Solvated Metal Ions Research Articles

Frequency- and time-resolved cluster photodissociation dynamics in Sr+(H2O) n , Sr+(NH3) n and Sr+(CH3OH) n

The study of photodissociation processes in mass-selected solvated metal ions affords a detailed look at half-collision dynamics and their relationship to structural and dynamical phenomena accompanying solvation. In photodissociation studies on the alkaline earth cation Sr+ solvated by polar solvent molecules, we have examined the nature of electronic to vibrational (E–V) energy transfer when metal-centred electronic transitions excite these systems above their dissociation thresholds. The excited electronic states of small Sr+(NH3)n and Sr+(H2O)n clusters with n= 1 or 2 show clear directional effects associated with the orientations of the excited 5p orbitals with respect to the bond axis. The interpretation of the photodissociation as an E–V energy-transfer process suggests that significant transfer of electron density from the metal centre to the solvent occurs at the intersections of the excited and ground-state potential surfaces. In larger clusters with n= 3–6, the absorption maxima shift from the visible through the infrared region of the spectrum, finally peaking near 1.5 µm for n= 6. A spectral moment analysis of the absorption cross-sections shows that 〈0|r2|0〉 for the radial distribution function of the valence electron in the ground state increases by more than a factor of 20 as n increases from 1 to 6 solvent molecules. We discuss these spectral shifts in terms of the increasing Rydberg character of the ground and excited states of the clusters, arising from the rapid solvent-dependent stabilization of ion-pair states with increasing number of solvent molecules. Our most recent experiments attempt to address the timescale for photodissociation by using picosecond pump–probe laser techniques. Our initial results on the Sr+(NH3)2 system suggest that the dissociation is dominated by a slow process with a lifetime of 7 ns, but there is also a small contribution from a process taking place on a timescale faster than 10 ps. The extension of these measurements to a range of cluster sizes, with the goal of extracting characteristic solvent motion times in well characterized solvation environments, provides us with a probe of the solvent reorganization process accompanying electron transfer in condensed phase systems.

Solvent structure around cations determined by proton ENDOR spectroscopy and molecular dynamics simulation

Classical molecular dynamics simulations of metal ion solvation have been found to confirm the experimental 1 H ENDOR and EPR spectroscopic results on the coordination structure of water molecules surrounding paramagnetic Mn 2+ ions in frozen aqueous solutions. The well-known simplification and intensification of the six-line Mn 2+ EPR signal in frozen solutions upon reducing the pH was found to coincide with the appearance of three strong 1 H ENDOR resonances, reflecting symmetrization of the first two solvation shells

Preparation and characterization of Tl(1,2-C2H4Cl2)B(OTeF5)4: a metal complex of a least coordinating solvent and a least coordinating anion

Addition of B(OTeF5)3 to TIOTeF5 in the weakly coordinating solvents dichloromethane, 1,2-dichloroethane, and 1,1,2-trichlorotrifluoroethane produces solutions of M(solv)x+B(OTeF5)4−. When the solvent was 1,2-dichloroethane, the crystalline compound Tl(1,2-C2H4Cl2)B(OTeF5)4 was isolated and studied by X-ray crystallography: triclinic, space group [Formula: see text], a = 9.221 (4), b = 11.396(5), c = 12.538 (4) Å, α = 110.75 (3)°, β = 101.72(3)°, γ = 99.74 (3)°, Z = 2, T = −116 °C. The Tl(1,2-C2H4Cl2)+ cation contains a five-membered chelate ring with Tl—Cl distances of 3.138 (4) and 3.179 (3) Å. The metal ion is weakly bonded to four B(OTeF5)4− counterions, with nine Tl—F interactions that range from 2.950 (5) to 3.981 (8) Å. When the solvent is dichloromethane or 1,1,2-trichlorotrifluoroethane, only the unsolvated solid salt TlB(OTeF5)4 can be isolated by crystallization. This salt is thermally unstable, slowly forming TlOTeF5 and volatile B(OTeF5)3. Keywords: noncoordinating anion, noncoordinating solvent, metal ion solvation.

