Cyanide-bridged FeIII–MnIII bimetallic chain derived from [Fe(bipy)(CN)4]−: synthesis,structure and magnetic characteristics

A chain-like compound of [Mn(salpn)][Fe(bipy)(CN)₄] (1) (salpn = N,N′-propylenebis(salicylideneiminato)dianion; bipy = 2,2′-bipyridine), assembled from building blocks of [Fe(bipy)(CN)₄]^? and [Mn(salpn)]⁺, has been characterized by elemental analyses, ICP, IR, thermoanalysis, single crystal X-ray structure analysis and magnetic measurements. In 1, each [Fe(bipy)(CN)₄]^? anion coordinates with two [Mn^III(salpn)]⁺ cations via two trans-CN^? groups, and each [Mn^III(salpn)]⁺ cation is axially coordinated by two [Fe(bipy)(CN)₄]^? ions, resulting in a straight 1-D chain. The chains stack via aromatic π–π-type interactions. Magnetic studies reveal the presence of weak antiferromagnetic interactions between adjacent Fe^III and Mn^III ions through cyanide-bridges.     

Molecular Magnetic Materials Based on {CoIII(Tp*)(CN)3}− Cyanidometallate: Combined Magnetic,Structural and 59Co NMR Study

The cyanidocobaltate of formula fac-PPh₄[Co^III(^Me2Tp)(CN)₃] ⋅ CH₃CN ( 1 ) has been used as a metalloligand to prepare polynuclear magnetic complexes (^Me2Tp=hydrotris(3,5-dimethylpyrazol-1-yl)borate). The association of 1 with in situ prepared [Fe^II(bik)₂(MeCN)₂](OTf)₂ (bik=bis(1-methylimidazol-2-yl)ketone) leads to a molecular square of formula {[Co^III{(^Me2Tp)}(CN)₃]₂[Fe^II(bik)₂]₂}(OTf)₂ ⋅ 4MeCN ⋅ 2H₂O ( 2 ), whereas the self-assembly of 1 with preformed cluster [Co^II₂(OH₂)(piv)₄(Hpiv)₄] in MeCN leads to the two-dimensional network of formula {[Co^II₂(piv)₃]₂[Co^III(^Me2Tp)(CN)₃]₂ ⋅ 2CH₃CN}_∞ ( 3 ). These compounds were structurally characterized via single crystal X-ray analysis and their spectroscopic (FTIR, UV-Vis and ⁵⁹Co NMR) properties and magnetic behaviours were also investigated. Bulk magnetic susceptibility measurements reveal that 1 is diamagnetic and 3 is paramagnetic throughout the explored temperature range, whereas 2 exhibits sharp spin transition centered at ca. 292 K. Compound 2 also exhibits photomagnetic effects at low temperature, selective light irradiations allowing to promote reversibly and repeatedly low-spin⇔high-spin conversion. Besides, the diamagnetic nature of the Co(III) building block allows us studying these compounds by means of ⁵⁹Co NMR spectroscopy. Herein, a ⁵⁹Co chemical shift has been used as a magnetic probe to corroborate experimental magnetic data obtained from bulk magnetic susceptibility measurements. An influence of the magnetic state of the neighbouring atoms is observed on the ⁵⁹Co NMR signals. Moreover, for the very first time, ⁵⁹Co NMR technique has been successfully introduced to investigate molecular materials with distinct magnetic properties.     

Syntheses,Crystal Structures and Magnetic Studies of Heterobimetallates Based on Paramagnetic Ruthenium(Ⅲ) Building Block [Ru~Ⅲ(salchda)(CN)_2]

The syntheses, crystal structures and magnetic properties of two cyano-bridged heterobimetallic compounds prepared from a paramagnetic Ru Ⅲ building block, transK[RuI II(salchda)(CN)_2](1, salchda = N,N?-bis(salicylidene)-o-cyclohexylenediamine), are described.1 reacts with hydrated CoCl_2 and [Mn Ⅲ(salchda)(Cl)(H_2O)] in MeOH to produce a trinuclear compound {[Ru~Ⅲ(salchda)(CN)]_2(μ-CN)_2[Co(MeOH)_4]?4MeOH}_n(2) and a dinuclear{[Ru~Ⅲ(salchda)(CN)](μ-CN)[Mn~Ⅲ(salchda)(MeOH)]?2MeOH}n(3), respectively. Both compounds exhibit intramolecular ferromagnetic coupling between Ru~Ⅲ and 3-d metal centers via the cyano bridge and intermolecular antiferromagnetic coupling. Moreover, 2 exhibits antiferromagnetic ordering below 3.4 K.     

