Crowding out: ligand modifications and their structure directing effects on brucite-like {Mx(μ3-OH)y} (M = Co(II), Ni(II)) core growth within polymetallic cages

Previous employment of the ligands 2-methoxy-6-[(methylimino)methyl]phenol (L1H) and 2-methoxy-6-[(phenylimino)methyl]phenol (L2H) has resulted in the self-assembly of pseudo metallocalix[6]arene complexes of general formulae: [M7(μ3-OH)6(Lx)6](NO3)y (M = Ni(II), x = 1, y = 2 (1) and Co(II/III), x = 2, y = 3 (2)). Extrapolating upon this work, we report the coordination chemistry of ligands 2-methoxy-6-{[(2-methoxyphenyl)imino]methyl}phenol (L3H), 2-[(benzylimino)methyl]-6-methoxyphenol (L4H), 2-[(benzylamino)methyl]-6-methoxyphenol (L5H) and 2-[(benzylamino)methyl]-4-bromo-6-methoxyphenol (L6H), whose structures are modifications of ligands L1–2H. These ligands are employed in the synthesis and characterisation of the dimetallic complex [Ni(II)2(L3)3(H2O)](NO3)·2H2O·3MeOH (3); the monometallic complexes [Ni(II)(L4)2] (4) and [Co(III)(L4)3]·H2O·MeOH (5a); and the tetranuclear pseudo metallocalix[4]arene complexes: [(NO3)⊂Co(II)4(μ3-OH)2(L5)4(H2O)2](NO3)·H2O (6), [(NO3)⊂Ni(II)4(μ3-OH)2(L5)4(H2O)2](NO3)·H2O (7) and [Ni(II)4(μ3-OH)2(L6)4(NO3)2]·MeCN (8). The tetrametallic ‘butterfly’ core topologies in 6–8 are discussed with respect to their structural and topological relationship with their heptanuclear [M7] (M = Co(II), Ni(II)) pseudo metallocalix[6]arene ancestors (1 and 2).