Investigating the Formation of Different Crystallohydrates

Three hybrid compounds based on decavanadates, i.e., (NH[sub.4])[sub.2][Co(H[sub.2]O)[sub.5](β-HAla)][sub.2][V[sub.10]O[sub.28]]·4H[sub.2]O (1), (NH[sub.4])[sub.2][Ni(H[sub.2]O)[sub.5](β-HAla)][sub.2][V[sub.10]O[sub.28]]·4H[sub.2]O (2), and (NH[sub.4])[sub.2][Cd(H[sub.2]O)[sub.5](β-HAla)][sub.2][V[sub.10]O[sub.28]]·2H[sub.2]O (3), (where β-Hala = zwitterionic form of β-alanine) were prepared by reactions in mildly acidic conditions (pH ~ 4) at room temperature. These compounds crystallise in two structure types, both crystallising in monoclinic P2[sub.1]/n space group but with dissimilar cell packing, i.e., as tetrahydrates (1 and 2) and as a dihydrate (3). An influence of crystal radii and spin state of the central atom in [M(H[sub.2]O)[sub.5](β-HAla)][sup.2+] complex cations on the crystal packing leading to the formation of different crystallohydrate forms was investigated together with previously prepared (NH[sub.4])[sub.2][Zn(H[sub.2]O)[sub.5](β-HAla)][sub.2][V[sub.10]O[sub.28]]·4H[sub.2]O (4) and (NH[sub.4])[sub.2][Mn(H[sub.2]O)[sub.5](β-HAla)][sub.2][V[sub.10]O[sub.28]]·2H[sub.2]O (5) and spin states of [M(H[sub.2]O)[sub.5](β-HAla)][sup.2+] (M = Co[sup.2+], Ni[sup.2+], and Mn[sup.2+]) cations in solution were confirmed by [sup.1]H-NMR paramagnetic effects. FT-IR and FT-Raman spectra for 1–5 are in agreement with the X-ray structure analysis results.