Structure and spectroscopic studies of cis-bis(bipyridine) cobalt(III) complexes of phenylcyanamide ligands

• Published in: Inorganica Chimica Acta 2002-07, Vol.336, p.125-130
• Main Authors: Rezvani, Ali R, Hadadzadeh, Hassan, Patrick, Brian
• Format: Article
• Language: English
• Subjects: Bipyridyne; Cobalt; Electrochemical structure; Phenylcyanamide; Spectroscopy
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(02)00837-X

Several new cobalt complexes, cis-[(bpy) 2Co(L) 2]PF 6, where bpy=2,2′-bipyridine and L=monoanion of phenylcyanamide (pcyd), 2-chlorophenylcyanamide(2-Clpcyd), 2,5-dichlorophenylcyanamide(2,5-Cl 2pcyd), 2-methylphenylcyanamide(2-Mepcyd) and 2,4-dimethylphenylcyanamide(2,4-Me 2pcyd) have been prepared and characterized by UV–Vis, IR and 1H NMR spectroscopies. The complex of cis-[(bpy) 2Co(2-Clpcyd) 2]PF 6 crystallized with one third of a molecule of acetonitrile with empirical formula of C 34.67H 25N 8.33F 6Cl 2PCo, in a triclinic crystal system and space group of P 1 ̄ with a=10.937(1) Å, b=12.716(1) Å, c=13.452(1) Å, β=91.019(4)°, V=1789.3(3) Å 3, and Z=2. The structure was refined by using 5385 Mo Kα reflections with I>3 σ( I) and R factor of 0.065. These Co-complexes possess low-energy ligand to metal charge-transfer bands associate with Co(III)NCN chromophore. Comparison between the properties of cis-[Ru(bpy) 2(L) 2]PF 6 and cis-[Co(bpy) 2 (L) 2]PF 6 complexes shows the same behavior in the covalency of the MNCN π-bond. Several novel cobalt complexes, cis-[Co(bpy) 2 (L) 2]PF 6, where bpy=2,2′ bipyridine and L=monoanion of phenylcyanamide derivatives have been prepared and characterized by spectroscopies and X-ray structure. The Co(III)NCN bond angle (127.8, 136.7°) in cis-[Co(bpy) 2 (2-Clpcyd) 2]PF 6 is largely determined by the σ-bonding interaction of a cyanamide nonbonding electron pair in an sp 2 hybrid orbital.