Triazacyclononane ligand

A triazacyclononane ligand with a diphenyl phosphine pendant connected via a propyl linker formed a dimeric complex of zinc [Zn2L2Cl3][C104], 10... 

H NMR studies of the zinc complex formed with the hexadentate aniline functionalized triazacyclononane ligand (70) showed C3 symmetry in solution. It is suggested a six-coordinate complex is formed with all A-donors bound.664 This compares with the benzyl amino derivative,... 

Bis(triazacyclononane) ligands (73) where the two macrocycles are linked with chains two to eight carbons in length have been complexed with zinc to form monomeric and dimeric... 

A series of structurally characterized di-yttrium(III) complexes bearing alkoxy-derivatized triazacyclononane ligands have been examined as initiators for lactone ROP.886 Both (296) and (297) are active for the polymerization of rac-LA at RT, but little control is afforded over molecular weights. Chain length distributions are broad, (Mw/Mn= 1.5-2.2) and attempts to identify the initiating group via end-group analysis have not been successful. 

A new imidazole-functionalized calix[4]arene ligand, able to form a dinuclear Cu2+ complex, has been reported to hydrolyze HPNP and ethyl p-nitropheny lphosphate [70]. The dinuclear complex was found to be 22-and 330-fold more reactive than the corresponding monomer towards the above substrates, respectively. Dinuclear Cu2+ complexes of linked triazacyclononane ligands are reported to promote the hydrolysis of the monoribonucleotide GpppG, a model for the 5 -cap structure of mRNA [71]. The dinuclear complexes offer some 100-fold higher reactivity compared to the mononuclear Cu2+-triazacyclononane system. 

L. Prodi, M. Maestri, R. Ziessel, and V. Balzani, Luminescent Eu3+, Tb3+, and Gd3+ complexes of a branched-triazacyclononane ligand containing three 2,2 -bipyridine units, Inorg. Chem. 30, 3798-3802(1991). 

Fig. 5. Tris-aryloxide triazacyclononane ligand for uranium coordination chemistry.

The triazacyclononane ligand with o-aminophenylmethyl pendant arms (140) forms a bis-ligand complex with Fe +, isolated as its perchlorate. Aerial oxidation of this salt gives an uncharged iron(III) complex containing the ligand in triply-deprotonated form. ... 

Its one-electron oxidation (Fe Fe ) product has a comproportionation constant of 10 and near IR absorption band with 940 = 27,000, both consistent with Robin and Day334,335 jjj valence character7 The bis-triazacyclononane ligand (142), btacn,... 

In 1996, an optimization of the oxidation protocol was described by De Vos and Bein who found a dependence of catalytic activity on temperature, solvent, and ligand structure . Their investigations showed that different substituents on the nitrogen atoms of the triazacyclononane ligands 168 have a great effect on the activity... 

Finally we note that enzymatic reduction of N02 and N03 is important in the natural nitrogen cycle. Copper-containing reductases are known and, as models, copper(I) nitrite complexes with triazacyclononane ligands have been shown to evolve NO.54... 

The use of a triazacyclononane ligand (L) has led to isolation of other N-ligand species such as anti-[L2Rh2(H)2(/i-H)2](PF6)2 while HBPz3 as ligand gave (HBPzf)Rh(H2)(H)2.39 An unusually stable cation, [LRh(PMe3)(H)(Me)]+, is also known.40... 

The Ta-Li alkylidene (29) (Section 4.2) containing an anionic triazacyclononane ligand (Pb2-tacn ) reacts with FeCl2(TEMDA) or [RhCl(COD)]2 to form bimetallic (90) and (91), respectively. In both products, the two metals in close proximity and linked by single-atom bridges. 

A wide series of ferrocenyl-molybdenum complexes of known redox properties bear the tris(3,5-dimethylpyrazolyl)borato ligand or the N,iV, N"-trimethyl-l,4,7-triazacyclononane ligand. They are illustrated in Scheme 7-7 [55 — 59]. 

A few other complexes with N-N coordinating atoms have been tested as olefin polymerization catalysts. The aminopyridinato complex 181 is only able to oligomerize propylene and 1-butene (Mn < 3500) with low activity.1222 The /3-diketiminato Zr complex 182 exhibits moderate ethylene polymerization activity ( 50gPE(mmol M)-1 h-1 bar-1), but molecular masses were disappointingly low (Mn up to 30000).1117 Finally, at 100°C, the MAO-activated Ti complex 183, with a tridentate triazacyclononane ligand, yields PE with very high activity (104gPE(mmol M)-1 h-1 bar-1) but rather low molecular masses and broad polydispersity (Mn = 39500 Mw/Mn = 7.0).1223... 

The 0-0 bond in side-on dicopper-dioxygen complexes can be easily cleaved, affording dicopper(III) bis-p-oxo diamond core-type structures.40,85,106 The first crystallographically crystallized complex of this type, described by Tolman and coworkers, contained /V-alkylated triazacyclononane ligands.106 Subsequently, a large number of bis-p-oxo dicopper(ffl) intermediates were observed in various chemical systems.97 In many cases, dicopper(II) X-T 2 T 2 peroxo species and dicopper... 

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