Organo Halide Addition to Pd2(Ph2PCH2PPh2)3. Preparation of Novel Methylene- and Phenylene-Bridged Complexes by Two-Center, Three-Fragment Oxidative Addition

Article abstract of DOI:10.1021/ja00403a025

Dihalomethanes react with Pd2(dpm)3 (dpm = bis(diphenylphosphino)methane) to form Pd2(dpm)2(μ-CHR)X2 (X = I, Br, Cl; R = H, CH3).Pd2(dpm)2(μ-CH2)I2 undergoes substitution to form Pd2(dpm)2(μ-CH2)L2²⁺ (L = pyridine, methyl isocyanide).The Pd - C (methylene) bond resists insertion of carbon monoxide, isocyanides, or sulfur dioxide.Reaction of Pd2(dpm)3 with 1,2-diiodobenzene yields Pd2(dpm)2(μ-C6H4)I2.Addition of phenyl isocyanide dichloride to Pd2(dpm)3 yeilds Pd2(dpm)2(μ-CNPh)Cl2 while a corresponding reaction involving oxalyl chloride produces Pd2(dpm)2(μ-CO)Cl2.Addition of methyl halide to Pd2(dpm)3 produces Pd2(dpm)2(CH3)2X2 (X = Br, I) which exist as the molecular A-frame ⁺X^- in solution.Protonation of Pd2(dpm)2(μ-CH2)I2 with fluoroboric acid yields brown, crystalline BF4 in which a bridging methylene has been converted into a terminal methyl group.Dynamic aspects of the structure of ⁺ and ⁺ are described.