Kinetics and mechanisms of ligand substitution reactions of the vanadium triad metals. Syntheses and reactivities of (. eta. sup 5 -C sub 5 H sub 5 )M(CO) sub 3 (C sub 4 H sub 8 E) (M = Nb, E = S, Se, Te; M = Ta, E = S)

• Published in: Organometallics 1991-01, Vol.10:1
• Main Authors: Freeman, J.W., Basolo, F.
• Format: Article
• Language: English
• Subjects: 400201 - Chemical & Physicochemical Properties; ALKENES; CARBONYLS; CHEMICAL REACTION KINETICS; CHEMICAL REACTIONS; COMPLEXES; CYCLOALKENES; CYCLOPENTADIENE; DECOMPOSITION; DIENES; DISSOCIATION HEAT; ELECTROMAGNETIC RADIATION; ELEMENTS; ENTHALPY; ENTROPY; FURANS; HETEROCYCLIC COMPOUNDS; HYDROCARBONS; INFRARED SPECTRA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KINETICS; LIGANDS; NIOBIUM COMPLEXES; NMR SPECTRA; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; ORGANIC SULFUR COMPOUNDS; PHOSPHINES; PHOSPHORUS COMPOUNDS; PHOTOCHEMICAL REACTIONS; PHOTOLYSIS; PHYSICAL PROPERTIES; POLYCYCLIC SULFUR HETEROCYCLES; POLYENES; RADIATIONS; REACTION HEAT; REACTION KINETICS; SELENIUM; SEMIMETALS; SPECTRA; TANTALUM COMPLEXES; TELLURIUM; TETRAHYDROFURAN; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENT COMPLEXES; ULTRAVIOLET RADIATION; VANADIUM COMPLEXES
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om00047a058

Kinetic studies were performed for CO substitution reactions of CpM(CO){sub 4} (M = Nb, Ta) and for dialkylchalcogenide substitution reactions of CpM(CO){sub 3}(C{sub 4}H{sub 8}E) (M = V, E = S; M = Nb, E = O, S, Se, Te; M = Ta, E = O, S) with phosphines. The syntheses and characterization of the new compounds CpM(CO){sub 3}(C{sub 4}H{sub 8}E) (M = Nb, E = S, Se, Te; M = Ta, E = S) are reported. Both CpM(CO){sub 4} and CpM(CO){sub 3}(C{sub 4}H{sub 8}E) were found to react by the same mechanism. For M = V, a dissociative mechanism was observed, while for M = Nb, Ta both dissociative and associative mechanisms were observed. This change in mechanism is attributed to the larger size of the Nb and Ta centers. The reactivity of the compounds was found to increase in the order V > Nb > Ta. The higher reactivity of the V compounds compared to the Nb compounds is unusual when compared to other triads, where the second-row metal usually forms the most reactive compound. The reactivity of the CpM(CO){sub 3}(C{sub 4}H{sub 8}E) compounds was found to increase in the order Te < Se < S < O, indicating that the heavier chalcogenides form more stable complexes than the higher chalcogenides.