Syntheses, Structures, and Spectroscopic Properties of 1,10-Phenanthroline Based Macrocycles threaded by PtC8Pt, PtC12Pt, and PtC16Pt Axles: Metal-capped Rotaxanes as Insulated Molecular Wires.

The platinum polyynyl complexes trans-(C6F5)(p-tol(3)P)(2)Pt(C equivalent to C)(n/2)H undergo oxidative homocoupling (O-2, CuCl/TMEDA) to diplatinum polyynediyl complexes trans, trans-(C6F5)(p-tol(3)P)(2)Pt(C equivalent to C)(n)Pt(Pp-tol(3))(2)(C6F5) (n=4, 2; 6, 5; 8, 8; 92-97 %) as reported previously. When related reactions are conducted in the presence of CuI adducts of the 1,10-phenanthroline-based macrocycles 2,9-(1,10-phenanthrolinediyl)(p-C6H4O(CH2)(6)O)(2)(1,3-C6H4) (10, 33-membered) or 2,9-(1,10-phenanthrolinediyl)(p-C6H4O(CH2)(6)O)(2)(2,7-naphthalenediyl) (11, 35-membered), excess K2CO3, and I-2 (oxidant), rotaxanes are isolated that feature a Pt(C equivalent to C)(n)Pt axle that has been threaded through the macrocycle (210, 9 %; 510, 41 %; 511, 28 %; 810, 12 %; 811, 9 %). Their crystal structures are determined and analyzed in detail, particularly with respect to geometric perturbations and the degree of steric sp carbon chain insulation. NMR spectra show a number of shielding effects. UV/Vis spectra do not indicate significant electronic interactions between the Pt(C equivalent to C)(n)Pt axles and macrocycles, although cyclic voltammetry data suggest rapid reactions following oxidation.