Borates, hydroxo

B-C bonds, 3, 97 B-N bonds, 3, 97 B-O bonds, 3,94 B-P bonds, 3, 97 B-Si bonds, 3, 97 oxo acid anion complexes, 3, 96 Borates, alkoxo-, 3, 94 Borates, amidotrihydro-, 3,92 Borates, aryloxo-, 3, 94 Borates, carboxylato-, 3,96 Borates, catechol, 3,95 Borates, chlorosulfato-, 3,97 Borates, dicarboxylato-, 3,96 Borates, dipyrazol-l-yl-, 3, 92 Borates, halogeno-, 3,92 Borates, halogenohydro-, 3,90 Borates, hydro-, 3,90 Borates, hydrohydroxo-, 3,90 Borates, hydropyrazol-l-yl-, 3, 92 Borates, hydroxo-, 3,94 Borates, hydroxycarboxylato-, 3,96 Borates, inositol, 3, 95 Borates, monoalkyl-, 3, 92 Borates, monophosphido-, 3, 92 Borates, peroxohydroxo-, 3, 94 Borates, polyol, 3, 95 Borates, pyrrol-l-yl-, 3, 92 Borates, sulfato-, 3, 97 Borates, tetrabromo-, 3, 92 Borates, tetrachloro-, 3, 92 Borates, tetrafluoro-, 3, 92 minerals, 6, 847 Borates, tetrahalogeno-mixed, 3, 93 nB NMR, 3, 92 Borates, tetraiodo-, 3, 92 Borates, tetranitrato-, 3, 96 Borates, tetraperchlorato-, 3, 97 Borates, tripyrazol-l-yl-, 3, 92 Borax, 3,101 Borazines... 

Dehydrative condensation of transition metal hydroxo complexes is a versatile synthetic method, when the conjugated acid of the incoming ligand (H-A) is a protic compound. There are reports of the synthesis of two types of square-planar hydroxopalladium complexes, mononuclear [TplPr2 x(L)Pd-OH] (X = H, Br) and dinuclear complexes [TplPr2Pd(H20)( -0H)2 (H20)PdTplPr2] (TplPr2 = hydrotris(3,5-diisopropylpyrazolyl)borate), and some dehydrative condensations of them.278... 

A structurally characterized example of a dinuclear zinc complex with a bridging phosphate monoester was provided by Kitajima and co-workers using the tris(pyrazolyl)borate ligand system. The P—O bond in a tris- or bis-phosphate ester is cleaved by a hydroxo zinc complex resulting in the monoester compound.443... 

The thermodynamic stability of the binuclear site has been demonstrated by the spontaneous assembly of [Fe20(02CR)2L2] (13) from ferric salts in the presence of water, an alkyl carboxylate salt, and a tridentate nitrogen donor ligand L that can cap an octahedral face on iron (8). Suitable ligands include tris(pyrazolyl)borates and 1,4,7-triazacyclononanes. Structure (13) is in essence a portion of the basic ferric acetate structure. The complexes are excellent physical and structural models of the diiron sites and model some aspects of reactivity including redox activity and interconversion of the oxo and hydroxo bridge. 

Hydrothermal methods, for molecuarlar precursor transformation to materials, 12, 47 Hydrotris(3,5-diisopropylpyrazolyl)borate-containing acetylide, in iron complex, 6, 108 Hydrotris(3,5-dimethylpyrazolyl)borate groups, in rhodium Cp complexes, 7, 151 Hydrotris(pyrazolyl)borates in cobalt(II) complexes, 7, 16 for cobalt(II) complexes, 7, 16 in rhodium Cp complexes, 7, 151 Hydrovinylation, with transition metal catalysts, 10, 318 Hydroxides, info nickel complexes, 8, 59-60 Hydroxo complexes, with bis-Cp Ti(IV), 4, 586 Hydroxyalkenyl complexes, mononuclear Ru and Os compounds, 6, 404-405 a-Hydroxyalkylstannanes, preparation, 3, 822 y-Hydroxyalkynecarboxylate, isomerization, 10, 98 Hydroxyalkynes, in hexaruthenium carbido clusters, 6, 1015 a-Hydroxyallenes... 

The first evidence for activation of exogenous 02 on a vanadium(TV) center was obtained recently.154 The reaction of vanadium(IV) hydroxo tris(3,5-diisopropylpyrazol-l-yl)borate with 02 resulted in the corresponding peroxo complex, which was structurally characterized and found to belong to the class of compounds illustrated in (22).154... 

SCHEME 11.42 Calculated transition states for benzene C—H activation by Ru hydroxo and methyl complexes ([Ru] = (Tab)Ru(PH3), Tab = tris(azo)borate calculated bond distances are... 

In the reaction of the iron(iii) macrocycle dichloro-me5o-2,12-dimethyl-3,7,11,17-tetra-azobicyclo[l 1.3.1 jheptadeca-1 (17), 13,15-trieneiron(iii) tetrafluoro-borate, [Fe(CRH)Cl2]BF4 (1), the reactive form of the complex is the trans-aquo-hydroxo-species where the axial chloride ions are lost in the pH range (4—6) under consideration. Reaction with H2O2 was followed by monitoring O2... 

Protonation of the borate forms a H2O ligand, and causes an increase in the B-0 bond length tind a decrease in the symmetry (T —> C3 ). The B(OH)3(OH2) complex is not stable, and water is easily eliminated from the coordination sphere. Boron is too small to maintain four-coordination (t B3+/ o - = 0.19 < 0.225, the characteristic value of tetrahedral coordination in the ionic model). In addition, a switch to D3/, symmetry allows the three hydroxo ligands to establish Pn-p,r interactions between the empty pj orbital of boron and an orbital of tt symmetry... 

In the case of boron, the hydroxo ligands in B(OH) i bear a negative partial charge. However, boric acid does not condense because the partial charge on the cation is too small. The monomeric form B(OH)3 is stable in solution. The solid phase, obtained after drying, is made of monomeric units connected by hydrogen bonds [15,21]. Boron appears to be a unique element in the respeet that the coordination 3 in boric acid is stabilized by the strong tt character of the B-OH bonds. After alkalinization, borates.are in tetrahedral coordination and are able to form polyanions with boric acid (see Chapter 4). 

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