COMPARATIVE REACTIVITIES OF ANIONIC GROUP-6 ALKYL, SILYL, AND STANNYL PENTACARBONYL METALATES TOWARD CARBON-DIOXIDE AND SULFUR-DIOXIDE - CRYSTAL-STRUCTURE OF [PPN][W(CO)5SI(CH3)3]
Additional Document Info
The syntheses of [PPN][M(CO)5SiR3] (M = Cr, R = CH3; M = W, R = CH3, C2H5) and [PPN] [W(CO)5SnR3] (R = CH3, C6H5) from the reactions of Na2M(CO)s and the corresponding R3SiCl or R3SnCl reagents are reported. The complex [PPN] [W(CO)5Si(CH3)3] has been characterized in the solid state via X-ray crystallography. [PPN] [W(CO)5Si(CH3)3] crystallizes in the space group P1, with cell dimensions a = 10.664 (2) , b = 12.739 (4) , c = 5.75 , = 97.75 (2), = 92.18 (2), = 96.13 (2), V= 2105.0 (9) 3, Z = 2, and RF = 4.12%. Comparisons of the (CO)5W-group 14 element bond lengths reveal the W-Si and W-Sn bonds to be shorter than that which would be anticipated on the basis of the sum of the single-bond covalent radii. This bond shortening is ascribed to d-d back-bonding from the metal to Si or Sn. Consistent with a stronger W-Si and W-Sn bond as compared with that for the carbon analogue [W(CO)5CH3]-, unlike the alkyl species, these silyl and stannyl derivatives were found to be inert toward CO2, even when dissolved in pure carbon dioxide at 800 psi. On the other hand, all (CO)5W-group 14 element bonds readily undergo reactions with the more electrophilic sulfur dioxide to provide the corresponding sulfinate-S complexes. For example, [(CO)5W-Sn(CH3)3]- reacts instantaneously at ambient temperature with SO2 to eventually yield [(CO)5W-S(O)2Sn(CH3)3]-. In this instance infrared and NMR spectral evidence for the intermediacy of the sulfinate-O complex is found. In a subsequent process this complex isomerizes to the thermodynamically more stable sulfinate-S derivative. 1988, American Chemical Society. All rights reserved.