Syntheses, Structures, and Spectroscopic Properties of 1,10‐Phenanthroline‐Based Macrocycles Threaded by PtC 8 Pt, PtC 12 Pt, and PtC 16 Pt Axles: Metal‐Capped Rotaxanes as Insulated Molecular Wires

The platinum polyynyl complexes trans ‐(C 6 F 5 )( p ‐tol 3 P) 2 Pt(C≡C) n /2 H undergo oxidative homocoupling (O 2 , CuCl/TMEDA) to diplatinum polyynediyl complexes trans, trans ‐(C 6 F 5 )( p ‐tol 3 P) 2 Pt(C≡C) n Pt(P p ‐tol 3 ) 2 (C 6 F 5 ) ( 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 ‐C 6 H 4 O(CH 2 ) 6 O) 2 (1,3‐C 6 H 4 ) ( 10 , 33‐membered) or 2,9‐(1,10‐phenanthrolinediyl)( p ‐C 6 H 4 O(CH 2 ) 6 O) 2 (2,7‐naphthalenediyl) ( 11 , 35‐membered), excess K 2 CO 3 , and I 2 (oxidant), rotaxanes are isolated that feature a Pt(C≡C) n Pt axle that has been threaded through the macrocycle ( 2⋅10 , 9 %; 5⋅10 , 41 %; 5⋅11 , 28 %; 8⋅10 , 12 %; 8⋅11 , 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≡C) n Pt axles and macrocycles, although cyclic voltammetry data suggest rapid reactions following oxidation.