Triaqua(1,4,7-triazacyclononane-κ³N¹,N⁴,N⁷)nickel(II) bromide nitrate

Abstract

In the title half-sandwich compound, [Ni(C6H15N3)(H2O)3]Br(NO3), the central NiII ion, lying on a threefold rotation axis, is six-coordinated by three amine N atoms from the face-capping triaza macrocycle and three water O atoms in a slightly distorted octa­hedral geometry. In the crystal, O—H⋯O hydrogen bonding and weak O—H⋯Br inter­actions associate the NiII cations and the counter-ions into a three-dimensional supra­molecular network.

The Disproportionation of [Ni(tacn)]2+ in Ni2+ and [Ni(tacn)2]2+ Crystallographically Demonstrated (tacn=1,4,7‐Triazacyclononane)

“…It should be noted that the molecular structure of the [Ni(tacn)(H 2 O) 3 ] 2 + cation had been previously reported in the [Ni(tacn)(H 2 O) 3 ](NO 3 )(Br) crystal salt. [8] The two complex salts exhibit similar geometries. In particular, both nitrate and nitrate-bromide salts crystallise in the same P2 1 3 non-centrosymmetric chiral space group.…”

“…Then, at the 1:1 molar ratio, the complex [Ni(tacn) On the other hand, the crystallisation of [Ni(tacn)(H 2 O) 3 ]-(NO 3 )(Br) took place under completely different conditions. [8] In particular, the reaction was carried out in much more dilute conditions (< 2 10 À3 m, 1:1 molar ratio) and, after 2 h of reflux, the solution was left at room temperature in open air. Crystals of the sole 1:1 complexes were obtained after two months.…”