Functionalised Alkaline Earth Iodides from Grignard Synthons PhAeI(thf)n (Ae = Mg-Ba)

Derivatisation of Grignard synthons PhAeI(thf)(n) (Ae = Mg-Ba) prepared in situ from reactions of metal filings and iodobenzene provides a one-pot synthesis of heteroleptic N donor alkaline earth iodide complexes. Protolysis of PhAeI(thf)(n) with 3,5-diphenylpyrazole (Ph(2)pzH) yields pyrazolate complexes [Mg-2(mu-Ph(2)pz)(2)(I)(2)(thf)(3)] (1), [Ae(Ph(2)pz)(I)(thf)(4)] (Ae = Ca (2), Sr (3)), and [Ba-2(Ph(2)pz)(2)(mu-I)(2)(thf)(8)] (4). Addition of the Ae-Ph moiety to carbodiimide MesN=C=NMes (Mes = 2,4,6-(CH3)(3)C6H2) gave a series of benzamidinate iodide complexes [Ca-2{(MesN)(2)CPh}(2)(mu-I)(2)(thf)(4)] (6), [Sr{(MesN)(2)CPh}(I)(thf)(4)] (7), and [{Ba{(MesN)(2)CPh}(mu-I)(thf)(3)}(infinity)] (8). By contrast a symmetrical magnesium complex [Mg{(MesN)(2)CPh}(2)(thf)] (5) was obtained by Schlenk redistribution. These syntheses proceed without pre-activation of the metal for strontium and barium, and after activation with 2 mol-% iodine for calcium. The heavy alkaline earth metal complexes are the first examples of heteroleptic halide pyrazolate or amidinate complexes for strontium and barium. Complexes 1, 3, 4 and 6-8 were characterised crystallographically, revealing diverse structural chemistry of heteroleptic amidinate and pyrazolate iodide complexes across the alkaline earth series. A highlight is [Ba{(MesN)(2)CPh}(mu-I)(thf)(3)](infinity) (8) - an iodide bridged infinite 1-D polymer.