Harald Euler

Potassium lithium carbonate, KLiCO3: single-crystal X-ray structure analysis and thermal expansion

Single crystals of KLiCO3, the intermediate compound in the eutectic system K2CO3-Li2CO3, were synthesized from the melt and the crystal structure was redetermined at room temperature by single-crystal X-ray diffraction: a = 7.232(1 ) Å, b = 7.085(2 )Å, c = 6.579(1) Å, ß = 113.40(1)°, space group P21/n (No 14), Z = 4. Earlier literature results obtained by neutron time-of-flight powder diffraction are corroborated. The structure is composed of distorted face and edge sharing LiO5 and KO9 coordination polyhedra which are arranged in a layered manner and are connected by distorted but planar carbonate anions. In addition to the structure analysis, the thermal expansion of the crystal was measured and analyzed up to melting at 504.5 ± °C. It exhibits a significant anisotropy with a maximum in direction c* about three times as large as the almost equal expansions in the a,b plane. This anisotropy is clearly understood from the distribution of bonds in the structure rather than from its layered nature.

Symmetry and crystal structure of biaxial elbaite-liddicoatite tourmaline from the Transbaikalia region, Russia

Abstract Optical anomalies and crystal structures have been studied for an elbaite-liddicoatite tourmaline specimen from the Malkhan pegmatite field (Transbaikalia region, Russia). The specimen is characterized by a complicated zoning and sector zoning distribution of anomalous biaxiality, with the axial angle 2V increasing from 3 up to 23° going from the first to the last growth zones of the most developed growth sector, o{022̅1}. The crystal structures of three samples cut out from different growth zones of that sector and characterized by the axial angles 11, 16, and 23° were refined in the trigonal space group R3m as well as in its monoclinic and triclinic subgroups Cm, R1, and P1, respectively (R = 0.019-0.039). The final choice of the low symmetry space group R1 is based on the analysis of the diffraction patterns and on the results of crystal structures refinements, which revealed ordered Al/Li distributions over the Y octahedral sites. The degree of order at Y sites correlates with the axial angle 2V, which implies a causal relationship. The Al/Li ordering reflects the geometrical differences of the octahedral sites with respect to the growth front orientation. The results obtained suggest that a growth dissymmetrization mechanism is the main reason for the observed cation ordering and optical anomalies.

Regioselective synthesis of 7,8-dihydroimidazo[5,1-c][1,2,4]triazine-3,6(2H,4H)-dione derivatives: A new drug-like heterocyclic scaffold.

Summary Dihydroimidazo[5,1-c][1,2,4]triazine-3,6(2H,4H)-dione derivatives were prepared by successive N3- and N1-alkylation of hydantoins, followed by regioselective thionation and subsequent cyclization under mild conditions. In a final alkylation step a further substituent may be introduced. The synthetic strategy allows broad structural variation of this new drug-like heterobicyclic scaffold. In addition to extensive NMR and MS analyses, the structure of one derivative was confirmed by X-ray crystallography.

Symmetry reduction and cation ordering in solid solutions of strontium-lead and barium-lead nitrates

Abstract Kinetic ordering of the cations in (Sr,Pb)(NO3)2 and (Ba,Pb)(NO3)2 solid solutions with anomalous birefringence was studied by means of single crystal X-ray diffraction. The crystal structures of two samples of (Sr0.62Pb0.38)(NO3)2 and (Ba0.20Pb0.80)(NO3)2, respectively, taken from the {111} growth sectors as well as of two samples of (Sr0.62Pb0.38) (NO3)2 taken from the {100} growth sector were refined in the ideal structure space group Pa-3 and in two of its subgroups – trigonal R-3 and triclinic P-1 with R = 0.009 — 0.027. The final choice of trigonal symmetry for the samples from the {111} growth sectors is based on the analysis of the diffraction patterns and of the cation distributions over the crystallographic sites, which reflects the different orientations of the cation coordination polyhedra with respect to the (111) growth face (cubic setting). The observed optical indicatrices were successfully reproduced in the point-dipole approximation.

