Organonitriles as ligands in low-spin di[1,2-bis(diethylphosphino)ethane]iron complexes

Abstract

The complex trans-[FeCl₂(depe)₂][depe = 1,2-bis(diethylphosphino)ethane] reacts with Organonitriles, RCN, to give 1 : 1 complexes of the type trans-[FeCl(NCR)(depe)₂]⁺ which have been isolated as their tetraphenylborate salts. When R = alkyl the 2 : 1 complexes trans-[Fe(NCR)₂(depe)₂]²⁺ are also formed. The reaction of the dinitriles. malononitrile (maln), 1,2-dicyanobenzene (dcb), and succinonitrile (sucn) have also been studied, I.r. and Mössbauer spectra for a selection of these complexes have been recorded and are discussed in an attempt to assess the relative importance of the σ-donor and π-acceptor properties of the various ligands in determining their co-ordinating ability.