Self-assembly of square-planar halide complexes of phosphine-stabilised stibenium salts

Chloride and bromide ions direct the self-assembly of supramolecular square-planar halide complexes in which four trimethylphosphine-stabilised diphenylstibenium ions surround the central halide ion in discrete centrosymmetrical structures of C4h symmetry

Triphenylphosphine-Stabilized Diphenyl-Arsenium, -Stibenium, and -Bismuthenium Salts

Two series of triphenylphosphine-stabilized diphenyl-arsenium, -stibenium, and -bismuthenium salts of the types [(Ph3P)EPh2]PF 6 (where E = As, Sb, Bi) and [(Ph3P)2EPh 2]PF6 (where E = Sb, Bi) have been synthesized and their structures and bonding investigated by X-ray crystallography and density functional theory at the PBE/TZP level. The coordination geometries around the central group 15 elements are distorted trigonal pyramidal in the mono(triphenylphosphine) complexes and distorted trigonal bipyramidal in the bis(triphenylphosphine) complexes, where in each case the stereochemically active lone pair of the six-electron, angular diphenyl-arsenium, -stibenium, or -bismuthenium ion occupies an equatorial position in the trigonal plane containing the C-E-C bonds. For the complexes [(Ph3P)EPh 2]-PF6 (E = As, Sb, Bi), the theoretical results for the cations are consistent with the dative covalent formulation [Ph 3P→EPh2]+, especially for E = As and Sb, but for [(Ph3P)2EPh2]PF6 (E = Sb, Bi) the bonding between the phosphines and the stibenium or bisthmuthenium ion is best described as an induced dipole-ion interaction

Synthesis and characterization of [( η 6 -arene)RuCl 2 (R 2 AsCH=CH 2 )] and tethered arsinopropylarene�ruthenium(II) complexes.

The complexes [(η6-arene)RuCl2(R2AsCH=CH2)] [arene = MeC6H5, R = Ph (1a), R = Cy (1b); p-MeC6H4Me, R = Ph (2a), R = Cy (2b); o-MeC6H4Me, R = Ph (3a), R = Cy (3b); 1,3,5-Me3C6H3, R = Ph (4a); p-MeC6H4CHMe2, R = Ph (5a), R = Cy (5b); 1,2,4,5-Me4C6H2, R =

Self-Assembly of Square-Planar Halide Complexes of Trimethylphosphine-Stabilized Diphenyl-Arsenium, -Stibenium, and -Bismuthenium Hexafluorophosphates

Square-planar halide complexes in which four trimethylphosphine-stabilized diphenyl-stibenium or-bismuthenium ions surround a central halide ion in discrete centrosymmetrical structures of C₄h symmetry have been isolated and their structures determined by X-ray crystallography. The structures are stabilized by electrostatic interactions between the halide ion and four positively charged trimethylphosphine-stabilized diphenyl-stibenium or-bismuthenium ions, as well as four edge-to-face phenyl-phenyl embraces above and below the plane containing the nine main group elements. The parent halide-free trimethylphosphine-stabilized diphenyl-arsenium,-stibenium, and-bismuthenium hexaflurophosphate complexes have also been prepared and structurally characterized.RS and SBW gratefully acknowledge the Australian Research Council for financial support

Automorphism groups of circulant digraphs with applications to semigroup theory

We characterize the automorphism groups of circulant digraphs whose connection sets are relatively small, and of unit circulant digraphs. For each class, we either explicitly determine the automorphism group or we show that the graph is a "normal" circulant, so the automorphism group is contained in the normalizer of a cycle. Then we use these characterizations to prove results on the automorphisms of the endomorphism monoids of those digraphs. The paper ends with a list of open problems on graphs, number theory, groups and semigroups