FT-IR and fluorometric investigation of rare-earth and metal ion solvation. Part 11. Interaction between DMSO and lanthanide perchlorates in anhydrous acetonitrile

The interaction between DMSO and lanthanide perchlorates in anhydrous acetonitrile has been investigated by FT-IR and Raman spectroscopy. A quantitative study was performed on 0.05 M solutions with R=[DMSO] t/ [Ln] t=7−20. The v 7(SO) vibration of DMSO was used to determine the concentration of free DMSO in solution. None of the investigated systems shows any interaction with either perchlorate ions or acetonitrile molecules. The average coordination number ( CN) of the Ln(III) ions is therefore equal to the average number of bonded DMSO molecules. Changes in coordination numbers are observed both with increasing atomic number and with the solvent composition. The data may be interpreted in terms of equilibria between six-, seven-, eight-, nine- and ten-coordinate species. For R=8, a gradual change is observed between 7.8 (La) and 6.6 (Lu). For R=12 and 15, the overall change amounts to 1.3 (8.7−7.4) and 1.7 units (9.7−8.0), respectively, but in addition, a clear discontinuity is observed at Gd (c. 1 unit). For R=15, additional breaks (c. 0.5 unit) occur around Nd and Er. For a single ion, changes in coordination number with increasing DMSO composition ( R=7−15) amounts to almost 2 units for lighter Ln ions and to 1.0−1.2 units for heavier ions. All the DMSO molecules in the inner-coordination sphere appear to be equivalent, so that the increase in CN is interpreted in terms of an expansion of the first coordination sphere to accommodate additional donor molecules. Equilibrium constants have been estimated from the average CNs. They vary between log K 8=2.2 (La) to 0.6 (Lu), log K 9=1 (La) to 0.4 (Lu) and log K 10=0.9 (La) to 0.3 (Sm).

Co-Intercalation of Tetrahydrofuran and Propylene Carbonate with Alkali Metals in β-ZrNCl Layer Structured Crystal

Abstract Alkali metal intercalation compounds of β-ZrNCl were prepared by both chemical and electrochemical processes in tetrahydrofuran (THF) and propylene carbonate (PC), used as solvents. Among the six combinations of alkali metals (Li, Na, and K) with THF and PC, only the Na–THF system did not form a co-intercalation phase. In the other systems, the solvent molecules co-intercalated with alkali metals in mono- and double layer arrangements between the chloride layers of β-ZrNCl, the structures of which were estimated from one-dimensional electron distribution maps along the direction normal to the basal plane. The electrochemical characteristics of β-ZrNCl, used as the cathode of a lithium battery, were greatly influenced by the electrolyte solvent used. The co-intercalation mechanisms are discussed in terms of the energetics of the solvation of alkali metal ions with polar molecules and an expansion of the β-ZrNCl interlayers.

Structure of solvated metal ions in nitrate and chloride solutions of erbium(III) and yttrium(III) in dimethyl sulfoxide

X-ray diffraction measurements on 1M yttrium(III) and erbium(III) nitrate and chloride solutions in dimethyl sulfoxide (DMSO) have shown that Er(III) and Y(III) solutions of equal compositions are isostructural. The intensity difference functions can then be used to derive the detailed structure of the coordination sphere around the metal ions. The DMSO molecules are coordinated over oxygen with average M-O-S bond angles of about 130°. Two different conformations, corresponding to different relative orientations of the M-O and O-S bonds, seem to be prevalent. In the nitrate solutions an average of about 1.5 nitrate ions are coordinated as bidentate ligands to each metal ion. In the chloride solutions about 1.3 chloride ions belong to the inner-coordination sphere.

Solvent Extraction Separation of Alkaline Earth Metal Ions with Thenoyltrifluoroacetone and Trioctylphosphine Oxide in Carbon Tetrachloride

Abstract The selective distribution of alkaline earth metal ions between carbon tetrachloride and aqueous sodium perchlorate solutions has been investigated by adding chelate forming llgand (thenoyltrifluoroacetone, TTA) and adduct forming llgand (trloctylphosohlne oxide, TOPO) of high concentrations (0.1 M) at 298 K. The separation of alkaline earth metal ions Is explained in terms of their solvent extraction with hydrogen ion in aqueous solutions. The selectivity series, Mg2 + > Ca2 +> Sr2+> Ba2+was established by the solvent extraction method. On the other hand, the selectivity series by the ion-exchange method has been known as Ba2+> Sr2+> Ca2+> Mg2+ using crystalline dihydrogen tetratitanate hydrate fibers, H2Ti4O9-nH2O, and aqueous solutions at 298 K. The difference in the two selectivity series is interpreted by the solvation (former) and hydration (latter) effects of metal ions. The values of the separation factors for alkaline earth metal ions given by the combination of the two methods is extrem...

