REACTIONS OF TUNGSTEN AND MOLYBDENUM PROPARGYL COMPLEXES WITH CO2(CO)8, CO4(CO)12, AND CP2MO2(CO)4 - A CROSSOVER STUDY OF FORMATION OF (CO)3CO(MU-RC=CME)WCP(CO)2

The nature of the protonation reaction of (CO)3Co(μ-RCCCH2MCp(CO)3)Co(CO)3 (M = Mo, W; R = Me, Ph, p-MeC6H4) (2) (obtained from (CO)3CpMCH2CCR (1) and Co2(CO)8) to give (CO)3Co(μ-RCCMe)MCp(CO)2 (3) was further investigated by a crossover experiment. Thus, reaction of an equimolar mixture of 2b (M = W, Cp = η5-C5H5, R = Ph) and 2e (M = W, Cp = η5-C5H4Me; R = p-MeC6H4) with CF3COOH affords only 3b (same M, Cp, and R as 2b) and 3e (same M, Cp, and R as 2e) to show an intramolecular nature of this transformation. Reaction of (CO)3CpWCH2CCPh (1b) with Co4(CO)12 was also examined and found to yield 2b exclusively. Treatment of 1 with Cp2Mo2(CO)4 at 0-5°C provides thermally sensitive compounds, possibly (CO)2CpMo(μ-RCCCH2MCp(CO)3)MoCp(CO)2 (5), which decompose at room temperature to give Cp2Mo2(CO)6 as the only isolated product. © 1990.