Quinoxaline-1,2,3-dithiazolyls — Synthesis, EPR characterization, and redox chemistry

2001 ◽  
Vol 79 (9) ◽  
pp. 1352-1359
Author(s):  
A Wallace Cordes ◽  
James R Mingie ◽  
Richard T Oakley ◽  
Robert W Reed ◽  
Hongzhou Zhang
Keyword(s):  
Epr Spectroscopy ◽  
Ring Closure ◽  
Coupling Constants ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Molecular Conductors ◽  
Vacuum Sublimation ◽  
Space Group ◽  
X Ray Crystallography ◽  
Sulfenyl Chlorides

Oxidation of quinoxalineaminothiol with SCl2 or S2Cl2/Cl2 affords a series of compounds based on the quinoxaline-1,2,3-dithiazole framework QDTA. Under highly oxidizing conditions, the 1,2,3-dithiazolyl ring is opened to afford the acyclic dichlorosulfimino-sulfenyl chlorides Clx-QDTA-Cl3 (x = 0, 1, 2). Reduction of these "trichloro" compounds leads to ring closure. For x = 2, reduction using S2Cl2 affords the dithiazolylium chloride [Cl2-QDTA][Cl]. For all values of x, reduction with iodide ion (3 mol equiv) affords the corresponding dithiazolyl radical [Clx-QDTA]. The radicals can be isolated in good yield in crude form, but attempts to purify them by vacuum sublimation lead to thermal degradation. The radicals have nonetheless been fully characterized by EPR spectroscopy, and the assignments of the observed hyperfine coupling constants cross-matched with those obtained by computation at the B3LYP/6-31G** level. The structures of the trichloro compounds Clx-QDTA-Cl3 (x = 1, 2) have been confirmed by X-ray crystallography. Crystal data: Cl-QDTA-Cl3, monoclinic, space group C2/c, a = 30.561(5) Å, b = 4.9764(9) Å, c = 22.247(4) Å, β = 131.822(14)°, V = 2521.4(8) Å3, Z = 8, R(F) = 0.043, and Rw(F) [I [Formula: see text] σ (I)] = 0.049; Cl2-QDTA-Cl3, orthorhombic, space group Pnma, a = 18.627(12) Å, b = 6.848(4) Å, c = 10.926(7) Å, V = 1393.7(15) Å3, Z = 4, R(F) = 0.047, and Rw(F) [I [Formula: see text] 3σ(I)] = 0.060.Key words: thiazyl radicals, molecular conductors, EPR spectroscopy, quinoxaline, DFT calculations.

Crystal Structures of (3S*,4S*,5S*,6S*)-3,4-Epoxy- 1,7-dioxaspiro[5.5]undecan-5-ol, (3R*,5S*,6S*)-1,7- Dioxaspiro[5.5]undecane-3,5-diyl Diacetate and (4S*,5S*,6S*)-1,7-Dioxaspiro[5.5]undecane-4,5-diol

1997 ◽  
Vol 50 (2) ◽  
pp. 123
Author(s):  
Margaret A. Brimble ◽  
Andrew Johnston ◽  
Trevor W. Hambley ◽  
Peter Turner
Keyword(s):  
Hydrogen Bonding ◽  
Hydroxy Group ◽  
Axial Position ◽  
Monoclinic Space Group ◽  
Equatorial Position ◽  
Intermolecular Hydrogen Bonding ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray Crystallography

The structures of (3S*,4S*,5S*,6S*)-3,4-epoxy-1,7-dioxaspiro[5.5]undecan-5-ol (2), (3R*,5S*,6S*)-1,7- dioxaspiro[5.5]undecane-3,5-diyl diacetate (4) and (4S*,5S*,6S*)-1,7-dioxaspiro[5.5]undecane-4,5-diol (5) have been determined by X-ray crystallography. The unsubstituted tetrahydropyran ring in (2) adopts an axial position with respect to the epoxy-substituted ring and the hydroxy group at C5 is syn to the epoxide group. Intermolecular hydrogen bonding is observed between the C5 hydroxy group and O1. The two six-membered rings in (4) adopt chair conformations and the two acetate groups adopt 1,3-diaxial positions. The C5 hydroxy group in (5) assumes an axial position anti to the C-O bond of the neighbouring ring whilst 4-OH occupies an equatorial position. Intermolecular hydrogen bonding is also observed between 4-OH and 5-OH. Compound (2), C9H14O4, M 186·21, crystallized in the monoclinic space group P 21/c with a 7·867(1), b 12·2060(9), c 9·3676(8) Å, b 102·744(8), V 877·4(1) Å 3 and No 1163 [I > 2·5s (I)], R 0·031, Rw 0·035. Compound (4), C13H20O6, M 272·30, crystallized in the triclinic space group P 1 with a 9·902(1), b 11·0024(9), c 6·9183(5)Å, a 104·078(8), b 96·769(9), g 101·980(8), V 703·8(1) Å 3 , No 1657 [I > 2·5s(I)], R 0·047, Rw 0·044. Compound (5), C9H16O4, M 188·22, crystallized in the orthorhombic space group Pbca with a 25·504(3), b 8·909(2), c 8·038(2) Å, V 1826·4(5) QA 3 , No 1096 [I > 2·5s(I)], R 0·030, Rw 0·030.

