Limits...
Preparation, structural characterization, and decomposition studies of two new γ-octamolybdates of 4-methylpyridine.

Szymańska A, Nitek W, Rutkowska-Zbik D, Łasocha W - Monatsh. Chem. (2014)

Bottom Line: Thermal stability and decomposition studies of the obtained two new γ-octamolybdates were performed using TG/DSC and XRPD methods.Both compounds decomposed with the formation of 4-methylpyridinium β-octamolybdate.The two compounds are pseudo-polymorphs, exhibiting both striking similarities as well as significant differences in their structures and properties.

View Article: PubMed Central - PubMed

Affiliation: Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow, Poland.

ABSTRACT

Abstract: We synthesized two new γ-octamolybdates, and determined their crystal structures from single-crystal X-ray diffraction data. Orange-yellow tetrakis(4-methylpyridinium) bis(4-methylpyridine)-γ-octamolybdate 1 crystallizes in space group P21/c with a = 11.586(2) Å, b = 15.526(2) Å, c = 16.247(2) Å, β = 118.753(1)º, Z = 2. White tetrakis(4-methylpyridinium) bis(4-methylpyridine)-γ-octamolybdate hydrate 2 crystallizes in space group C2/c with a = 27.086(4) Å, b = 11.917(2) Å, c = 19.332(2) Å, β = 124.427(1)º, Z = 4. Results of crystal structure determinations are presented and discussed in this paper. Thermal stability and decomposition studies of the obtained two new γ-octamolybdates were performed using TG/DSC and XRPD methods. Both compounds decomposed with the formation of 4-methylpyridinium β-octamolybdate. The two compounds are pseudo-polymorphs, exhibiting both striking similarities as well as significant differences in their structures and properties.

No MeSH data available.


Related in: MedlinePlus

Projection of the structure of 4-methylpyridinium octamolybdate(VI) (1) along b axis
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4495051&req=5

Fig3: Projection of the structure of 4-methylpyridinium octamolybdate(VI) (1) along b axis

Mentions: In the structure of this compound, each centrosymmetric γ-octamolybdate anion is directly connected to two molecules of 4-methylpyridine by a nitrogen–molybdenum bond (N11–Mo3, 2.249(2) Å). Molecules of protonated amines are connected with octamolybdate anions through hydrogen bonds formed by nitrogen from 4-methylpyridine and oxygen atoms from γ-[Mo8O26]4− anion. In particular, N21 atoms, from the N21..C27 ring, form strong hydrogen bonds (N21…O11, d(D..A) = 2.668 Å), whereas N31 atoms form trifurcated bonds N31…O6, N31…O3, and N31-H…O13 with d(D..A) = 2.89, 3.01, and 3.169 Å, respectively. As can be expected, trifurcated H-bonds are weaker than single bonds created by atoms in a similar environment. Selected bond distances and details of hydrogen bonds are collected in Tables 2 and 3. The asymmetric unit, labeling scheme for the symmetry-independent atoms, and projection of the unit cell are shown in Figs. 2 and 3. It is noteworthy that each octamolybdate anion is surrounded by four 4-methylpyridinium cations (creating seven-element semi-isolated clusters, where the [Mo8O26]4− fragment is surrounded by six methylpyridine moieties). What is interesting is that there are no H-bonds linking neighboring amines, as they are mutually interacting only by π–π interactions (shifted face-to-face). In the structure, one can find infinite channels (along [100], passing through 0, ½, 0, 0 and 0, 0, ½), built of 4-methylpyridine moieties placed almost in parallel to each other in a distance of 3.8–4.25 Å. The γ-octamolybdate anions surrounded by cations form columns along the direction [100] (see Fig. 3).Table 2


Preparation, structural characterization, and decomposition studies of two new γ-octamolybdates of 4-methylpyridine.

Szymańska A, Nitek W, Rutkowska-Zbik D, Łasocha W - Monatsh. Chem. (2014)

Projection of the structure of 4-methylpyridinium octamolybdate(VI) (1) along b axis
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4495051&req=5

Fig3: Projection of the structure of 4-methylpyridinium octamolybdate(VI) (1) along b axis
Mentions: In the structure of this compound, each centrosymmetric γ-octamolybdate anion is directly connected to two molecules of 4-methylpyridine by a nitrogen–molybdenum bond (N11–Mo3, 2.249(2) Å). Molecules of protonated amines are connected with octamolybdate anions through hydrogen bonds formed by nitrogen from 4-methylpyridine and oxygen atoms from γ-[Mo8O26]4− anion. In particular, N21 atoms, from the N21..C27 ring, form strong hydrogen bonds (N21…O11, d(D..A) = 2.668 Å), whereas N31 atoms form trifurcated bonds N31…O6, N31…O3, and N31-H…O13 with d(D..A) = 2.89, 3.01, and 3.169 Å, respectively. As can be expected, trifurcated H-bonds are weaker than single bonds created by atoms in a similar environment. Selected bond distances and details of hydrogen bonds are collected in Tables 2 and 3. The asymmetric unit, labeling scheme for the symmetry-independent atoms, and projection of the unit cell are shown in Figs. 2 and 3. It is noteworthy that each octamolybdate anion is surrounded by four 4-methylpyridinium cations (creating seven-element semi-isolated clusters, where the [Mo8O26]4− fragment is surrounded by six methylpyridine moieties). What is interesting is that there are no H-bonds linking neighboring amines, as they are mutually interacting only by π–π interactions (shifted face-to-face). In the structure, one can find infinite channels (along [100], passing through 0, ½, 0, 0 and 0, 0, ½), built of 4-methylpyridine moieties placed almost in parallel to each other in a distance of 3.8–4.25 Å. The γ-octamolybdate anions surrounded by cations form columns along the direction [100] (see Fig. 3).Table 2

Bottom Line: Thermal stability and decomposition studies of the obtained two new γ-octamolybdates were performed using TG/DSC and XRPD methods.Both compounds decomposed with the formation of 4-methylpyridinium β-octamolybdate.The two compounds are pseudo-polymorphs, exhibiting both striking similarities as well as significant differences in their structures and properties.

View Article: PubMed Central - PubMed

Affiliation: Jerzy Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow, Poland.

ABSTRACT

Abstract: We synthesized two new γ-octamolybdates, and determined their crystal structures from single-crystal X-ray diffraction data. Orange-yellow tetrakis(4-methylpyridinium) bis(4-methylpyridine)-γ-octamolybdate 1 crystallizes in space group P21/c with a = 11.586(2) Å, b = 15.526(2) Å, c = 16.247(2) Å, β = 118.753(1)º, Z = 2. White tetrakis(4-methylpyridinium) bis(4-methylpyridine)-γ-octamolybdate hydrate 2 crystallizes in space group C2/c with a = 27.086(4) Å, b = 11.917(2) Å, c = 19.332(2) Å, β = 124.427(1)º, Z = 4. Results of crystal structure determinations are presented and discussed in this paper. Thermal stability and decomposition studies of the obtained two new γ-octamolybdates were performed using TG/DSC and XRPD methods. Both compounds decomposed with the formation of 4-methylpyridinium β-octamolybdate. The two compounds are pseudo-polymorphs, exhibiting both striking similarities as well as significant differences in their structures and properties.

No MeSH data available.


Related in: MedlinePlus