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Synthesis of Chelate-Supported Dialkyl and Alkylidene Complexes of Molybdenum(VI)

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journal contribution
posted on 23.09.1999 by Carlos G. Ortiz, Khalil A. Abboud, James M. Boncella
The use of chelating diamide [o-(Me3SiN)2C6H4]2- as a coligand for high-oxidation early transition metal complexes has been investigated. Reaction of Mo(NPh)2Cl2DME with Li2[o-(Me3SiN)2C6H4] afforded green microcrystals of [Mo(NPh)(μ-NPh)(o-(Me3SiN)2C6H4)]2 (1), while reaction of Mo(NPh)2Cl2DME with H2[o-(Me3SiN)2C6H4] gave Mo(NPh)Cl2(o-(Me3SiN)2C6H4)(NH2Ph) (2). Two derivatives of 2 are reported, Mo(NPh)Cl2(o-(Me3SiN)2C6H4)(PMe3) (3) and Mo(NPh)Cl2(o-(Me3SiN)2C6H4)(THF) (4). Structural studies of 3 are reported. Reaction of 3 or 4 with RMgX (X = Cl or Br) gave Mo(NPh)R2(o-(Me3SiN)2C6H4) (R = Me 5, Ph 6, CH2CMe3 7, CH2Ph 8, CH2SiMe3 9). Reaction of 2 with RMgCl (R = CH2CMe3, CH2SiMe3) gave mixtures of Mo(NPh)R2(o-(Me3SiN)2C6H4) and Mo(NPh)2R2. Both Mo(NPh)2(CH2CMe3)2 (10) and Mo(NPh)2(CH2SiMe3)2 (11) were isolated form the reaction of Mo(NPh)2Cl2DME and RMgCl (R = CH2CMe3, CH2SiMe3). The alkylidene, Mo(NPh)(C(H)CMe3)(o-(Me3SiN)2C6H4)(PMe3) (13), was isolated from the reaction of 7 and an excess of PMe3 at 80 °C, while Mo(NPh)(C(H)SiMe3)(o-(Me3SiN)2C6H4)(PMe3) (14) was only observed by 1H NMR under similar conditions.