Synthesis and Molecular Structures of Meta-Substituted Arylcalcium Iodides

The reduction of meta-methyl-substituted
iodobenzene with activated calcium in tetrahydrofuran (THF) yields
[(3-MeC6H4)­CaI­(thf)4] (1) and [(3,5-Me2C6H3)­CaI­(thf)4] (2). The reaction of 3-halo-1-iodobenzene with
calcium powder leads to the formation of the corresponding post-Grignard
reagents [(3-XC6H4)­CaI­(thf)4] [X
= F (3), Cl (4), Br (5), and
I (6)]. The synthesis of the thf adducts of 3-methoxyphenylcalcium
iodide (7) and β-naphthylcalcium iodide (8) follows the same strategy. All post-Grignard reagents show
a characteristic low-field shift for the calcium-bound carbon atoms
in 13C NMR spectra. The molecular structures of 1, 2, 4, and 8 show distorted
octahedral environments for the calcium centers with the aryl and
halide anions in a trans arrangement.