Syntheses, Crystal Structures and Mass Spectrometry of Mononuclear NiII Inclusion Product and Self-Assembled [2 x 1+1 x 2] NiII 3MII (M = Cu, Ni, Co, Fe or Mn) Cocrystals Derived from N,N′-Ethylenebis(3-ethoxysalicylaldimine)

The syntheses, characterization and structures of a mononuclear nickel(II) compound [(NiLI)-L-II subset of(H2O)] (1) and [2 X 1+1 X 2] cocrystals [((NiLMII)-L-II-M-I(H2O)3}{(NiLI)-L-II)(2)](ClO4)(2) [M = Cu (2), Ni (3), Co (4), Fe (5) and Mn (6)] derived from the hexadentate Schiff base compartmental ligand N,N'-ethylenebis(3-ethoxysalicylaldimine) (H2L1) have been described in this investigation. Compound 1 is an inclusion product in which the water molecule is encapsulated in the O-4 compartment by forming bifurcated hydrogen bonds. Reactions of I with perchlorate salts of copper(IT), nickel(II), cobalt(H), iron(II) and manganese(II) in open atmosphere produce compounds 2-6, which have similar structures, These compounds are 12 X 1+1 X 21 tetrametallic systems containing self-assembled and cocrystallized one dinuclear [(NiLMII)-L-II-M-I(H2O)(3)](2+), cation and two mononuclear [(NiLI)-L-II] moieties, Among three coordinated water molecules of the dinuclear cores in 2-6, two are encapsulated in the O-4 cavity of two mononuclear [(NiLI)-L-II] moieties by forming bifurcated hydrogen bonds. Evidently, the formation of inclusion product 1 and dinuclear-mononuclear cocrystals 2-6 are related to the affinity of the 04 compartment to encapsulate a water molecule. Electrospray ionization mass spectrometry (ESI+) spectra of compounds 1-6 have been recorded, The mass spectra of 2-6 reveal that not only the tetrametallic self-assemblies are ruptured but also the second metal ion in the dinoclear core leaves the 04 cavity. For the (Ni3CuII)-Cu-II (2) and (Ni3FeII)-Fe-II (5) compounds, metal substitution takes place in Solution, resulting in the formation of [(CuLNa)-L-II-Na-I](+) and [{(CuLI)-L-II}(2)Na](+) for 2 and [1 X 1+1 X 1] species [{(NiLI)-L-II}center dot{(FeLI)-L-III}(+) for 5.