A Lipophilic Salt of a Transition-Metal Polyhydride: KOsH3(PMe2Ph)3

Article abstract of DOI:10.1021/ja00304a016

The polyhydride OsH4P3 (P=PMe2Ph) is deprotonated by KH in THF to yield K(fac-OsH3P3), characterized by 1H and 31P NMR spectroscopy.This reaction also proceeds in aromatic solvents, and the ether-free product is soluble in benzene and toluene.Spectral properties in toluene are similar to those in THF but reveal subtle differences.The crystal structure of KOsH3(PMe2Ph)3, crystallized from toluene, reveals the reason for the lipophilic character of this material.It consists of centrosymmetric K2Os2H6(PMe2Ph)6 dimers composed of (PhMe2P)3Os(μ-H)3K monomers (an intimate ion pair) bound into dimers by one additional hydride bridge from each K to one hydride hydrogen in the second monomer unit.Equally important to the dimerization is the enfolding of each K(1+) by two phenyl rings of the second monomer unit with the result that the periphery of the molecule is entirely hydrocarbon in character.The hard acid/soft base character of the K(1+)/phenyl interaction is particularly surprising.Crystal data for KOsH3(PMe2Ph)3 (at -160 deg C) are the following: a=9.990 (2) Angstroem, b=22.867 (8) Angstroem, c=12.381 (3) Angstroem, β=111.44 (1) deg with z=4 in space group P2₁/n.