Reaction of trimethylaluminium with sulphur derivatives of bis(diphenylphospino)methane and bis(diphenylphosphino)ethane. Synthesis and molecular structure of [Al(CH 3) 2][(C 6H 5) 2P(S)CHP(S)(C 6H 5) 2][Al(CH 3) 3] and [Al(CH 3) 3] 2[(C 6H 5) 2P(S)CH 2CH 2P(S)(C 6H 5) 2

Abstract

Reaction of trimethylaluminium with bis(diphenylthiophosphinoyl)methane and bis(diphenylthiophosphinoyl)ethane affords the crystalline compounds [Al(CH 3) 2][(C 6H 5) 2P(S)CHP(S)(C 6H 5) 2][Al(CH 3) 3] ( I) and [Al(CH 3) 3] 2[(C 6H 5) 2P(S)CH 2CH 2P(S)(C 6H 5) 2] ( II), respectively. Compound I crystallizes in the monoclinic space group P2 1/ n (No. 14) with unit cell parameters a = 18.126(2), b = 9.569(2), c = 19.394(3) Å, β = 110.20(1)°, V = 3156.7(7) Å 3, and ϱ = 1.21 g cm −3 for Z = 4. Least-squares refinement based on 2891 observed reflections [ I > 3σ( I)] converged at R = 0.040, R w = 0.051. Compound II crystallizes in the triclinic space group P 1 (No. 2) with unit cell parameters a = 12.076(3), b = 13.148(3), c = 13.114(3) Å, α = 98.32(2), β = 100.55(2), γ = 116.41(2)°, V = 1772.1(7) Å 3, and ϱ = 1.14 g cm −3 for Z = 2. Least-squares refinement based on 3012 observed reflections [ I > 3σ( I)] converged at R = 0.049, R w = 0.056. Compound I results from a unique condensation reaction in which one of the central methylene CH bonds was cleaved in addition to one AlCH 3 bond, resulting in an unusual AlPSC four-membered ring. The length of the hydrocarbon chain in bidentate phosphine ligands appears to play an important role in their reactivity with organo-aluminium species, as reaction of bis(diphenylthiophosphinoyl)ethane with trimethylaluminium did not facilitate condensation, but resulted in an addition compound, II. These results demonstrate a comparatively greater acidity of the hydrocarbon chain hydrogen atoms of bis(diphenylthiophosphinoyl)methane relative to bis(diphenylthiophosphinoyl)ethane.