Silver tris borate

Silver(I) complexes are known with the tris(pyrazolyl)borate [HB(pz)3] and the methyl, phenyl, bromo, or trifluoromethyl-substituted derivatives. The structure of the silver tri(pyrazolyl)borato species has been a puzzle since it was first reported.385,386 It was suggested that the structure could be oligomeric, but recently the crystal structure of the compound [Ag HB(3,5-Me2pz)3 ]2 shows that it has a dimeric structure387 where the silver(I) centers are tricoordinated by a bidentate arm of one ligand and a monodentate arm of the other ligand (29). The related complexes [Ag HB(4-Brpz)3 ]2, [Ag HB(4-Mepz)3 ]2, [Ag HB(3,5-Me2pz)3 ]2, [Ag HB(3-Mepz)3 ] , [Ag B(pz)4 ], and... 

Following their investigations on nitrene, carbene, and oxo transfer reactions catalyzed by fluorinated silver tris(pyrazoyl)borate (see Chapter 6 on nitrene chemistry), Lovely et al. looked for a combined carbene transfer and [2,3]-sigmatropic rearrangement. On the basis of these mechanistic considerations, these authors showed that diazoacetates, indeed, reacted with allyl halides in the presence of this silver catalyst to give a-halo-y-unsaturated esters (Scheme 3.51).77... 

Using a similar strategy, Dias and coworkers were able to prepare classical AgI-CO and AgJ-C2H4 complexes supported by the mesityl-substituted tris(pyrazolyl)borate ligand L9 (Fig. 11) (102). The isolation of such complexes is a challenging task because silver(I) is a poor u-acceptor, a poor 7t-donor, and in... 

A dimethylaluminum complex [HB(3,5-(CF3)2Pz)3]AlMe2 (Figure 22) of the highly fluorinated tris(pyrazolyl)borate ligand [HB(3,5-(CF3)2Pz3] was obtained from the reaction between the silver adduct [HB(3,5-(GF3)2Pz)3]Ag(THF)... 

A comparison of the carbonyl frequencies of a tris(pyrazolyl borate) complexes of copper [TpBr3Cu(CO), v(CO) = 2105cm 1] provides good evidence for a lower electron density at silver [TpBr3Cu(CO), v(CO) = 2157cm 1].14a... 

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... 

Substituted tris(pyrazolyl)borates were recently employed as silver(l) ligands due to their ability to yield heat and air stable metal complexes. Two research groups have prepared very similar sUver(l)-tris(pyrazolyl)borate compounds for catalyzing carbene insertion chemistry. Both systems require electron-withdrawing groups on the tris(pyrazolyl)borate ligands to stabilize the sUver(l) complexes and enhance the electrophilicity of the putative silver-carbenoids (129,130). Dias et al. (129) found that, with CF3 substitutes, a complex of [HB(3,5-(Cp3)2pz)3] Ag(thf) could activate ethyl diazoacetate (EDA) to react with different C X (X = Cl, Br, 1) bonds to afford either C—X bond insertion products or 1,1-hydrochlorination products. At the time of this writing, this unique reactivity was reported only with a silver catalyst (Fig. 27). 

The heterobimetallic compounds 79-83 comprise Ag(I)-Sn(II) covalent bonds, with similar Ag—Sn bonding distances (Table 2.11.3). In particular, compounds 79 and 80 give dimeric arrangements, while in for 81-83, the use of silver fluorinated tris(pyrazolyl)borates and tin(II) N-alkyl-2-(alkylamino)troponiminates allow the isolation of monomeric compounds. 

The reaction of tetrachlorocyclopropene (3) with thiols in the presence of silver(I) tetrafluoro-borate in acetonitrile afforded the tris(alkylsulfanyl)cyclopropenylium tetrafluoroborates... 

An overview of fluorinated tris(pyrazolyl)borate ligands and their use in the synthesis of silver adducts containing group 14 ligands has been presented by Dias and Fianchini.101... 

A family of tris(pyrazolyl)borate (Tp) silver complexes (Scheme 1, catalysts 1-7) have been independently developed by Dias and Perez s groups, which proved to be efficient for carbene insertion in sp C-H bonds with diazoacetates [8, 15-24]. For example, in 2004, Dias, Lovely, and coworkers reported early examples of carbene insertion into sp C-H bond of alkanes and ethers by silver with tris (pyrazolyl)borate complex 1 [18,19]. In this reaction, using neat alkane as substrate... 

By using a tris(pyrazolyl)borate decorated with nine trifluoromethyl groups as ethylene silver and copper adducts have been prepared... 

Kou X, Rasika Dias HV. Carbon monoxide and ethylene complexes of copper and silver supported by a highly fluorinated tris(triazolyl)borate. Dalton Trans. 2009 38 7529-7536. 

Jayaratna NB, Gems II, Mironets RV, Mykhaihuk PK, Yousufiiddin M, Rasika Dias HV. Silver(I) and copper(I) adducts of tris(pyrazolyl)borate decorated with nine trifluoromethyl groups. Inorg Chem. 2013 52 1691-1693. 

Jayaratna NB, PArdue DB, Ray S, et al. Silver(I) complexes of tris(pyrazolyl)borate ligands bearing six trifluoromethyl and three additional electron-withdrawing substituents. Dalton Trans. 2013 42 15399-15410. 

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