FT-IR and fluorometric investigation of rare-earth and metal ion solvation. Part 10. Inner-sphere interaction between perchlorate and lanthanide ions in anhydrous acetonitrile

The interaction between perchlorate and Ln(III) ions has been investigated in anhydrous acetonitrile for Ln=La, Pr, Sm, Gd, Dy, Ho, Tm and Yb. Control experiments have been carried out with Ln=Nd, Eu and Er. Vibrations assigned to unassociated (u), monodentate (m) and bidentate (b) perchlorate anions were identified in 0.05 M solutions of Ln(ClO 4) 3. Quantitative FT-IR measurements allowed the determination of the number of uncoordinated perchlorate ions, ClO 4-(u), per Ln(III) ion, n u, which increases from 1.43 (La) to 1.8-1.9 (Pr-Gd) and to 2.0-2.1 (Tb-Yb). Examination of other parameters such as the value and the variation of the v 4(E)- v 1(A 1) and v 8(B 2)- v 1(A 1) splittings for ClO 4 -(m), and ClO 4 -(b) ions, respectively, the area of vibrational bands assigned to CIO 4-(m), and the hypsochromic shift of vibrations assigned to bonded acetonitrile molecules, leads to the following interpretation. Both ClO 4 -(m) and ClO 4 -(b) ions are in the inner coordination sphere and the quantitative data point to a complicated situation in which several equilibria take place between species differing by the number of coordinated perchlorate ions, by the coordination mode of the perchlorate ions, and, probably, by the number of coordinated acetonitrile molecules. Changes in the average coordination number of the Ln(III) ions occur between La and Pr and at Gd. The equilibrium ratios for the formation of the monoperchlorato species could be evaluated for the heavier lanthanides: log K 1 ranges between 1.8 and 2.7. Water molecules replace bonded perchlorate ions in the inner coordination sphere and so do chloride ions. The affinity of Ln(III) ions for chloride ions relative to perchlorate ions has been calculated to be log K Cl/ ClO4=1.1, 1.2 and 0.5 for La, Nd and Er, respectively. Finally, an estimate of the formation constant of the monochloro complex of Er yielded log K Cl=2.6 ±0.7.

Absorption spectra of size-selected solvated metal cations: Electronic states, symmetries, and orbitals in Sr+(NH3)1,2 and Sr+(H2O)1,2

This paper presents photodissociation spectra for the solvated metal ion clusters Sr+(NH3)1,2 and Sr+(H2O)1,2 from 420 to 740 nm in the visible region of the spectrum. The spectra have a banded structure, corresponding to transitions from ground electronic states based upon the 2S configuration of the Sr+ ion to excited states based primarily upon p-orbitals of the excited Sr+. The photodissociation cross sections are large, ∼10−17–10−16 cm2. For the same solvent, spectral band positions are only weakly dependent upon the degree of solvation. We show that a dramatic reduction in intensity of the second excited state band in the Sr+(NH3)2 spectrum suggests that this state has strong atomic ion d-orbital parentage and that the molecule is centrosymmetric. Photodissociation of the H2O solvated species proceeds through three excited electronic states corresponding principally to three different orientations of the metal p orbitals with respect to solvent symmetry axis. Absorption band positions for Sr+(H2O)2 are shifted slightly from those of Sr+(H2O) and the presence of a substantial unstructured continuum appears in the doubly solvated ion. The absorption spectra for the Sr+(H2O)1,2 species are significantly blue-shifted and narrowed relative to those of Sr+(NH3)1,2, an observation that is understood through simple molecular orbital diagrams incorporating the fact that the ionization potential of H2O is 2.4 eV larger than that of NH3.

