N,N′-Bis(2,6-diisopropylphenyl)formamidinate complexes of the heavy alkaline earths

Abstract

The heavy alkaline earth elements calcium, strontium and barium react with two equivalents of N,N′-bis(2,6-diphenyl)formamidine (DippFormH) in the presence of bis(pentafluorophenyl)mercury to afford the bis(formamidinate) species [M(DippForm)2(THF)n] (M = Ca, n = 1 (1), M = Sr (2) or Ba (3), n = 2) in good to moderate yield. Use of one equivalent of DippFormH during the preparation of 1–3 putatively results in the formation of the organoamide heavy alkaline earth Grignard species “[(X)M(DippForm)]” (M = Ca, Sr or Ba, X = F or C6F5). These compounds participate in the nucleophilic substitution of the para-fluorine of pentafluorobenzene, a by-product of prior ligand exchange, to render DippForm(4-HC6F4).