Three-coordinate shape

Using 1,4,8,11-tetraazacyclotetradecane, the structure of complex (800) (distorted trigonal planar Cu-Cu 6.739 A) was determined. Reactivity with 02 was investigated to demonstrate the formation of trans-l,2-peroxo species.585 As part of their work with copper(I) complexes with 02, the structure of a dicopper(I) complex ((801) distorted tetrahedral 7.04 A), supported by macrocyclic ligand environment, was reported by Comba and co-workers. Tolman and co-workers structurally characterized a three-coordinate copper(I)-phenoxide complex (802) (planar T-shaped) that models the reduced form of GO.587 The copper(I) analogue [Cu(L)][CF3-SO3]-0.43MeOI I (803) of a copper(II) complex (534) was also reported to demonstrate the role of ligand framework conformability in CV /Cu1 redox potentials.434 Wilson and co-workers... 

Perhaps the most controversial suggestion is that spontaneous isomerizations may proceed through a dissociative mechanism, invoking two three-coordinated intermediates (probably T-shaped). The labile intermediates may be cis-like (A) or trans-like (B) in structure. Applied to the monoorganoplatinum(II) complexes, PtL2XR, the scheme is ... 

Turning to the X-ray absorption edge spectrum of the T3 site In T2D laccase (Figure 10a), a peak Is observed below 898A eV. This energy Is characteristic of Cu(I) while the shape of the peak suggests that It is due to three coordinate copper. The amount of reduced copper present can then be quantitated from the normalized edge intensities of copper model complexes with the appropriate... 

Symmetry requirements for concerted reductive elimination of dialkyls have been considered (314), and for trialkylgold(III) species reductive elimination from a trigonal, three-coordinate intermediate was found to be symmetry forbidden. Solvent participation or the involvement of T-shaped species, however, was suggested as possible. Charge transfer to the high-oxidation state gold(III) center and reductive elimination from such a charge transfer state was proposed as an alternative reaction pathway. 

HS — high spin LS = low spin. b In case of tetrahedral geometry. c In case of square-planar geometry. i In feet two Cu—N bonds are elongated. T-shape three-coordination. 

Durola, F., Russo, L., Sauvage, J. P., Rissanen, K., Wenger, 0. S., Three-component entanglements consisting of three crescent-shaped bidentate ligands coordinated to an octahedral metal centre. Chem. Eur. J. 2007,13, 8749-8753. 

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