Triisopropylsilyl (TIPS) Alkynes as Building Blocks for Syntheses of Platinum Triisopropylsilylpolyynyl and Diplatinum Polyynediyl Complexes

摘要

Hay oxidative cross coupling (O-2/CuCl/TMEDA) of trans-(p-tol)(p-tol(3)P)(2)Pt(C C)(2)H ((PtC4H)-C-T) and excess H(C C)(2)Si-i-Pr-3 (TIPSC4H) gives (PtC8TIPS)-C-T (55%). Subsequent addition of n-Bu4N+F- and repetition of the Hay protocol yields (PtC12TIPS)-C-T (56%) and the byproduct trans-i-Pr3Si(C C)(2)(p-tol(3)P)(2)Pt(C C)(6)Si-i-Pr-3 (TIPSC4PtC12TIPS, 5%); another cycle gives (PtC16TIPS)-C-T (13%). Analogous cross couplings of trans-(C6F5)(p-tol(3)P)(2)Pt(C C)(2)H ((PtC4H)-C-F) and excess TIPSCxH yield (PtC6TIPS)-C-F (x = 2, 58%) and (PtC8TIPS)-C-F (x = 4, 23%). Each is treated with n-Bu4N+F-, and repetition of the Hay protocol with TIPSC4H gives (PtC10TIPS)-C-F (58%) and (PtC12TIPS)-C-F (47%). When the Hay conditions are applied to (PtCxTIPS)-C-F (x = 6, 8, 10, 12) without a cross-coupling partner, homocoupling to (PtC2xPtF)-C-F occurs (68-99%). The reaction of trans-(p-tol(3)P)(2)PtCl2 and TIPSC4H (4.5 equiv; cat. CuI, CH2Cl2/HNEt2) yields TIPSC4PtC4TIPS (95%). Hay cross coupling of HC4PtC4H and excess TIPSC4H gives TIPSC4PtC4TIPS (6%), TIPSC4PtC8TIPS (12%), TIPSC8PtC8TIPS (10%), TIPSC4PtC12TIPS (7%), and TIPSC8PtC12TIPS (3%). Although TIPS can be a superior protecting group, it offers no advantage vs triethylsilyl in the preceding reactions. The crystal structures of (PtC8TIPS)-C-T, (PtC12TIPS)-C-T, (PtC6TIPS)-C-F, (PtC8TIPS)-C-F, TIPSC4PtC4TIPS, TIPSC8PtC8TIPS, TIPSC4PtC12TIPS. and (PtC20PtF)-C-F are determined. The last is the longest dimetallapolyyne so characterized to date. The C-13 NMR chemical shifts of the sp carbon atoms are accurately modeled by DFT calculations.