X-ray diffraction and
halogen nuclear quadrupole resonance (n.q.r.) methods
show that Rb3ZnBr5, (NH4)3ZnBr5,
and CsZnI5 are isostructural with
orthorhombic (NH4)3ZnCl5, and that Rb3ZnCl5
has the tetragonal Cs3CoCl5 structure. ZnI2,2NH3
is isomorphous with the corresponding chloride and bromide diammines.
Rb2ZnBr4 and (NH4)2ZnBr4
have structures of Cs2ZnBr4 type, although the rubidium
salt shows some stacking faults. In the complex chlorides 35Cl
n.q.r. frequencies are grouped about 9 MHz, while the
bromides have 81Br frequencies grouped around 60 MHz. The � →
3/2 transitions of 127I in the iodides are in the region of 76 MHz.
The diammine compounds ZnBr2,2NH3
and ZnI2,2NH3 have frequencies close to the mean values
for the ZnBr42- and ZnI42- ions
respectively, but in the hydrates ZnCl2,l⅓H2O,ZnBr2,2H2O,
β-KZnBr3,2H2O, and KZnI3,2H2O
the halogen frequencies are increased.
N.q.r. and X-ray data are also reported for the compound
Cs3CuCl5, formed by quenching the melt. This compound
slowly disproportionates at room temperature into Cs2CuCl4
and CsCl.