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New J. Chem., 2007, 31, 1594 - 1604, DOI: 10.1039/b708690n

sp Carbon chains surrounded by sp3 carbon double helices: wire-like Pt(CC)nPt moieties that are spanned by two ,-diphosphines that bear heteroatoms or alkyl substituents

Laura de Quadras, Eike B. Bauer, Jürgen Stahl, Fedor Zhuravlev, Frank Hampel and John A. Gladysz

Reactions of trans-(C6F5)L2PtCl ( 2, L = Ph2P(CH2)4O(CH2)2CHCH2; 6, L = Ph2P(CH2)2C(CH3)2(CH2)3CHCH2) and H(CC)2H (HNEt2, cat. CuI) give trans-(C6F5)L2Pt(CC)2H ( 3, 7; 86–97%). Oxidative homocouplings (O2, cat. CuCl/TMEDA, acetone) yield trans,trans-(C6F5)L2Pt(CC)4PtL2(C6F5) ( 4, 8; 75–86%). Reactions with Grubbs catalyst, followed by hydrogenation, give mainly trans,trans-(C6F5)(Ph2P(CH2)4O(CH2)6O(CH2)4PPh2)Pt(CC)4Pt(Ph2P(CH2)4O(CH2)6O(CH2)4PPh2)(C6F5) ( 5), with termini-spanning diphosphines, and trans,trans-(C6F5)(Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2)Pt(CC)4Pt(Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2)(C6F5) ( 9), with trans-spanning diphosphines, respectively. Reactions of trans,trans-(C6F5)(p-tol3P)2Pt(CC)4Pt(Pp-tol3)2(C6F5) with Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2 and p-tol2P(CH2)3(CF2)8(CH2)3Pp-tol2 give 10 (70%), the isomer of 9 with termini-spanning diphosphines, and the analogous adduct of the fluorinated diphosphine. However, the latter oligomerizes upon attempted workup. The crystal structure of 5 shows that the sp3 chains adopt a chiral double-helical conformation about the sp chain, with the endgroups defining a 164.1° angle. Additional conformational properties of the preceding complexes are analyzed in detail, and dynamic properties are probed by low temperature NMR experiments.

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