Synthesis and characterization five-coordinate molybdenum compounds bearing bi- or tridentate substituted pyrrole ligands: Molecular structures of {Mo(NC6H3Pri 2-2,6)2 R[NC4H3(CH2NMe2)-2]}
Journal
Inorganica Chimica Acta
Journal Volume
321
Journal Issue
1-2
Pages
142-148
Date Issued
2001
Author(s)
Abstract
Reacting [Mo(NC6H3Pri2-2,6)2Cl 2(dme)] with 1 equiv. of Li [NC4H3(CH2NMe2)-2] in diethyl ether at -78°C yields a red crystalline solid of {Mo(NC6H3Pri2-2,6)2Cl [NC4H3(CH2NMe2)-2]} 1 in 86% yield. Alkylation of 1 with RLi in diethyl ether generates {Mo(NC6H3Pri2-2,6)2 R[NC4H3(CH2NMe2)-2]} (2a, R = Me; 2b, R = Bu) in high yield. Similarly, reacting [Mo(NC6H3Pri2-2,6)2Cl 2(dme)] with 1 equiv. of Li[NC4H2(CH2NMe2)2- 2,5] in diethyl ether at -78°C affords dark red crystals of {Mo(NC6H3Pri2-2,6)2Cl [NC4H2(CH2NMe2)2-2,5]} 3 in 92% yield, in which one NMe2 unit of the pyrrole ligand of 3 coordinates to molybdenum whilst the other one dangles outside the coordination sphere. Variable-temperature 1H NMR study of 3 reveals fluxional behavior of the two NMe2 units of the pyrrole ligand. The activation energy of the fluxionality has been determined as ΔG≠ = 10.5 kcal mol-1. Compounds 1, 2a, 2b and 3 have been characterized by NMR spectroscopy and X-ray crystallography. © 2001 Elsevier Science B.V. All rights reserved.
Type
journal article