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

• Published in: Chemistry : a European journal Vol. 25; no. 69; pp. 15896 - 15914
• Main Authors: Amini, Hashem, Baranová, Zuzana, Weisbach, Nancy, Gauthier, Sébastien, Bhuvanesh, Nattamai, Reibenspies, Joseph H., Gladysz, John A.
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 10-12-2019
• Subjects: Adducts; Chemistry; conjugated polyynes; copper; Copper chloride; Crystal structure; Insulation; macrocycles; Molecular chains; NMR; NMR spectroscopy; Nuclear magnetic resonance; Oxidants; Oxidation; oxidative homocoupling; Oxidizing agents; Platinum; Potassium carbonate; Rotaxanes; Shafts (machine elements); Shielding; structure elucidation
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201903927

The platinum polyynyl complexes trans‐(C6F5)(p‐tol3P)2Pt(C≡C)n/2H undergo oxidative homocoupling (O2, CuCl/TMEDA) to diplatinum polyynediyl complexes trans, trans‐(C6F5)(p‐tol3P)2Pt(C≡C)nPt(Pp‐tol3)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)6O)2(1,3‐C6H4) (10, 33‐membered) or 2,9‐(1,10‐phenanthrolinediyl)(p‐C6H4O(CH2)6O)2(2,7‐naphthalenediyl) (11, 35‐membered), excess K2CO3, and I2 (oxidant), rotaxanes are isolated that feature a Pt(C≡C)nPt 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)nPt axles and macrocycles, although cyclic voltammetry data suggest rapid reactions following oxidation.
Strung up between two metals: The syntheses of the title compounds are templated by a copper(I) adduct of a macrocycle, which two platinum terminal polyynyl precursors Pt(C≡C)n/2H (n=4, 6, 8) can approach from opposite sides prior to oxidative homocoupling.