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 [Ni3(L)(CO3)(H2O)(py)7] (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 J1=−15.5cm−1, J2=−0.4cm−1, J3=−3.1cm−1 (in agreement with the values calculated by DFT) and presumably a very unusually strong intermolecular coupling of J4=−19.8cm−1. All the above constants in the convention of H=−2ΣJij(SiSj) for the exchange Hamiltonian.