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Facile Synthesis and Structural Characterization of [Cp2TiIV(NCX)2][AsF6]2 Complexes:  Adducts of Cp2Ti(AsF6)2 with Halogen Cyanides (X = Cl, Br, I)

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posted on 02.01.2006, 00:00 by Margaret-Jane Crawford, Peter Mayer, Heinrich Nöth, Max Suter
A series of adducts between the highly reactive dicationic Cp2TiIV 2+ center and the weak Lewis base halogen cyanides (ClCN, BrCN, ICN) have been prepared in a facile synthesis and in quantitative yields from the reaction of Cp2Ti(AsF6)2 with ClCN, BrCN, or ICN in liquid SO2. The extremely air-sensitive Cp2Ti(NCX)2(AsF6)2 (X = Cl (1), Br (2), I (3)) complexes were characterized using IR and 1H, 14N, 19F, and 75As NMR spectroscopy, as well as X-ray diffraction. The structures of 13 were determined using X-ray diffraction techniques. The synthetic route employed should generally be applicable for the synthesis of a range of new cationic Cp2TiIVL22+ (L = neutral ligand) species using anhydrous conditions and demonstrates the usefulness of liquid SO2 as a solvent for such systems. Compounds 13 are the first structurally characterized Cp2TiIVL2(EF6)2 (L = neutral ligand; E = As, Sb) complexes with the weakly coordinating AsF6- anion and are also the first adducts between cationic Cp2Mx+ (M = transition metal) centers and the halogen cyanides, which are weak Lewis bases in comparison with other nitriles such as CH3CN.