Crystal structure of methyltriphenylphosphonium (η4-decaborato)-dimethylthallate(III)

Abstract

The title compound crystallizes in the orthorhombic space group Pbca, with a= 15.254(1), b= 20.576(2), c= 17.840(2)Å, and Z= 8. The structure was solved from diffractometer data by the heavy-atom method and refined by least squares to R0.074 for 2 378 observed reflections. The structure is built up from methyltriphenylphosphonium cations with a normal configuration about the phosphorus atom, ant [Tl(η⁴-B₁₀H₁₂)Me₂]^– anions in which the thallium atom is bonded to two methyl groups at 2.22(3)Å and to four boron atoms [B(5) 2.51(2), B(10) 2.61(2), B(6) 2.76(2), and B(9) 2.77(2)Å]. The anion has an approximate mirror-plane containing C₂Tl,B(1), B(3) and there is no indication of preferential η²-bonding to B(5)–B(6) as implied by the complex ¹¹B n.m.r. spectra of the compound in donor solvents.