Polymorphism in Spin Transition Systems. Crystal Structure, Magnetic Properties, and Mössbauer Spectroscopy of Three Polymorphic Modifications of [Fe(DPPA)(NCS)(2)] [DPPA = (3-Aminopropyl)bis(2-pyridylmethyl)amine

Three polymorphic modifications A-C of [Fe(II)(DPPA)(NCS)(2)], where DPPA = (3-aminopropyl)bis(2-pyridylmethyl)amine is a new tetradentate ligand, have been synthesized, and their structures, magnetic properties, and M?ssbauer spectra have been investigated. For polymorph A, variable-temperature magnetic susceptibility measurements as well as M?ssbauer spectroscopy have revealed the occurrence of a rather gradual HS if LS transition without hysteresis, centered at about 176 K. The same methods have shown that polymorph B is paramagnetic over the temperature range 4.5-295 K, whereas polymorph C exhibits a very abrupt S = 2 if S = 0 transition with a hysteresis. The hysteresis width is 8 K, the transitions being centered at T(c) downward arrow = 112 K for decreasing and T(c) upward arrow = 120 K for increasing temperatures. The crystal structures of the three polymorphs have been solved by X-ray diffraction at 298 K. Polymorph A is triclinic, space group P&onemacr; with Z = 2, a = 8.710(2) ?, b = 15.645(2) ?, c = 7.985(1) ?, alpha = 101.57(1) degrees, beta = 112.59(2) degrees, and gamma = 82.68(2) degrees. Polymorph B is monoclinic, space group P2(1)/c with Z = 4, a = 8.936(2) ?, b = 16.855(4) ?, c = 13.645(3) ?, and beta = 97.78(2) degrees. Polymorph C is orthorhombic, space group Pbca with Z = 8, a = 8.449(2) ?, b = 14.239(2) ?, and c = 33.463(5) ?. In the three polymorphs, the asymmetric units are almost identical and consist of one chiral complex molecule with the same configuration and conformation. The distorted [FeN(6)] octahedron is formed by four nitrogen atoms belonging to DPPA and two provided by the cis thiocyanate groups. The two pyridine rings of DPPA are in fac positions. The main differences between the structures of the three polymorphs are found in their crystal packing. The stabilization of the high-spin ground state of polymorph B is tentatively explained by the presence of two centers of steric strain in the crystal lattice resulting in the elongation of the Fe-N(aromatic) distance. The observed hysteresis in polymorph C seems to be due to the existence of an array of intermolecular contacts in the crystal lattice making the spin transition more cooperative than in polymorph A.     

Synthesis,Crystal Structure and Spectroscopic Properties of Cyanide-bridged Complex [Ru~Ⅱ(ttpy)(CN)_3Mn~Ⅲ(salen)]

Tricyanide building block K[Ru(ttpy)(CN)_3] and [Mn~Ⅲ(salen)](ClO_4) have been used to design and synthesize a heterobimetallic one-dimensional(1D) zigzag chain complex 1,[Ru~Ⅱ(ttpy)(CN)_3 Mn~Ⅲ(salen)](ttpy = 4?-(p-tolyl)-2,2?:6?,2??-terpyridine, salen = N,N?-ethylenebis-(salicylideneaminato)dianion). Single-crystal X-ray diffraction analysis shows complex 1 crystallizes in orthorhombic Pbca space group and the asymmetric unit of 1 contains one[-NC-Ru~Ⅱ(ttpy)(CN)(m-CN)-Mn ~Ⅲ-(salen)-] molecule. In the structure of 1, each [Ru ~Ⅱ(ttpy)(CN)_3]~-connects two [Mn~Ⅲ(salen)]~+ with two cyanide groups in a cis-conformation, and in turn each[Mn~Ⅲ(salen)]~+ unit links two [Ru~Ⅱ(ttpy)(CN)_3]~-building blocks in a trans-conformation, resulting in a 1D [-NC-Ru~Ⅱ-CN-Mn~Ⅲ-]_n chain. Furthermore, the electronic absorption spectra and luminescence spectroscopy of complex 1 have also been studied.     

