Diphosphanes derived from phobane and phosphatrioxa-adamantane: similarities, differences and anomalies

The homodiphosphanes CgP-PCg (1) and PhobP-PPhob (2) and the heterodiphosphanes CgP-PPhob (3), CgP-PPh(2) (4a), CgP-P(o-Tol)(2) (4b), CgP-PCy(2) (4c), CgP-P(t)Bu(2) (4d), PhobP-PPh(2) (5a), PhobP-P(o-Tol)(2) (5b), PhobP-PCy(2) (5c), PhobP-P(t)Bu(2) (5d) where CgP = 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamant-9-yl and PhobP = 9-phosphabicyclo[3.3.1]nonan-9-yl have been prepared from CgP(BH(3))Li or PhobP(BH(3))Li and the appropriate halophosphine. The formation of 1 is remarkably diastereoselective, with the major isomer (97% of the product) assigned to rac-1. Restricted rotation about the P-P bond of the bulky meso-1 is detected by variable temperature (31)P NMR spectroscopy. Diphosphane 3 reacts with BH(3) to give a mixture of CgP(BH(3))-PPhob and CgP-PPhob(BH(3)) which was unexpected in view of the predicted much greater electron-richness of the PhobP site. Each of the diphosphanes was treated with dimethylacetylene dicarboxylate (DMAD) in order to determine their propensity for diphosphination. The homodiphosphanes 1 and 2 did not react with DMAD. The CgP-containing heterodiphosphanes 4a-d all added to DMAD to generate the corresponding cis alkenes CgPCH(CO(2)Me)=CH(CO(2)Me)PR(2) (6a-d) which have been used in situ to form chelate complexes of the type [MCl(2)(diphos)] (7a-d) where M = Pd or Pt. The PhobP-containing heterodiphosphanes 3 and 5a-d react anomalously with DMAD and do not give the products of diphosphination. The X-ray crystal structures of the diphosphanes 2, 3, 4a, and 5a, the monoxide and dioxide of diphosphane 1, and the platinum chelate complex 7c have been determined and their structures are discussed.     

Predicting the solubility of xenon in n-hexane and n-perfluorohexane: a simulation and theoretical study

The solubility of xenon in n-hexane and n-perfluorohexane has been studied using both molecular simulation and a version of the SAFT approach (SAFT-VR). The calculations were performed close to the saturation line of each solvent, between 200 K and 450 K, which exceeds the smaller temperature range where experimental data are available in the literature. Molecular dynamics simulations, associated with Widom's test particle insertion method, were used to calculate the residual chemical potential of xenon in n-hexane and n-perfluorohexane and the corresponding Henry's law coefficients. The simulation results overestimate the solubility of xenon in both solvents when simple geometric combining rules are used, but are in good agreement if a binary interaction parameter is included. With the SAFT-VR approach we are able to reproduce the experimental solubility for xenon in n-hexane, using simple Lorentz-Berthelot rules to describe the unlike interaction. In the case of n-perfluorohexane as a solvent, a binary interaction parameter was introduced, taken from previous work on (xe + C₂F₆) mixtures. Overall, good agreement is obtained between the simulation, theoretical and experimental data.     

A synthetic route to heteronuclear clusters containing iridium and rhodium: X-ray crystal structures of [IrOs3(μ-H)2(μ-Cl)(CO)12] and [Ir2Rh2(μ-CO)(μ3-CO)2(CO)4(η-C5Me5)2]

The iridium and rhodium complexes [MCl(CO)₂(NH₂C₆H₄Me-4)] (M = Ir or Rh) react with [Os₃(μ-H)₂(CO)₁₀] to give the tetranuclear clusters [MOs₃(μ-H)₂(μ-Cl)(CO)₁₂]; the iridium compound being structurally identified by X-ray diffraction. Similarly, [IrCl(CO)₂(NH₂C₆H₄Me-4)] and [Rh₂(μ-CO)₂(η-C₅Me₅)₂] afford the tetranuclear cluster [Ir₂Rh₂(μ-CO)(μ₃-CO)₂(CO)₄(η-C₅Me₅)₂], also characterised by single-crystal X-ray crystallog     

Three sulfur‐containing diborane(4) compounds

The preparation and structures of three diborane(4) compounds are described. The compound B₂(3,4‐S₂C₄H₂‐1‐S)₂ [2,2′‐bi(1,3,5,2‐tri­thia­borapentalene), C₈H₄B₂S₆] is planar and lies at a crystallographic inversion centre. The amine adducts [B₂(C₃S₅)₂(NHMe₂)₂] [2,2′‐bis­(di­methyl­amino)‐2,2′‐bi(1,3,4,6,2‐tetra­thia­borapentalene‐5‐thione), C₁₀H₁₄B₂N₂S₁₀] and [B₂(1,2‐S₂C₂H₄)₂(NHMe₂)₂]·0.33CH₂Cl₂ [1,2‐bis­(di‐methylamino)‐1,1:2,2‐bis(dimethylenedithioxy)diborane(4) di­chloro­methane solvate, C₈H₂₂B₂N₂S₄·0.33CH₂Cl₂] contain di­methyl­amine ligands bound to each boron in an anti conformation about the B—B bond, with tetrahedral geometry at the B atoms. The crystal structures display a number of S?S interactions, which appear to dictate the packing arrangements.     

Potassium S2N-heteroscorpionates: structure and iridaboratrane formation

The potassium salts of the new S(2)N-heteroscorpionate ligand hydrobis(methimazolyl)(3,5-dimethylpyrazolyl)borate [HB(mt)(2)(pz(3,5-Me))](-) and its known analogue hydrobis(methimazolyl)(pyrazolyl)borate [HB(mt)(2)(pz)](-) (prepared from KTp' or KTp and methimazole, Hmt), and the adduct KTp·Hmt have polymeric structures in the solid state (the first a ladder and the other two chains). The iridaboratranes [IrHLL'{B(mt)(2)X}] (X = pz(3,5-Me) or pz), prepared from the heteroscorpionate anion and [{Ir(cod)(μ-Cl)}(2)] (LL' = cod), subsequent carbonylation [LL' = (CO)(2)] and then reaction with phosphine [LL' = (CO)(PR(3)), R = Ph or Cy], have a pendant pyrazolyl ring and a bicyclo-[3.3.0] cage formed by an S(2)-bound B(mt)(2) fragment. The binuclear species [(cod)HIr{μ-B(mt)(3)}IrCl(cod)], the only isolated product of the reaction of KTm with [{Ir(cod)(μ-Cl)}(2)], also has an S(2)-bound iridaboratrane unit but with the third mt ring linked to square planar iridium(I).     

A cationic, four-coordinate, ten-electron bismuth(III) complex: Synthesis and structure of [BiPh2(HMPA)2][BF4] (HMPA = hexamethylphosphoramide)

The synthesis and structure of the cationic, four-coordinate, ten-electron bismuth(III) complex [BiPh₂(HMPA)₂]⁺ (HMPA = hexamethylphosphoramide) is reported. The coordination geometry around the bismuth centre is that of a trigonal bipyramid with one equatorial site vacant and with phenyls in the other equatorial positions and the HMPA ligands in axial sites.