sp Carbon Chains Surrounded by sp3 Carbon Double Helices: Coordination-Driven Self-Assembly of Wirelike Pt(CC)n
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- 作者：Jü ; rgen Stahl ; Wolfgang Mohr ; Laura de Quadras ; Thomas B. Peters ; James C. Bohling ; José ; Miguel Martí ; n-Alvarez ; Gareth R. Owen ; Frank Hampel ; John A. Gladysz
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：July 4, 2007
- 年：2007
- 卷：129
- 期：26
- 页码：8282 - 8295
- 全文大小：743K
- 年卷期：v.129,no.26(July 4, 2007)
- ISSN：1520-5126
文摘
Reactions of trans,trans-(C6F5)(p-tol3P)2Pt(C
C)4Pt(Pp-tol3)2(C6F5) and diphosphines Ar2P(CH2)mPAr2 yield ja0716103a10001">trans,trans-(C6F5)(Ar2ja071610300000">P(CH2)mPAr2)ja071610300001">Pt(CC)4 Pt(Ar2P(CH2)m PAr2)(C6F5), in which the platinumatoms are spanned via an sp and two sp3 carbon chains (Ar/m = 3, Ph/14, 87%; 4, p-tol/14, 91%; 5,p-C6H4-t-Bu/14, 77%; 7, Ph/10, 80%; 8, Ph/11, 80%; 9, Ph/12, 36%; only oligomers form for m > 14).Crystal structures of 3-5 show that the sp3 chains adopt chiral double-helical conformations that shieldthe sp chain at approximately the van der Waals distance, with both enantiomers in the unit cell. Theplatinum square planes define angles of 196.6
-189.9 or more than a half twist. Crystal structures of7-9, which have shorter sp3 chains, exhibit nonhelical conformations. Reaction of the corresponding Pt(CC)6Pt complex and Ph2P(CH2)18PPh2 gives an analogous adduct (27%). The crystal structure showstwo independent molecules, one helical and the other not. Low-temperature NMR data suggest that theenantiomeric helical conformations of 3-5 rapidly interconvert in solution. Cyclic voltammograms of 3-5show more reversible oxidations than model compounds lacking bridging sp3 chains. These are the onlydouble-helical molecules that do not feature bonding interactions between the helix strands, or covalentbonds to templates dispersed throughout the strands, or any type of encoding. The driving force for helixformation is analyzed.
C)4Pt(Pp-tol3)2(C6F5) and diphosphines Ar2P(CH2)mPAr2 yield C)4-189.9 or more than a half twist. Crystal structures of7-9, which have shorter sp3 chains, exhibit nonhelical conformations. Reaction of the corresponding Pt(CC)6Pt complex and Ph2P(CH2)18PPh2 gives an analogous adduct (27%). The crystal structure showstwo independent molecules, one helical and the other not. Low-temperature NMR data suggest that theenantiomeric helical conformations of 3-5 rapidly interconvert in solution. Cyclic voltammograms of 3-5show more reversible oxidations than model compounds lacking bridging sp3 chains. These are the onlydouble-helical molecules that do not feature bonding interactions between the helix strands, or covalentbonds to templates dispersed throughout the strands, or any type of encoding. The driving force for helixformation is analyzed.