Arsenic(III) halide complexes with phosphine and arsine co-ligands: synthesis, spectroscopic and structural properties

AsX3 (X = Cl, Br or I) reacts with one molar equivalent of L [L = o-C6H4(PMe2)(2), o-C6H4(PPh2)(2), o-C6H4(AsMe2)(2) or MeC(CH2AsMe2)(3)] in rigorously anhydrous CH2Cl2 or thf solution to give colourless or yellow solids of composition [AsX3L]. Using two molar equivalents of PMe3 with AsX3 affords solids of empirical formula [AsX3(PMe3)(2)], whereas one molar equivalent of PMe3 with AsCl3 gives the 1 : 1 complex [AsCl3(PMe3)]. Reaction of AsX3 with AsMe3 gives only the 1 : 1 product [AsX3(AsMe3)], whether using a 1 : 1 or 1 : 2 AsCl3 : AsMe3 ratio. The products have been characterised by microanalysis, and IR, H-1 NMR and P-31{H-1} NMR spectroscopies, where appropriate. The crystal structures of three species, [AsCl3(PMe3)], [AsBr3{o-C6H4(AsMe2)(2)}] and [AsI3{o-C6H4(AsMe2)(2)}] have been determined. [AsCl3(PMe3)] adopts a dimeric structure formed through mu-dichloro-bridged edge-shared square pyramidal moieties with anti PMe3 ligands in the axial sites. Interestingly, in the lattice, there are two crystallographically independent dimers which are arranged orthogonally with long range As ? ? ? Cl contacts between between them, giving rise to in finite chains. Thus, in one dimer the As centres are formally 5-coordinate, while in the adjacent dimer the coordination is [5 + 1]. The complexes [AsX3{o-C6H4(AsMe2)(2)}] (X = Br or I) are both dimeric through mu-dihalo-bridged bioctahedra in the isomer (A) form. Trends in bond length and angle distributions are considered and the stereochemical activity of the lone pair on the As(III) acceptor discussed.

crystal-structure, bismuth(iii)

10.1039/b107926n

1477-9226

1188-1192

Hill, Nicholas J.

c588ad7e-5668-46b9-b84a-791b664f37aa

Levason, William

e7f6d7c7-643c-49f5-8b57-0ebbe1bb52cd

Reid, Gillian

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