The crystal and molecular structure of the title complexes have been determined by X-ray diffraction using visually estimated intensity data. The nickel compound has a = 13.965(10), b = 7.403( lo), c = 8.91 2 ( 9 ) A, p = 99.3(9)", Z = 2, and space group P2,/a, while the copper compound has a = 10.871 ( 8), b = 7.576(10), c = 27.579(7)A, (3 = 127.0(8)", Z = 4, and space group P2,/c. The co-ordination plane in the nickel case is tilted by ca. 22" towards the salicylaldimine plane and the two salicylaldimine planes have a significant step ca. 1.02 A at Ni. The salicylaldimine groups in the copper case are only slightly tilted relative to the co-ordination plane, which has a small tetrahedral distortion.

presence of aqueous ammonium phosphate solutions. Particularly, struvite is reported to react with a saturated solution of ammonium dihydrogen phosphate to form hannayite, which is then slowly replaced by schertelite; these reactions can be summarized as follows:3 struvite + 3NH4H2PO4 hannayite + 2(NH4)2HPO4 + 10H20 ~-3 schertelite + 6H20.Inversely, schertelite and hannayite undergo hydrolytic reactions dissolving incongruently in water:schertelite + 2H20 struvite + NH4H2PO4, hannayite + 4H20 struvite + 2 newberyite + NH4HzPO 4.Such transformations also probably occur in human renal liquids under pathological conditions. They can be explained by the strong tendency of systems with this chemical composition to give crystals characterized by a layered structure, where the amount of NH + ions between layers and the degree of condensation of coordination polyhedra inside the layers vary according to the concentrations of the different chemical species. When hannayite transforms into schertelite, for instance, the condensation of polyhedra decreases strongly, with the formation of isolated Mg(H20)4(OPO2OH)2 groups. The first bonds which break in hannayite are likely to be Mg(2)-O(3) and Mg(2)-O(7) (Fig. 2), since they involve the most underbonded O atoms in the structure (~si = 1.83 v.u.); this should be true both for complete solubilization of crystals and for incomplete solubilization with partial solid-state reaction. The latter mechanism would agree with the fact that, by breaking Mg(2)-O(3), isolated groups of Mg(H20)4(OPO2OH)2 are formed, which could build up the schertelite crystal framework.The X-ray intensities were measured at the Centro di Studio del C.N.R. per la Cristallografia Strutturale, Pavia.Research was supported by the Consiglio Nazionale delle Ricerche, Roma. The structure of bis-(N-p-tolylsalicylaldiminato)copper(II) has been determined by the photographic method and refined to R= 0.09. The crystals are monoclinic needles, a= 13.584, b= 7.546, e= 12-221 A, fl= 110-8 °, Z=2. The structure consists of discrete molecules in which the metal atom exhibits trans-planar fourfold coordination and has Cu-O 1.899 and Cu-N 2-010 ,~. The p-tolyl group is inclined by 124 ° to the salicylaldimine plane. References

Crystal and Molecular Structure of Bis(N-n-decyl-o-hydroxyacetophenoniminato)copper(ir) t

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