Benzonitrile metal complexes

Attempts have been made to catalyze the arrangement of 3-oxaquadricyclane to oxepins with transition-metal complexes.1 32 1 35 When dimethyl 2,4-dimethyl-3-oxaquadricyclane-l,5-dicarboxylate is treated with bis(benzonitrile)dichloroplatinum(II) or dicarbonylrhodium chloride dimer, an oxepin with a substitution pattern different from that following thermolysis is obtained as the main product. Instead of dimethyl 2,7-dimethyloxepin-4,5-dicarboxylate, the product of the thermal isomerization, dimethyl 2,5-dimethyloxepin-3,4-dicarboxylate (12), is formed due to the cleavage of a C O bond. This transition metal catalyzed cleavage accounts also for the formation of a 6-hydroxyfulvene [(cyclopentadienylidene)methanol] derivative (10-15%) and a substituted phenol (2-6%) as minor products.135 The proportion of reaction products is dependent on solvent, catalyst, and temperature. 

Very recently, the formation of azabutadienylosmium complexes through transfer of the isopropenyl group of a phosphine ligand to benzonitriles on a Cp-Os metal complex has been reported (Scheme 79).373... 

Pinacolone, o-(diphenylphosphino)benzoyl-coordination chemistry, 401 Piperidine, IV-hydroxy-metal complexes, 797 pA a values azole ligands, 77 Plant roots amino acids, 962 carboxylic acids, 962 Plastocyanin copper binding site, 557 copper(II) complexes, 772 copper(II) site in, 770 Platinum, dichlorobis(benzonitrile)-IR spectrum, 264 Platinum, cis-dichlorodianunine-antitumor activity, 34, 979 Platinum, ethylenebis(triphenylphosphine)-reactions with 5,6-dimethyl-2,l,3-benzothiadiazole, 194 Platinum blue formation, 265 Platinum complexes acetylacetone reactions, 380 amides, 491 amidines... 

Lu atom (Lu-N 2.352(4) A). The formation of the dianion complex apparently proceeds by nucleophilic addition of the imido unit to the C N group of benzoni-trile, which demonstrates that a lanthanide-imido bond, even in a bridging form, is very reactive. This is in contrast with what was observed previously for bonds between transition metals and bridging imido ligands, which are usually robust and unreactive. Moreover, the resultant product represented the first metal complex of an amidinate dianion, in contrast to the well-known complexes of various metals with amidinate monoanions [RNC(R0NR] as ligands [6,7]. The dianion complex and related complexes derived from imido lanthanide species react with excess of benzonitrile under selective formation of the cyclotrimerization product 2,4,6-triphenyl-1,3,5-triazine [72]... 

Benzoic acid, mercapto-lithographic printing plates, 101 Benzonitrile hydrolysis metal catalysis, 449 Benzoquinone dioximates metal complexes non-integral oxidation states, 144 Benzylamine oxidase, 700 Benzyl halides carbonylation... 

So it became very surprising to see that the middle transition metal complexes 21-24 with Re(l) centers bearing chelate cw-diphosphine ligands were efficient catalysts in homogeneous hydrogenations of nitriles [75]. For instance, the hydrogenation of benzonitrile furnished the products dibenzylimine (PI), dibenzylamine (P2), and tribenzylamine (P3) with P2 as the major product (Scheme 27). Formation of benzylimine or benzylamine was not observed. Dibenzylimine was formed by the hydrogenation of dibenzylimine, while the... 

Protonation of the product of this reaction (pi Ta 3.02) occurs at the carbonyl oxygen atom rather than at the NH group. Data are also reported for the base hydrolysis of benzonitriles in complex ions of the type [Co(NH3)6(NCC8H4R)] + (R = 4-CN, 3-CN, 4-Ac, 3-CHO, or 4-CHO). The results of these studies are compared with analogous results for other metal nitriles in Table 20. Ruthenium(m) is seen to be most effective in catalysing the base hydrolysis of acetonitrile, and this is attributed... 

As a result of strong electronic interactions between the two metalloporphyrin units, there is a substantial uncertainty in assigning oxidation states in mixed-valence group 2 complexes of redox-active metals, such as Co. Thus, although reduced neutral C02 derivatives can be reasonably well described as those of Co the location (metal versus porphyrin) of the electron hole(s) in the singly and doubly oxidized derivatives is not known definitively, and may be very sensitive to the medium [LeMest et al., 1996, 1997]. For example, in benzonitrile, the UV-vis spectmm of [(FTF4)Co2]" ... 

Some gold(I) derivatives have been obtained with other type of /V-donor ligands as acetonitrile the compound [Au(NCMe)2]+ can be obtained by halide-catalyzed electrolysis of gold metal in MeCN.2412 This cation is very moisture sensitive and thermally labile, but the more stable cation [Au(NCPh)2]+ has been obtained by oxidation of gold with the nitrosyl cation in benzonitrile.2413 From EXAFS spectroscopic studies it has been suggested that the solvated gold(I) cations are tetra-coordinate in pyridine or acetonitrile solutions.2414 Other gold(I) complexes have been... 

Cyclopentadienylamine)scandium(2,3-dimethyl-l,3-butadiene) 7 was synthesized in good yield, as shown in Scheme 2. Complex 7 reacted with benzonitrile to form a /rz-imido complex 8, the structure of which was characterized by single crystal X-ray diffraction. This product 8 was proposed to be formed by nitrile insertion followed by an attack of another diene methylene group on the carbon atom of the imido intermediate.3 An unsaturated metal imido species was formed, which easily dimerized to produce 8. However, the yield of 8 was not reported. 

The isopropenyl-benzonitrile units were then released from the phosphine group via cleavage of the P-C bond to afford osmapyrroles, whose metal centers were protonated to furnish the desired azabutadienylosmium(iv) hydride complexes 180. 

In solvents, the complexes of metal ions with organic ligands are more soluble, which makes studies easier moreover, in anhydrous and aprotic media, it is possible to reduce the catalysts and their oxygen complexes out of reach of protons and thus to study the first steps of the catalytic cycle. It has been possible to show by studies in benzonitrile that the mixed-valence Co Co redox state of the... 

---