No abstract

31P solid-state NMR spectroscopy is a powerful tool to get structural information about the environment of the phosphorus atoms in zinc phosphonates. In a series of various known structures taken as reference, the connectivity of the RPO3 groups (i.e., the number of zinc atoms bonded to each of the three oxygen atoms of the phosphonate units) can be differentiated on the basis of the value of the chemical shift asymmetry and anisotropy.

No abstract

Two original layered copper(II) hydroxyphosphonates Cu 2.5 (O 3 P(CH 2 ) 2 NH 3 )(OH) 2 (SO 4 ) (monoclinic P2 1 /n (No. 14), a ) 5.442(1) Å, b ) 20.570(4) Å, c ) 8.529(2) Å, β ) 93.18(3)°, Z ) 4) and Cu 2 (O 3 P(CH 2 ) 2 NH 2 were prepared from copper sulfate or nitrate, (2-aminoethyl)phosphonic acid, and sodium hydroxide in water. In both cases, the anion of the starting copper salt was retained in the structure. For the first compound, the sulfate groups were part of the layer, while, for the second, the nitrate groups were present in the interlayer space, in a manner similar to that observed in layered double hydroxides.

On the basis of XANES-EXAFS experiments, neither the dehydration nor the subsequent n-alkylamine intercalation in Zn(O,PCH,)-H,O appears to be topotactic. On the contrary, the whole process consists of breaking Zn-0 bonds present in the hydrated material, so that no bridging oxygen remains in the inorganic sheet. This hypothesis is supported by the structuralo determination of an aniline intercalate: Zn(0,PC2H4C02H).0.5C6H5NH2 [orthorhombic, space group Pbcn, a = 29.880( 6) A, b=8.526(2) A, c = 14.720(3) A, V=3750.3(8) A3, Z = 16, R=0.043 and R,=0.047; 2063 observed reflections, I >20(1)]. For steric reasons, only half of the zinc atoms are coordinated to aniline; the second half of the metal atoms that are not bound to the amine retain the environment present in the initial anhydrous phase.

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