Crystal and molecular structure of tin(IV) dithiocarbamates: IV. monoclinic and triclinic bis (N,N-diethyldithiocarbamato)dimethyltin(IV), unusual six coordination

Abstract

The structure of the title compound has been determined by three-dimensional X-ray diffaction techniques in two crystallographic modifications, containing a total of three symmetry-independent molecules. This has clearly established that the observed rather unusual six-coordinated geometry is not a result of crystal packing effects. The triclinic modification (P¯1) has cell dimensionsa = 10.600(3),b = 10.899(3),c = 10.585(4) A, α = 95.8(1), β = 85.4(1), and γ = 126.2(1) °. The observed density of 1.52 g cm−3 agrees well with the calculated density of 1.51 g cm−3, based on two molecules per unit cell. For the structure solution and refinement 3156 reflections measured with a scintillation detector and withF 0 2 ⩾ 3σ(F 0 2 ) were used and gave a final agreement factor (R) of 0.027. The monoclinic modification is described by the following:a = 27.630(1),b = 12.350(1),c = 17.777(1) A,β = 100.9(2) °, space group =C2/c,Z = 12,d 0 = 1.48 g cm−3,d c = 1.489 g cm−3. The structure was solved and refined using 3289 reflections measured with a scintillation detector and withF 0 2 ⩾3σ(F 0 2 ). The final agreement factor was 0.065. The molecular structure involves bidentate coordination of the sulfur atoms of the two dithiocarbamate ligands and coordination of the two methyl groups to the tin(IV) atom. The bidentate coordination of each of the dithiocarbamate ligands involves one short Sn-S distance (average = 2.52 A) and one long Sn-S distance (average = 2.95 A). The average Sn-C distance is 2.12(1) A, and the C-Sn-C bond angle is 141(1) °. The geometry about the tin atom is then highly distorted from octahedral and cannot be considered eithercis- ortrans-octahedral. The structure is compared with several other six-coordinated tin(IV) dithiocarbamate complexes and with spectroscopic predictions of the structure.