Cyclopentadienylmetal group 6 metal carbonyl derivatives with 2-propanoneoximato and related ligands

• Published in: New journal of chemistry 2021-11, Vol.45 (45), p.2192-2199
• Main Authors: D nescu, Theodor M, Silaghi-Dumitrescu, Radu, Lupan, Alexandru, King, R. Bruce
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Carbonyls; Chromium; Crystallography; Density functional theory; Isomers; Ligands; Molybdenum; Stoichiometry; Tungsten
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d1nj04379j

The structures and energetics of species with the stoichiometries (Me 2 CNO)M(CO) n Cp (M = Cr, Mo, W; n = 3, 2, 1; Cp = η 5 -C 5 H 5 ) have been studied by density functional theory. The experimental structure Mo2-1S with an NO-dihapto Me 2 CNO ligand found by X-ray crystallography for (Me 2 CNO)Mo(CO) 2 Cp is shown to be the lowest energy isomer by a substantial margin. The expected initial Me 2 CNOMo(CO) 3 Cp product from the reaction of NaMo(CO) 3 Cp with Me 2 C(NO)Br used to synthesize (Me 2 CNO)Mo(CO) 2 Cp is predicted to undergo facile CO dissociation based on Δ H and Δ G values. The energetics of the currently unknown analogous chromium and tungsten systems appear to be similar to that of the molybdenum system. The structures Me 2 NC(CO)OM(CO) 2 Cp (M = Cr, Mo, W) with a dimethylcarbamate ligand are much lower energy (Me 2 CNO)M(CO) 3 Cp isomers but are clearly not accessible from reactions of the anions CpM(CO) 3 − with Me 2 C(NO)Br. The lowest energy structures for the monocarbonyl (Me 2 CNO)M(CO)Cp are of the type (Me 2 C&z.dbd;N)M(O)(CO)Cp with separate dimethylimino and oxo ligands formed by oxidative addition of the Me 2 CNO unit to the central metal atom. The experimental NO-dihapto (Me 2 CNO)Mo(CO) 2 Cp dicarbonyl structure is found by density functional theory to be the lowest energy isomer by a substantial margin. The lowest energy structures for the corresponding monocarbonyls are of the type (Me 2 C&z.dbd;N)M(O)(CO)Cp with separate dimethylimino and oxo ligands.