Hydridotris complex

Complex [VO(Cl)L(Hpz )]-2AN, where L is hydridotris (3,5-dimethylpyra-zdyl)borate, reacted with the product rfinteraction of triediylamine and ferroceno-carboxylic acid to give the N2-coordinated [(Hpz )LV0(/i--rj -C5H4C02)Fe(ri -Cp)] [97JCS(D)1201]. 

Hydridotris(pyrazolyl)borate (N,N,N)-containing ruthenium(ll) complexes activate benzene in stoichiometric amounts to give the isolable complex B. A catalytic hydroarylation of ethylene led to ethylbenzene and a ca. 1 1 mixture of branched and linear alkylbenzenes was obtained when employing propylene (Equation (62)).63,63a... 

The C-C bond-forming coupling of solvent molecules via sp2- and r/ -C-H bond functionalizations can be achieved using an iridium complex based on the TpMe2 ligand (hydridotris(3,5-dimethylpyrazolyl)borate) (Equation (64)).65... 

The hydroarylation of olefins is also achieved by using a ruthenium catalyst, TpRu(CO)(NCMe)(Ph) (Tp = hydridotris(pyrazolyl)borate) (Equation (34)).39 The reaction of benzene with ethene is catalyzed by the ruthenium complex to give ethylbenzene (TN = 51, TOF = 3.5 x 10 3mol 1 s-1 at 90 °G for 4h). The ruthenium-catalyzed reaction of benzene with propene gives the hydroarylation products with a 1.6 1.0 ratio of -propyl to isopropylbenzene, with 14 catalytic turnovers after 19 h. 

The reactive anionic hydridometalcarbonyl complexes can be preformed from the neutral metal carbonyls using quaternary ammonium borohydrides either under homogeneous conditions or two-phase catalytic conditions [5] and are used in a range of reductive processes. The preparation of tetraethylammonium hydridotri-iron undecylcarbonyl is used as an illustrative example. 

Aniline has also been obtained (93%) from a homogenous reduction with preformed tetraethylammonium hydridotri-iron undecacarbonyl [10], In this reduction, the yield is comparable, or superior, to that obtained when the more reactive iron pentacarbonyl or di-iron nonacarbonyl complex is used in the absence of a phase-transfer catalyst. 

Attempts to prepare fluoro derivatives of (102) failed and resulted in the formation of the unusual /i-pyrazolyl fi-oxo dimer [ ReO HBF(pz)2-A,A 2(/i-pz)2(M-0)] (105)." An X-ray structural analysis shows that one pyrazolyl residue of each tridentate ligand has been substituted by fluoride. With the analogous complex containing hydridotris(3,5-dimethyl-l-pyrazolylborate), however, mixed Cl/F, I/F, or OSO2CF3/F derivatives of (102) are readily formed. The different reactivity of the hydridotris(pyrazolyl)borato rhenium complexes has been attributed to the greater steric protection of the boron atom afforded by the dimethyl-substituted ligand. 

The analogous coordination behavior of hydridotris(pyrazolyl)borate and tetrakis(pyrazolyl)-borate has been demonstrated by numerous reactions. Reduction of the rhenium(VII) complex [Re03 B(pz)4] with PPh3 in THF gives a reactive dimeric intermediate which reacted with monodentate and bidentate protic substrates to yield products with tridentate B(pz)4 ligands... 

Hydridotris(pyrazolyl)borates, as cobalt complex ligands, 44 274-278 Hydroboration, 16 230-234 chain lenghtening, 16 231-232 role in sythesis, 16 231, 232 Hydrocarbons clusters, 18 57-59... 

Hydridotris(3,5-dimethyl-l-pyrazolyl)borate]molybdenum-(i72-acyl) complexes, such as 1, are deprotonated by butyllithium or potassium hydride to generate enolate species, such as 488.8> jjie overa]] structure of these chiral complexes is similar to that of the iron and rhenium complexes discussed earlier the hydridotris(3,5-dimethyl-l-pyrazolyl)borate ligand is iso valent to the cyclopentadienyl ligand, occupying three metal coordination sites. However, several important differences must be taken into account when a detailed examination of the stereochemical outcome of deprotonation-alkylation processes is undertaken. 

The hydridotris(pyrazolyl)borate (Tp) ligand has become well known and well established as a formal analogue of the cyclopentadienyl (Cp) ligand (43). Unlike Cp, however, when appropriately substituted, Tp can become what has been described (44, 45) as a tetrahedral enforcer ligand, producing complexes that are constrained to be tetrahedral even when other factors might allow octahedral coordination. 

Holmes, S. and CJ. Carrano. 1991. Models for the binding site in bromoperoxidase Mononuclear vanadium(V) phenolate complexes of the hydridotris(3,5-dimethylpyra-zolyl)borate ligand. Inorg. Chem. 30 1231-1235. 

