174281-06-2Relevant articles and documents
Bent vs. linear imido ligation at the octahedral molybdenum(VI) dithiocarbamate stabilised centre
Barrie, Patrick,Coffey, Therese A.,Forster, Glyn D.,Hogarth, Graeme
, p. 4519 - 4528 (2007/10/03)
Molybdenum(VI) bis(imido) complexes [Mo(NR)2(S2CNEt2)2] 3a-3p have been prepared via two synthetic routes and their structures investigated. Thermolysis of [MoO2(S2CNEt2)2] 1 with 2,6-disubstituted aryl isocyanates affords air-stable bis(imido) complexes 3i-3m in high yields after column chromatography, a route which fails for sterically less demanding isocyanates. A more general preparation involves room temperature addition of two equivalents of [S2CNEt2]- to the labile bis(imido) complexes [Mo(NR)2Cl2(dme)] 2a-2p (dme = 1,2-dimethoxyethane) to afford 3a-3p in high yields. In this manner related complexes [Mo(NR)2(S2CNMe2)2] 4 (R = Ph or But) and [Mo(NPh)2(S2PPh2)2] 5a have also been prepared. Structural and spectroscopic studies have been carried out in order to determine the degree of bending of the imido ligands. Six complexes have been characterised by X-ray crystallography. In all cases one of the imido ligands is linear (Mo-N-C ≥ 160°), while the angle at the second is dependent upon the nature of R and ranges from 180 to 139°. Solid-state 13C CPMAS spectroscopy reveals that the difference in bond angles at the two nitrogen centres (Δ°) correlates closely with the difference in chemical shifts of the ipso-carbon atoms (Δδ). This then has been used to probe the relative bond angles at nitrogen for non-crystallographically characterised complexes. In solution even at low temperatures both imido ligands are equivalent indicating a rapid interconversion between linear and bent bonding modes. The Royal Society of Chemistry 1999.
