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-(C6 F5 )(p-tol3 P)2 Pt(C identical withC)n/2 H undergo oxidative homocoupling (O2 , CuCl/TMEDA) to diplatinum polyynediyl complexes trans, trans-(C6 F5 )(p-tol3 P)2 Pt(C identical withC)n Pt(Pp-tol3 )2 (C6 F5 ) (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-C6 H4 O(CH2 )6 O)2 (1,3-C6 H4 ) (10, 33-membered) or 2,9-(1,10-phenanthrolinediyl)(p-C6 H4 O(CH2 )6 O)2 (2,7-naphthalenediyl) (11, 35-membered), excess K2 CO3 , and I2 (oxidant), rotaxanes are isolated that feature a Pt(C identical withC)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 identical withC)n Pt axles and macrocycles, although cyclic voltammetry data suggest rapid reactions following oxidation.