Tungsten iron heterobimetallic complexes: Preparation and reactions

Article abstract of DOI:10.1021/om00106a027

Organometallic cyclopentadienyl-substituted phosphines (η⁵-C₅H₄PPh₂)Fe(CO) ₂CH₃ (3) and (η⁵-C₅H₄PPh₂)W(CO) ₃CH₃ (4) were prepared from (η⁵-C₅H₅)M(CO)_nCH₃ (M = Fe, n = 2; M = W, n = 3) by lithiation of the cyclopentadienyl ring followed by reaction with chlorodiphenylphosphine. Complexes 3 and 4 were used to synthesize heterobimetallic compounds CH₃(CO)₂Fe(η⁵-C₅H ₄PPh₂-μ) WCH₃(CO)₂Cp (5) and CH₃(CO)₃W(η⁵-C₅H ₄PPh₂-μ)Fe(COCH₃)(CO)Cp (8), whose X-ray structures were determined. CH₃(CO)₂Fe(η⁵-C₅H ₄PPh₂-μ)WCl(CO)Cp (6) was also prepared by the substitution of a carbonyl ligand on Cp(CO)₃WCl by 3. The reaction of 3 with [Cp(CO)₃W]⁺BF4^- gave the heterobimetallic cation [CH₃-(CO)₂Fe(η⁵-C₅H ₄PPh₂-μ)W(CO)₃Cp]⁺BF ₄^- (7). The reduction of 6 with sodium amalgam gave the heterobimetallic anion, and although this anion could be alkylated with methyl iodide to yield 5, protonation of the anion did not produce the hydride. The reaction of the heterobimetallic cation 7 with methyllithium produced CH₃(CO)₂Fe(η⁵-C₅H ₄PPh₂-μ)W(COCH₃)(CO)Cp (12). Reaction of 7 with excess sodium borohydride gave low yields of the tungsten hydride heterobimetallic complex CH₃(CO)₂Fe(η⁵-C₅H ₄PPh₂-μ)W(H)(CO)₂Cp (10).