Preparation,Crystal Structure and Density Functional Theory Calculations of the Ion-pair Compound [Cl2Bz（3-MeQl）]（TCNQ）

A novel compound [Cl2Bz(3-MeQl) ](TCNQ) ([Cl2Bz(3-MeQl) ]+ = 1-(3,4-dichlo-robenzyl) 3-methlquinoline cation,TCNQ-= 7,7,8,8-tetracyanoquinodimethanide anion) has been synthesized by the reaction of [Cl2Bz(3-MeQl) ]Br and LiTCNQ,and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic,space group P21/c. The structure analysis shows that the anions are stacked into a column with isolated π-dimers,and there is one type of TCNQ entries(TCNQ) ,in agreement with the IR spectra analysis and density functional theory calculations of the compound. The most prominent structural features are the completely segregated stacking columns of the TCNQ- anions and [Cl2Bz(3-MeQl)]+ cations.     

11B-11B cosy NMR studies of derivatives of the octahydrotriborate anion, [B3H7(X)]− and [B3H6(X)2]−

2-D ¹¹B-¹¹B correlation (COSY) spectra have been obtained on the series of monosubstituted and disubstituted octahydrotriborate anions, [B₃H₇(X)]⁻ (X = Cl, NCS, NCSe, NCBH₃, NCBH₂Cl, NCBPh₃, NCBH₂CN, NCB₃H₇ or CNB₃H₆Cl) and [B₃H₆(Cl)(X)]⁻ (X = Cl, NCS, NCBH₂Cl or NCB₃H₇). All monosubstituted derivatives and [B₃H₆(Cl)₂]⁻ showed a coupling correlation between the substituted and unsubstituted borons. The unsymmetrically disubstituted derivatives showed only one coupling correlation, between the borons carrying the substituents. The absence of other correlations is attributed to relaxation phenomena. The correlations are independent of the solid-state structural type.     

Probing spin density and local structure in the Prussian blue analogues CsCd[Fe/Co(CN)6]·0.5H2O and Cd3[Fe/Co(CN)6]2·15H2O with solid-state MAS NMR spectroscopy

Magic-angle spinning (MAS) NMR spectroscopy is used to study the local structure and spin delocalisation in Prussian blue analogues (PBAs). We selected two common archetypes of PBAs (A(I)M(II)[M(III)(CN)(6)]·xH(2)O and M(II)(3)[M(III)(CN)(6)](2)·xH(2)O, in which A(I) is an alkali ion, and M(II) and M(III) are transition-metal ions) that exhibit similar cubic frameworks but different microscopic structures. Whereas the first type of PBA contains interstitial alkali ions and does not exhibit any [M(III)(CN)(6)](3-) vacancies, the second type of PBA exhibits [M(III)(CN)(6)](3-) vacancies, but does not contain inserted alkali ions. In this study, we selected Cd(II) as a divalent metal in order to use the (113)Cd nuclei (I=1/2) as a probe of the local structure. Here, we present a complete MAS NMR study on two series of PBAs of the formulas Cd(II)(3)[Fe(III)(x)Co(III)(1-x)(CN)(6)](2)·15H(2)O with x=0 (1), 0.25 (2), 0.5 (3), 0.75 (4) and 1 (5), and CsCd(II)[Fe(III)(x)Co(III)(1-x)(CN)(6)]·0.5H(2)O with x=0 (6), 0.25 (7), 0.5 (8), 0.75 (9) and 1 (10). Interestingly, the presence of Fe(III) magnetic centres in the vicinity of the cadmium sites has a magnifying-glass effect on the NMR spectrum: it induces a striking signal spread such that the resolution is notably improved compared to that achieved for the diamagnetic PBAs. By doping the sample with varying amounts of diamagnetic Co(III) and comparing the NMR spectra of both types of PBAs, we have been able to give a view of the structure which is complementary to that usually obtained from X-ray diffraction studies. In particular, this study has shown that the vacancies are not randomly distributed in the mesoporous PBAs. Moreover the cadmium chemical shift, which is a measure of the hyperfine coupling, allows the estimation of the spin density on the cadmium nucleus, and consequently, the elucidation of the spin delocalisation mechanism in these compounds along with its dependency on structural parameters.     

