En route to diplatinum polyynediyl complexes trans,trans-(Ar)(R3P)2Pt(C≡C)nPt(PR3)2(Ar): Untold tales, including end-group strategies

Abstract

Reactions of {(C6F5)Pt[S(CH2CH2-)2](μ-Cl)}2 and R3P yield the bis(phosphine) species trans-(C6F5)(R3P)2PtCl [R = Et (Pt'Cl), Ph, (p-CF3C6H4)3P; 88-81 %]. Additions of Pt'Cl and H(C≡C)nH (n = 1, 2; HNEt2, 20 mol % CuI) give Pt'C2H (37 %, plus Pt'I, 16 %) and Pt'C4H (88 %). Homocoupling of Pt'C4H under Hay conditions (O2, CuCl, TMEDA, acetone) gives Pt'C8Pt' (85 %), but Pt'C2H affords only traces of Pt'C4Pt'. However, condensation of Pt'C4H and Pt'Cl (HNEt2, 20 mol % CuI) yields Pt'C4Pt' (97 %). Hay heterocouplings of Pt'C4H or trans-(p-tol)(Ph3P)2Pt(C≡C)2H (Pt*C4H) and excess HC≡CSiEt3 give Pt'C6SiEt3 (76 %) or Pt*C6SiEt3 (89 %). The latter and wet n-Bu4N+ F- react to yield labile Pt*C6H (60 %). Hay homocouplings of Pt*C4H and Pt*C6H give Pt*C8Pt* (64 %) and Pt*C12Pt* (64 %). Reaction of trans-(C6F5)(p-tol3P)2PtCl (PtCl) and HC≡CH (HNEt2, 20 mol % CuI) yields only traces of PtC2H. However, an analogous reaction with HC≡CSiMe3 gives PtC2SiMe3 (75 %), which upon treatment with silica yields PtC2H (77 %). An analogous coupling of trans-(C6F5)(Ph3P)2PtCl with H(C≡C)2H gives trans-(C6F5)(Ph3P)2Pt(C≡C)2H (34 %). Advantages and disadvantages of the various trans-(Ar)(R3P)2Pt end-groups are analyzed.