The Lewis acidity of organylbismuth(III) compounds. New organylbismuth(III) dithiocarbamate chemistry. The crystal and molecular structure of bis(diethyidithiocarbamato)phenylbismuth(III) and bis(diethyldithiocarbamato)-[2-(2′-pyridyl)phenyl]bismuth(III)

Abstract

The compound BiBr₂L [L = 2-(2′-pyridyl)phenyl] has been prepared via a transmetallation reaction between BiBr₃ and [HgCl(L)]. It reacts with [NEt₄]l and Na(O₂CEt) to give the ionic derivatives [NEt₄][BiBr₂l(L)] and Na[BiBr₂(O₂CEt)L]. I.r. evidence suggests that the co-ordination of the extra ligands is accompanied by a reduction of the strength of the Bi–N interaction. The compound undergoes a substitution reaction with Na(S₂CNEt₂) to give [Bi(S₂CNEt₂)₂L](1), and a new preparation of [BiPh(S₂CNEt₂)₂], (2), via[BiPh(O₂CCHCHCO₂H)₂] is reported. Some ¹³C n.m.r. data are presented and, in particular, the first definitive assignments of ipso-carbon resonances in arylbismuth compounds are given. The crystal and molecular structures of compounds (1) and (2) determined from three dimensional X-ray data are compared. Compound (1) is triclinic, space group P with a= 10.126(1), b= 10.447(2), c= 12.512(8)Å, α= 82.06(4), β= 71.27(4), γ= 86.92(1)°, and Z= 2; R= 0.0297 for 4 063 observed reflections. The co-ordination about bismuth is pseudo-pentagonal bipyramidal with four diethyldithiocarbamato S atoms and the pyridyl N atom constituting the equatorial plane, and the phenyl carbon atom and the lone pair of electrons occupying the apical positions. The compound is essentially monomeric with two long contacts [Bi ⋯ Bi′ 3.954(1) and Bi ⋯ S′ 3.876(2)Å] to a neighbouring molecule. Bond lengths are Bi–C 2.263(7), Bi–S 2.766(2)–2.895(2), and Bi–N 2.553(6)Å. Compound (2) is monoclinic, space group P2₁/c, with a= 14.796(7), b= 9.437(9), c= 16.942(8)Å, β= 109.50(5), and Z= 4; R= 0.0374 for 3 017 observed reflections. The co-ordination about bismuth is also pseudo-pentagonal bipyramidal with the equatorial plane comprising the four diethyldithiocarbamato sulphur atoms and a bridging interaction with a sulphur in a centrosymmetrically related molecule, the phenyl carbon atom and the lone pair of electrons are located in the apical positions. Bond lengths are Bi–C 2.241(10), Bi–S 2.671(2)–2.942(2), and Bi ⋯ S′ 3.421 (2)Å.