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Control of redox properties of cobalt macrobicyclic hexaamine (cage) complexes by substituent modification is important for their use as electron-transfer agents, and the resultant derivatives can also change the lipophilicity of the complexes for a variety of biological and other applications. Such derivatization is also important for incorporating cage complexes into a range of redoxactive conjugates. Here, the derivatization of the amine groups in the 1 and 8 positions of [Co(sar)]3+(sar = sarcophagine = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) are reported. The synthesis and properties of methylamide (from the reactions with acetic anhydride), arylimine (from Schiff base reactions), benzylamine, phthalimido, and tosylate derivatives are described. These reactions provide synthons that have the potential to act as precursors for building a range of conjugates containing metal cage complexes, including dimers. The effects of the substituents on the ligand conformations, which affect other chemical and physical properties of the cage complexes, are discussed. [ABSTRACT FROM AUTHOR]

Dedication: One of Alan Sargeson's great abilities was to seek out knowledge on topics of which he was not the master from those people with the expertise. This led occasionally to publications with a ‘cricket team' of authors but with a rich brew of information, often international. Alan also insisted that all authors were equal since, without any one, the paper would not be what it was. Hence, he endeavoured to pursue the policy, difficult to maintain over a period where an obsession with absurdities such as the order of authors and point-scoring based on meaningless publication indices became so important in the maintenance of research, of listing authors simply in alphabetical order. In describing work begun while he was still with us, we have attempted to adhere to his principles. Analysis of a body of crystallographic information concerning metal(ii) and metal(iii) complexes of macrobicyclic hexamine ligands and some of their derivatives provides evidence for the action of a variety of intermolecular forces within the lattices. Hydrogen bonding is universal and its forms depend strongly upon the oxidation state and the particular nature of the metal ion bound to the macrobicycle. The introduction of both aliphatic and aromatic substituents leads to lattices in which these substituents associate, although, in the case of aromatic substituents, this is not necessarily a consequence of ‘π-stacking', despite the fact that the aromatic ring planes form parallel arrays. At least in the case of CoIII, stable enantiomers of the complexes can be obtained, and in {Δ-(+)589-[Co{(NH3)(CH3)sar}]}2Cl2(C6(CO2)6)·26H2O (sar = 3,6,10,13,16,19-hexa-azabicyclo[6.6.6]icosane), the benzene hexacarboxylate anion adopts a chiral conformation in the presence of the optically active cation. [ABSTRACT FROM AUTHOR]

Treatment of the complex Δ,Λ-[Co(en)2(S-ornithineH-κ2N,O)](CF3SO3)3with SOCl2in DMF gives a mixture of the expected imino complex [Co(en)2(2-iminoornithineH-κ2N,O)]3+and the amidine complex [Co(en)2(5-{[(1E)-(dimethylamino)methylene]amino}-2-iminopentanoate-κ2N,O)]3+, which is proposed to result from the reaction of the Vilsmeier reagent [ClCH=N(CH3)2]+with the terminal amine of coordinated ornithine. Treatment of the imino complex with nitromethane in alkaline solution gives the complex [Co(en)2(2-nitromethylornithineH-κ2N,O)]3+, which contains the potential suicide inhibitor 2-nitromethylornithine. X-ray crystal structures of Δ-[Co(en)2(S-ornithineH-κ2N,O)]Br3and Δ,Λ-[Co(en)2(5-{[(1E)-(dimethylamino)methylene]amino}-2-iminopentanoate-κ2N,O)](ClO4)3are reported. [ABSTRACT FROM AUTHOR]

The crystal structure of the bicyclic hexaamine complex [Cu(fac-Me5-tricosane-N6)](ClO4)2·H2O (fac-Me5-tricosane-N6 = facial-1,5,9,13,20-pentamethyl-3,7,11,15,18,22-hexaazabicyclo[7.7.7]tricosane) at 100 K defines an apparently tetragonally compressed octahedral geometry, which is attributed to a combination of dynamic interconversion and static disorder between two tetragonally elongated structures sharing a common short axis. This structure is fluxional at 60 K and above as shown by EPR spectroscopy. Aqueous cyclic voltammetry reveals that a remarkably stable CuI form of the complex is stabilised by the encapsulating nature of the expanded cage ligand. [ABSTRACT FROM AUTHOR]