Reactions of Bis(tri-tert-butylphosphine)platinum with Metal Hydride Complexes. The Reactions of Pt(P-t-Bu3)2 with HRe(CO)4SbPh3

Abstract

Pt(P-t-Bu3)2 reacts with the rhenium hydride complex HRe(CO)4(SbPh3), 1, at 25 °C to give the complex PtRe(CO)4(Ph)(P-t-Bu3)(μ-SbPh2)(μ-H), 2, in 75% yield by the oxidative-addition of a Sb−C bond on the SbPh3 ligand of 1 to a Pt(P-t-Bu3) group generated by loss of a P-t-Bu3 ligand from Pt(P-t-Bu3)2. Compound 2 contains a Pt−Re bond [Pt(1)−Re(1) = 3.0971(7) Å] with a bridging SbPh2 ligand and a bridging hydrido ligand. At 98 °C, Pt(P-t-Bu3)2 reacts with two equivalents of 1 to yield the compounds PtRe2(CO)8[PH(t-Bu2)](Ph)(μ-SbPh2)2(μ-H), 3, PtRe2(CO)8(SbPh3)(Ph)(μ-SbPh2)2(μ-H), 4, and PtRe2(P-t-Bu3)(μ-SbPh2)2(μ-SbPh), 5. Compounds 3 and 4 both contain five-membered Re2Sb2Pt rings formed from two mutually bonded Re(CO)4 groups and two bridging SbPh2 ligands that are both bonded to the Pt atom. Compound 4 was obtained from 2 independently by reaction with 1. Pt(P-t-Bu3)2 reacts with 1 at 68 °C under a hydrogen atmosphere to yield 2, 4, and the new compound, HPtRe2(CO)8(P-t-Bu3)(μ-SbPh2)2(μ-H), 6, which also contains a five-membered Re2Sb2Pt ring similar to those found in 3 and 4. Five compounds were obtained in low yields when 2 was thermally decomposed under nitrogen at 100 °C: 5 (4%); Re2(CO)8(μ-SbPh2)2, 7 (6% yield); RePh(CO)4SbPh3, 10 (4%); Re2(CO)8[PtH(CO)(P-t-Bu3)](μ3-SbPh)(μ-SbPh2), 11 (4%); RePh(CO)4[PtH(CO)P(t-Bu)3](μ-SbPh2), 12 (7%). Of these, only 12 is new. Compound 12 is a CO adduct of 2 and was obtained independently by the addition of CO to 2. The CO ligand was added to the platinum atom, the Pt−Re bond of 2 was cleaved, and the phenyl group was shifted to the rhenium atom. The two metal atoms are linked solely by the bridging SbPh2 ligand. Seven compounds, 5 (9% yield), 7 (26%), Pt3(CO)3(P-t-Bu3)3, 9 (71%), 11 (7%), 12 (8%), PtRe2(CO)9P(t-Bu)3(μ-H)2, 13 (13%), and Re3(CO)13(μ3-SbPh)(μ-SbPh2), 14 (18%), were obtained when 2 was allowed to react with CO at room temperature. Of these, only compound 14 is new. Compound 14 contains no platinum atoms. The structure of 14 contains two Re(CO)4 groups linked by a bridging SbPh2 ligand and a bridging SbPh ligand. The bridging SbPh ligand also contains a pendant Re(CO)5 group.