Crystal structure of trihydroxydicopper formate, Cu2(OH)3(HCOO)

CH4Cu2O5, monoclinic, P1211 (no. 4), a = 5.5894(2) Å, b = 6.0558(3) Å, c = 6.9321(3) Å, * = 105.926(2)°, V = 225.6 Å, Z = 2, Rgt(F) = 0.038, wRref(F) = 0.121, T = 295 K. Source of material Indoor museum air pollution by formaldehyde and formic acid (e.g., emitted from wood) may cause the formation of formates on historic objects made for example from limestone, glass, or lead [1]. Nevertheless, similiar observations on copper alloys are limited only to cases where sodium salts are present [2]. To help with future identifications, Scott et al. [3] synthesized basic copper formates following the methods given by Fowles [4] and published their hitherto unknown powder diffraction data from DebyeScherrer films. In a project to identify joint copper-glass corrosion compounds we found a diffraction pattern matching the film 770 on three corrosion samples from the contact zone of coppercontaining alloys with sodium-containing glass: a 200 year old glass flute with silver mounting (Rijksmuseum Amsterdam), a silver-mounted ruby glass box (Green Vault Dresden), and an enamelled St. Matthew cross made from brass or bronze (MAK Frankfurt) [5]. Single crystals of this compound could be grown via Fowles method. Experimental details As a result of the crystal growth via the Fowles method, we obtained crystals of poor quality. According to the systematic extinctions 0k0, k = 2n+1, the possible space groups were P21 and P21/m. The structure could only be solved in P21. First refinements indicated inversion twinning by the ratio 0.40(6) / 0.60(6). Three of the 4 hydrogen atoms (H2, H3, H4) were found by Fourier mapping. Their coordinates as well as a common isotropic displacement parameter were refined. The position of H1 was calculated and kept fixed, contrary to its displacement parameter. The refinement converged at R1 = 0.038, Rw2 = 0.121, GOOF = 1.086, Flack parameter x = 0.00(6). Upon structure inversion, only the twin ratio inverted to 0.60(6) / 0.40(6). Thus, due to inversion twinning, the resonant scattering was not sufficient to allow for the determination of the absolute structure. Discussion The crystal structure is characterized by puckered layers, made of two different edge-sharing, Jahn-Teller distorted CuO6 octahedra d(Cu1—O) = 1.931(1) 2.408(8) Å, d(Cu2—O) = 1.970(9) 2.389(2) Å, oriented parallel to (001). The basal plane corners of the octahedron, centered by Cu1, are provided by the hydroxyl groups, whereas the apices are occupied by the single-bonded oxygen atoms of the formate groups. For the Cu2 octahedron, the apices are occupied by the oxygen atoms of the formate and hydroxyl groups. Alternating chains of Cu1 and Cu2 octahedra, running parallel [010], are connected to puckered layers by three common edges. Correspondingly, the Cu atoms of each layer form a nearly regular two-dimensional hexagonal packing as do oxygen atoms above and below each Cu layer. These most likely fairly stable O–Cu–O ‘sandwiches’ are held together by hydrogen bonds between the hydrogens of hydroxyl groups and the oxygens of the formate groups d(O7—H4) = 0.97(5) Å, d(O7···O5) = 2.690(3) Å, d(H4···O5) = 1.96(6) Å, ∠O7–H4···O5 = 130(5)°. Z. Kristallogr. NCS 224 (2009) 609-610 / DOI 10.1524/ncrs.2009.0268 609

Crystal structures of Tutton’s salts Tl2[MII(H2O)6](SO4)2, MII=Mg, Mn, Fe, Co, Ni, Zn

