Bidentate base

The purple diamagnetic square planar complexes [Ni S2P(OR)2 2] readily add either monodentate or bidentate bases such as py and substituted pyridines,2040,2049 bipy, phen2040,2050 and N-substituted en2051 to form green paramagnetic derivatives which possess either a cis octahedral structure, [NifS OR bipy],2052 [Ni S2P(OEt)2 2phen],20 [Ni S2P(OEt)2 2-tmed]2054 (281) or a irons octahedral structure, [Ni S2P(OEt)2 2py2].1982 The... 

Reaction conditions polystyrene microencapsulated MTO-nitrogen base adduct (loading of 1 wt%), CH2CI2/CH3CN (1 1), a-pinene/MTO/base/fUCF ratio = 100 1 1 150 for monodentate bases or 100 1 0.5 150 for bidentate bases [53]... 

The strontium selenolate Sr(Se(2,4,6-t-Bu3C6H2))2(THF)4 has been synthesized by reaction of Srl2 with KSe(2,4,6-t-Bu3C6H2) in THF. The compound is low melting (120-125°C) and soluble in THF.227 Tellurium- and selenium-containing salts, Ca(DMF)6(Te4)228 and Ba(en)4(SbSe2)2 229 with mono- and bidentate bases such as dimethylformamide and ethylenedi-... 

The simplest model of an amide bond is found in formamide, and several features of protonated formamide are highly relevant to the cleavage of protonated peptides into b and y ions. Amides are bidentate bases, and it has been demonstrated from correlations between core electron energies and proton affinities [213] and from quantum chemical calculations [214] that the carbonyl oxygen is more basic than the amide nitrogen. As demonstrated by FT-ICR, metastable ion dissociation, and RRKM and quantum chemical model calculations [214], the unimolecular dissociation of a protonated formamide molecule depends on which site the proton is attached to ... 

Bidentate base. The chiral lithium amide of (S)-l has been used to generate the anion of the ethyl o-toluate 2 and as a chiral complcxing agent in reaction of the anion with acetaldehyde to give optically active mellein methyl ether (3) in 53% optical yield. Optical yields are markedly lower when a chiral base similar to 1 but lacking the OCH, group is used. 

Valence shell contraction on carbon could account for the shortened F—C and C=N bond lengths. For HCNH" (Table 14) the C=N bond also shortens relative to HCN while the atomic charge on carbon increases, but the H—C bond length increases. A general explanation of bond strengthening upon protonation of the less electronegative base in bidentate bases has recently been given... 

REACTIONS OF BIDENTATE BASES WITH [8,8-(PPh3)j-nidi -8,7-RhSB J(IV)... 

Several surface complexes can be formed with monoacids, such as monodentate, or bidentates (Fig. 4). Monodentate surface complexes can be distinguished from bidentates based on the occurrence or not of the free C=0 group band, with a stretching frequency at about 1700 cm-i. 

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