Reactions of the Platinum (Tri-tert-butylphosphine) Group with Bridging SbPh2 Ligands in Rhenium-Antimony Carbonyl Complexes

The reaction of [Re(CO)(4)(mu-SbPh2)](2) (1) with Pt[P(t-Bu)(3)](2) in n-octane solvent at reflux (125 degrees C) has yielded two platinum rhenium antimony compounds, Re-2(CO)(8)[(mu(3)-SbCH2CMe2)Pt(H)P(t-Bu)(2)]P(t-Bu)(3)(mu-SbPh2) (2), and Re-2(CO)(8)[Pt(CO)(CH2CMe2)P(t-Bu)(2)](mu(3)-SbPh)(mu-SbPh2) (3), in low yields. Both products were formed by the cleavage of phenyl group(s) from one of the bridging SbPh2 ligands in 1 and the addition of a PtP(t-Bu)(3) or Pt[P-(t-Bu)(3)](2) group to the antimony atom. In both products, one of the tert-butyl groups was metalated on one of its methyl groups. In 2, metalation occurred on the antimony atom, while in 3, it occurred on the platinum atom. When the same reaction was performed under an atmosphere of hydrogen (1 atm), two additional new platinum-rhenium-antimony compounds, PtRe2(CO)(8)P(t-Bu)(3)(mu(3)-SbPh)(mu-SbPh2)(mu-H) (4) and Re-2(CO)(8)[PtH(CO){P(t-Bu)(3)}](mu(3)-SbPh)-(mu-SbPh2) (5), were formed. In both products, a phenyl group was cleaved from one of the bridging SbPh2 ligands in 1 and the addition of a PtP(t-Bu)(3) group to the antimony atom, but there was no metalation of the tert-butyl groups in these products. Instead, a hydride ligand was added to the complex. Compound 5 was also obtained from 4 by the addition of CO. Compound 4 also reacts with SbPh3 to form the new compound Pt2Re2(CO)(7)P(t-Bu)(3)(mu(3)-SbPh)-(mu-SbPh2)(2) (6; 42% yield), which contains an additional bridging SbPh2 ligand across the Pt-Re bond. The reaction of 6 with Pt[P(t-Bu)(3)](2) in a hydrogen atmosphere yielded the new compound Pt2Re2(CO)(7)[P(t-Bu)(3)](2)(mu(3)-SbPh)(3) (7) by the cleavage of one phenyl ring from each of the two SbPh2 ligands in 6 and the addition of a PtP(t-Bu)(3) group to the resultant SbPh ligands. Compound 7 contains three triply bridging SbPh ligands. Compounds 2-7 were each characterized by a combination of IR, NMR, and mass spectrometry spectra and single-crystal X-ray diffraction analyses.