ISSN:
0009-2940
Keywords:
Imido complexes, organometallic
;
Molybdenum complexes
;
Tungsten complexes
;
Alkene complexes
;
Alkyne complexes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Highervalent Derivatives of the d-Metal Acids, 14[1]. - Diimido Complexes [M(NR)2(PMe3)2(L)] of Tetravalent Molybedenum and Tungsten: Structure, Molecular Dynamics, and Activation of π-Acidic Ligands[M(NMes)2Cl2(dme)] (M = Mo 1, W 2; Mes = mesityl) or the trans-phosphane complexes [M(NMes)2(PMe3)2Cl2] (3, 4) are reduced by C8K in the presence of PMe3 to give diamagnetic d2 complexes [Mo(NMes)2(PMe3}3] (5) and [W(NMes)2-(PMe3)3] (6). At least one PMe3 ligand in 5 and 6 is readily substituted by more π-acidic substrates such as ethene, ethyne, 2-butyne, and P(OEt)3. The reaction with ethene leads to [Mo(NMes)2(η2-C2H4)(PMe3)2] (7) and [W(NMes)2-(η2-C2H4)(PMe3)2] (8). Furthermore, pentacoordinate complexes [Mo(NMes)2(η2-C2Me2)(PMe3)2] (9), [W(NMes)2(η2-C2H2)(PMe3)2] (10), and [W(NMes)2(PMe3){P(OEt)3)2] (11) have been synthesized from 5 or 6. The X-ray structure analysis of 8 reveals a trigonal-bipyramidal geometry about tungsten with both arylimido groups perfectly lying in the equatorial mirror plane. The ethene ligand is occupying the third equatorial position. The C2 vector is oriented perpendicular to the WN2 plane. Dynamic NMR studies are consistent with a tbp geometry being also present in solution at the low-temperature limit. At higher temperatures a rapid exchange of the PMe3 ligands with noncoordinated phosphane according to a dissociative mechanism is observed.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19941271003
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