Two isosceles coordination [Ni3] triangles strongly interacting via hydrogen bonds

A ligand containing two 2-hydroxyphenylpyrazolyl groups around a pyridine core (H4L) reacts with Ni(II) in basic and aerobic conditions to produce a rare scalene triangular complex with formula [Ni-3(L)(CO3) (H2O)(PY)71 (1). This complex crystallizes in the form of pairs of molecules linked to each other through strong H-bonding interactions. The magnetic exchange interactions in this system have been studied, leading to intramolecular coupling constants J(1)= -15.5 cm(-1), J(2) = -0.4 cm(-1), J(3) = -3.1 cm(-1) (in agreement with the values calculated by OFT) and presumably a very unusually strong intermolecular coupling of J(4) = -19.8 cm(-1). All the above constants in the convention of H = -2 Sigma J(ij)(SiSj) for the exchange Hamiltonian. (C) 2012 Elsevier Ltd. All rights reserved.