Probing d8−d8 Interactions in Luminescent Mono- and Binuclear Cyclometalated Platinum(II) Complexes of 6-Phenyl-2,2‘-bipyridines

Abstract

A series of luminescent mono- and binuclear cyclometalated platinum(II) complexes, namely [Pt(L1-6)Cl] (1a−6a; HL1-6 = 4-(aryl)-6-phenyl-2,2‘-bipyridine; aryl = H (1), phenyl (2), 4-chlorophenyl (3), 4-tolyl (4), 4-methoxyphenyl (5), 3,4,5-trimethoxyphenyl (6)), [Pt(L1)E]+ (E = py (7), PPh3 (8)), [Pt2(L1-6)2(μ-dppm)]2+ (1b−6b, dppm = bis(diphenylphosphino)methane), [Pt2(L1)2(μ-pz)]+ (9, Hpz = pyrazole), and [Pt2(L1)2(μ-dppCn)]2+ (dppCn = bis(diphenylphosphino)propane (10, n = 3) and -pentane (11, n = 5)), were synthesized in order to examine fluid- and solid-state oligomeric d8−d8 and ligand−ligand interactions. The molecular structures of 4b(ClO4)2 and 9(PF6) reveal intramolecular Pt−Pt distances of 3.245(1) and 3.612(2) A, respectively. While minimal metal−metal communication is expected for 9, weak π−π interactions are possible. All complexes described in this work are emissive in fluid solution at room temperature. Negligible changes in emission energy are detected by incorporating different aryl subs...