Sp Carbon chains surrounded by sp(3) carbon double helices: wire-like Pt(C C)(n)Pt moieties that are spanned by two alpha,omega-diphosphines that bear heteroatoms or alkyl substituents
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abstract
Reactions of trans-(C6F5)L2PtCl (2, L = Ph2P(CH2)4O(CH2)2CH=CH2; 6, L = Ph2P(CH2)2C(CH3)2(CH2)3CH=CH2) 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. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
