Covalently linked donor-acceptor cyclometalated platinum(II) complexes. Structure and luminescent properties

Abstract

Reaction of [Pt(CH3CN)4]2+ with 2,9-diphenyl-1,10-phenanthroline (dpp) in acetonitrile gave the cyclometalated complex [Pt(C N N-dpp)(CH3CN)](ClO4) {here abbreviated as [7](ClO4)}, the structure of which has been established by 1H-1H COSY and X-ray crystallography: triclinic, P1̄, a = 13.322(3) Å, b = 13.877(3) Å, c = 14.164(6) Å, α = 86.74(3)°, β= 105.87(3)°, γ = 108.93(2)°, V = 2381.0(12) Å3, Z = 2. The resemblance between solution excimeric emission and solid-state emission of 7 suggests that the structure of excimer [7]2* in CH2Cl2 is similar to the dimeric unit in the crystalline state. The coordinated CH3CN in 7 is substitution labile and can be easily replaced by nitrogen bases upon heating in acetone to give covalently-linked donor-acceptor organometallic complexes. Crystal structures of coordinated 4-(4-nitrobenzyl)pyridine and 4-(2-(9-anthryl)vinyl)pyridine substituted complexes (10 and 11, respectively) have been determined: [10](ClO4), triclinic, P1̄, a = 10.143(2) Å, b = 13.025(4) Å, c = 13.581(2) Å, α = 68.64(2)°, β = 77.15(2)°,γ = 68.00(2)°, V = 1541.6(7) Å3, Z = 2; [11](ClO4), monoclinic, P21/c, a = 13.065(4) Å, b = 18.647(5) Å, c = 16.276(4) Å, β = 116.59(2)°, V = 3546(3) Å3, Z = 4. In both structures, one of the phenyl rings of (C N N-dpp) is nearly parallel with the nitrogen base ligand, which is perpendicular to the mean plane defined by the atoms N(1), N(2), C(13), and Pt. The photoluminescent properties of 7 and complexes with covalently linked organic quenchers are described.