New Dinuclear Transition Metal Complexes with the [M2(μ-dhbq)]n+ Core and 2-(2′-Pyridyl)quinoxaline (L) as a Terminal Ligand: Preparation and Characterization (dhbq2-= the Dianion of 2,5-Dihydroxy -1,4- benzoquinone; M = AgI, MnII, CoII, NiII, CuII, RuII, PdII, FeIII, RhIII; n = 0, 2, 4)

Abstract Synthetic procedures are described that allow access to the new complexes [Mn 2 (dhbq)L 2 (H 2 O) 4 (1), [Fe 2 (dhbq)L 2 (H 2 O) 4 ](NO 3 ) 4 · 6H 2 O (2), [Co 2 (dhbq)Cl 2 L 2 (H 2 O) 2 ] (3), [Ni 2 (dhbq)Cl 2 L 2 (H 2 O) 2 ] (4), [Cu 2 (dhbq)Cl 2 L 2 (H 2 O) 2 ] (5), [Ru 2 (dhbq)L 2 (H 2 O) 4 ](ClO 4 ) 2 (6), [Rh 2 (dhbq)Cl 2 L 2 (H 2 O) 2 ]Cl 2 ·2H 2 O (7), [Pd 2 (dhbq)L 2 ]Cl 2 ·5H 2 O (8) and [Ag 2 (dhbq)L 2 ] (9), where dhbq 2- is the dianion of 2,5-dihydroxy-1,4-benzoquinone and L is the biheteroaromatic ligand 2-(2′-pyridyl)quinoxaline. The new complexes were characterized by elemental analyses and by a variety of physical and spectroscopic techniques. Dinuclear structures are assigned for the complexes in the solid state. The two metal ions are bridged by the bischelating dhbq 2- ion, while L behaves as a bidentate chelate with the 2′-pyridyl nitrogen and the nearest quinoxaline nitrogen atom as the ligand atoms. The metal ion coordination geometries are octahedral, tetrahedral or square planar.