Isolated versus condensed anion structure VII: X-ray structure analysis of1,3-propanediammonium dibromodichlorocadmate(II), [H3N(CH2)(3)NH3]CdBr2Cl2, and estimation of stability of five-coordinated halide anions, MX53- (M =Cd, Zn; X = Cl, Br) by means of ab-initio MO calculations

The coordination capability of Cl and Br in halogenocadmate(II) complexes i s estimated by a solution of the structure of 1,3-propanediammonium dibromo dichlorocadmate(II). The compound crystallizes as a layered anion structure with Cl bridges and Br terminals at 293 K: Imma, a = 741.56(7), b = 1869.5 (5), and c = 771.55(8) pm, Z = 4. In order to explain the stronger tendency of halogenocadmate(II) complexes to form layered structures as compared to halogenozincate(II), ab-initio calculations were performed. The stability of MX53- (M = Cd, Zn; X = Cl, Br) is compared. Isolated ZnX53- and CdBr53- ions are not stable. On the other hand a trigonal bipyramid CdCl53- ion is considered to be subtly stable in the crystal mainly due to Coulomb attract ive interactions between the positively charged metal cation Cd2+ in a CdCl 3- fragment and two Cl- ions.