Metal ion catalysis in nucleophilic displacement reactions at carbon, phosphorus, and sulfur centers. III. Catalysis vs. inhibition by metal ions in the reaction of p-nitrophenyl benzenesulfonate with ethoxide

The rate of the nucleophilic displacement reaction of p-nitrophenyl benzenesulfonate (1) with alkali metal ethoxides in ethanol at 25 °C has been studied by spectrophotometric techniques. For lithium ethoxide, sodium ethoxide, potassium ethoxide, and cesium ethoxide, the observed rate constants increase in the order LiOEt < NaOEt < CsOEt < KOEt. The effect of added crown ether and cryptand complexing agents was also investigated. Addition of complexing agent to the reaction of KOEt results in the rate decreasing to a minimum value corresponding to the reaction of free ethoxide. Conversely, addition of complexing agent to the reaction of LiOEt results in the rate increasing to a maximum value that is identical to the minimum value seen in the reaction of KOEt in the presence of excess complexing agent. In complementary experiments, alkali metal ions were added in the form of unreactive salts. Addition of a K+ salt to the reaction of KOEt increases the reaction rate, while addition of a Li+ salt to the reaction of LiOEt decreases the rate. The involvement of metal ions in the reaction of 1 is proposed to occur via reactive alkali metal – ethoxide ion pairs. The kinetic data are analyzed in terms of an ion pairing treatment that allows the calculation of second-order rate constants for free ethoxide and metal–ethoxide ion pairs; the rate constants increase in the order LiOEt < EtO−< NaOEt < CsOEt < KOEt. Thus, Li+isaninhibitorofthereactionofethoxidewith1, whiletheothermetalsionsstudiedareallcatalysts. Equilibrium constants for the association of the various metal ions with the transition state are calculated using a thermodynamic cycle, and are compared to association constants in the ground state. Consistent with the observed kinetic results, Li+ is found to stabilize the ground state more than the transition state, while Na+, K+, and Cs+ all stabilize the transition state more than the ground state. The trend in the magnitude of the transition state stabilization is interpreted in terms of interactions of the transition state with bare or solvated metal ions. It is concluded that the transition state for the reaction of 1 with ethoxide forms solvent separated ion pairs with alkali metal ions. Analogous data were available for the reaction of p-nitrophenyl diphenylphosphinate (2) with ethoxides, where Li+, Na+, K+, and Cs+ all function as catalysts, and the results are analyzed as above. In contrast to the sulfonate system, it is proposed that the phosphinate transition state forms contact ion pairs with alkali metal ions. The difference is attributed to a greater localization of negative charge in the phosphinate transition state, leading to stronger interactions with metal ions, which overcome metal ion – solvent interactions. Keywords: nucleophilic substitution at sulfur, alkali metal ion catalysis.

FT-IR and fluorometric investigation of rare earth and metal ion solvation. 9. Evidence for a coordination number change along the lanthanide series: FT-IR investigation of the solvates [Ln(NO3)3(DMSO)n] in anhydrous acetonitrile

In this paper, we extend our previous work on the interaction between Ln(NO 3 ) 3 (Ln=Nd, Eu, Tb, Er) and DMSO in anhydrous acetonitrile (MeCN) 12,17 to all the remaining members of the Ln series, with the exception of Pm. The reported coordination numbers represent the first consistent series of such data for Ln(III) ions in organic solution. Apparent stability constants for the coordination of DMSO are also evaluated and discussed

Change in electrical conductivity of a gel made from decomposing liquid metal-ammonia solutions as the gel is dried to a xerogel

Liquid lithium-ammonia and sodium-ammonia solutions form a gel in some critically decomposed state. The current-carrying gel, while boiling down, solidifies to a xerogel. If the liquid ammonia is removed from the gel, the conductivity and current density decrease by orders of magnitude. This indicates that the strongly disordered lattice of solvated metal ions in the liquid solutions in their gel state is very likely to be responsible for the high conductivity and high current density observed in that state.

