Crystal Structures and Thermal Properties of L-MnC4H4O6•2H2O and DL-MnC4H4O6•2H2O

Abstract

Manganese L-tartrate dihydrate, L-MnC4H4O6·2H2O, and manganese DL-tartrate dihydrate, DL-MnC4H4O6·2H2O, crystals were grown at room temperature by the gel method using silica gels as the growth medium. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on both crystals. The space group symmetries (monoclinic P21 and P2/c) and structural parameters of the crystals were determined at room temperature. Both structures consisted of slightly distorted MnO6 octahedra, C4H4O6 and H2O molecules, and O–H···O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystals were found to occur in the temperature range of 300–1150 K. We inferred that the weight losses were caused by the evaporation of bound 2H2O molecules, and the evolutions of gases from C4H4O4 and of (1/2)O2 gas from MnO2, and that the residual black substance left in the vessels after decomposition was manganese oxide (MnO).

Structural and Thermal Investigations of L-CuC4H4O6·3H2O and DL-CuC4H4O6·2H2O Single Crystals

“…The theoretical weight losses were calculated based on the following considerations. The weight losses in the TG curves for both crystals may have been caused by the evolution of gases from the samples, similarly to our previous studies (Fukami, Hiyajyo, Tahara, & Yasuda, 2017;Fukami & Tahara, 2018;Fukami & Tahara, 2020). There are two crystallographically independent formula units in the unit cells of both crystals, as described in Table 2(a) and (b).…”

“…Furthermore, the number of water molecules in the formula unit reduces from three to two. (Fukami, Hiyajyo, Tahara, & Yasuda, 2017;Fukami & Tahara, 2018;Fukami & Tahara, 2020). 4) O( 13)-H(9)•••O(6) (5) 0.97(4) 1.73( 4) 2.698( 3) 171( 4) O( 13)-H( 10 (8) 0.87(7) 1.70( 7) 2.560(3) 166( 7) O( 4)-H(6)•••O(9) (9) 0.59(7) 2.22(7) 2.771(3) 157( 8) O( 9)-H(7)•••O(15) (10) 0.68(6) 2.08( 6) 2.754(3) 173( 7) O( 10)-H(8)•••O(7) (11) 0.65(5) 2.05(5) 2.692(3) 171( 6) O( 13)-H(9)•••O(1) (12) 0.66(7) 2.31( 7) 2.901(3) 151( 7) O( 13)-H(10)•••O(14) (13) 0.73(7) 2.17(7) 2.881( 5) 165( 7) O( 14)-H(11)•••O(5) (12) 0.77(8) 2.39(8) 3.136( 5) 166( 8) O( 14)-H(12)•••O(13) (14) 1.17(9) 1.97(9) 3.108( 6) 162( 7) O( 15)-H(13)•••O(8) (14) 0.86( 5 -z; (8) -x+1, -y+1, -z; (9) x+1, y, z; (10) x-1, y, z; (11) -x, -y+1, -z; (12…”

“…Many tartrate compounds are formed by the reaction of tartaric acid with compounds containing positive ions (i.e., two monovalent cations or one divalent cation) (Desai & Patel, 1988;Fukami, Hiyajyo, Tahara, & Yasuda, 2017;Fukami & Tahara, 2018;Fukami & Tahara, 2020;Labutina, Marychev, Portnov, Somov, & Chuprunov, 2011). Tartaric acid (chemical formula: C 4 H 6 O 6 ; systematic name: 2,3-dihydroxybutanedioic acid) has two chiral carbon atoms in its structure, which provides the possibility for four possible different forms of chiral, racemic, and achiral isomers: L(+)-tartaric, D(-)-tartaric, racemic (DL-) tartaric, and meso-tartaric acid (Bootsma & Schoone, 1967;Fukami, Tahara, Yasuda, & Nakasone, 2016;Song, Teng, Dong, Ma, & Sun, 2006).…”

Crystal Growth, Structural and Thermal Studies of FeC4H4O6·2.5H2O

“…The theoretical weight losses were calculated based on the following considerations. The weight losses in the TG curve of FeC 4 H 4 O 6 •2.5H 2 O may be caused by the evaporation of bound water molecules and the evolution of gases from the sample, similarly to our previous studies (Fukami & Tahara, 2018;Fukami & Tahara, 2020;Fukami & Tahara, 2021). The unit cell of the crystal contains two crystallographically independent formula units, and its chemical formula is expressed as (FeC 4 H 4 O 6 ) 2 •5H 2 O.…”

“…Tartrate compounds are formed by the reaction of tartaric acid with compounds containing positive ions (i.e., two monovalent cations or one divalent cation) (Desai & Patel, 1988;Fukami & Tahara, 2018;Fukami & Tahara, 2020;Fukami & Tahara, 2021;Labutina, Marychev, Portnov, Somov, & Chuprunov, 2011). Tartaric acid (C 4 H 6 O 6 ; systematic name: 2,3-dihydroxybutanedioic acid) has two chiral carbon atoms in its structure, which provides the possibility for four different forms of chiral, racemic, and achiral isomers: L(+)-tartaric, D(-)-tartaric, racemic (DL-) tartaric, and meso-tartaric acid (Bootsma & Schoone, 1967;Fukami, Tahara, Yasuda, & Nakasone, 2016;Song, Teng, Dong, Ma, & Sun, 2006).…”