Intercalation and co-ordination of ammonia and 1,2-diaminoethane into cobalt(II)-, nickel(II)-, copper(II)-, and vanadium(IV)-exchanged ?-tin phosphate

The reactions of gaseous ammonia and 1,2-diaminoethane (en) with ?-SnM(PO4)2·H2O (M = Co2+ Ni2+, Cu2+, or VO2+) have been investigated. Reactions occur with retention of the layered phosphate structure, the NH3-containing materials giving rise to an interlayer separation of 10.0 ± 0.05 Å. Co-ordination of NH3 occurs in all cases except for VO2+ (as deduced from electronic absorption spectra); Co2+ is present in a tetrahedral, probably CoN3O, environment not found in classical co-ordination chemistry, presumably as a consequence of the restricted space available in the interlayer. Ammonia co-ordinates to Ni2+ to give a cis-octahedral NiN3O3 environment and for Cu2+ a tetragonal octahedral environment, probably CuN2O2O?2. An extensive surface and interlayer complex chemistry is displayed by low (2%) loaded Cu2+-exchanged materials, for which e.s.r. studies have been made. The layer structure is retained on heating to 110 °C, stability to loss of ammonia being in the order: Cu2+ > Co2+ > Ni2+, with the greatest change in geometry for the partially dehydrated products occurring in the case of Ni2+ which adopts a five-co-ordinate environment. 1,2-Diaminoethane co-ordinates to both Cu2+ and Co2+, although only as a monodentate ligand; it does not appear to co-ordinate to either Ni2+ or VO2+, instead showing a tendency to hydrogen-bond to phosphate groups in the interlayer.