Structure of Sn(ND3)(2)F-4 - A molecular precursor for the synthesis of nitride fluorides

摘要

The molecular and crystal structure of Sn(ND3)(2)F-4 has been determined at room temperature using high resolution neutron powder diffraction. The compound crystallizes in a monoclinic unit cell containing two formula units with a = 7.7673(7) Angstrom, b = 6.2765(5) Angstrom, c = 5.1708(4) Angstrom, beta = 102.871(5) degrees, and space-group P2(1). The structure consists of isolated tin-centered octahedra with ammonia groups in trans configuration. The intramolecular stability of this compound has been investigated using Huckel molecular orbital calculations. Compared to Si(NH3)(2)F-4, the metal-nitrogen bonding interaction is found to be stronger, while the metal-fluorine bond is weaker in Sn(ND3)(2)F-4. Due to a different hydrogen bonding network the intermolecular orientation and packing of the octahedral M(NH3)(2)F-4 molecules in Sn(ND3)(2)F-4 is different from the arrangement observed in Si(NH3)(2)F-4. The implications for the use of these compounds as molecular precursors for the synthesis of SiNF and SnNF are discussed. (C) 1998 Academic Press. [References: 24]