Ligand substitution reactions of pentacyanoferrate(II) complexes with N-heterocyclic cations in aqueous solution

Abstract

This paper is dedicated to Professor Ronald J. Gillespie on the occasion of his 65th birthday DONAL HUGH MACARTNEY and LAUREN JEAN WARRACK. Can. J. Chem. 67, 1774 (1989). Kinetic and spectroscopic studies have been carried out in aqueous solution on the formation (from F~( c N )~O H~' -) and dissociation of pentacyanoferrate(I1) complexes containing 1-(4-pyridy1)pyridinium and the neutral, protonated, and N-methylated forms of 4,4'-bipyridine (BPY), 1,2-bis(4-pyridy1)ethane (BPA), and trans-l,2-bis(4-pyridy1)ethylene (BPE). The pH dependences of the formation kinetics have been analyzed in terms of the specific rate and acid dissociation constants for these ligands. The rate constants (25.0°C, I = 0.10 M) for the formation of the dinuclear complexes ( N C )~F~L F~( C N )~~-have been determined for BPY (50 M-' s-I), BPA (66 M-' s-), BPE (95 M-' s-I), and pyrazine (10 M-I S-I), and are compared with the respective rate constants for the formation of (NC)5FeLCo(NH3)5. The relationships between the formation rate constants and the size of the ligand, the number of donor sites, and the magnitude and position of charges on the ligand are discussed in terms of an ion-pair dissociative mechanism.

Pentacyanoiron(II) as an Electron Donor Group for Nonlinear Optics: Medium-Responsive Properties and Comparisons with Related Pentaammineruthenium(II) Complexes

“…Of particular relevance to our investigations, the complex [Fe II (CN) 5 (MeQ + )] 2- (MeQ + = N -methyl-4,4‘-bipyridinium) was first reported by Toma and Malin,5a but only very limited characterization data were presented at the time (i.e., UV−vis absorption data). Subsequent studies with this particular complex have included 13 C NMR spectroscopy, photochemical ligand loss,5b outer-sphere complexation, cyclic voltammetric data, 5d, formation kinetics, and the effects of inclusion into a cyclodextrin cavity . The outer-sphere complexation properties and formation kinetics of the closely related complex [Fe II (CN) 5 (Mebpe + )] 2- (Mebpe + = N -methyl-4-[ trans -2-(4-pyridyl)ethenyl]pyridinium) have also been investigated. , In the present study, we have prepared a series of complex salts Na 2 [Fe II (CN) 5 L] (where L is MeQ + , Mebpe + , or a related pyridyl pyridinium ligand) and investigated their electronic and optical properties by using a range of techniques.…”

“…Subsequent studies with this particular complex have included 13 C NMR spectroscopy, photochemical ligand loss,5b outer-sphere complexation, cyclic voltammetric data, 5d, formation kinetics, and the effects of inclusion into a cyclodextrin cavity . The outer-sphere complexation properties and formation kinetics of the closely related complex [Fe II (CN) 5 (Mebpe + )] 2- (Mebpe + = N -methyl-4-[ trans -2-(4-pyridyl)ethenyl]pyridinium) have also been investigated. , In the present study, we have prepared a series of complex salts Na 2 [Fe II (CN) 5 L] (where L is MeQ + , Mebpe + , or a related pyridyl pyridinium ligand) and investigated their electronic and optical properties by using a range of techniques. The results obtained allow us to make detailed comparisons between the new compounds and related complex salts containing {Ru II (NH 3 ) 5 } 2+ electron-donor groups and also to demonstrate a novel chemical approach to switching of molecular NLO responses.…”

“…A solution of 2,4-dinitrochlorobenzene (6.49 g, 32 mmol) and 4,4′-bipyridyl (5.00 g, 32 mmol) in ethanol (50 mL) was heated under reflux for 23 h. The solution was cooled to room temperature and added to diethyl ether (500 mL), with stirring. The golden-brown precipitate was filtered off and washed with diethyl ether: 9.46 g, 82%; δH (D2O)9.38 (1 H, d, J ) 2.4 Hz, H 3 ), 9.23 (2 H, d, J ) 6.9 Hz, C5H4N-Ph), 8.92 (1 H, dd, J ) 8.7, 2.5 Hz, H 5 ), 8.82 (2 H, d, J ) 6.3 Hz, C5H4N), 8.68 (2 H, d, J ) 6.8 Hz, C5H4N-Ph), 8.25 (1 H, d, J ) 8.6 Hz, H 6 ), 8.01 (2 H, d, J ) 6.3 Hz, C5H4N). Note: The product is hygroscopic and prolonged contact with air causes formation of a sticky brown solid.…”

Kinetics and equilibrium constants of some pentacyanoferrate(II) complexes of nitrogen and sulfur containing heterocycles

“…An extensive series of complexes have been synthesized from with N, O, and S donor ligands. These transfer from the d orbital of iron(II) to * orbitals of the heterocycles [6,7]. It has been demonstrated that the complexation reactions of with a In this article we report the kinetics of formation and dissociation, spectral properties, and equilibrium constants of pentacyanoferrate(II) complexes of 1,3,5-triazine(tri), isoxazole (isox), pyridinecarbonitrile(pyCN), indoline(ind), 1,2-bis(4-pyridyl)etan(bpe), 3-mercapto-1,2,4-triazole(mtr), 2-tiyazoline-2-thiol(tt), picoline(pcl), and pyrazine(pz) in aqueous solution.…”

Kinetics and equilibrium constants of some pentacyanoferrate(II) complexes of nitrogen and sulfur containing heterocycles

“…An extensive series of complexes have been synthesized from with N, O, and S donor ligands. These 3Ϫ Fe(CN) H O 5 2 complexes exhibit well-defined metal to ligand charge-transfer (MLCT) absorption, due to electron transfer from the d orbital of iron(II) to * orbitals of the heterocycles [6,7]. It has been demonstrated that the complexation reactions of with a 3Ϫ Fe(CN) H O 5 2 variety of ligands L and the dissociation reactions of in the presence of excess triazine, follow 3Ϫ Fe(CN) L , 5 a dissociative mechanism.…”