The Mössbauer effect in tin(II) compounds. Part X. Insertion reactions of tin(II) compounds with carbonyl-π-cyclopentadienyliron derivatives

Abstract

The products of the insertion reactions of a number of tin(II) compounds SnX₂(X = Cl, Br, I, NCS, HCO₂, and AcO) with [(π-C₅H₅)Fe(CO)₂]₂ and (π-C₅H₅)Fe(CO₂)₂Cl are compared with those from replacement of Cl from [(π-C₅H₅)Fe(CO)₂]₂·SnCl₂ and (π-C₅H₅)Fe(CO)₂SnCl₃. The ¹¹⁹Sn Mössbauer parameters of both series of compounds [(π-C₅H₅)Fe(CO)₂]₂·SnX₂ and (π-C₅H₅)Fe(CO)₂·SnX₃(X = Cl, Br, I, NCS, HCO₂, and AcO) show that the use of tin bonding electrons is dominated by the Sn–Fe bond. The trends in chemical isomer shift and quadrupole splitting can be explained with reference to the very short Sn–Fe bond lengths in these materials. The positive sign for e²qQ can also be explained in terms of a high p-electron density on the tin atom in the direction of the Sn–Fe bond. The i.r. for the products of the insertion reactions are also presented.