Complexes of rhenium and osmium polyhydrides with metallic Lewis acids: X-ray crystal structure of [Ag{ReH7(PPhPrI2)2}2][PF6]

Abstract

Bis(di-isopropylphenylphosphine) heptahydridorhenium(VII)(1) reacts with AgPF₆, Agl, Cul, and HgCl₂ to give the heterometallic complexes [Ag{ReH₇(PPhPr₂^I)₂}₂][PF₆](2) and [Ag{ReH₇(PPhPr₂^I)₂}][PF₆](3); [Agl{ReH₇(PPhPr₂^I)₂}](4); [Cul{ReH₇(PPhPr₂^I)₂}](5); and [HgCl₂{ReH₇(PPhPr₂^I)₂}](6) respectively, without loss of hydrogen. Similarly, [OsH₆(PPhPr₂^I)₂] reacts with HgCl₂ to give [HgCl₂-{OsH₆(PPhPr₂^I)₂}]. Complex formation is accompanied by only subtle changes in the hydride ¹H n.m.r. shifts (<1 p.p.m.). However, substantial changes occur in the ν(Re–H) i.r. absorption bands. Crystals of (2) are triclinic, space group P(Z= 2), with lattice parameters a= 13.188(6), b= 16.014(6), c= 14.827(6)Å, α= 112.47(3), β= 101.03(3), and γ= 90.65(3)°. The structure was solved and refined to R= 0.048 (R′= 0.047) for 4 452 reflections having 2θ⩽ 50°(Mo-K_αX- radiation) collected at 200 K. The complex cation comprises a silver atom and two Re(PPhPr₂^I)₂ fragments arranged linearly (Re–Ag–Re 172°, mean Re–Ag 2.873 Å). No evidence of the hydride ligands was found from the diffraction study.