Reactivity of inorganic complexes in organised media

Many reactions of inorganic complexes (solvated metal ions included in this category) proceed much more rapidly in micellar systems than in aqueous solution. Similarly, the appropriate use of microemulsions can permit the study of reactions involving water-insoluble substrates in media with a significant water content. Examples of such systems, involving substitution and electron transfer processes, will be discussed: (a) metal-ion catalysed equation of halogeno-metal complexes; (b) complex formation from solvated nickel (II) cations; (c) hydroxide and cyanide attack at low-spin iron (II) -diimine complexes; (d) outer-sphere redox reactions involving oxidation and reduction by such complexes as Fe (phen) 3 n+ , Fe (bipy) 2(CN) 2 +, and IrCl 6 2−. The mode of interaction in the organised media will be discussed, in relation both to the approach of the reactants and to the subsequent kinetically-controlled interchange or electron transfer steps. Some of the products from (c) are solvatochromic and can, therefore, be used as polarity indicators to probe solvation in micellar and microemulsion solvent systems.

Metal ion catalysis in nucleophilic displacement reactions at carbon, phosphorus, and sulfur centers. I. Catalysis by metal ions in the reaction of p-nitrophenyl diphenylphosphinate with ethoxide

The effect of macrocyclic crown ether and cryptand complexing agents on the rate of the nucleophilic displacement reaction of p-nitrophenyl diphenylphosphinate by alkali metal ethoxides in ethanol at 25 °C has been studied by spectrophotometric techniques. For the reactions of potassium ethoxide, sodium ethoxide, and lithium ethoxide, the observed rate constant increased in the order KOEt < NaOEt < LiOEt. Crown ether and cryptand cation-complexing agents have a retarding effect on the rate. Increasing the ratio of complexing agent to base results in a decrease in kobs to a minimum value corresponding to the rate of reaction of free ethoxide ion. In complementary experiments, alkali metal ions were added to these reaction systems in the form of unreactive salts, causing an increase in reaction rate. The kinetic data were analysed in terms of ion-pairing treatments, which allowed evaluation of rate coefficients due to free ethoxide ions and metal ion – ethoxide ion pairs. Possible roles of the metal cations are discussed in terms of ground state and transition state stabilization. Evaluation of the equilibrium constants for association of the metal ion with ground state (Ka) and the transition state (K′a) shows that catalysis occurs as a result of enhanced association between the metal ion and the transition state, with (K′a) values increasing in the order K+ < Na+ < Li+. A model is proposed in which transition state stabilization arises largely from chelation of the solvated metal ion to two charged oxygen centers. This appears to be the first reported instance of catalysis by alkali metal cations in nucleophilic displacement at phosphoryl centers. Keywords: nucleophilic displacement at phosphorus, alkali-metal-ion catalysis.

Synthesis of polyphenylene ether and thioether ketones

AbstractThe known polymerization of 4,4′‐difluorobenzophenone (DFB) with the dianion of hydroquinone to poly(phenylene ether ether ketone) (PEEK) and polymerization of either DFB with the dianion of 4,4′‐dihydroxybenzophenone or self polycondensation of the anion of 4‐hydroxy‐4′‐fluoro‐benzophenone to poly(phenylene ether ketone) (PEK) were studied in N‐cyclohexyl‐2‐pyrrolidone (CHP), which is a high‐boiling aprotic polar solvent. The formation of high‐molecular weight PEEK and PEK in this solvent was very efficient. The reactivity in CHP can be ascribed to effective solvation of metal ions rendering the anion very reactive toward nucleophilic substitution. The polymerization was extended to 4,4′‐bis(4‐fluorobenzoyl)diphenyl ether and 1,4‐bis[4‐(4‐fluorobenzoyl)phenoxy]benzene to give a high molecular weight polymer with PEK and PEEK repeating units and PEEK respectively. The polymerization of DFB with purified anhydrous sodium sulfide in CHP gave rapidly a high molecular weight poly(phenylene ketone sulfide) (PKS). In contrast, diphenyl sulfone (DPS) was not very effective in obtaining such a high molecular weight PKS even with prolonged heating, which suggests the uniqueness of CHP in promoting a high degree of polymerization.

