19 kcal mol–1. The observed trend is that, the greater the bulk, the higher the barrier. The magnitudes of the barriers to M–P bond rotation for the PhobPR complexes are of the same order as those previously reported for tBu2PR complexes. Rotational profiles have been calculated for the model anionic complexes [PhobPR-PdCl3]− using DFT, and these faithfully reproduce the trends seen in the NMR studies of trans-[MCl2(PhobPR)2]. Rotational profiles have also been calculated for [tBu2PR-PdCl3]−, and these show that the greater the bulk of the R group, the lower the rotational barrier: i.e., the opposite of the trend for [PhobPR-PdCl3]−. Calculated structures for the species at the maxima and minima in the M–P rotation energy curves indicate the origin of the restricted rotation. In the case of the PhobPR complexes, it is the rigidity of the bicycle that enforces unfavorable H···Cl clashes involving the Pd–Cl groups with H atoms on the α- or β-carbon in the R substituent and H atoms in 1,3-axial sites within the phosphabicycle