H12MgO14S2Tl2, monoclinic, P121/a1 (no. 14), a = 9.262(2) Å, b = 12.459(2) Å, c = 6.207(1) Å, / = 106.39(2)°, V = 687.1 Å, Z = 2, Rgt(F) = 0.024, wRref(F) = 0.042, T = 295 K. H12MnO14S2Tl2, monoclinic, P121/a1 (no. 14), a = 9.322(2) Å, b = 12.565(2) Å, c = 6.233(1) Å, / = 106.29(2)°, V = 700.8 Å, Z = 2, Rgt(F) = 0.028, wRref(F) = 0.066, T = 295 K. H12FeO14S2Tl2, monoclinic, P121/a1 (no. 14), a = 9.262(2) Å, b = 12.497(1) Å, c = 6.235(2) Å, / = 106.15(1)°, V = 693.2 Å, Z = 2, Rgt(F) = 0.033, wRref(F) = 0.075, T = 295 K. H12CoO14S2Tl2, monoclinic, P121/a1 (no. 14), a = 9.227(1) Å, b = 12.437(2) Å, c = 6.220(1) Å, / = 106.40(1)°, V = 684.7 Å, Z = 2, Rgt(F) = 0.025, wRref(F) = 0.037, T = 295 K. H12NiO14S2Tl2, monoclinic, P121/a1 (no. 14), a = 9.161(2) Å, b = 12.389(2) Å, c = 6.210(2) Å, / = 106.35(2)°, V = 676.3 Å, Z = 2, Rgt(F) = 0.022, wRref(F) = 0.042, T = 295 K. H12ZnO14S2Tl2, monoclinic, P121/a1 (no. 14), a = 9.219(2) Å, b = 12.426(2) Å, c = 6.226(1) Å, / = 106.29(2)°, V = 684.6 Å, Z = 2, Rgt(F) = 0.022, wRref(F) = 0.041, T = 295 K. Source of material All compounds of the probably isomorphous series Tl2[M(H2O)6](SO4)2 were prepared by dissolution of equimolar amounts of thallium sulfate Tl2SO4 and M sulfate hydrate MSO4.·.nH2O in hot destilled water and ensuing evaporation of the solvent. The M sulfate hydrates contained different amounts of crystal water. For the syntheses of the Tutton’s salts with M = Mg, Fe, Co, Zn, the M sulfate heptahydrates were used, for M = Ni the M sulfate hexahydrate and for M = Mn, sulfate monohydrate. Differently coloured, mostly ideomorphous single crystals of dimensions up to 10 mm were obtained. Experimental details To reduce errors introduced by insufficient corrections of absorption effects, it was attempted to grind a crystal sphere in order to apply a spherical absorption correction in the course of data processing. The grinding produced an ellipsoid, whose deviation from spherical is characterized by the given max, mid and min crystal dimensions. Discussion In continuation of our studies on crystal chemistry, metal-water interaction and system of hydrogen bonds in different series of Tutton salts (Rb sulfates [1], Rb selenates [2], Cs sulfates [3], Cs selenates [4], K sulfate [5], K selenates [6]) by single crystal and powder X-ray diffraction experiments we determined the so far unknown crystal structures of the compounds of the thallium sulfate series. As all other before studied Tutton salts, they are isotypic. Due to scattering power of Tl and data errors introduced by insufficient correct for the large absorption, the hydrogen positions could not be determined by difference Fourier mapping, as done in [1-6]. Therefore, all hydrogen coordinates were calculated from the linear correlations x(H(i)), y(H(i)), z(H(i), i = 1...6 vs the cation radius R(M) (M = K, Rb, Cs), derived for each of the 6 independend hydrogen bonds of the so far studied compounds. The evaluation of th O#H···O bond lengths and angles yielded resonable hydrogen coordinates for the title compounds. During the structure refinements, these predicted hydrogen coordinates were kept fixed, contrary to a common variable isotropic thermal displacement parameter, assigned to all hydrogens atoms. In all cases, the agreement indices were significantly lowered by introducing the H atoms into the models, e.g., R1(M = Mg) = 0.0235 vs R1(M = Mg) = 0.0262. The Tutton salt structure is characterized by irregular MO8 polyhedra (here with M = Tl), d(Tl—O) = 2.792(4) 3.363(4) Å, and M(H2O)6 octahedra, which are linked to the SO4 groups by a system of hydrogen bonds. Compared to the earlier studied isotypic Rb sulfates [1], one finds for the present compounds: Z. Kristallogr. NCS 224 (2009) 355-359 / DOI 10.1524/ncrs.2009.0157 355

Symmetry reduction and cation ordering in alum solid solutions

Kinetic ordering of cations in solid solutions of alums showing anomalous birefringence was studied by means of single crystal X-ray diffraction. The crystal structures of two samples of K(Al0.6Cr0.4)(SO4)2 · 12 H2O and (K0.45(NH4)0.55)Al(SO4)2 · 12 H2O, respectively, taken from {111} growth sectors were refined in the ideal space group Pa-3 and in two of its subgroups – trigonal R-3 and triclinic P-1 with R1 = 0.028 – 0.032. The final choice of trigonal symmetry is based on the analysis of the diffraction patterns and of the cation distributions over the crystallographic sites. The correctness of the crystal structure refinements is supported by the disappearance of both ordering and birefringence upon crystal annealing. Also, an optically isotropic sample of (Rb0.3(NH4)0.7)Al(SO4)2 · 12 H2O (growth sector {111}) exhibiting random cation distribution is found to have cubic symmetry (space group Pa-3, R1 = 0.027).

Synthesis, X-ray analysis and spectroscopic characterization of the hemiaminal cyclization product from 2,4-dipyridine substituted 3,7-diazabicyclo[3.3.1]nonanone 1,5-diesters

The 2,4-dipyridine substituted 3,7-dimethyl-3,7-diazabicyclo[3.3.1]nonan-9-one 1,5-diester, HZ2, is characterized by a high analgesic potency. The attempt to form ammonium salts of HZ2 or to N-demethylate position 7 resulted in an unexpected hemiaminal cyclization product 1. The structure was elucidated by an X-ray analysis, the 1H- and 13C-NMR spectra could be fully assigned by means of H,H-COSY, Grad-HSQC-EA and ACCORD-HMBC experiments. The MS spectra of 1 exhibit a ring opening. Interestingly, ESI-MS/MS experiments of HZ2 in aqueous solution showed the formation of a hydrated product. The fragmentation pathways of HZ2 and the hydrated product are rather different indicating the formation of a carboxylate.

