Steric solvent effect on small and large cations: calorimetric study of halogeno and thiocyanato complexes of beryllium(II) and cadmium(II) in N,N-dimethylacetamide

Koide, Makoto; Suzuki, Honoh; Ishiguro, Shin‐ichi

doi:10.1039/ft9959103851

Cited by 9 publications

(6 citation statements)

References 20 publications

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“…However, the halogeno complexation behavior of a metal ion in DMA is quite different from that in DMF. [53][54][55][56][57][58][59][60][61][62] This is due to the solvation steric effect. To elucidate the solvation steric effect on metal-ion complexation, a knowledge of the structure of both the metal ion and its complex is indispensable.…”

Section: Discussionmentioning

confidence: 99%

Individual solvation number of first-row transition metal(II) ions in solvent mixtures of N,N-dimethylformamide and N,N-dimethylacetamide—Solvation steric effect

Umebayashi

Matsumoto

Watanabe

et al. 2001

Phys. Chem. Chem. Phys.

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Raman spectra of solutions of manganese(II), nickel(II), copper(II) and zinc(II) perchlorate with varying molality were measured in N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA) and their mixtures by titration Raman spectroscopy at 298 K. The in-plane O¼C-N bending vibration at 660 cm À1 of DMF and the stretching N-CH 3 vibration at 740 cm À1 of DMA show an appreciable shift to a higher frequency upon coordination of the solvent molecules to the metal ion. These Raman spectra were deconvoluted and the bound solvent bands (n bound ) to the metal ion were extracted from the free solvent band (n free ). The number of solvent molecules bound to the metal ion or the individual solvation number n in a solvent mixture, i.e., n DMF and n DMA for DMF and DMA, respectively, were evaluated by analyzing the intensity decrease of the free solvent bands with increasing molality of the metal ion. It turned out that the manganese(II) ion is six-coordinated over the whole solvent composition range in the mixtures, i.e., n DMF þ n DMA ¼ 6, and the relationship n DMF =n DMA ¼ x DMF =x DMA , where x denotes the mole fraction of the solvent, holds in the mixture. With regard to the zinc(II) ion, the total solvation number decreases from 6 with increasing x DMA in the mixtures. In neat DMA, two bound solvent bands are extracted, indicating that two species, Zn(DMA) 6 2þ and Zn(DMA) 4 2þ , coexist in equilibrium. With the six-coordinate zinc(II) solvated ion, the relationship n DMF =n DMA > x DMF =x DMA holds in the mixture. This shows that the solvation steric effect of DMA operates for the six-coordinate zinc(II) solvated ion, unlike for the manganese(II) one. The copper(II) ion is six-coordinated, although the coordination structure is strongly distorted owing to the Jahn-Teller effect. Indeed, two bands ascribable to the solvents bound at the equatorial and axial positions were extracted. In the mixtures, the relationship n DMF =n DMA > x DMF =x DMA holds for solvents bound at the equatorial position, i.e., the solvation steric effect operates among solvent molecules, while the relationship n DMF =n DMA 4 x DMF =x DMA holds for solvents bound at the axial position. This is expected because the Cu-O(solvent) bond length is longer for the solvent at the axial position, and the electron-pair donating ability is slightly stronger for DMA. The magnitude of the shift Dn ( ¼ n bound À n free ) depends strongly on the metal ion. Indeed, the Dn values in neat DMF and DMA vary according to the relationship Dn ¼ (ar) Àn , a function of the ionic radius r of the metal ion, and the parameters a and n were evaluated. The shift Dn in the mixtures implies that the M-O(DMF) bond length in the M(DMF) 6 À n (DMA) n 2þ solvated ion is elongated with increasing coordination number n DMA of DMA.

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Section: Discussionmentioning

confidence: 99%

Individual solvation number of first-row transition metal(II) ions in solvent mixtures of N,N-dimethylformamide and N,N-dimethylacetamide—Solvation steric effect

Umebayashi

Matsumoto

Watanabe

et al. 2001

Phys. Chem. Chem. Phys.

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“…N , N -Dimethylformamide (DMF) is a widely used organic, aprotic solvent. It has a high liquid range of −60 to +150 °C, is miscible with most protic and aprotic organic solvents, and dissolves rather nonpolar organic compounds as well as inorganic salts, which makes it a versatile solvent. , It should therefore be an excellent choice for the coordination chemistry of beryllium because DMF is capable of dissolving BeSO 4 ·4H 2 O, Be(ClO 4 ) 2 ·4H 2 O − and Be(acac) 2 (acac = acetylacetone) . Nevertheless, little has been reported on beryllium chemistry in DMF, which is not surprising considering the fact that beryllium is the least investigated nonradioactive element .…”

Section: Introductionmentioning

confidence: 99%

“…The few studies on this topic refer to formation of the [Be(DMF) 4 ] 2+ cation , or the equilibrium between DMF, competing solvents (L), and anions (X = SCN – , Cl – , ClO 4 – , SO 4 2– ). As a result, compounds [Be(DMF) n (L) 4– n ] 2+ , and [Be(DMF) n (X) 4– n ] (2– n )– were postulated. , However, these species were only predicted through titration and electrochemical measurements. Solely [Be(DMF) 4 ](ClO 4 ) 2 was additionally characterized by elemental analysis .…”

Section: Introductionmentioning

confidence: 99%

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Solution Behavior of Beryllium Halides in Dimethylformamide

Müller

Buchner

2019

Inorg. Chem.

