Synthesis and reactivity in salt metathesis reactions of trivalent [La(Tp Me2) 2X] (X = Cl, I) complexes: crystal structures of [La(Tp Me2) 2Cl] and [La(Tp Me2) 2(κ 2-pz Me2)

Abstract

Reaction of LaX 3(THF) n (X = Cl, I) with two equiv. of K(Tp Me2) gave good yields of the bis-Tp complexes [La(Tp Me2) 2X] (X = Cl ( 1); I ( 3)). However, the formation of 1 and 3 is always accompanied by significant amounts of La(Tp Me2) 2(κ 2-pz Me2) ([pz Me2] − = 3,5-dimethyl-pyrazolato) ( 2). The pyrazolato complex 2, which presumably arises from decomposition of the [Tp Me2] − moiety during salt metathesis, was independently prepared in good yield from 1 and in situ generated [pz Me2] −. The solid-state structures of 1 and 2 were determined by single-crystal X-ray diffraction studies. Subsequent reactions of halogeno-Tp Me2 complexes 1 and 3 with various alkali metal salts MR (M = Li, R = CH 2SiMe 3, Ph, N(SiMe 3) 2; M = K, R = OAr) gave M(Tp Me2) as the major product. Alternatively, the mono-Tp bis(aryloxide) derivatives [Ln(Tp Me2)(OC 6H 2-2,6- t Bu-4-Me) 2] (Ln = La ( 4); Nd ( 5)) were obtained in high yields by salt metathesis of [Ln(OC 6H 2-2,6- t Bu-4-Me) 3] with one equiv. of K(Tp Me2).