[Cr(CO)5PCl3] - A starting material for phosphorus-rich Px ligand complexes

Article abstract of DOI:10.1002/cber.19971300919

[Cr(CO)₅PCI₃] reacts with different metallates K[Cp^xMo(CO)₃] [Cp^x = η⁵-C₅H₄tBu (Cp′), η⁵-C₅H₃tBu₂-1,3 (Cp″)], K[Cp″Fe(CO)₂], K[Cp′Cr(CO)₃], K[CpNi (CO)] and Na₂[Cr₂(CO)₁₀] at -78 °C in THF to yield various P₂, cycloP₃ and cycto-P₅ ligand complexes of the formulae [Cp′-Mo(CO)₂(η³-P₃)] (1a), [Cp″Mo(CO)₂(η³-P₃)] (1b), [{Cp′Mo-(CO)₂)₂(μ,η²-P ₂)] (2a), [{Cp″Mo(CO)₂)₂(μ,η²-P ₂)] (2b), [Cp″Fe(η⁵-P₅)] (3), [(Cp′Cr)₂(μ,η⁵-P₅)] (4), [|Cp′Cr(CO)₂)₂-(μ,η²-P ₂)1 (5), [(CpNi)₂(μ,η²-P ₂)(Cr(CO)₅)₂ (6), [{(CO)₅Cr)Cl₂PPCl₂{Cr(CO)₅)] (7) and [(Cr(CO)₅}₂PCl] (8). Comprehensive studies of the reaction pathway leading to formation of the cyclo-P₃ product la give strong indications that a sequence involving metal-halogen exchange and stepwise P-P bond formation takes place, proceeding via [{(CO)₅Cr)Cl₂PPCl₂{Cr(CO)₅)] (7) and the cydo-P₃ precursor compound [(Cp′Mo(CO)₃){Cp′Mo(CO)₂) ₂(Cr(CO)₅)(μ,η^3:1:1 P₃)] (9). The latter two complexes have been isolated and structurally characterized. VCH Verlagsgescllschaft mbH,.