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

Stahl, Jürgen; Bohling, James C.; Peters, Thomas B.; de Quadras, Laura; Gladysz, John A.

doi:10.1351/pac200880030459

Pure Appl. Chem., 2008, Vol. 80, No. 3, pp. 459-474

http://dx.doi.org/10.1351/pac200880030459

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

Jürgen Stahl¹, James C. Bohling², Thomas B. Peters², Laura de Quadras¹ and John A. Gladysz^1,3

¹ Institute for Organic Chemistry and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 42, 91054 Erlangen, Germany
² Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
³ Department of Chemistry, Texas AM University, P.O. Box 30012, College Station, TX 77842-3012, USA

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.