Isolation of the Metalated Ylides [Ph3P−C−CN]M (M=Li,Na, K): Influence of the Metal Ion on the Structure and Bonding Situation

The isolation and structural characterization of the cyanido-substituted metalated ylides [Ph₃P−C−CN]M ( 1-M ; M=Li, Na, K) are reported with lithium, sodium, and potassium as metal cations. In the solid-state, most different aggregates could be determined depending on the metal and additional Lewis bases. The crown-ether complexes of sodium ( 1-Na ) and potassium ( 1-K ) exhibited different structures, with sodium preferring coordination to the nitrogen end, whereas potassium binds in an unusual η²-coordination mode to the two central carbon atoms. The formation of the yldiide was accompanied by structural changes leading to shorter C−C and longer C−N bonds. This could be attributed to the delocalization of the free electron pairs at the carbon atom into the antibonding orbitals of the CN moiety, which was confirmed by IR spectroscopy and computational studies. Detailed density functional theory calculations show that the changes in the structure and the bonding situation were most pronounced in the lithium compounds due to the higher covalency.     

Ethylenediamine-N,N"-Diacetate Ion (Edda2–) as a Tridentate Ligand: Synthesis and Structure of the [Co(Edda)(Dien)]ClO4 · H2O and [Co(Edda)(En)(CN)] · 2H2O Complexes

The cobalt(III) complexes with tridentate ethylenediamine-N,N"-diacetate ions (Edda^2–) and additional ligands, namely, diethylenetriamine (Dien) or ethylenediamine (En) and cyanide ions, were synthesized. As follows from X-ray diffraction analysis of [Co(Edda)(Dien)]ClO₄· H₂O (monoclinic crystals with a = 9.243 (2) Å, b = 14.167 (4) Å, c = 13.046 (3) Å, = 91.19 (2)°, Z = 4, space group P2₁/c), the secondary N atom of the Dien ligand occupies the trans-position relative to the N atom of the Edda^2– ligand, which contains a free acetate group. Two fac-isomers of [Co(Edda)(En)(CN)] with the CN^– ion in the cis- and trans-positions relative to the oxygen atom of the carboxyl group were isolated, and the structure of the trans-(O,CN)-[Co(Edda)(En)(CN)]· 2H₂O was determined: monoclinic crystals with a = 9.136 (3) Å, b = 15.484 (3) Å, c = 10.564 (3) Å, = 110.67 (5)°, Z = 4, space group P2₁/c.     

Structure of [Dy(Phen)(C4H8NCS2)3]·3CH2Cl2 solvate. Magnetic properties and photoluminiscence of [Ln(Phen)(C4H8NCS2)3] (Ln = Sm,Eu, Tb,Dy, Tm) complexes

It is found that diffraction patterns of complexes I–V of the composition [Ln(Phen)(C₄H₈NCS₂)₃] (Ln = Sm, Eu, Tb, Dy, and Tm respectively) are similar. Single crystals of [Dy(Phen)(C₄H₈NCS₂)₃]·3CH₂Cl₂ (VI) obtained are. According to the X-ray crystallographic data, in the structure of VI the unit cell contains two crystallographically independent molecules of the [Dy(Phen)(C₄H₈NCS₂)₃] complex and six CH₂Cl₂ molecules. The N₂S₆ coordination polyhedron of the Dy atom is a distorted square antiprism. In the range of 2–300 K the magnetic properties of complexes I–V are studied. It is found that complex III passes to the magnetically ordered state; the spontaneous magnetization at 2 K is 24 600 G·cm³/mol. At 300 K compounds I–IV exhibit photoluminescence in the visible spectral range. It is found that the photoluminescence intensity of complex I is several times higher than the photoluminescence intensity of complexes II–IV.     

