Date: September 6, 2008
Creator: Kuiper, David S.; Wolczanski, Peter T.; Lobkovsky, Emil B. & Cundari, Thomas R., 1964-
Description: This article discusses low coordinate, monomeric molybdenum and tungsten(III) complexes. Treatment of (silox)3MCI (M = Mo, 1-CI; W, 2-CI; silox = tBu3SiO) with PMe3 and Na/Hg led to formation of monomeric, d3 phosphine adducts, (silox)3MPMe3 (M = Mo, 1-PMe3; W, 2-PMe3) via (silox)3CIMPMe3 (M = Mo, 1-CIPMe3; W, 2-CIPMe3). Structural studies show 1-PMe3 and 2-PMe3 to be highly distorted; calculations on full chemical models corroborate experimentally determined S = ½ ground states and their structural features. The compounds contain a bent M-P bond that is characteristic of significant σ/π-mixing. PMe3 may be thermally removed from 1-PMe3 in vacuo to produce 4A2´ (silox)3Mo (1), which was derivatized with CO, NO, and 1/4 P4 to form (silox)3Mo (1-CO), (silox)3MoNo (1-NO), and (silox)3MoP (1-P), respectively. Calculations revealed (silox)3W (2´) to have as S = ½ ground state, which may render it too reactive to be isolated. Treatment of 2-PMe3 with CO, NO, and 1/4 P4 formed (silox)3WCO (2-CO), (silox)3WNO (2-NO), and (silox)3WP (2-P), respectively. 2-CO and 2-NO are more conveniently prepared from Na/Hg reductions of 2-CI in the presence of CO and NO, respectively. Calculations reveal subtle effects of ndz2/(n+1)s mixing in differentiating the chemistry of Mo and W and in rationalizing the ...
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