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The reactivity of beryllium compounds in N,Ndimethylformamide (DMF) is fairly uncharted. However, as a versatile O-donor solvent, DMF enables reaction conditions that are inaccessible in solvents more commonly applied in beryllium chemistry. Here we present a comprehensive study on the interaction of beryllium halides BeX 2 (X = F, Cl, Br, I) with DMF. Through NMR and IR spectroscopy as well as single-crystal X-ray diffraction, we were able to characterize several Be(DMF) 1−4 X 2 species and distinguish the competitiveness of the investigated halides against DMF. On the basis of titration experiments, [BeCl(DMF) 3 ] + was identified as the dominant compound when BeCl 2 was dissolved in DMF. The unpredicted high beryllium−halide bond strength in chloro complexes as well as the instability of iodo compounds is discussed. The latter showed a distinctively different coordination chemistry compared to the other beryllium halides. In addition to that, the first example of a compound with the hexaiodidodiberyllate anion ([Be 2 I 6 ] 2− ) was characterized. On the basis of our results, BeBr 2 is a superior starting material compared to the other beryllium halides for the synthesis of coordination chemistry compounds.

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“…[7][8][9][10] Indeed, it has been found that the metal-ion complexation with simple halide and pseudohalide ions is generally enhanced in N,N-dimethylacetamide (DMA) over N,N-dimethylformamide (DMF), despite physicochemical properties of the solvents being similar. [11][12][13][14][15][16][17][18][19][20][21][22] Also, the complexation is significantly enhanced in hexamethylphosphoric triamide (HMPA) over DMF, and the solvation number of a metal ion decreases in HMPA relative to DMF, indicating a strong solVation steric effect operates in HMPA. [23][24][25][26][27] Solvation steric effect also modifies an aspect of preferential solvation (sterically controlled preferential solVation) of a metal ion in solvent mixtures.…”

Section: Introductionmentioning

confidence: 99%

Conformation of Solvent N,N-Dimethylpropionamide in the Coordination Sphere of the Zinc(II) Ion Studied by Raman Spectroscopy and DFT Calculations

et al. 2005

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Solvation structure of the zinc(II) ion in N,N-dimethylpropionamide (DMPA) was studied by Raman spectroscopy at varying temperature and by quantum mechanical calculations. No significant ion-pair formation was found for the Zn(ClO4)2 solution in the molality range m(Zn) < 1.5 mol kg(-1), and the solvation number of the zinc(II) ion was determined to be 4, indicating that 6-coordination of DMPA is sterically hindered. Interestingly, DMPA molecules are under equilibrium between planar cis and nonplanar staggered conformers, and the latter is more preferred in the coordination sphere, while the reverse is the case in the bulk. The DeltaG degrees , DeltaH degrees , and TDeltaS degrees values of conformational change from planar cis to nonplanar staggered in the coordination sphere were obtained to be -0.9, -8.5, and -7.5 kJ mol(-1), respectively. Density functional theory (DFT) calculations show that the planar cis conformer is more favorable than the nonplanar staggered one in the 1:2 cluster, as is the case for a single DMPA molecule and H(DMPA)+, indicating that there hardly occurs solvent-solvent interaction through the metal ion in the Zn2+-DMPA 1:2 cluster. On the other hand, the SCF energy of [Zn(planar cis-DMPA)4-n(nonplanar staggered DMPA)n]2+ (n = 0-4) decreases with increasing n, implying that the nonplanar staggered conformer is preferred in the solvate ion. It is thus concluded that solvent-solvent interaction through space, or solvation steric effect, plays a crucial role in the conformational equilibrium in the coordination sphere of the four-solvate metal ion.

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Steric solvent effect on small and large cations: calorimetric study of halogeno and thiocyanato complexes of beryllium(II) and cadmium(II) in N,N-dimethylacetamide

Cited by 9 publications

References 20 publications

Individual solvation number of first-row transition metal(II) ions in solvent mixtures of N,N-dimethylformamide and N,N-dimethylacetamide—Solvation steric effect

Individual solvation number of first-row transition metal(II) ions in solvent mixtures of N,N-dimethylformamide and N,N-dimethylacetamide—Solvation steric effect

Solution Behavior of Beryllium Halides in Dimethylformamide

Conformation of Solvent N,N-Dimethylpropionamide in the Coordination Sphere of the Zinc(II) Ion Studied by Raman Spectroscopy and DFT Calculations

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