An interesting approach to the substituted oxepine 102 has been described involving thermolysis of the bicyclic system 101, obtained from the rhenium complex 100 (Melm = N-methylimidazole Tp = hydridotris(pyrazolyl)borate) [02JA7395],... 

J. Sundermeyer et al., Chem. Ber. 1994,127, 1201 M. Etienne, Coord. Chem. Rev. 1996, 156, 201 (this review has many references to other hydridotris(pyrazolylborato)vanadium complexes in oxidation states II-V). 

Furan was demonstrated to function as a 1,3-propene dipole when it was dihapto-coordinated to a rhenium 7t-base, which enhanced the nucleophilicity of the uncoordinated C-3-position. As represented in Scheme 30, the 2,5-dimethylfuran complex 50 (Tp = hydridotris(pyrazolyl)borate Melm = 1-methylimidazole) reacted with Michael acceptors to form substituted cyclopentenes <2003JA14980, 20050M2903>. 

Similar TRIR experiments were performed with Tp Rh(CO)2 and Bp Rh(CO)2 [Tp = hydridotris(3,5-dimethylpjn azolyl)borate Bp = dihydridobis(3,5-dimethyIpyrazolyl)borate] in liquid Xe solution at 223 K 48). From the positions of the observed transient infrared bands, it was found that the Tp species forms two xenon complexes upon photolysis, (7j -Tp )Rh(CO)Xe and (>j -Tp )Rh(CO)Xe, and that Bp Rh(CO)Xe is produced from Bp Rh(CO)2. 

In a related study, the complex Tp Pt (CH3)2H (TpMe2 hydridotris(3,5-dimethyl pyrazolyl)borate) undergoes reductive elimination of methane, but here labeling studies revealed that the rate-determining step is loss of methane from an intermediate methane a complex. Following loss of methane, the 16e intermediate complex can be... 

Substituted hydridotris(pyrazolyl)borato (Tp ) complexes Tp NbMe2(PhC=CMe), when treated with B(C6Fs)3, polymerize ethylene. It is interesting to note that bulky (TpM 2.4-ci j ]y[g2 pjj0=0]y[g yiglds a catalyst that is far more active than TpNbMe2(PhC=CMe). ... 

The NIR emission intensity of the lanthanide porphyrinate complexes follows the trend Yb > Nd > Er. This agrees with observations on other luminescent lanthanide complexes and reflects the fact that the efficiency of nonradiative decay increases as the energy of the luminescent state decreases. The emission yields of the ternary lan-thanide(III) monoporphyrinate complexes with hydridotris(pyrazol-l-yl)borate or (cyclopen-tadienyl)tris(diethylphosphito)cobaltate as a co-ligand are generally higher than those of other Yb(III), Nd(III), and Er(III) complexes because the coordination environment provided by the porphyrinate in combination with the tripodal anion effectively shields the Ln + ion from interacting with solvent (C-H) vibrational modes that enhance the rate of nonradiative decay. 

A titanium complex with a pyrazolylborate ligand was studied by Campbell and Malanga [19]. Similarities between the cyclopentadienyl ligand and the hydridotris(pyrazolyl)borate ligand have been noted for transition metal complexes. Catalyst efficiencies are much lower than those of the analogous penta-methylcyclopentadienyl complexes. 

The anionic complexes [ j -CpM(CO)3] (M = Cr, Mo, W) react with alkyl halides to provide the air-sensitive complexes j -CpM(CO)3R . With respect to reaction with Mel, the relative nucleophilicities of these anions are in the order W > Mo > Cr . Anionic complexes in which the Cp ligand bears alkyl substituents as well as [TpMo(CO)3]" [Tp = hydridotris(pyrazolyl)borate] , behave analogously. The course of the reaction of [f7 -CpCr(CO)3] with allyl chlorides has been studied In diglyme, one cleanly obtains [>) -CpCr(CO)3]2 and coupling of allyl radicals . In THE, the reaction is somewhat more complex one obtains as the major product the same dimer, though a small amount of (jj -6-alkenylfulvene)Cr(CO)3 also forms . Presumably, the products are derived via initial formation of j -CpCr(CO)3( Callyl). 

The superoxide complexes typically bind end-on r/1 though this is not always the case, as in TpCon02 (Tp = hydridotris(3-tert-butyl-5-methylpyrazolyl)borate) (3),12 in which the superoxo species was found to bind rj1. Interestingly this compound had an O—O stretching frequency between superoxo and peroxo species of 961 cm-1, though the crystal structure showed the O—O bond to be 1.262 A, identifying it as a superoxo species. 

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