Chromium-carbonyl complex octahedral

The neutral complexes of chromium, molybdenum, tungsten, and vanadium are six-coordinate and the CO molecules are arranged about the metal in an octahedral configuration as shown in stmcture (3). Vanadium carbonyl possesses an unpaired electron and would be expected to form a metal—metal bond. Steric hindrance may prevent dimerization. The other hexacarbonyls are diamagnetic. 

Group VI.—Chromium, Molybdenum, and Tungsten. Further evidence for cis labilization in substituted octahedral complexes of metal carbonyls is found in the reactions of [M(CO)4(amine)2] with which give complexes c/s-[M(CO)4-... 

Copper(I) complexes show a lamellar structure not conclusively assigned [175]. Liquid crystalline complexes with chromium, molybdenum and tungsten as metallic centers have also been reported. The 1,4,7-trisubstituted 1,4,7-triazacyclononane and three carbonyl groups, 80, are coordinated in an octahedral geometry. 

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