6- Methyl-1,4,8,11-tetraazacyclotetradecane

In the square pyramidal complex [Ni(Me4cyclam)N3](C104) (379) (Me4cyclam is 1,4,8,11-tetramethylT,4,8,ll-tetraazacyclotetradecane) the coordinated azide anion is on the same side of the four methyl groups with the nickel atom 33 pm from the N4 plane. The five- and six-membered chelate rings are in the usual gauche and chair conformations respectively.2681 This complex is labile in comparison with the very inert dinuclear complex... 

Hambley et al. have also predicted isomer distributions of chlorocobalt(IIl) complexes of pendant-arm macrocycles.The force field used had been detailed earlier. Of the ligands studied (12-methyl-l,4,7,10-tetraazacyclotridecan-12-amine, 6-methyl-l,4,8,1 l-tetraazacyclotetradecan-6-amine, lO-methyl-1,4,8,12-tetraazacyclopentadecan-10-amine, and 3-methyl-l,5,9,13-tetraazacyclohexa-decan-3-amine), the cis isomer (the pendant primary amine is coordinated cis to the chlorine) was found to be the lowest energy form in each case. For 6-methyl-1,4,8,ll-tetraazacyclotetradecan-6-amine, the cis isomer was 4.4 kj/mol more stable than trans (cis/trans = 86 14). The calculated ratio was in reasonable agreement with experiment (cis/trans = 98 2). 

Despite the large numbers of water-soluble monomers that can be polymerized by ATRP, several problems remain to be solved. For example, Brittain et al. [217] have shown that the aqueous polymerization of 45 (DMA), catalyzed by CuBr/L (L= HMTETA, tris[2-(dimethylamino)ethyl]amine (Meg-TREN) and 1,4,8,11-tetra-methyl-1,4,8,11-tetraazacyclotetradecane (Me4Cyclam)) is not controlled because of the slow but irreversible decomposition of the bromo-terminated end-group of the dormant chains. Aqueous polymerization of acryhc [199] and styrenic monomers [203] also appears to be difficult to control, as imphed by the rarity of known examples. 

As Cu has many interesting radionuclides for therapeutic as well as for diagnostic applications (O Tables 45. i and O 45.2), the development of ideal chelators for this metal is of interest. BFCs used for the coupling of Cu-radioisotopes to biomolecules are based on the 14-membered tetraazamacrocycle cyclam 14 (1,4,8,11-tetraazacyclotetradecane) O Fig. 45.17). Two bifunctional versions of cyclam-14, 4-[(l,4,8,ll-tetraazacyclotetradec-l-yl)methyl]-benzoic acid (= CPTA) and [6-(p-bromoacetamido)benzyl]-l,4,8,ll-tetraazacyclotetradecane-l,4,8,ll-tetraacetic acid (= BAT) (O Fig. 45.17), were coupled to monoclonal antibodies and somatostatin analogs (Smith-Jones et al. 1991 Anderson et al. 1995 Wilder et al. 1996). In addition to... 

Cyclam 1,4,8,11-tetraazacyclotetradecane DME dimethoxyethane DMF dimethylformamide dppm 1,1-diphenylphosphinomethane HMPA hexamethylphosphoric triamide Hpz unsubstituted pyrazole Hpz 3,5-dimethylpyrazole Me methyl... 

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