Homopolyatomic anions and configurational questions. Synthesis and structure of the nonagermanide(2-) and nonagermanide(4-) ions, Ge/sub 9//sup 2 -/ and Ge/sub 9//sup 4/-
Reaction of solid KGe with 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazobicyclo(8.8.8)hexacosane) in ethylene-diamine yields deep-red rods which have been shown to be (crypt-K/sup +/)/sub 6/Ge/sub 9//sup 2 -/Ge/sub 9//sup 4 -/.2.5en by x-ray crystallography. The compound crystallizes in P anti 1 space group with Z = 2 and a = 20.037 (2) A, b = 28.944 (2) A, c = 14.546 (2) A, ..cap alpha.. = 99.356 (8)/sup 0/, ..beta.. = 94.077 (8)/sup 0/, and ..gamma.. = 87.60 (1)/sup 0/, V = 8312.9 (12) A/sup 3/ at 25/sup 0/C. Diffraction data were measured over four octants using a four-circle automated diffractometer and monochromatized Mo K..cap alpha.. radiation, and the structure was solved by direct methods and Fourier techniques. The 190 independent (nonhydrogen) atoms in the structure yield, with anisotropic thermal parameters for germanium and potassium, R = 0.149 and R/sub w/ = 0.169 for 8409 independent observed reflections with 2theta equal to or less than 50/sup 0/. Charges on two Ge/sub 9/ cluster ions were assigned according to their relationship to isoelectronic Sn/sub 9//sup 4 -/ (C/sub 4/v) and B/sub 9/H/sub 9//sup 2 -/ (D/sub 3h/). The Ge/sub 9//sup 4 -/ ion configuration is quite close to the ideal C/sub 4v,//sup 2/ with a nearly square base (3.58 and 3.64 A diagonals and a vicinal dihedral angle delta 5.3/sup 0/) and delta 162 and 156/sup 0/ for the characteristic opposed faces parallel to the fourfold axis (158/sup 0/ in Sn/sub 9//sup 4 -/). The Ge/sub 9//sup 2 -/ ion exhibits essentially C/sub 2nu/ symmetry but clearly derives from the D/sub 3h/ limit, with 2.81, 2.86, and 3.17 A for the parallel edges of the trigonal prism, delta 171/sup 0/ for the opposed faces therein, and capping atoms separated by 4.00, 4.16, and 4.22 A. Atomization energies from SCF-MO-CNDO calculations support the charge assignment deduced geometrically, the differentiation of configurations arising almost entirely from the Ge/sub 9//sup 2 -/ ion. The configurational contrast between the highly polar Sn/sub 9//sup 4 -/ and Ge/sub 9//sup 4 -/ (C/4nu/) and the isoelectronic but apolar Bi/sub 9//sup 5 +/ (D/sub 3h/) is considered further.
- Research Organization:
- Ames Lab., IA
- OSTI ID:
- 5219437
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 99:22
- Country of Publication:
- United States
- Language:
- English
Similar Records
Stable homopolyatomic anions. Synthesis and crystal structures of salts containing the pentaplumbide(2-1) and pentastannide(2-1) anions. [Stabilized by complexation with 2,2,2-crypt]
Polybismuth anions. Synthesis and crystal structure of a salt of the tetrabismuthide(2-) ion, Bi/sub 4//sup 2 -/. A basis for the interpretation of the structure of some complex intermetallic phases