Carbodiimide ligands

Transition metal carbodiimides, such as MnNCN and CuNCN, and carbodiimides derived from zinc, mercury,silver and thallium are also known. A preceramic polymeric titanium carbodiimide is obtained in the reaction of TiCU with bis(trimethyl-silyl)carbodiimide. Liganded carbodiimidotitanium complexes are obtained in the reaction of CpaTiCla with Me3SnN=C=NSi(i-Pr)3. ° Also, dicyclopentadienyl titanium (IV) diisocyanates are converted into carbodiimides with LiN(SrMe3)2. ... 

Hessell ET, Jones WD (1992) Synthesis and structure of rhodium complexes containing a photolabile 72-carbodiimide ligand. 1,3-dipolar cycloaddition of phenyl azide to Tp Rh(CNR)2 (Tp = Hydrotris(3,5-dimethylpyrazolyl)borate). OrganometaUics 11 1496-1505... 

Photolysis of the carbodiimide complex 395 in hydrocarbon solvents similarly effects C H activation, via initial dissociation of the carbodiimide ligand to afford Tp Rh(CNCH2 Bu) as the active species. The reaction proceeds in a variety of neat aliphatic hydrocarbons, with apparently exclusive selectivity for the primary C H of terminal methyl groups. This includes the case of chloroalkanes, for which no oxidative addition of the C Cl bond is observed. Competition is, however, noted for aromatic substrates bearing methyl substituents, " with both benzylic and aromatic activation proceeding under kinetic control, though the aromatic activation products are thermodynamically favoured. Thus, toluene affords a kinetic mixture of aryl and benzyl complexes, which thermally redistributes to a 2 1 mixture of meta and para isomers of the aryl complex, while mesitylene yields a 3 1 mixture of the mesityl and benzyl complexes. 

No C-H activation was seen when [(HBpz3)Rh(CO)] or its HBpz 3 analogue was photolysed in a CH4 matrix at 12K, but it did occur in a Nujol matrix at room temperature. 83 Photolysis of [(HBpz 3)Rh(CNR)(PhN=C=NR)] (R = CH2BUO in alkanes or arenes results in loss of the carbodiimide ligand and formation of [(HBpz "3)Rh(CNR)(H)(R )]. Methane can be activated by exchange with the R = Cy derivative, as activation of primary C-H bonds is preferred over... 

Palladium(II) complexes with a carbodiimide ligand, in which a nitrogen of the linear N=C=N moiety is bonded to the metal center, and bis(carbodiimido)palla-dium(II) complexes, both derived from isocyanides, have been described [1284]. 

Homoleptic lanthanide(III) tris(amidinates) and guanidinates are among the longest known lanthanide complexes containing these chelating ligands. In this area the carbodiimide insertion route is usually not applicable, as simple, well-defined lanthanide tris(alkyls) and tris(dialkylamides) are not readily available. A notable exception is the formation of homoleptic lanthanide guanidinates from... 

Closely related mixed amido/imido/guanidinato tantalum complexes of the type Ta(NR R )[(R R2N)C(NR )2]( = NR ) (R R = Me, Et R = Cy, Pr R = Pr", BuO were synthesized by the insertion of carbodiimides into to tantalum-amide bonds in imidotantalum triamide precursors, and the effects of ligand substitution on thermal properties were studied by TGA/DTA measurements. In addition, selected compounds were pyrolyzed at 600 °C and the decomposition products were studied by GC-MS and NMR spectroscopy. ... 

A similar approach, i.e., carbodiimide insertion into M-N bonds was used to prepare unusual zirconacarboranes containing guanidinate ligands. In an alternative approach, these compounds were also synthesized by the route outlined in Scheme... 

Oxalamidinate anions represent the most simple type of bis(amidinate) ligands in which two amidinate units are directly connected via a central C-C bond. Oxalamidinate complexes of d-transition metals have recently received increasing attention for their efficient catalytic activity in olefin polymerization reactions. Almost all the oxalamidinate ligands have been synthesized by deprotonation of the corresponding oxalic amidines [pathway (a) in Scheme 190]. More recently, it was found that carbodiimides, RN = C=NR, can be reductively coupled with metallic lithium into the oxalamidinate dianions [(RN)2C-C(NR)2] [route (c)J which are clearly useful for the preparation of dinuclear oxalamidinate complexes. The lithium complex obtained this way from N,N -di(p-tolyl)carbodiimide was crystallized from pyridine/pentane and... 

Reaction of Ph2PLi with Pr N = C = NPr in THF proceeds via insertion of the carbodiimide into the Li-P bond, affording the lithium phosphaguanidinate salt Li[Ph2PC(NPr )2] in 72% yield. The preparation and reactivity of this new ligand are summarized in Scheme 217. An X-ray crystal structure analysis of the product obtained after removal of the solvent from the reaction mixture revealed the presence of a mono-solvated, centrosymmetric dimer in the solid state (Figure... 

