Design, synthesis, and characterization of a sterically encumbered dioxo molybdenum (VI) core

• Published in: Inorganica Chimica Acta 2007-04, Vol.360 (6), p.2092-2099
• Main Authors: Sengar, Raghvendra S., Basu, Partha
• Format: Article
• Language: English
• Subjects: Dendrimer; Molybdenum complexes; Oxygen atom transfer reactivity; Redox reactivity
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2006.10.041

Sterically encumbered diooxomolybdenum complexes have been synthesized and characterized. These complexes exhibit sluggish electrochemistry and size selective reactivity. Dioxo-Mo VI complexes of general formula Tp ∗MoO 2( p-SC 6H 4Dn) ( 6a– 6c) (where Tp ∗ = hydrotris(3,5-dimethyl-pyrazol-1-yl)borate and Dn = dendritic unit) have been synthesized and characterized by spectroscopy and mass spectrometry. 1H NMR spectra of the metal complexes indicate that the C s local symmetry about the metal core does not change by the incorporation of dendritic functionality at the thiophenolato ring. Electrochemical data show a ∼20 mV change in the redox potential in the complexes with dendritic ligands suggesting a very small perturbation in the redox orbital, which is also supported by small changes in the electronic spectra. The peak-to peak separation (Δ E p) increases from 125 mV in 6( a) to 240 mV in 6( c), suggesting sluggish electron transfer in molecules with larger dendritic ligands.