233283-56-2Relevant academic research and scientific papers
Organomolybdenum(VI) and lithium organomolybdate(VI) and -(V) complexes with C,N-chelating aminoaryl ligands
Brandts, Jim A. M.,Van Leur, Marloes,Gossage, Robert A.,Boersma, Jaap,Spek, Anthony L.,Van Koten, Gerard
, p. 2633 - 2641 (2008/10/08)
The synthesis and characterization of new, five-coordinate molybdenum bis(imidoaryl) complexes [Mo(NAr)2(C-AT)X] (Ar = C6H3i-Pr2-2,6; C-N= [C6H4(CH2NMe2)-2]-; X = Cl (1), Me (2), Et (3), Bu (4), CH2SiMe3 (5), (p-tolyl) (6), (C-N) (7)) is reported. The solid-state structure of 2 has been elucidated by single-crystal X-ray analysis. Compounds 2, 3, 4, 5, and 6 react with alkyl- or aryllithium compounds to form lithium molybdate(VI) derivatives, of which [Li(DME)Mo(NAr)2(C-N(Me)(p-tolyl)] (10), formed by the reaction of 2 with [Li-(p-tolyl)], has been structurally (X-ray) characterized. Thermal activation of these lithium molybdates leads to the formation of paramagnetic lithium molybdate(V) compounds instead of the anticipated molybdenum(VI) alkylidenes. The actual temperature (between -10 and 80 °C) at which paramagnetic Mo(V) radical anions are formed is dependent on both the type of alkyl or aryl substituent (introduced via LiR′) and the solvent. The synthesis of [LiMo-(NAr)2(C-N)2] (11) by reaction of 7 with n-BuLi is described. The initially formed lithium molybdate(VI) compound [Li(DME)nMo(NAr)2(C-N(n-Bu)] is not stable at room temperature and converts directly to the lithium molybdate(V) derivative 11. The solid-state structure of 11 has been elucidated by single-crystal X-ray analysis. None of the lithium molybdate(VI) nor -(V) derivatives described herein are active catalysts for ROMP, as thermal activation does not lead to the formation of a molybdenum alkylidene complex but to electron transfer and formation of a lithium molybdate(V) instead. However, upon treatment of a solution of any of the molybdate(V) derivatives with dry air, catalytic ROMP is observed.
