Terpy ligand

Activation volumes for aquation of Schiff base complexes [Fe(C5H4NCH=NHR)3]2+ (R = Me, Et, nPr, nBu) are between +11 and +14 cm3 mol-1 (107), and thus within the range established earlier (108) for (substituted) tris-l,10-phenanthroline-iron(II) complexes, viz. +11 to +22 cm3 mol-1. These positive values are consistent with dissociative activation. Kinetic studies of the reaction of a CH2S(CH2)3SCH2 -linked bis(terpy) ligand (L6) with [Fe(terpy)2]2+ showed a very slow two-step process. The suggested mechanism consisted of slow loss of one terpy, rapid formation of [Fe(terpy)(L6)], and finally slow displacement of the second terpy as the partially-bonded L6 becomes hexadentate (109). 

Heat treatment of carbon black impregnated with a salt of [Fe(phen)3] gives an oj gen reduction catalyst. i The compounds [Fc2(88)Cl4], [Fe(89)Cl2] and [Fe(90)Cl2] are potential ethene polymerization catalysts they all contain five-coordinated iron(II). The chiral terpy ligands (91) (R R = all three combinations of H, Pr ) and the Schiff base analogue (92), also... 

These are triad systems, i.e., made of three component units weakly interacting, where a separation of charges occurs over nanometric distances. All systems described here are based on a central Ir(terpy)23+ unit, with functional units appended at the 4 position of the terpy ligands. As discussed above, this allows the construction of linear arrays without complications due to the formation of isomers as is the case for bidentate ligands. 

Zn11] ions, furnishes the colorless contracted isomer 44+. In the contracted form, the bidentate phen ligand in the ring and the remote terdentate terpy ligand... 

A number of organoindium complexes with terpy have been described, and include [RIn(terpy)Cl2] (R = Me or CgFj) it was proposed that these species incorporate a bidentate terpy ligand (120,161). 

The complex [Mn(CO)3(terpy)Br] has been isolated, and is thought to contain a bidentate terpy ligand, on the basis of the similarity of its infrared spectrum to that of [Mn(CO)3(bipy)Br] (205). The reaction of [Re(C0)5(N03)] with terpy leads to the formation of [Re(C0)3(terpy)(N03)] this complex is a nonelectrolyte in nitromethane, and is also thought to contain a bidentate terpy ligand (4). 

Both cis- and trans-[Ru(terpy)(CO)Cl2] have been structurally characterized (162) the cis complex is obtained by reaction of [Ru(terpy)(CO)2Cl2] with Me3NO, and the trans by reaetion of terpy with RuCl3-3H20 in DMF (117,162,429). The two (red and yellow) forms of [Ru(CO)2Br2(terpy)] have also been structurally characterized (Fig. 16) each contains a bidentate terpy ligand. The color differences arise from differences in intermolecular ligand contacts (162). 

The majority of interest in cobalt(III) complexes of terpy has centered on the [Co(terpy)2] cation, although a few 1 1 complexes have been reported. A crystal structural analysis of the complex [Co(terpyXC03XOH)]-4H20, obtained by the reaction of [Co(terpy)2] with aqueous carbonate, has revealed the expected distorted octahedral geometry about the metal ion, with a bidentate chelating carbonate and meridional terpy ligands 287). The... 

Burmeister and colleagues have described the related pseudohalogen derivatives MfterpyjXj (X = SCN or SeCN) (90-92). The platinum compound exhibits the two thiocyanate stretching frequencies expected for a square-planar complex, and is formulated [Pt(terpy)(NCS)][NCS], However, the palladium complexes are less easily formulated, exhibiting absorptions due to coordinated ECN (E = S or Se) only. These observations were interpreted in terms of a square-planar structure, with a bidentate terpy ligand in view of the known ability for palladium and platinum diimine complexes to form five-coordinate species, this formulation must also be considered. In the absence of definitive structural evidence, the formulation as five-coordinate species must be regarded as speculative. 

Although Morgan and Burstall had difficulties in isolating 1 2 complexes of terpy with copper(II), salts of [Cu(terpy)2] are readily prepared with excess terpy 8, 18, 236, 243, 309). Crystal structural analyses of [Cu(terpy)2]X2 (X = NO3 or PFg) have been reported 8,18,309) the cation is Jahn-Teller distorted. As a result of the initial local symmetry, the two terpy ligands become nonequivalent upon Jahn-Teller distortion. ESR studies indicate the presence of a static Jahn-Teller distortion (5, 62, 236). 

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