Solid state structure of a rhenium bibenzimidazole complex

ISSN： 0095-8972

Source： Journal of Coordination Chemistry, Vol.57, Iss.17-18, 2004-11, pp. : 1587-1590

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Abstract

Re(CO) 5 Br readily forms a complex with 2,2′-bibenzimidazole (bbimH 2 ) of the general composition (bbimH 2 )Re(CO) 3 Br, 1 . The complex was characterized by NMR, IR, electronic and emission spectroscopy. The orange-brown compound is sparingly soluble in apolar solvents but could be crystallized from a DMF/toluene mixture. An X-ray structural investigation shows that the rhenium ion has a distorted octahedral geometry. Nitrogen atoms of the bibenzimidazole are trans to two carbonyl ligands. The secondary amine protons of the bibenzimidazole ligand form a hydrogen bond to the amide oxygen of a DMF molecule; N3-O4 2.725(7) Å, N4-O4 2.761(7) Å. The bending angle of the two benzimidazole units is 168°; the greatest deviation from planarity within the ligand is 0.14 Å. Crystal data: monoclinic, space group P 2 1 / n , a = 10.9743(2), b = 12.9182(2), c = 15.1864(3) Å, β = 91.647(1)°, V = 2152.06(7) Å 3 , T = −90°C, Z = 4, R 1 = 0.025, wR 2 = 0.062 for 4296 reflections with F o > 4σ( F o ) out of 4886 independent reflections.