Thermodynamic study of the interaction of N-Carboxymethyl chitosan with divalent metal ions

Potentiometry and microcalorimetry indicate that calcium is not chelated by N-carboxymethyl chitosan and that the order of affinity of N-carboxymethyl chitosan for the other divalent metal ions studied is Cu > Cd ⪢ Pb, Ni > Co. For these metals the following binding constants were obtained, respectively: 7 × 10 5; 4 × 10 5; 3 × 10 3 and 1 × 10 3. The number of water molecules liberated in the binding process by the solvated metal ions and by carboxylate were 25, 14 and 16 for Cu(II), Cd(II) and Pb(II), respectively. The binding was enthalpy driven and the negative ΔH values were thus attributed to the interaction of metal ions with nitrogen atoms. Cu(II) and Pb(II) introduced new bands in the CD and UV spectra, whilst the other metal ions did not: for Cu(II) they were a positive band at 237 nm and a negative one at 277 nm in the CD spectrum, and an absorption band at 246 nm in the UV spectrum; for Pb(II) they were a positive band at 229 nm and a negative one at 244 nm in the CD spectrum, and an absorption band at 231 nm in the UV spectrum.

Application of Kirkwood–Buff theory to free energies of transfer of electrolytes from one solvent to another

Solute n.m.r. may be used to obtain quantitative information concerning the preferential solvation of alkali metal and halide ions in binary solvent mixtures. Using the exact theory due to Kirkwood and Buff one can relate the n.m.r. data to the free energies of transfer of individual ions from one pure solvent to another or to the binary mixture. The results obtained are similar although not identical to less rigorous approaches published earlier. The results obtained, when combined to give data for neutral combinations of ions, may be compared with thermodynamically measured free energies of transfer.

A new approach to measurement of the donor strength and co-ordination chemistry of various solvents by oxidation of metal amalgam electrodes in dichloromethane

Electrochemical oxidation of thallium, lead, and cadmium amalgam electrodes in dichloromethane containing 0.2 mol dm–3[NBu4][PF6] produces highly activated metal cations. The cations generated in this non-co-ordinating medium react rapidly with added donor solvents (solv) such as dimethyl sulphoxide, dimethylformamide, tetrahydrofuran, methanol, ethanol, and acetonitrile but not benzene to produce solvated metal ions. The kinetics of solvation are more rapid than precipitation of the metal salts which occurs in longer-time-scale bulk electrolysis experiments. The co-ordination number and equilibrium constants have been calculated for many of the solvated metal complexes, and the equilibrium constants compared with the solvent donor strengths. In the case of the dropping thallium amalgam electrode, the oxidation process is a well defined, strictly reversible one-electron step. From the data obtained for the thallium oxidation process, the value of the equilibrium constant, β1, may be calculated for the reaction TI++ solv [graphic omitted] [TI(solv)]+ and correlated with the Gutmann donor number. Measurement of β1 values calculated in this way is proposed as a simple method of estimating the donor strengths of co-ordinating solvents.

Photodissociation of mass-selected solvated metal ions: monoaquastrontium(+)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotodissociation of mass-selected solvated metal ions: monoaquastrontium(+)M. H. Shen, J. W. Winniczek, and J. M. FarrarCite this: J. Phys. Chem. 1987, 91, 26, 6447–6449Publication Date (Print):December 1, 1987Publication History Published online1 May 2002Published inissue 1 December 1987https://doi.org/10.1021/j100310a003RIGHTS & PERMISSIONSArticle Views38Altmetric-Citations29LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (421 KB) Get e-Alerts

The Relationships between the Formation Constants of 2,2′-Bipyridine Metal(II) Complexes and the Donor Numbers of Solvents

Abstract The complex formation constants of cobalt(II) or zinc(II) with 2,2′-bipyridine (bpy) were determined spectrophotometrically in various solvents. The values of logK1, logK2, and logK3 for the Co(II) complexes obtained were 4.06±0.06, 3.09±0.04, and 1.15±0.02 respectively in dimethyl sulfoxide, while those of logK1 for the Zn(II)–bpy complexes were 6.27±0.10, 4.14±0.01, 4.71±0.03, and 3.44±0.12 in trimethyl phosphate, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide respectively. It was found that the linear relationships hold between logarithms of the formation constants of the bpy complexes and the donor numbers of the solvents when both the solvated metal ions and the bpy complexes are octahedral in the solvents.