Organometallic Molybdenum(V) Complexes with Primary Phosphine Ligands. Syntheses, Spectroscopic Properties and Molecular Structures of [Cp°MoCl4(PH2R)] (R = But, 1‐Ad, Cy, Ph, 2, 4, 6‐Me3C6H2, 2, 4, 6‐Pri3C6H2, Cp° = C5EtMe4)

Abstract [Cp°MoCl4] (Cp° = C5EtMe4) reacts with primary phosphines PH2R to give the paramagnetic phosphine complexes [Cp°MoCl4(PH2R)] [Cp° = C5EtMe4, R = But (1), 1‐Ad (1‐Ad = 1‐adamantyl; 2), Cy (3), Ph (4), Mes (Mes = 2, 4, 6‐Me3C6H2; 5), Tipp (Tipp = 2, 4, 6‐Pri3C6H2; 6)]. 1—6 were characterized spectroscopically (IR, MS), and X‐ray crystal structures were determined for 1—4 and 6. EPR investigations in liquid and frozen solution confirmed the presence of MoV species, and the data were used to analyze the spin‐density distribution in the first coordination sphere. Complexes 3 and 4 react with two equivalents of NEt3 with formation of [Cp°MoCl2(η3‐P4Cy4H)] (7) and [Cp°2Mo2(μ‐Cl)2(μ‐P4Ph4)] (8), respectively, in low yield. Complexes 7 and 8 were characterized by X‐ray crystallography.