Luminescent platinum(II) dimers with a cyclometallating aryldiamine ligand.

Triflate salts of three (Pt(pip2NCN))2(μ-L)2+ (pip2NCNH = 1,3-bis(piperidylmethyl)benzene) dimers bridged by a series of nitrogen-donor ligands (L = pyrazine (pyz), 1,2-bis(4-pyridyl)ethane (bpa), trans-1,2-bis(4-pyridyl)ethylene (bpe)) are reported. These complexes have been fully characterized by 1H NMR spectroscopy and elemental analysis. The X-ray crystal structures of [(Pt(pip2NCN))2(μ-pyz)](CF3SO3)2 and [(Pt(pip2NCN))2(μ-bpe)](CF3SO3)2·2CH2Cl2 are reported. [(Pt(pip2NCN))2(μ-pyz)](CF3SO3)2:  triclinic, P1, a = 12.5240(5) A, b = 14.1570(6) A, c = 14.2928(6) A, α = 106.458(1)°, β = 92.527(1)°, γ = 106.880(1)°, V = 2303.46(17) A3, Z = 2. [(Pt(pip2NCN))2(μ-bpe)](CF3SO3)2·2CH2Cl2:  monoclinic, P21/c, a = 10.1288(6) A, b = 16.3346(9) A, c = 17.4764(10) A, β = 90.882(2)°, V = 2891.1(3) A3, Z = 2. These structures and solution measurements provide evidence for the strong trans-directing properties of the pip2NCN- ligand. The electronic structures of these complexes and those of the 4,4‘-bipyridine (bpy) di...