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Magnetic exchange in Cis-bis(glycinato)aquocopper(II), Bis-(hydrogen-o-phthalato)aquocopper(II), (o-phthalato) aquocopper(II) and the corresponding dehydrated complexes. A possible correlation between copper(II)Water bond lengths and the ability of hydrated copper(II) carboxylates to form magnetically-subnormal anhydrous complexes

1976; Elsevier BV; Volume: 19; Linguagem: Inglês

10.1016/s0020-1693(00)91073-9

1873-3255

Kenneth E. Hyde, Peter L. Bocko, Michael W. Lynch, Richard M. Adams, Gerald F. Kokoszka,

Spectroscopy and Quantum Chemical Studies

The temperature dependence of the magnetic susceptibility has been determined for several hydrated copper(II) carboxylate complexes. The susceptibility-temperature data for the hydrates bis(glycinato) aquocopper(II), bis(hydrogen-o-phthalato)diaquocopper(II) and o-phthalatoaquocopper(II) are described by the Curie-Weiss Law [θ(°K) = −7 ± 6,−0.6 ± 3.3 and −26± 7, respectively]. Additional epr studies suggest the presence of a low dimensional pathway for interactions between copper(II) ions in (o-phthalato)aquocopper(II) but only very weak interactions in bis (hydrogen-o-phtalato)diaquocooper(II). The anhydrous bis(glycinato)copper(II) also exhibits Curie-Weiss behavior (θ = −21 ± 4°K) but the anhydrous o-phthalatocopper(II) has a susceptibility maximum at about 250°K and the susceptibility - temperature data may be fit to the Bleaney-Bower's equation (J∼280 cm−1). Thermogravimetric analyses and differential scanning calorimetry have been used to characterize the dehydration process in the hydrated complexes. A possible correlation between copperwater bond lengths and the ability of a hydrated copper(II) carboxylate to form magnetically subnormal anhydrous complexes is proposed. Specifically, dehydration of magnetically normal hydrated copper(II) carboxylates, where water molecules occupy one or more of the short contact positions, tends to produce a magnetically subnormal anhydrous complex.