Reactions of Co-ordinated Ligands

In the base hydrolysis of j8-[Co(glycylglycine) trien] + the rate of fission of the peptide linkage is over 10 times faster than in free glycylglycine. The effects of chelation on rates of ester hydrolysis have been investigated 

Examples of reactions of co-ordinated ligands in square-planar complexes include hydrolysis of /rfl j-[PtCl(CO)(PR3)2], the reaction of platinum(ii)-alkene complexes with ethylamine, and of palladium(ii)-alkene complexes with n-butylamine. In the last case there is evidence that the amine co-ordinates to the palladium before attack at the coordinated alkene occurs. 

Broomhead, N. Kane-Maguire, and I. Lauder, Inorg. Chem., 1970, 9, 1243. 

Saurai, and S. Makishima, Bull. Chem. Soc. Japan, 1970, 43, 1148. 

The arrangement of Chapters 1 to 5 of this Part of this Report by type of compound results in a dispersal of references dealing with the role of the solvent. To remedy this, some of these references have been collected together here, both to illustrate current approaches to determining the role of solvents in inorganic reaction mechanisms and the use of rate-constant variation with solvent composition trends as diagnostic tools. 

Other interesting uses of iron carbonyl complexes include the synthesis of N-substituted l//-l,2-diazepine (95) and the synthesis of cyclic hydrocarbons (96) via intramoleculai coupling of bis-pentadienyl iron tricarbonyl cations. 

The electron withdrawing effect of the Cr(CO)3 unit 7r-bonded to an aromatic ring has a dramatic effect on the reaction pathway of aromatic compounds. Reaction 

A novel synthesis of 7r-allylpalladium compounds (114) using vinylmercurials and a variety of functionalized olefins affords a range of useful complexes in high yield under mild conditions. The advantages of the method include the use of 

Reactions of Co-ordinated Ligands. Rates of mercuration of o-, m-, and p-hydroxy-benzoates (L) in [Co(NH3)5L] + ions and iodination of salicylate (L) in [Co(en)2(L)J and in free salicylate ion have been compared. At 40 °C [(H+] = 0.1—0.25 M) the mercuration reactions have rates k) and activation energies ( a) which are very similar (u-, m-, and / -hydroxybenzoates 10 / /M- s = 3.5, 3.0, and 2.0 a=13.4, 12.3, and 11.7 kcal mol respectively). Iodination of free and co-ordinated salicylate ions is catalysed by acetate ion and by water, the rates varying in the order L [Co(en)2(L)]+ L (H2L = salicylic acid). Chelation of the dianion of salicylic acid to Co reduces its rate of iodination by a factor of 10 . 

The rate of reaction of bromide ion with rranj-[Co(dmgH)2 P(OMe)3)X] to give tra j-[Co(dmgH)2 P(0)(OMe)a X] varies by a factor of 10 as X is varied from NO3 to Et. The logarithm of the constant for nucleophilic attack at the methyl group of co-ordinated trimethyl phosphite correlates well with the C chemical shift of this group. 

SH = 18.3 kcal mol- and 3.1 calK- mol The reaction of co-ordinated 1,2-dicyanobenzenc has also been investigated.  

In the reaction of cij-[Co(en)2(NH2CH2R)(NH2CH2COMe)] ion with base, imine complexes (11) are formed by condensation of the co-ordinated amino-acetone with the NH2 group of co-ordinated en and not with the co-ordinated RCH2NH2 (L). Favourable orientation of the carbonyl group is invoked to 

Balahura and W. L. Purcell, Inorg. Chim. Acta, 1978, 31, L383. 

Reactions of Co-ordinated Ligands. The topic of the attack of pyridine at co-ordinated ethene and co-ordinated dienes in appropriate platinum(ii) complexes has already been alluded to in an earlier section. The reaction of c -[PtCl2(p-tolyl isocyanide) 2] with methylhydrazine in dichloromethane, which gives a carbene complex, follows a two-term rate law of this type shown in equation (1). As usual the term is assigned to a solvolytic path, but here the term is attributed to bimolecular attack of the hydrazine at the co-ordinated isocyanide. There is some discussion 

Bartocci, A. Ferri, V. Carassiti, and F. Scandola, Inorg. Chim. Acta, 1977, 24, 251. SokHwa Goh and Chup Yew Mok, J. Inorg. Nuclear Chem., 1977, 39, 531. 

An interesting and potentially useful route to fulvenes is the reaction of thiobenzophenones with dicarbonylcyclopentadienyliron [equation (23)]. The reaction, which involves an unusual cleavage of a cyclopentadienyl ligand and desulphurization, proceeds in yields of up to 82%. 

The use of 7r-arene-Cr(CO)3 complexes in organic synthesis continues to attract attention. Carbanion attack on 7r-anisole- and 7r-toluene-chromium tricarbonyl complexes gives, after oxidative work-up, meta-substituted aromatics as the major product [equation (24)]. With the anisole complex the me/a-substituted product 

Reaction of the sodium salts of 2-bromobenzoic acids with -Tr-allylnickel complexes gives the 2-allylbenzoic acids (68) which on treatment with PdClj cyclize to the isocoumarins (69) in good yields.The reaction, which occurs under very 

The reactions of methyl-lithium with the hexacarbonyls [M(CO)6] (M = Cr, Mo, or W) and the derivatives [ML(CO)5] have been studied using stopped-flow techniques. The reactions obey the rate law 

Carbonyls.—Primary and secondary amines react with a range of cationic metal carbonyl complexes equation 

Kinetic studies on the reactions of primary aliphatic amines with manganese and rhenium complexes of the type trans- M CO)J-, (L = tertiary phosphine ligand) show that the reaction 

Palladium(ii).—Aquation and Anation. Discussion and controversy continue over the interpretation of the kinetics of the anation and aquation reactions which constitute the equilibria (2). Bekker and Robb report rate constants and activation para- 

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PS. Braterman, Reactions of Co-ordinated Ligands, Vol. 2, Plenum, New York, 1989. 

Other Reactions of Co-ordinated Ligands with Nucleophiles... 

G. Ingrosso, in Reactions of Co-ordinated Ligands, P. S. Braterman (ed.), Plenum Publishing Co. (in press). 

Hay, R. W., Nolan, K. B. (1975). Reactions of co-ordinated ligands. Hydrolysis of tetram-ethyl-ethylenediaminetetra-acetate and its copper(II) complexes, J. Chem. Soc., Dalton Trans., pp. 1348. 

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