Synthetic routes to Ga(CN)(3) and MGa(CN)(4) (M=Li, Cu) framework structures

Ga(CN)(3) has been prepared for the first time with a new method for preparation of inorganic cyanides. Pure crystalline material is formed by reaction of Cl2GaN3 with SiMe3CN via elimination of SiMe3N3 and SiMe3Cl. Reaction of GaCl3 with SiMe3CN also provides Ga(CN)(3). A new convenient route to GeMe3CN and SnMe3CN is described. but reactions of GaCl4 with these compounds result in Lewis acid-base adducts. The composition of Ga(CN)3 was confirmed by spectroscopic and elemental analysis. Quantitative X-ray powder diffraction was used to refine the cubic structure, which has CN groups with orientational disorder in a Prussian-blue-like network structure. The symmetry is Pm (3) over bar m, a = 5.295(2) Angstrom. Ga is octahedrally surrounded by on average three C and three N atoms with a Ga-(C,N) bond length of 2.072(2) Angstrom, and the C-N bond length is 1.148(1) Angstrom. LiGa(CN)(4) was prepared by reaction of Ga(CN)(3) with LiCN and was characterized by quantitative X-ray diffraction. The symmetry is P4 (3) over bar m, a = 5.874(2) Angstrom, and the structure consists of LiN4 and GaC4 tetrahedra linked by C-N bonds to form two interpenetrating networks of the Zn(CN)2 type. CuGa(CN)(4) has a similar structure with a = 5.729(5) Angstrom, but Cu,Ga and/or C,N disorder cannot be ruled out.