1.4.7- Tris 1,4,7-triazacyclononane derivatives

The octahedral complexes, pale green [VmL], purple VlvL]PF6, and blue-black [VvL](C104)2, where L represents a l,4,7-tris(2-hydroxybenzyl)-l,4,7-triazacyclononane derivative, serve as an example where all one-electron redox processes are clearly metal centered as depicted in Eq. (6). Table III lists the complexes prepared (148b, 152, 153). 

The A,A A"-tris(carboxymethyl) derivative of the 12-membered macrocycle 1,5,9-triazacyclo-dodecane yields a complex of type [MnL] in aqueous solution which is approximately two orders of magnitude less stable than the corresponding complex of l,4,7-tris(carboxymethyl)-1,4,7-triazacyclononane, as might be expected for the substitution of three six-membered chelate rings in the former for three five-membered chelate rings in the latter. " ... 

An easily accessible hexadentate derivative of tacn, namely 1,4, 7-tris(u-aminobenzyl)- 1,4,7-triazacyclononane (tabtacn), forms a 1 1 complex [Cd(tabtacn)](C104)2 0.5 H20 Pc2 njPna2, Z = 4) with a distorted trigonal prismatic CdN6 core. The Cd—N bonds to the N donors in both the tacn moiety and in the aniline pendant arms are very similar in a rather narrow range (rav(Cd—N) 237 pm).178 Both solution and solid-state H, 13C, and 113Cd NMR spectra have been measured and analyzed with respect to details of the stereochemistry and to dynamics in solution. 

The 1 1 complex of the tris-A-propionate derivative of 1,4,7-triazacyclononane has been synthesized and X-ray diffraction has confirmed that all ligand donors are bound to the manganese(III) ion surprisingly there was no evidence for a Jahn-Teller distortion of the type expected for a high-spin rf system of this type." ... 

Tris-N-functionalization of 1,4,7-triazacyclononane has yielded a variety of sexadentate ligands, which form stable complexes with manganese(II). For example, the l,4,7-tris(2-pyridyl-methyl) derivative gives a complex of type [MnL](C104)2 in which the manganese ion has a... 

Although 1,4,7-triazacyclononane was first incorporated into linked macrocyclic systems around three decades ago [7], it was only in 1997 that the corresponding three-ring analogue 1 was synthesised and investigated. The synthesis of 1 [8] (Scheme 1) proceeds from the tricyclic orthoamide derivative of 1,4,7-triazacyclononane 2 [9] and involves reaction with l,3,5-tris(bromomethyl)benzene in acetonitrile in a 3 1 molar ratio followed by base hydrolytic work-up of the product. The addition of excess HBr to the reaction mixture led to isolation of 1 as its nonahydrobromide salt in 76% yield. 

Many substituted triazacyclononane (TACN) derivatives have been reported in the literature. Here, we highlight the chemistry of one particular hexadentate platform derived from the symmetric tri-A-alkylation of TACN with phenolate or thiolate derivatives. The first report of this class of L3X3 molecules was in 1989 by Moore ef al. who prepared the 3,5-dimethyl-substituted aryloxide derivative. Subsequent work from Wieghardt s group explored the utility of various substituted hexadentate derivatives incorporating either N3O3 " or N3S3 donor... 

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