Nitriles ligands

A variation of the Pd/Cu Wacker-Hoechst process, termed OK Technology, has been proposed by Catalytica Associates (40—46). This process avoids the use of chlorides and uses a Pd/Cu catalyst system which incorporates a polyoxoanion and a nitrile ligand. 

Many ruthenium complexes with nitrile ligands also feature tertiary phosphines, but simpler complexes can be synthesized [136]... 

Pd(H20)4] at 40°C [73]. A kinetic study indicated that internal attack on the Pd-co-ordinated nitrile ligand by the aqua (not hydroxide) ligand and external attack on the nitrile ligand by solvent water occur at a similar rate. 

Numerous examples of nucleophilic attack on coordinated nitrile ligands are found in the literature, particularly when the transition metal is platinum(II).224 The nucleophilic attack of two equivalents of CIO I2CII20 on the electrophilic nitrile carbon atoms of both nitrile ligands in cis-or /r<7H.v-[PtC12(RCN)2] (R = Et, Prn, Pr1, Bu p-CF3C6H4, p- and o-MeC6H4) affords the corresponding A2-l,3-oxazoline complexes ((76) and (77), respectively), in which the heterocycle acts as a... 

Figure 7 Rigid nitrile ligands which form polymeric silver(I) complexes.

Figure 87 The silver carborane salts Ag(CBnH12) (165) and AgfCo BpHu ] (166), and the nitrile ligands (167,168,169, and 170) utilized in the construction of coordination polymers. (Adapted from ref. 166.)...

ISOCYANIDES AND NITRILE LIGANDS IN POLYNUCLEAR LINEAR COMPLEXES... 

Upon reoxidation of the Os(II) complexes, hydration of the ligands bound to Os(III) is much slower than the dehydration of the ligands bound to Os(II). Thus, reversible redox couples are found for the oxidation of the Os(II) dehydration products. Though the S02 and nitrile ligand will hydrate in the Os(III) oxidation state, the latter forms amides and is quite slow. In the case of the CO complex, the Os(III) complex is too labile for any appreciable CO hydration to occur within the lifetime of the complex. 

Scheme 5.23 Proposed mechanism for the Pd(0)-catalyzed telomerization of 1,3-butadiene with C02 (example with hemi-labile phosphino-nitrile ligands) [71].

Many of the reactions which have been reported for carbonyl compounds (hydration, alcoholysis, aminolysis, etc.) are also shown by co-ordinated nitrile ligands. The reaction of a nucleophile with a nitrile is a two-stage process, which may involve one or two molecules of the incoming nucleophile (Fig. 4-6). 

Figure 4-11. The attack of an external nucleophile upon a complex containing the nitrile ligand 4.1.

An article about the reactions of co-ordinated nitrile ligands... 

The homoleptic lanthanide(III) benzamidinates 20-23 can be regarded as analogues of the well known tris(cyclopentadienyl)lanthanide complexes (C5H5)3Ln [7, 8]. One of the most characteristic reactions of the homoleptic cyclopentadienyls is the formation of 1 1 adducts with Lewis bases such as ethers, nitriles, esters etc. [7, 8], Recently it was discovered that the homoleptic lanthanide benzamidinates [PhC(NSiMe3)2]3Ln (20) form similar adducts with THF and nitrile ligands such as acetonitrile or benzonitrile [59]. The molecular and crystal structures of two benzonitrile adducts (26g, h) have been determined by X-ray diffraction. Figure 8 depicts the molecular structure of the europium... 

RajanBabu and Casalnuovo [19, 20] tested diphosphinite ligand systems (5 and 6 in Figure 4) based on carbohydrate backbones. The steric and electronic properties depended on the substituents on the aryl groups on the phosphorus atoms. The use of different chlorophosphine precursors led to the electronically asymmetric ligand 6. This approach resulted in both enantiomers of naproxen nitrile from MVN in 91 % ee (S)-nitrile (ligand 5) and 95 % ee (R)-nitrile (ligand 6) at 0 °C. 

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