Iron salts with the tetracyanidoborate anion: [Fe(III)(H2O)6][B(CN)4]3, coordination polymer [Fe(II)(H2O)2{κ2N[B(CN)4]}2], and [Fe(II)(DMF)6][B(CN)4]2

The reaction of Fe(OH)(3) with tetracyanidoboronic acid, H[B(CN)(4)]·xH(2)O, in water leads to the first examples of tetracyanidoborates with a triply charged metal cation, [Fe(III)(H(2)O)(6)][B(CN)(4)](3) (1). Using elemental iron powder as starting material, [Fe(II)(H(2)O)(2){κ(2)ΝB(CN)(4)]}(2)] (2) is obtained. Anhydrous iron(II) tetracyanidoborate, which is synthesized by heating of 2, is soluble in dry dimethylformamide. After evaporation of the DMF solvent, single crystals of the third title compound, [Fe(II)(DMF)(6)][B(CN)(4)](2) (3), are obtained. Compound 3 is the first metal tetracyanidoborate soluble in nonpolar solvents. The title compounds have been characterized by single-crystal X-ray diffraction (1 rhombohedral, R3c (no. 167), a = 14.9017(7) ?, c = 20.486(1) ?, Z = 6; 2 tetragonal, I42d (no. 122), a = 12.3662(3) ?, c = 9.2066(4) ?, Z = 4; 3 triclinic, P1 (no. 2), a = 8.6255(3) ?, b = 11.0544(4) ?, c = 12.2377(5) ?, Z = 1). The metal ions in all three compounds are octahedrally coordinated. Whereas 1 and 3 are built up from isolated complex ions, 2 comprises a coordination polymer, in which the Fe(II) ion is coordinated by two oxygen atoms of two water molecules in a trans orientation and four nitrogen donor atoms of the [B(CN)(4)](-) groups, which bridge between neighboring iron ions. The iron(III) ion in 3 is in a perfect octahedral environment, which is formed by the O atoms of 6 molecules of water. The single-crystal X-ray structures, vibrational spectra, thermal properties, solubilities, and electrochemical characteristics are reported and compared with those of other known tetracyanidoborates.     

Synthesis,Crystal Structure and Magnetic Behavior of a New Manganese(Ⅱ) Coordination Polymer [Mn(DPPZ)(PZDC)(H_2O)] (DPPZ=Dipyrido[3,2-a:2',3'-c]-phenazine and H_2PZDC=Pyrazine-2,3-dicarboxylic Acid)

The title complex, [Mn(DPPZ)(PZDC)(H2O)] 1 (DPPZ = dipyrido[3,2 -a:2',3'- c]phenazine and H2PZDC = pyrazine-2,3-dicarboxylic acid), has been hydrothermally synthesized and structurally characterized by X-ray single-crystal diffraction, elemental analyses, IR, TG- DTA and magnetic susceptibility measurement. It crystallizes in triclinic, space group P1 with a = 6.6842(5), b = 7.5741(6), c = 20.5755(15) , α = 90.1160(10), β = 97.0560(10), γ = 97.3350(10)°, V = 1025.16(13) 3, Z = 2, MnC24H14N6O5, Mr = 521.35, Dc = 1.689 g/cm3, F(000) = 530, μ(MoKa) = 0.699 mm-1, R = 0.0366 and wR = 0.0810. Compound 1 contains one- dimensional chains which are further stacked through π-π interactions to form a 3D supra- molecular architecture. The water molecule O(1W) is involved in hydrogen bonding interactions with symmetric carboxylate oxygen atom O(4) at (x+1, y+1, z) and symmetric PZDC nitrogen atom N(6) at (1–x, 1–y, 1–z), which completes the structure of 1. Magnetic susceptibility measurement indicates that the compound behaves a weak antiferromagnetic exchange inter- action.     

Crystal Structure and Electrochemical,Fluorescent and Magnetic Properties of a New Complex [Ag(2,2ˊ-bipy)(C_(14)H_9O_3)]·(C_(14)H_(10)O_3)

A novel silver(I) complex [Ag(2,2ˊ-bipy)(C14H9O3)]·(C14H10O3) has been synthesized with 2-benzoylbenzoic acid as the ligand. Crystal data for the title complex: monoclinic, space group Cc, a = 27.4089(13), b = 10.2897(5), c = 12.0024(6)A, β = 111.864(4)o, Mr = 715.49, V = 3141.5(3) A3, Dc = 1.513 g/cm3, Z = 4, μ(Mo Kα) = 0.694 mm-1, F(000) = 1456, the final R = 0.0473 and w R = 0.1146. In the title complex, the central Ag(I) ion is located in a triangular coordination environment. The electron transfer is quasi-reversible in the electrode reaction and it shows a strong emission peak in the range of 495~520 nm under 502 nm excitation. In addition, it displays diamagnetic property from 3 to 300 K.     

