“Scorpionate-like” complexes that are held together by hydrogen bonds: Crystallographic and spectroscopic studies of (3-NH(t-butyl)-5-methyl-pyrazole)_nMX₂ (M = Zn, Ni, Co, Mn; n = 3, 4; X = Cl, Br)

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• 作者：Lee Serpas^a ; Robert R. Baum^c ; Alyssa McGhee^c ; Ismael Nieto^a ; Katherine L. Jernigan^e ; Matthias Zeller^b ; Gregory M. Ferrence^d ; David L. Tierney^c ; Elizabeth T. Papish^a ; ^e ; ^{etpapish@ua.edu" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Hydrogen-bonds ; Scorpionates ; Transition metal complexes ; Pyrazoles ; Anion binding
• 刊名：Polyhedron
• 出版年：2016
• 出版时间：16 August 2016
• 年：2016
• 卷：114
• 期：Complete
• 页码：62-71
• 全文大小：1731 K

文摘

The hydrogen bonding ligand, 3-NH(t-butyl)-5-methyl-pyrazole, forms “scorpionate-like” first row transition metal complexes that are held together by hydrogen bonds rather than covalent bonds. The formulae of these complexes are (LH)_nMX₂, where n = 3, 4; X = Cl, Br; and LH = 3-NH(t-butyl)-5-methyl-pyrazole. The amino-substituted pyrazole can hydrogen bond via both the amino group and the pyrazole NH to form intramolecular NH to halide hydrogen bonds. These complexes have been well characterized and show a 3:1 ratio of ligand to metal for zinc and cobalt (1 and 2), and a 4:1 ratio of ligand to metal for manganese and nickel (3 and 4). The hydrogen bonding interactions appear to be stronger for the 3:1 complexes. The crystallographic and spectroscopic studies (EPR and NMR) have shown that these hydrogen-bonding interactions are strong enough to perturb metal halogen bond distances and, with non-hydrogen bonding solvents, the hydrogen bonds appear to hold these complexes together in solution.