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Amidinate–carboxylate complexes of dimolybdenum and ditungsten: M2(O2CR)2((NiPr)2CR′)2. Preparations, molecular and electronic structures and reactions†‡§
Douglas J. Brown,Malcolm H. Chisholm,Judith C. Gallucci
Dalton Transactions Pub Date : 02/22/2008 00:00:00 , DOI:10.1039/B715258B
Abstract

The compounds M2(O2CMe)4 and the lithium amidinates Li[(NiPr)2CR] react to give the new compounds trans-M2(O2CMe)2[(NiPr)2CR]2 where M = Mo or W and R = Me (M = Mo only), –C[triple bond, length as m-dash]CtBu, –C[triple bond, length as m-dash]CPh and –C[triple bond, length as m-dash]C–Fc where Fc = 1-ferrocenyl. The limitations of this type of reaction are described based on steric considerations together with the preparation and characterization of the compound Mo2(µ-O2C-9-anthracene)22-(NiPr)2CMe]2. The electronic structures of the bis-amidinate–bis-carboxylate M2 complexes are described based on model compounds employing density functional theory and are correlated with the experimental observations of their physicochemical properties and in particular their observed electronic absorption spectra which show intense MLCT absorption bands. Preliminary studies of the reactions of these bis-amidinate–bis-carboxylate complexes in the preparation of 1-D oligomers are also described along with the preparation and molecular structures of the compounds [Li(NiPr)2CR·THF]2 where R = 2-thienyl or –C[triple bond, length as m-dash]C–Ph. The kinetic lability of these new M2-containing compounds toward ligand exchange is also noted.

Graphical abstract: Amidinate–carboxylate complexes of dimolybdenum and ditungsten: M2(O2CR)2((NiPr)2CR′)2. Preparations, molecular and electronic structures and reactions
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