sp Carbon chains surrounded by sp3 carbon double helices: wire-like Pt(C
C)nPt moieties that are spanned by two α,ω-diphosphines that bear heteroatoms or alkyl substituents
Abstract
Reactions of trans-(C6F5)L2PtCl (2, L = Ph2P(CH2)4O(CH2)2CHCH2; 6, L = Ph2P(CH2)2C(CH3)2(CH2)3CH
CH2) and H(C
C)2H (HNEt2, cat. CuI) give trans-(C6F5)L2Pt(C
C)2H (3, 7; 86–97%). Oxidative homocouplings (O2, cat. CuCl/TMEDA,
C)4PtL2(C6F5) (4, 8; 75–86%). Reactions with Grubbs’
P(CH2)4O(CH2)6O(CH2)4PPh2)
Pt(C
C)4Pt
(Ph2P(CH2)4O(CH2)6O(CH2)4P
Ph2)(C6F5) (5), with termini-spanning diphosphines, and trans,trans-(C6F5)(Ph2
P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2PPh2)Pt
(C
C)4
Pt(Ph2P(CH2)2C(CH3)2(CH2)8C(CH3)2(CH2)2P
Ph2)(C6F5) (9), with trans-spanning diphosphines, respectively. Reactions of trans,trans-(C6F5)(p-tol3P)2Pt(C
C)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