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Coordination‐Driven Self‐Assembly, Structures, and Dynamic Properties of Diplatinum Hexatriynediyl and Butadiynediyl Complexes in which the sp Carbon Chains are Shielded by sp 3 Carbon Chains: Towards Endgroup–Endgroup Interactions
Author(s) -
Owen Gareth R.,
Stahl Jürgen,
Hampel Frank,
Gladysz John A.
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200701268
Subject(s) - chemistry , platinum , crystallography , crystal structure , stereochemistry , medicinal chemistry , catalysis , organic chemistry
Sequential reactions of trans ‐(C 6 F 5 )( p ‐tol 3 P) 2 Pt(CC) 3 SiEt 3 ( PtC 6 SiEt 3 ) with n Bu 4 N + F − (THF/methanol), PtCl , KPF 6 / t BuOK, and CuCl give trans , trans ‐[(C 6 F 5 ){( p ‐tol 3 P) 2 }Pt(CC) 3 Pt{(P p ‐tol 3 ) 2 }(C 6 F 5 )] ( PtC 6 Pt ) in 95 % yield on multigram scales. Reactions of PtC 6 Pt and Ar 2 P(CH 2 ) m PAr 2 afford substitution products trans,trans ‐[(C 6 F 5 ){(Ar 2 P(CH 2 ) m PAr 2 )}Pt(CC) 3 Pt {(Ar 2 P(CH 2 ) m PAr 2 )}(C 6 F 5 )] ( PtC 6 Pt ‐ m / Ar ; m /Ar=8/ p ‐tol, 78 %; 10/Ph, 82 %; 11/Ph, 69 %; 12/Ph, 57 %; 14/ p ‐tol, 57 %; 14/ p ‐C 6 H 4 ‐ t Bu, 71 %), in which the diphosphines span the square planar platinum endgroups. An analogous reaction with PEt 3 gives a tetrakis PEt 3 complex Pt′C 6 Pt′ (72 %). The crystal structures of PtC 6 Pt , Pt′C 6 Pt′ , PtC 6 Pt ‐ 10 / Ph , PtC 6 Pt ‐ 11 / Ph , and PtC 6 Pt ‐ 14 / p ‐tol or solvates thereof are compared. In PtC 6 Pt , the endgroups can avoid van der Waals contact, and define angles of 0°. In PtC 6 Pt ‐ 14 / p ‐tol , the sp 3 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 PtC 6 Pt ‐ 14 / p ‐tol rapidly interconvert in solution at low temperature. A crystal structure of PtC 4 Pt shows endgroups that are in van der Waals contact and define an angle of 41°. Reactions with Ar 2 P(CH 2 ) 8 PAr 2 give PtC 4 Pt‐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.