| Abstract
| - Reaction of the terminal electrophilic phosphinidene complexes [Cp*M(CO)3{PN(i-Pr)2}][AlCl4] (3,M = Mo; 4, M = W) with PEt3 results in replacement of a metal carbonyl by the phosphine. The reactionsoccur via initial nucleophilic attack by the phosphine at the phosphinidene phosphorus, followed bycarbonyl loss and migration of the phosphine to the metal. Reactions of 3 and 4 with bis(dimethylphosphino)methane (dmpm) lead to [Cp*M(CO)2{P(N(i-Pr)2)P(Me2)CH2P(Me2)-κ2P1,P4}][AlCl4](9, M = Mo; 10, M = W), in which one end of the diphosphine coordinates to phosphorus and the otherend coordinates to the metal. The reactions proceed by initial nucleophilic attack by one end of thediphosphine at phosphorus, followed by carbonyl loss and coordination of the other end of the ligand tothe metal. Compound 3 (M = Mo) reacts with bis(dimethylphosphino)ethane (dmpe) to give the analogousproduct [Cp*Mo(CO)2{P(N(i-Pr)2)P(Me2)CH2CH2P(Me2)-κ2P1,P5}][AlCl4] (12), in which the two endsof the dmpe ligand coordinate to phosphorus and molybdenum, respectively. Reaction of compound 4(M = W) with dmpe leads to two products, [Cp*W(CO)2{P(N(i-Pr)2)P(Me2)CH2CH2P(Me2)-κ2P1,P5}][AlCl4] (13) and [{Cp*W(CO)2(PN(i-Pr)2)}2(μ-dmpe)][AlCl4]2 (14). Compound 13 is analogous to 12.In compound 14, the two ends of the diphosphine ligand displace carbonyl ligands from two moleculesof 4, resulting in a novel bis-phosphinidene structure in which the diphosphine ligand bridges two metalcenters, each of which retains a terminal phosphinidene ligand. Loss of an additional carbonyl ligandfrom 12, followed by migration of one end of the phosphine from phosphorus to the metal, results inre-formation of a terminal phosphinidene ligand, leading to [Cp*Mo(CO)(PN(i-Pr)2)(dmpe-κ2P)][AlCl4](17). The structural characterization of the phosphine adducts and carbonyl substitution products of theterminal phosphinidene complexes 3 and 4 has provided valuable insights into metal−phosphinidenebonding in these compounds.
- Electrophilic aminophosphinidene complexes of molybdenum and tungsten react with phosphines and diphosphines at the phosphinidene phosphorus. Phosphine coordination to the phosphinidene induces CO loss from the metal, followed by either phosphine migration from the phosphinidene to the metal or diphosphine bridging between the phosphinidene and the metal.
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