Cyclohexyneplatinum(0) Complexes Containing Di-t-butylphenylphosphine, t-lutyldiphenylphosphine or Trimethylphosphine

Abstract

Cyclohexyneplatinum(0) complexes Pt(CsHg)L2 [L = PBut2Ph (4), PButPhz (S)] analogous to the known complex (3) (L=PPh3) have been prepared by reaction of the two-coordinate complexes PtL2 with 1, 2-dibromocyclohexene and 1% sodium amalgam. The corresponding tricyclohexylphosphine complex is formed by a similar reaction but it could not be isolated in a pure state. Attempts to prepare analogues of (4) and (5) containing cycloheptyne or cyclooctyne were unsuccessful, possibly because the bulky t-butyl groups of the tertiary phosphines hinder coordination of the larger rings. Bulky tertiary phosphines do not displace PPh3 from (3) but trimethylphosphine reacts with (3) to give successively P˜(CGH˜)(PM˜˜)(PP˜˜) (10) and Pt(c˜Hs)(PMe3)(2l l), as shown by 31˜{1n.˜m).r. spectroscopy. The tertiary phosphines in these complexes equilibrate rapidly at room temperature in benzene and only (10) can be isolated as a solid from the reaction. Complexes (4) and (5) react with HCI (I molar proportion) to give r)l-cyclohexen-l-yl complexes trans-PtCI(C6Hg)L; [L= PBut2Ph (6), PButPhz (711. In the absence of air, (4) reacts with methanol at 65°C to give the hydrido complex trans-PtH(CsHg)(PBut2Ph)2 (8). In the presence of oxygen from the air, however, the main product is the dioxygen complex P˜(O˜)(PBU(9˜).˜ TPh˜is) r˜ep resents an unusual example of complete displacement of cyclohexyne from a platinum(0) complex by a T-acceptor ligand. Show more