Tris methane, ligand

Although the poly(pyrazolyl)borate complexes of iron(II) have been well known for many years, [1] it is only recently that the complexes with the tris(l-pyrazolylmethane ligand, HC(pz)3, [45-48] have been studied in detail. It should be noted that poly(pyrazolyl)methane ligands, such as the tris(l-pyrazolylmethane ligand, are neutral, whereas the poly(pyrazolyl)bo-rate ligands, such as the tris(l-pyrazolyl)borate ligand, HB(pz)3", are monoanions. As a consequence, the metal(II) poly(pyrazolyl)methane complexes are dications and often have quite different properties from those of the analogous metal(II) poly(pyrazolyl)borate molecular complexes. But, in spite of these differences there are often very close structural similarities between the dicationic complexes and the neutral complexes. Therefore the study of the pyrazolylmethane complexes will parallel that of the borate complexes discussed above. 

The tris(N-(3-tm-butyl)pyrazolyl)methane ligand, with an extremely bulky 3-substituent, favors the formation of tetrahedral complexes2 in much the same way as observed in the chemistry of the hydrotris(3-tert-butyl-pyrazolyl)borate ligand.1... 

A family of ionic 1 1 589 or 590 and 2 1 591 or 592 complexes was recently prepared by the reaction of RSnCls (R = Me, Ph or n-Bu) and SnX4 (X = Cl, Br, or I) with appropriate amounts of potentially tridentate tris(pyrazol-l-yl)methane ligands (Pz = pyrazole), as shown by equations 92a-d . The stoichiometries of the compounds obtained depend strongly on the number and position of the methyl groups on the azole ring of the neutral ligand. 

This methane based tris-NHC ligand system behaves very similar to its boron based analogue. The most obvious difference is of course its neutral charge compared with the monoanionic borate ligand. As a consequence, the corresponding silver complex [ Agj HC(MeBenzIm)3 )2](BF )3, although supposedly isostructural with the borate complex... 

Yttrium and cationic and zwitterionic complexes bearing tris(pyrazolyl) borate and the related tris(pyrazolyl)methane ligand systems have also been reported. The Y dicatioitic complex is much less active than the related neutral Mg and Ca complexes for the ROP of rac-LA and forms atactic PLA.p > The formally zwitterionic Ca analog is heteroselective with a P value up to 0.80 at room temperature and up to 0.90 at lower temperatures (Figure 3). ... 

The catalytic potential of Re complexes bearing tris(pyrazol-l-yl)methane ligands and with the metal in a wide range of oxidation states, for the BV peroxidative oxidation of ketones, is presented as an extension of the above oxidation studies to other substrates and catalytic transformations. 

Kodera and co-workers have also reported on copper-mediated C-H bond oxygenation in two tris-pyridyl methane ligands at the methine position when the corresponding Cu(II) complexes are exposed to O2. Labeling... 

Cyclic voltammetry studies indicated that these complexes undergo an irreversible oxidation.The ether-containing tris(pyrazolyl)methane ligands HC[3,5-(MeOCH2)2pz]3 and FIC[3,4,5-(MeOCH2)3pz]3 have... 

Multidentate thioethers are readily introduced into the coordination sphere of low-valent cobalt. As an example, the tridentate thioethers 1,3,5-trithiacyclohexane and tris(methylthio)methane both replace three facially arranged carbonyl ligands in Co3(CO)9(/i-CPh), leaving the cluster otherwise intact.169... 

The first copper(I) complex of tris(hydroxymethyl)phosphine ((760) tetrahedral) has been reported by Samuelson and co-workers. This group addressed the question of anion-controlled nuclearity and metal-metal distances in copper(I)-bis(diphenylphosphino)methane complexes, and in this endeavor they reported the structures of complexes (761) (Cu-Cu separation 3.005-3.128 A), (762) (Cu-Cu separation 3.165 A) and (763) (tetrahedral Cu-Cu 3.293 A). 6 They synthesized and provided structural evidence of oxy anion- encapsulated copper(I) complexes of this ligand. The complexes (764) (distorted tetrahedral Cu-Cu 3.143 A), (765) (distorted tetrahedral Cu-Cu 3.424A), (766) (distorted trigonal Cu-Cu 3.170A), and (767) (Cu-Cu 3.032-3.077A) were reported. They studied solid-state emission spectra of these complexes.567 During this pursuit they... 

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