Coordination-driven self-assembly, structures, and dynamic properties of diplatinum hexatriynediyl and butadiynediyl complexes in which the sp carbon chains are shielded by sp3 carbon chains: Towards endgroup-endgroup interactions

Gareth R. Owen, Jürgen Stahl, Frank Hampel, John A. Gladysz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Sequential reactions of trans(C6F5)(p-tol 3P)2Pt(C≡C)3SiEt3 (PtC 6-SiEt3) with nBu4N+ F- (THF/methanol), PtCl, KPF6/tBuOK, and CuCl give trans,trans-[(C 6F5){(p-tol3P)2}Pt(C≡ C) 3Pt{(Pp-tol3)2}(C6F5)] (PtC6Pt) in 95% yield on multigram scales. Reactions of PtC 6Pt and Ar2P(CH2)mPAr2 afford substitution products trans,trans-[(C6F5){(Ar 2P(CH2)mPAr2)}Pt(C≡C) 3Pt{(Ar2P(CH2)mPAr 2)}(C6F5)] (PtC6Pt-m/Ar; m/Ar = 8/p-tol, 78%; 10/Ph, 82%; 11/Ph, 69%; 12/Ph, 57%; 14/p-tol, 57%; 14/p-C 6H4-tBu, 71%), in which the diphosphines span the square planar platinum endgroups. An analogous reaction with PEt3 gives a tetrakis PEt3 complex Pt′C6Pt′ (72%). The crystal structures of PtC6Pt, Pt′C6Pt′, PtC6Pt-10/Ph, PtC6Pt-11/Ph, and PtC6Pt-14/p-tol or solvates thereof are compared. In PtC6Pt, the endgroups can avoid van der Waals contact, and define angles of 0°. In PtC6Pt-14/p- tol, the sp3 chains twist around the sp chain in a chiral double-helical motif, with an endgroup/endgroup angle of 189°. The sp 3 chains are too short to adopt analogous conformations in the other complexes, but laterally shield the sp chain. NMR spectroscopy shows that the helical enantiomers of PtC6Pt-14/p-tol rapidly interconvert in solution at low temperature. A crystal structure of PtC4Pt shows endgroups that are in van der Waals contact and define an angle of 41°. Reactions with Ar2P-(CH2)8PAr2 give PtC4Pt-8/Ar (Ar = Ph, 53%; p-tol, 87%). Low-temperature NMR spectroscopy establish non-helical chiral conformations. Electrochemical oxidations of the diplatinum complexes are analyzed, the reversibilities of which decrease with increasing sp chain length.

Original languageEnglish
Pages (from-to)73-87
Number of pages15
JournalChemistry - A European Journal
Volume14
Issue number1
DOIs
Publication statusPublished - 18 Jan 2008
Externally publishedYes

Keywords

  • Helical structures
  • NMR spectroscopy
  • Platinum
  • Self-assembly
  • Structure elucidation

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