Quasi-1D chains of dinickel lantern complexes and their magnetic properties.

Four new quasi-1D Ni ₂ -lantern chain complexes of the form [Ni ₂ (SOCR) ₄ (L)] _∞ (R = Ph, L = DABCO (1); R = Ph, L = pyz (2); R = CH ₃ , L = DABCO (3); R = CH ₃ , L = pyz (4)) were prepared from the reaction of [Ni ₂ (SOCR) ₄ (EtOH)], R = CH ₃ or Ph, with the N,N'-donor bridging ligands pyrazine (pyz) or 1,4-diazabicyclo[2.2.2]octane (DABCO). Reaction of [Ni ₂ (tba) ₄ (EtOH)], (tba = thiobenzoate) with the mono-N donor ligand quinuclidine (quin) gave the discrete Ni ₂ -lantern complex [Ni ₂ (tba) ₄ (quin)] (5), whereas reaction with pyridine led to fragmentation of the lantern and formation of the known [Ni(tba) ₂ (py) ₂ ] (6). Single-crystal X-ray diffraction reveals 2-4 to be 1D chain complexes comprising DABCO or pyz ligands which bridge the Ni ₂ -lantern units. Complex 5 forms dimers through two equivalent NiS interactions. The Ni-Ni distances within the Ni ₂ -lanterns are 2.5316(18)-2.595(2) Å for the 1D chain complexes 2-4, and 2.5746(4) Å in the dimeric complex 5, respectively. Comparing the solid state magnetism of 5 to precursor [Ni ₂ (tba) ₄ (EtOH)] demonstrates a change in coupling upon change of capping ligand. Meanwhile, chains 1-4 exhibit magnetic properties consistent with an S = 1 system, due to a mixed valent system where the two Ni centers differ in spin state, while 5 possesses two S = 1 Ni(ii) centers. DFT calculations confirm low-spin S = 0 {NiS ₄ } and high-spin S = 1 {NiO ₄ } centers in each lantern. Fits to the magnetic susceptibility data of the chains suggest a weak antiferromagnetic mean field interaction is present that is largely 1-D in nature, though neither pyrazine nor DABCO promote significant magnetic interaction between neighboring Ni ₂ -lanterns.