INTERACTION OF PH2ZN WITH 1,3-XYLYL CROWN ETHERS - CRYSTAL-STRUCTURES OF 3 1-1-COMPLEXES

The behavior of diphenylzinc toward four 1,3-xylyl crown ethers was investigated. Only "simple" complexation occurred, whereas diphenylmagnesium had previously been shown to lead to halogen-metal exchange, metalation, or rotaxane formation. Three of the 1:1 complexes were obtained as crystalline solids and characterized by X-ray crystal structure determination; 1,3-xylyl 15-crown-4 (1) gave an oily adduct. Crystals of diphenylzinc-2-bromo-1,3-xylyl 15-crown-4 (8) are monoclinic, space group P2(1)/n, with unit cell dimensions a = 9.800 (1) angstrom, b = 12.887 (1) angstrom, c = 19.671 (2) angstrom, beta = 95.66 (1)-degrees, and Z = 4. Crystals of diphenylzinc-2-bromo-1,3-xylyl 18-crown-5 (9) are monoclinic, space group P2(1)/n, with unit cell dimensions a = 9.368 (1) angstrom, b = 10.975 (1) angstrom, c = 27.051 (2) angstrom, beta = 97.48 (2)-degrees, and Z = 4. Crystals of diphenylzinc-1,3-xylyl 18-crown-5 (10) are monoclinic, space group P2(1)/n, with unit cell dimensions a = 14.775 (3) angstrom, b = 18.252 (3) angstrom, c = 20.082 (1) angstrom, beta = 103.29 (1)-degrees, and Z = 8; two independent but chemically equivalent residues are present in the unit cell. The three molecular structures are closely related: the zinc atom is tetrahedrally surrounded by two phenyl groups and by two of the oxygens of the crown ether. These organozinc complexes may serve as (stable) models for intermediate stages in the above-mentioned reactions of organomagnesium compounds with crown ethers.