Silver(I), Copper(I) and Copper(II) Complex of the New N,Se-Chelate Ligand 2-Phenylselenomethyl-1H-benzimidazole: Electrochemistry and Structure
Abstract. 2-Phenylselenomethyl-1H-benzimidazole (psbi) can form complexes in 2:1 ratio with coinage metal ions. Crystal structure analysis revealed a flattened metal coordination for [AgI(psbi)2](BF4) (1), approaching a distorted planar arrangement with weak Ag-Se bonds (d > 2.9 A) and confirmed as energy minimum by DFT calculations. The typical Jahn-Teller system [CuII(psbi)2Cl2] (2) exhibits a planar CuN2Cl2 core with weak Se---Cu---Se axial ligation (3.2944(8) A Cu--Se distance). The oxygen-sensitive compound [CuI(psbi)2](BF4) (3) exhibits electrochemically reversible oxidation in contrast to the silver(I) analogue 1.
Heterotetranuclear Complexes of Reduced and Non-reduced Bridging 1,2,4,5-Tetrazine Ligands with 1,1′-Bis(diphenylphosphanyl)-ferrocene-copper(I)
The complexes {(μ-bptz)[Cu(dppf)]2}(BF4)2 [(1)(BF4)2] [bptz = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, dppf = 1,1′-bis(diphenylphosphanyl)ferrocene] and {(μ-bpztz)[Cu(dppf)]2}(PF6)2 [(2)(PF6)2] [bpztz = 3,6-bis(2-pyrazinyl)-1,2,4,5-tetrazine] contain two redox-active heterodinuclear FeIICuI moieties, bridged by a redox-active ligand. A crystal structure determination of (1)(BF4)2·2CH2Cl2 confirms the non-reduced aromatic nature of the bridge, in contrast to previous results on dicopper(I) complexes of bptz. Facile one-electron reduction produces the radical complexes {(μ-bptz)[Cu(dppf)]2}+ (1+) and {(μ-bpztz)[Cu(dppf)]2}+ (2+), which could be isolated [as (1)(BF4)] and studied by variable freq…