Reactivity of 1-alkynylplatinum(II) complexes towards trialkylboranes

Article abstract of DOI:10.1016/S0022-328X(97)00319-7

1-Alkynylplatinum(II) complexes of the type cis-[(dppe)Pt(C≡C-R¹)₂] [4, R¹ = Me (a), ^tBu (b), C(Me)=CH₂ (c), Ph (d), SiMe₃ (e)], cis-[(dmpe)Pt(C≡C-Me)₂] (5a), cis-[(depe)Pt(C≡C-Ph)₂] (6d), cis-[(Et₃P)₂Pt(ⁿBu)(C≡C-R¹)] [7, R¹ = Me (a), Ph (d)] and trans-[(Et₃P)₂Pt((E)-2-pentenyl)(C≡C-Me)] (8a) react with trialkylboranes R₃B [2, R = Me (a), Et (b), ⁱPr (c)] by 1,1-organoboration. This involves cleavage of a Pt-C ≡ bond, and formation of an alkynylborate-like intermediate in which a positively charged platinum fragment is coordinated to the C≡C bond. In most cases, the alkenylplatinum complexes of the type 9-13, 28, 30 which result from 1,1-organoboration are not stable, and either η²-alkyne platinum(0) (15-21, 29) or η³-borylalkene platinum(0) complexes (22-27) or both are the next products. The proposed structures of all new platinum complexes in solution are based on ¹¹B, ³¹P, ¹⁹⁵Pt NMR data, and in some cases also on complete ¹³C NMR data sets.