Refinement of the crystal structure of potassium hexaaquairon(II) sulfate, K2[Fe(H2O)6](SO4)2 and potassium hexaaquazinc(II) sulfate, K2[Zn(H2O)6](SO4)2

FeH12K2O14S2, monoclinic, P121/a1 (no. 14), a = 9.065(1) Å, b = 12.252(1) Å, c = 6.1646(5) Å, . = 104.536(7)°, V = 662.8 Å, Z = 2, Rgt(F) = 0.020, wRref(F) = 0.055, T = 295 K. H12K2O14S2Zn, monoclinic, P121/a1 (no. 14), a = 9.029(1) Å, b = 12.204(1) Å, c = 6.1470(5) Å, . = 104.795(9)°, V = 654.8 Å, Z = 2, Rgt(F) = 0.022, wRref(F) = 0.058, T = 295 K. Source of material Both representatives of the most probably isomorphous Tutton’s salts series K2[M(H2O)6](SO4)2 were prepared by dissolution of equimolar amounts of potassium sulfate K2SO4 and M sulfate heptahydrate MSO4 · 7H2O in hot destilled water and ensuing evaporation of the solvent. Differently coloured, mostly ideomorphous single crystals of dimensions up to 10 mm were obtained. Discussion Studying crystal chemistry, metal water interaction and the system of hydrogen bonds in different series of Tutton salts (Rb sulfates [1], Rb selenates [2], Cs sulfates [3], Cs selenates [4]) by single crystal and powder diffraction, it is essential to conduct the experiments as similar as possible in order to reduce errors and to obtain truly comparable results. Therefore, we redetermined the known structures of the K sulfates [5-10] with X-ray diffraction under similar conditions and confirmed, that all compounds are isotypic with space group P21/a (no. 14), Z = 2 [11]. For the present paper, only crystal structure determinations of two more Tutton salts K2[M(H2O)6](SO4)2, M = Fe, Zn with improved R-values are presented, but for the following considerations, all quoted results were used [11]. The Tutton salt crystal structure is characterized by irregular MO8 polyhedra (here with M = K), d(K—O) = 2.717(1) 3.288(1) Å, and M(H2O)6 octahedra, which are linked to the SO4 groups by a system of hydrogen bonds. According to expectations, the most distorted M(H2O)6 octahedron is obtained for M = Cu (Jahn-Teller distortion) with d(M—O) = 1.940(1) 2.227(1) Å. Compared to the earlier studied isotypic Rb sulfates [1], one finds for the present compounds: 1. Except for Mg and Cu, the lattice parameters a, b, c of all the different M compounds decrease on average by 1.9 %, 2.2 %, 1.5 %, respectively. This follows from the smaller K ion and hence to the smaller volume of the KO8-polyhedron [12,13]. The unit cell angle . decreasing for all compounds, except for M = Cu, by about 1.1°, shows a more negative slope in the linear correlation between . and the M cation radius. With respect to the exchange of M, the linear correlations between the lattice parameters and the cation radii exhibit i) for a, the same slope as in the Rb sulfates, but ii) for b, a significantly smaller and iii) for c, a significantly larger slope, respectively. 2. The volumes of the various KO8 coordination polyhedra in the K-salts is on average 10.5 % smaller. This corresponds to the 3rd power of the ratio of the mean K—O and Rb—O distances, (d(K—O)/d(Rb—O))= 0.892. 3. The volumes of the MO6 coordination octahedra agree with those of the corresponding Rb sulfates. 4. While in agreement with chemical expectation, the sulfate group is practically invariant against the M cation exchange in the hexahydrate-complex, the volumes of both the MO6 and the KO8 coordination polyhedra increase as the cation radius R(M) [13] increases. For V(KO8), the increase is more than three times smaller than that for V(MO6) and it is also significantly smaller than that for the analog Rb sulfates. 5. As in the Rb sulfates, the a parameter of the Mg and Cu compounds deviate significantly from the a vs R(M) relation. The Z. Kristallogr. NCS 224 (2009) 171-173 / DOI 10.1524/ncrs.2009.0077 171

Refinement of crystal structure of copper acetate diammine, Cu(CH3COO)2 · 2NH3

C4H12CuN2O4 ,m onoclinic, P121/c 1( no. 14), a =5 .452(2) A, b =1 0.220(5) A, c =7 .518(5) A, * =1 07.067(3)°, V =4 00.5 A 3 , Z =2 , Rgt(F) =0 .032, wRref(F 2 ) =0 .082, T =2 95 K.