Hydrotris borate ligand

Cobalt(III)-alkylperoxo complexes find use in the oxidation of hydrocarbons.1342,1343 Since they release ROO and RO radicals upon mild heating in solution, they are effective oxidants under mild conditions, and produce catalytic systems in the presence of excess ROOH. Aliphatic C—11 bond oxidation by ConOOR (R = Con, alkyl, H) complexes including a hydrotris(pyrazolyl) borate ligand have also been reported, with homolysis of the peroxo O—O bond believed to be important in oxygenation of the C—H bond.1344... 

Pyridyl functionalized tris(pyrazolyl)borate ligands show some interesting properties including the formation of polynuclear zinc complexes.23,1 Some of these contain extensive H bonding and have potential as models for multinuclear zinc enzymes such as phospholipase C or PI nuclease.235 A bis-ligand complex of the hydrotris(5-methyl-3-(3-pyridyl)pyrazolyl)borate ligand (23) shows octahedral coordination of all six pyrazole nitrogen donors despite the steric bulk. 

Rhenium(V) 4-tolylimido complexes with the hydrotris(pyrazolyl)borate ligand, HB(pz)3, are formed on heating the 0x0 derivatives [ReOX2 HB(pz)3 ] (X = Cl, I) with 4-toluidine, whereas reactions with amines at ambient temperatures only give 0x0 complexes of the composition [ReO(NHR)Cl HB(pz)3 ]. The [Re(NC6H4-4-Me)X2 HB(pz)3] complexes react with ZnEt2 with formation of imido-ethyl complexes of the composition [Re(NC6H4-4-Me)Cl(Et) HB(pz)3 ]. " ... 

Square-planar Pd (23) and octahedral Rh (24) hydroperoxide complexes containing hydrotris(3,5-diisopropylpyrazolyl)borate ligand have been prepared as well and characterized in the solid state. Strong hydrogen-bond interaction between —OOH moiety and ligands has been detected in these complexes. 

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... 

Kitajima, N., Tolman, W. B., Coordination chemistry with sterically hindered hydrotris(pyrazolyl)borate ligands -organometallic and bioinorganic perspectives, in Progr. Inorg. Chem., 1995, Vol. 43, pp. 419-531. 

A tris(imidazolyl)borate (138) complex of thallium(I) has been synthesized.The solid-state structure of hydrotris(imidazolyl)boratothallium(I) consists of one-dimensional, twisted, ladderlike strands, and three-coordinate thallium centers. Due to the position of the nitrogen donors, the tris(imidazolyl)borate ligand is not capable of forming metal chelates as are observed in tris(pyrazolyl)borates. Poly(benzotriazolyl)borate ligands have some features of both tris(pyrazo-lyl)borate and tris(imidazolyl)borate systems. Thallium(I) complexes of bis-, tris-, and tetrakis (benzotriazolyl)borates are reported. These adducts have been synthesized by treating the corresponding potassium derivative with an equimolar quantity of thallium(I) formate. ... 

Deprotonation of the zinc alcohol complexes shown in Fig. 12 to produce zinc alkoxide species has not been reported. Instead, mononuclear, tetrahedral zinc alkoxide complexes, supported by hydrotris(pyrazolyl)borate ligands, ([TpBut,Me or Tpph,Me, Scheme 8), have been generated via treatment of zinc hydride precursor complexes with aliphatic alcohols.68-70 A zinc ethoxide complex, [TpBut,Me]Zn-OEt, was also prepared via decarboxylation of the ethyl carbonate complex, [TpBut,Me]Zn-0C(0)0Et.49 X-ray crystallographic studies of [Tpph Me] Zn-OCH3 and [TpBut,Me]Zn-OEt revealed Zn-O bond lengths of 1.874(2) and 1.826(2) A, respectively.68,71 These bond distances are 0.1 A shorter than found for the alcohol complexes shown in Fig. 12. 

TpAd.iPr the most hindered hydrotris(pyrazolyl)borate ligand, has been reported by Fujisawa et al.172 [CuCl(TpAd,lPr)] has been also prepared and characterized by X-ray diffraction.172... 

Ln(III) methyl and methylidene complexes stabilized by a bulky hydrotris(pyrazolyl)borate ligand... 

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