17-Electron, four-legged piano stool CpMoX2L2 complexes (X = halogen, L = tertiary phosphine). EPR evidence for the existence of a second isomer in solution

Rinaldo Poli (1) , Beth Owens (1) , Steven Krueger (1) , Arnold Rheingold (2)

1 University of Maryland [College Park]
2 University of Delaware [Newark]

Several 17-electron molybdenum(III) complexes of the type CpMoCl2L2 have been generated by either (1) reaction between CpMoCl2 and the appropriate L, (2) reaction between MoCl3(THF)3, the appropriate L and CpTl, and (3) phosphine exchange from CpMoCl2(PPh3)2. The iodide complexes CpMoI2L2 (L = PMePh2, PPh3) have been generated from the corresponding chloride and NaI. The complexes have been investigated by EPR (X-band and Q-band) and cyclic voltammetry. The four-legged piano stool structure is found by single crystal X-ray diffraction studies of the PMePh2 and PPh3 dichloride compounds. However, this structure equilibrates in solution with at least one other isomeric form which is observable for the PMe2Ph complexes by X-band EPR and for other complexes, including the previously reported CpMoCl2(dppe), by Q-band EPR. Phosphine exchange equilibria show a thermodynamic stability trend that parallels the phosphine σ-donor strength.

Domaines: Chimie de coordination

Rinaldo Poli, Beth Owens, Steven Krueger, Arnold Rheingold. 17-Electron, four-legged piano stool CpMoX2L2 complexes (X = halogen, L = tertiary phosphine). EPR evidence for the existence of a second isomer in solution. Polyhedron, 1992, 11 (18), pp.2301-2312. ⟨10.1016/S0277-5387(00)83516-0⟩. ⟨hal-03534689⟩