Difference in the Formation of Two Structural Types of V-Shaped MII3 Clusters: Diffraction, Mass Spectrometry, and Magnetism

A way to understand kinetics and explore mechanism of reactions is to identify the intermediates and their relative energetics. In this respect, low-energy electrospray ionization mass spectrometry is providing information on possible intermediates that can be tandemly verified using crystallography of the products. This has been extended to the study of the formation of functional clusters of transition metals under varying conditions. The reaction of NiL2 (L = 2-ethoxy-6-(N-methyliminomethyl)phenolate) with MII(H2O)6(ClO4)2 in the presence of Et3N base leads to [NixM7-x(μ3-OH)6L6]2+ according to NiL2 → [M2L3]+ → [M4(OH)2L4]2+ → [M7(OH)6L6]2+. In contrast, its reaction with MII(H2O)6(NO3)2 in the absence of base leads to two crystallographic structural types [MII3L4(NO3)2(H2O)2]·CH3CN for M = Ni (I-Ni3) or Co (I-CoxNi3-x, x = 0–3) and [MIINiII2L4(NO3)2] for M = Zn (II-ZnNi2) or Co (II-CoNi2). Interestingly, ESI–MS suggests three slightly different formation processes: for I-Ni3, {NiL2 → [Ni2L(NO3)2]+ → [...