Jürgen Stahl

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

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.

Syntheses and structures of monoplatinum model complexes for diplatinum polyynediyl adducts LnPt(CC)zPtLn

Abstract The CuI-catalyzed reactions of trans-(Ph3P)2PtCl2 with HCCSiMe3 or HCCCCSiMe3 (greater than two equivalents, HNEt2), and trans-(p-tol)(Ph3P)2PtCl (4) or trans-(C6F5)(p-tol3P)2PtCl with HCCCCH, give trans-(Ph3P)2Pt(CCSiMe3)2 (2), trans-(Ph3P)2Pt(CCCCSiMe3)2 (3), trans-(p-tol)(Ph3P)2PtCCCCH (5), and trans-(C6F5)(p-tol3P)2PtCCCCH (7) in 74–81% yields. These compounds are characterized crystallographically, and their physical properties compared. A convenient three-step synthesis of 4 from (COD)PtCl2 is described.