Cp*Mo-halide chemistry. Rapid halide scrambling during the conproportionation of Cp2*Mo2Y4 (Y = Cl, Br, I) and Cp*MoX4(X = Cl, Br): A paramagnetic 1H NMR study

Heinz-Bernhard Kraatz (1) , Rinaldo Poli (1)

1 University of Maryland [College Park]

The reaction of the d1 four-legged piano-stool complexes Cp*MoX4 (X = Cl, Br) with the d3-d3 binuclear complexes Cp2*Mo2Y4 (Y = Cl, Br, I) results in electron transfer and formation of the salts [Cp2*Mo2Y2]+[Cp*MoX4]−. Solutions of [Cp2*Mo2I4]+[Cp*MoX4] − (X = Cl, Br) are stable indefinitely in chlorocarbon solvents. However, for the Cp2*Mo2Y4 /Cp*MoX4 (Y, X = Cl, Br) systems, conversion to the complexes Cp2*Mo2Y6-nXn is observed together with halide exchange reactions between the cation and the anion. The formation of Cp2*Mo2 Y6-nXn and the halide exchange are postulated to proceed via a common associative intermediate. The rate of formation of Cp2*Mo2Y6-nXn depends mostly on the Lewis acidity of the cation Cp2*Mo2Y4+, which varies in the order [Cp2*Mo2Cl4] >> [Cp2Mo2Br4] >> [Cp2*Mo2I4]+, and has little dependence on the nature of X.

Mots clés: Molybdenum; Conproportionation; Cyclopentradienyl; Halide; Paramagnetism; Nuclear magnetic resonance

Domaines: Chimie de coordination

Heinz-Bernhard Kraatz, Rinaldo Poli. Cp*Mo-halide chemistry. Rapid halide scrambling during the conproportionation of Cp2*Mo2Y4 (Y = Cl, Br, I) and Cp*MoX4(X = Cl, Br): A paramagnetic 1H NMR study. Journal of Organometallic Chemistry, 1994, 475 (1-2), pp.167-175. ⟨10.1016/0022-328X(94)84019-9⟩. ⟨hal-03533299⟩