Coordination-Driven Self-Assembly of a Novel Carbonato-Bridged Heteromolecular Neutral Nickel(II) Triangle by Atmospheric CO₂ Fixation

Formation of a quasi-symmetrical μ3-carbonato-bridged self-assembled heteromolecular triangle of Ni(II), [(μ3-CO3){Ni2(salmeNH)2(NCS)2}{Ni(salmeNH2)2]·Et2O·H2O (HsalmeNH = 2-[(3-methylamino-propylimino)-methyl]-phenol) involves atmospheric CO2 uptake in a neutral medium, by spontaneous self-reorganization of the starting mononuclear Ni(II)−Schiff-base complex, [Ni(salmeNH)2]. The environment around Ni(II) in two of the subunits is different from the third one. The starting complex, [Ni(salmeNH)2], and one of the possible intermediate species, [Ni(salmeNH2)2(NCS)2], which has a very similar coordination environment to that in the third Ni(II) center, have been characterized structurally. A plausible mechanism for the formation of such a triangle has also been proposed. The compound shows a very strong antiferromagnetic coupling. Fit as a regular triangular arrangement gave J = −53.1, g = 2.24, and R = 1.5 × 10−4.