121Sb Mössbauer Spectra of Hypervalent Complexes Having an Antimony-transition Metal Bond and Partial Quadrupole Coupling Constants

Abstract

Antimony-121 Mössbauer spectra for hypervalent pentacoordinate antimony compounds having Sb-transition metal bond [Rf2SbMCp(CO)n {RfH = o-C6H4C(CF3)2OH- , M = Fe, Ru, Cr,Mo, W}, Rf2SbFeCp(CO)PPh3, Rf2SbFeCp(dppe)] and closely related compounds Rf2SbTol (Tol = p-CH3C6H4), Rf2SbX (X = Cl, Br) are described. The strong -donor power of the metal fragments is demonstrated by theM¨ossbauer parameters. The -donor power decreases in the order FeCp(dppe) > FeCp(CO)PPh3 > FeCp(CO)2 > RuCp(CO)2 > CrCp(CO)3 > MoCp(CO)3 > WCp(CO)3 ≫Tol. The essential trends in the molecular structure and the Berry pseudorotation are interpreted by this order. In addition, the e2qQ values for 32 hypervalent antimony compounds are successfully calculated using the additivity model for the e2qQ value. A unique electronic feature for Rf2SbX is clarified through the calculation