Panoply of P: An Array of Rhenium–Phosphorus Complexes Generated from a Transition Metal Anion

Abstract

We expand upon the synthetic utility of anionic rhenium complex Na[(BDI)ReCp] (1, BDI = N,N '-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate) to generate several rhenium−phosphorus complexes. Complex 1 reacts in a metathetical manner with chlorophosphines Ph 2 PCl, Me NHP-Cl, and OHP-Cl to generate XL-type phosphido complexes 2, 3, and 4, respectively ( Me NHP-Cl = 2-chloro-1,3-dimethyl-1,3,2diazaphospholidine; OHP-Cl = 2-chloro-1,3,2-dioxaphospholane). Crystallographic and computational investigations of phosphido triad 2, 3, and 4 reveal that increasing the electronegativity of the phosphorus substituent (C < N < O) results in a shortening and strengthening of the rhenium−phosphorus bond. Complex 1 reacts with iminophosphane Mes*NPCl (Mes* = 2,4,6-tritert-butylphenyl) to generate linear iminophosphanyl complex 5. In the presence of a suitable halide abstraction reagent, 1 reacts with the dichlorophosphine i Pr 2 NPCl 2 to afford cationic phosphinidene complex 6 + . Complex 6 + may be reduced by one electron to form 6 • , a rare example of a stable, paramagnetic phosphinidene complex. Spectroscopic and structural investigations, as well as computational analyses, are employed to elucidate the influence of the phosphorus substituent on the nature of the rhenium−phosphorus bond in 2 through 6. Furthermore, we examine several common analogies employed to understand metal phosphido, phosphinidene, and iminophosphanyl complexes.