Synthesis, characterization and in vitro antitumour activity of diorganotin bisxanthates [R2Sn(S2COR′)2] (R=Me, Et, nBu, Ph; R′=Et, iPr, Hex) and crystal structure of bis(O‐ethyldithiocarbonato)diphenyltin(IV)

A series of diorganotin bisxanthate compounds, [R2Sn(S2COR′)2] (R=Me, Et, nBu, tBu, and Ph; R′Et, iPr and cHex) have been prepared and characterized by spectroscopic methods (IR, NMR and FAB MS). The xanthate ligands chelate the R2Sn moieties forming disparate Sn–S bonds leading to skew‐trapezoidal biypramidal tin atom geometries. The crystal structure of a representative compound, [Ph2Sn(S2COEt)2], confirms the spectroscopic results and shows the tin atom to be coordinated by two asymmetrically chelating xanthate ligands [Sn–S(1) 2.486(1), Sn–S(2) 3.052(1) Å and Sn–S(3) 2.484(1), Sn–S(4) 3.220(1) Å] with the two phenyl substituents lying over the weaker Sn–S interactions so that C–Sn–C is 126.5(1)∘. Crystal data for [Ph2Sn(S2COEt)2]: monoclinic space group P21/n: a=9.645(1), b=23.723(3), c=9.798(2) Å, ß=100.23(1)∘, V=2206.2 Å3, Z=4; 2708 data refined to final R 0.023. A selection of these compounds has been evaluated for activity against the L1210 mouse leukaemia cell line.