Acetylenes and noble-metal compounds. Part 15. Reactions of dialkylacetylenes with bis(acetonitrile)dichloroplatinum(II) and tin(II) chloride to give ionic cyclobutadieneplatinum–tin complexes
Abstract
Acetylenes (C2R2, R = Me or Et) react with [Pt(NCMe)2Cl2] and SnCl2 to give the ionic tetra-alkylcyclobutadiene complexes [Pt2(C4R4)2Cl3][Pt(C4R4)(SnCl3)3](2) which can be converted into the tin-feer complexes [Pt2-(C4R4)2Cl4](3) by reaction with HCl and acetone, or into the salts [N(PPh3)2][Pt(C4R4)(SnCl3)3](4) plus (3) by reaction with [N(PPh3)2]Cl. Structures are assigned on the basis of spectroscopic data, in particular the intensities of the 195Pt, 117Sn, and 119Sn satellites of the methyl resonances in the 1H n.m.r. spectra of (2 and 4; R = Me). Two new complexes of di-t-butylacetylene (2,2,4,4-tetramethylhex-3-yne), [Pt(C2But2)(NCMe)(SnCl3)-Cl] and [Pt2(C2But2)2(SnCl3)2Cl2], are also described. The mechanism of the acetylene dimerisation reaction leading to (2) is discussed by comparison with the acetylene oligomerisation reactions induced by PdII.