Bridging cyclopentadienyl M-Sn(IV) bonded polymetallic complexes: X-ray crystal structures of [(Me2SnCl)(CO)(3)MoC5H4C(O)CH2](2)center dot CH2Cl2 and[(Ph3Sn)(CO)(3)WC5H4C(O)CH2](2)center dot 3H(2)O

The dianions [(CO)(3)MC5H4C(O)CH2](2)(2-) reacted with RnSnX4-n in a 1:2 or 1:1 ratio to give tetranuclear complexes [(RnSnX3-n)(CO)(3)MC5H4C(O)CH2](2 ) (M = Mo or W; R = Ph or Me; X = Cl or Pr; n = 2 or 3), which have been ch aracterized by elemental analysis, H-1 NMR and IR spectroscopy. The electro n-withdrawing groups on the cyclopentadienyl rings greatly decrease the nuc leophilicity of the metallic anions. Thus, only one halogen atom on tin was replaced by the metallic anion when the dianions reacted with SnR2X2. The crystal structures of complexes 4 (M = Mo; R = Me; X = Cl; n = 2) and 5 (M = W; R = Ph; n = 3) were determined by X-ray crystallography, indicating th at both Mo and W atoms adopt a 3:4 piano stool structure, and the Sn-M bond length is 2.7755(3) Angstrom in complex 4 (Sn-Mo) and 2.8154(7) Angstrom i n complex 5 (Sn-W). (C) 2001 Elsevier Science B.V. All rights reserved.