Synthesis,structures, and properties of the niobium and tantalum telluride cubane clusters [M4(μ4-O)(μ3-Te)4(CN)12]6– (M = Nb or Ta)

The new cubane cluster complex K₆[Ta₄(₄-O)(₃-Te)₄(CN)₁₂]·KOH·4H₂O was prepared from a mixture of TaTe₄ and KCN by the high-temperature synthesis followed by crystallization from aqueous solutions. The compound was characterized by cyclic voltammetry, X-ray diffraction analysis, and IR, Raman, and electronic spectroscopy. A comparative study of the clusters [M₄(₄-O)(₃-Te)(CN)₁₂]^6– (M = Nb or Ta) containing the ₄-O ligands was carried out. These clusters are the first molecular chalcogenide cubane complexes of Group V metals.     

Chemisorption Synthesis of the Ion-Polymeric Heteronuclear Gold(III)–Bismuth(III) Complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n Based on [Bi2{S2CN(C3H7)2}6]: 13C MAS NMR,Supramolecular Structure,and Thermal Behavior

Russian Journal of Coordination Chemistry - Chemisorption synthesis on the basis of the binuclear compound [Bi2{S2CN(C3H7)2}6] (I) and preparative isolation of the ion-polymeric heteronuclear...     

Synthesis, Crystal Structure, and Magnetic Properties of the Two-Dimensional Nickel(II) Complex via Covalent and Hydrogen Bonds: [Ni(L)(H2O)2][Ni2(L)(NTA)2]ċ6H2O (L = 3,14-di-methyl-2,6,13,17-tetra- azatricyclo[14,4,01.18,07.12]docosane, NTA = Nitrillotriacetate)

A new compound [Ni(L)(H₂O)₂][Ni₂(L)(NTA)₂]6H₂O (1) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]- docosane, NTA = nitrillotriacetate) was prepared and its structure was determined by the X-ray diffraction method. Complex 1 crystallizes in the monoclinic space group P2_1/c with a = 11.217(2) , b = 18.048(5) , c = 15.393(3) , = 90.78(2)°, V = 3115.9(12) ³, and Z= 2, Each nickel atom in complex 1 has a distorted octahedral coordination geometry with an inversion center. Magnetic susceptibility measurement showed a weak intramolecular antiferromagnetic interaction between two Ni(1) and Ni(2) centers with a J value of -0.93(1) cm^–1. The intermolecular hydrogen-bonding interaction gives rise to a two-dimensional network.     

Structure and Molecular Lability of N-(Thio)phosphoryl(thio)amides: XL. Interpretation of the N-Benzoyl(acetyl)amidothiophosphate → N-Thiobenzoyl(acetyl)amidophosphate Rearrangement by means of 1H, 1 3C,and 3 1P NMR Spectroscopy

The N-benzoyl(acetyl)amidothiophosphateN-thiobenzoyl(acetyl)amidophosphate in CCl₄ and toluene-d ₈ solutions was studied by means of ¹H, ^{1 3}C, and ^{3 1}P NMR spectroscopy. The transformation of one amide form to the other is accompanied by intramolecular migrations of the amide proton and (thio)phosphoryl group and is a complex equilibrium of two dynamic systems.     

Structure of tetraphenylarsonium tricyano- 2,2′,6′,2′′-terpyridylferrate(II), AsPh4[FeII(terpy)(CN)3]; and kinetics of oxidation of the complex anion by peroxodisulfate in water and in binary aqueous mixtures

The structure of the title compound has been determined by X-ray crystallography. The octahedral arrangement of ligands about the iron(II) centre is somewhat distorted, with the axial NC–Fe–CN bond angle being 174.3(4)°. The oxidation of the tricyano-2,2,6,2- terpyridylferrate(II) anion by the peroxodisulfate anion has been investigated in water and in binary aqueous mixtures. The reaction follows a second order rate law, with a second-order rate constant of 0.126± 0.001dm3mol–1s–1 at 295.2K. The enthalpy and entropy of activation in water are 51.3±1.8kJmol–1 and –89±5JK–1mol–1 respectively. The rate is retarded on addition of organic cosolvent. The transfer chemical potential of the initial state from water into mixed solvents has been determined from solubility measurements, and compared with the transfer potential of the transition state. Solvent effects on the reaction are discussed in terms of initial state versus transition state solvation.