Crowding out: Ligand modifications and their structure directing effects on brucite-like {M x (μ 3 -OH) y } (M = Co(ii), Ni(ii)) core growth within polymetallic cages

Abstract

Previous employment of the ligands 2-methoxy-6-[(methylimino)methyl]phenol (L 1 H) and 2-methoxy-6-[(phenylimino)methyl]phenol (L 2 H) has resulted in the self-assembly of pseudo metallocalix[6]arene complexes of general formulae: [M 7 (μ 3 -OH) 6 (L x ) 6 ](NO 3 ) 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 (L 3 H), 2-[(benzylimino)methyl]-6-methoxyphenol (L 4 H), 2-[(benzylamino)methyl]-6-methoxyphenol (L 5 H) and 2-[(benzylamino)methyl]-4-bromo-6-methoxyphenol (L 6 H), whose structures are modifications of ligands L 1-2 H. These ligands are employed in the synthesis and characterisation of the dimetallic complex [Ni(ii) 2 (L 3 ) 3 (H 2 O)](NO 3 )·2H 2 O·3MeOH (3); the monometallic complexes [Ni(ii)(L 4 ) 2 ] (4) and [Co(iii)(L 4 ) 3 ]·H 2 O·MeOH (5a); and the tetranuclear pseudo metallocalix[4]arene complexes: [(NO 3 )⊂Co(ii) 4 (μ 3 -OH) 2 (L 5 ) 4 (H 2 O) 2 ](NO 3 )·H 2 O (6), [(NO 3 )⊂Ni(ii) 4 (μ 3 -OH) 2 (L 5 ) 4 (H 2 O) 2 ](NO 3 )·H 2 O (7) and [Ni(ii) 4 (μ 3 -OH) 2 (L 6 ) 4 (NO 3 ) 2 ]·MeCN (8). The tetrametallic 'butterfly' core topologies in 6-8 are discussed with respect to their structural and topological relationship with their heptanuclear [M 7 ] (M = Co(ii), Ni(ii)) pseudo metallocalix[6]arene ancestors (1 and 2).