Note that carbon monoxide inserts into the Zr-H bond of 1 (2 equiv.) to afford an T -formaldehydo-type complex [(Cp2ZrCl)]2(g-CH20) [200-202]. Iminoacyl zir-conocene complexes are formed after addition of 1 to isonitriles [203]. Carbon dioxide [183, 202] is reduced to formaldehyde with 1 (2 equiv.). C02-like molecules such as isocyanates RNCO [204], isothiocyanates RNCS [205], and carbodiimides RNCNR [204] are readily converted to the corresponding bidentate form-amido ligands. 

Carboxylated silica particles may be coupled with amine-containing ligands, such as proteins, using a carbodiimide reaction with EDC. A similar protocol to that previously described for coupling to carboxylate polymer particles may be used. The following protocol is based on the method of Zhao et al. (2004), which was used for immobilizing monoclonal antibodies to E. coli 0157. 

Such carbonyls may be further oxidized using potassium permanganate (KMnO and perchloric acid (HCIO4) to convert all of these groups into carboxylic acids. Once functionalized in this manner, the nanotubes can be fully dispersed in aqueous systems. Kordas et al. (2006) used these derivatives to print nanotube patterns on paper or polymer surfaces to create conductive patterns for potential use in electronic circuitry. The carboxylates also may be used as conjugation sites to link other ligands or proteins to the nanotube surface using a carbodiimide reaction as previously discussed (Section 1, this chapter Chapter 2, Section 1.11 Chapter 3, Section 1). 

Nickel(ll) acetylacetonate catalyzes the addition of acetylacetone or ethyl acetoacetate to carbodiimides (Equation (89)).447 The acetylacetonate ligand of Ni(acac)2 may react with a carbodiimide to give a nickel complex having a 3-substituted acetylacetonate, which is then protonated by another acetylacetone to afford an adduct and Ni(acac)2. 

Carbocations, 12 161—162, 163 from alkanes, 12 187 Carbocation salts, stable, 14 269 Carbochlorination, zircon, 13 82 Carbocyclic azo dyes, 9 245, 251 Carbodiimide (CDI) method, for covalent ligand immobilization, 6 396t Carbohydrate chemistry, microwaves in, 16 547-548... 

Ethyl dimethylaminopropyl carbodiimide (EDC) method, for covalent ligand immobilization, 6 396t Ethylene, 10 486, 593-632, 708 13 24 20 211 24 254. See also Coke suppression technologies Polyethylene entries... 

For the determination of these compounds a binding inhibition immunoassay, consisting of the competitive immunoreaction of the unbound antibody present in an analyte-antibody mixture with the hapten derivative immobilized at the sensor surface, has been applied. With the aim of assuring the regeneration and reusability of the surface without denaturation of the immobilized molecule, the formation of an alkanethiol monolayer was carried out to provide covalent attachment of the ligand to the functionalized carbodiimide surface in a highly controlled way. For DDT, the assay sensitivity was evaluated in the 0.004 - 3545 pg/l range of pesticide concentration by the determination of the limit of detection 0.3 pg/1 and the I50 value 4.2 pg/1. 

Cyclocarbonylation of o-iodophenols 503 with isocyanates or carbodiimides and carbon monoxide in the presence of a catalytic amount of a palladium catalyst (tris(dibenzylideneacetone)dipalladium(O) Pd2(DBA)3) and l,4-bis(di-phenylphosphino)butane (dppb) resulted in formation of l,3-benzoxazine-2,4-diones 504 or 2-imino-l,3-benzoxazin-4-ones 505 (Scheme 94). The product yields were dependent on the nature of the substrate, the catalyst, the solvent, the base, and the phosphine ligand. The reactions of o-iodophenols with unsymmetrical carbodiimides bearing an alkyl and an aryl substituent afforded 2-alkylimino-3-aryl-l,3-benzoxazin-4-ones 505 in a completely regioselective manner <1999JOC9194>. On the palladium-catalyzed cyclocarbonylation of o-iodoanilines with acyl chlorides and carbon monoxide, 2-substituted-4f/-3,l-benzoxazin-4-ones were obtained <19990L1619>. 

The palladium-phosphine-catalyzed cycloaddition reactions of vinyloxetanes 530 with aryl isocyanates or diaryl-carbodiimides led to 4-vinyl-l,3-oxazin-2-ones 531 or l,3-oxazin-2-imines 532, respectively (Scheme 101). In the absence of phosphine ligands (PPhs, bis(diphenylphosphino)ethane (DPPE), l,3-bis(diphenylphosphino)propane (dppp), no conversion of heterocumulenes was observed. Starting from fused-bicyclic vinyloxetanes, both types of cycloadditions proceeded in a highly stereoselective fashion, affording only the r-isomers of alicycle-condensed 1,3-oxazine derivatives <1999JOC4152>. 

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