Structure, photochemistry and magnetic properties of tetrahydrogenated Schiff base chromium(III) complexes

•Five tetrahydrogenated Schiff base Cr(III) complexes were composed.•The stability relates to the chelate effect of rings.•The photochemistry reaction was studied.•Complex 5 exhibits a strong antiferromagnetic coupling.

Four mononuclear chromium(III) complexes [Cr(L(1))(en)]Br0.3Cl0.7 (1), [Cr(L(1))(pr)]Cl (2), [Cr(L(2))(en)]ClO4 (3), [Cr(L(2))(pr)]Cl (4) along with one dinuclear μ-methoxo [Cr(μ-OMe)(L1)]2 (5) were synthesized (en = 1,2-ethanediamine, pr = 1,3-diaminopropane H2L(1) = Tetrahydrosalen = H2[H4]salen = N,N′-bis(2-hydroxybenzyl)-1,2-ethanediamine, H2L(2) = Tetrahydrosalpr = H2[H4]salpr = N,N′-bis(2-hydroxybenzyl)-1,3-diaminopropane). The competitive reactions in the presence of EDTA were carried out and the first-order rate constants k(1) = (5.2 ± 0.2) × 10−3 h−1 < k(2) = (6.7 ± 0.3) × 10−3 h−1 < k(3) = (8.0 ± 0.1) × 10−3 h−1 < k(4) = (9.5 ± 0.2) × 10−3 h−1 were obtained by spectroscopic measurements. In addition, photo-induced decomposition was monitored under irradiation of xenon lamp. The sequence of first-order rate constants is k′(1) = (4 ± 0.1) × 10−4 s−1 < k′(2) = (6 ± 0.3) × 10−4 s−1 < k′(3) = (1.1 ± 0.2) × 10−3 s−1 < k′(4) = (1.4 ± 0.2) × 10−3 s−1, which is in accordance with that of kinetics studies with EDTA. Dinuclear complex 5 exhibits a strong antiferromagnetic coupling with the J = −10.8 cm−1.

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