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.