some of the weaknesses of CFT, which are explained by ligand field theory (LFT) and molecular orbital theory which are beyond the scope of the present study. . . Limitations of Crystal Field Theory The homoleptic carbonyls (compounds containing carbonyl ligands only) are formed by most of the transition metals.
These carbonyls have simple, well defined structures. Tetracarbonylnickel( ) is tetrahedral, pentacarbonyliron( ) is trigonalbipyramidal while hexacarbonyl chromium( ) is octahedral. Decacarbonyldimanganese( ) is made up of two square pyramidal Mn(CO) units joined by a Mn – Mn bond. Octacarbonyldicobalt( ) has a Co – Co bond bridged by two CO groups (Fig.