Preparations, X-ray crystal structures, and spectral studies of seleninyl bis(trifluoromethanesulfonate) and seleninyl bis(acetate)

1988 ◽  
Vol 66 (9) ◽  
pp. 2367-2374 ◽  
Author(s):  
Ramesh Kapoor ◽  
Poonam Wadhawan ◽  
Pratibha Kapoor ◽  
Jeffery F. Sawyer
Keyword(s):  
Crystal Packing ◽  
Spectral Studies ◽  
Monoclinic Space Group ◽  
Coordination Geometry ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Intermolecular Contacts ◽  
Ir And Raman

The compounds seleninyl bis(trifluoromethanesulphonate) (1) and seleninyl bis(acetate) (2) have been prepared and characterized by elemental analysis, ir and Raman spectroscopy, and X-ray crystallography. Crystals of 1 are monoclinic, space group P21/n with a = 12.735(1) Å, b = 5.163(4) Å, c = 16.133(2) Å, β = 96.426(8)°, U = 1054 Å3, Dx = 2.48 g cm−3 for Z = 4, R = 0.038 for 1745 observed reflections with I > 2.5σ(I). Those of 2 are orthorhombic, space group Pcab with a = 6,845(3) Å, b = 8.992(2) Å, c = 23.560(9) Å, U = 1450 Å3Dx = 1.95 g cm−3 for Z = 8, R = 0.074 for 1073 observed reflections with I > 3.0σ(I). The primary geometry of the Se atom in SeO(O3SCF3)2 is AX3E with a Se=O distance of 1.571(3) Å and Se—O bond lengths to the CF3SO3 ligands of 1.902(3) and 1.922(3) Å. Completing the overall coordination geometry of the Se atom are 2 intramolecular and 4 intermolecular Se … O contacts which are less than van der Waals limits. The overall coordination geometry is somewhat irregular since the two triflate anions are significantly differently arranged with respect to the SeO3E tetrahedron. The crystal packing consists of layers of interacting molecules. In 2 there is some disorder. However, the major arrangement of the molecule has Se=O and Se—O(1), Se—O(3) distances to the acetate ligands of lengths 1.575(9), 1.847(7), and 1.831(8) Å respectively. The overall geometry of the Se atom in this compound is completed by two intramolecular secondary Se … O contacts involving the second O atoms of both acetates and two intermolecular contacts involving the seleninyl oxygen atom and atom O(2) of an acetate group in two different symmetry related molecules. Overall, the crystal packing consists of essentially centrosymmetric dimeric units linked together through Se=O—Se bridges. A 1:2 adduct of 1 with pyridine has also been prepared and characterised.

[Ni5(SEt)10] und [Ni4(SC6H11)8], homoleptische Nickel-Thiolate mit pentagonal-prismatischen und cubanartigen Schwefelgerüsten /[Ni5(SEt)10] and [Ni4(SC6H11)8], Homoleptic Nickel-Thiolates with Pentagonal-Prismatic and Cubane-Like Sulfur Frameworks

1987 ◽  
Vol 42 (9) ◽  
pp. 1121-1128 ◽  
Author(s):  
Michael Kriege ◽  
Gerald Henkel
Keyword(s):  
Methylene Chloride ◽  
Methanol Solution ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Coordination Sites ◽  
Square Planar ◽  
Solvent Molecules

NiCl2 reacts with NaSR in methanol solution to give the black diamagnetic complexes [Ni5(SR)10] (R = Et, 1) and [Ni4(SR)8] (R = C6H11 , 2). Crystals of 1 are monoclinic, space group P21/h with a = 13.149(4), b = 15.571(4), c = 17.917(5) Å , β = 105.31(2)° and Z = 4. 2 crystallizes from methylene chloride with sixteen solvent molecules per unit cell in the orthorhombic space group Ibca with a = 17.902(8), b = 18.289(8), c = 37.99(2) Å and Z = 8. The structures of 1 and [Ni4(SC6HM)8] · 2 CH 2Cl2 (3) have been determined by X-ray crystallography and refined to R(RW) = 0.072 (0.062) and 0.119 (0.128), respectively. Both complexes are cyclic neutral molecules and contain square planar NiS4 coordination sites (1: mean Ni - S 2.200 Å , mean S -Ni -S 81.8 ( 2 x ) . 98.3 ( 2 x ) , 170.8° ( 2 x ) ; 2: mean Ni - S 2.213 Å , mean S - Ni - S 80.9 (2 x ) , 98.2 ( 2 x ) , 167.5°(2 x )) condensed via opposite edges. A s a result, prismatic sulfur frameworks are observed which are pentagonal in the case of 1 and tetragonal in the case of 2. Their lateral faces are centered by Ni atoms. The symmetry of the Ni-S core portion approaches D5h for 1 and D4h for 2. With reference to the toroidal N i-S frameworks, the sulfur-carbon bonds of each pair of opposite ligands are in axial and equatorial positions, respectively. This configuration alternates around the prismatic sulfur arrangement which is completely compatible with the even number of nickel atoms present in 2, but results in a node for 1 due to the five-fold symmetry.

1-Aminocyclohexene-2,4-dicarbonitrile derivatives. Syntheses and structural study

1995 ◽  
Vol 73 (9) ◽  
pp. 1546-1555 ◽  
Author(s):  
Antonio Lorente ◽  
Carmen Galan ◽  
Isabel Fonseca ◽  
Juliana Sanz-Aparicio
Keyword(s):  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
Benzyl Cyanide ◽  
X Ray Crystallography ◽  
Conformational Preferences ◽  
Cell Dimensions ◽  
Substituted 1

Substituted 1-aminocyclohexene-2,4-dicarbonitriles were obtained by reaction of α,β-unsaturated nitriles (two equivalents) with benzyl cyanide. By recrystallization from ethanol one diastereomeric racemate was isolated in each case. The cyclohexene structures were established from spectroscopic data (IR, MS, and one- and two-dimensional NMR). Relative stereochemical configurations and conformational preferences in the solid state of cyclohexenes 2 and 3 and propanedicarbonitrile 1 were established from X-ray crystallography. Crystals of 1 (C17H14N2) belong to the orthorhombic space group Pbca. Cell dimensions are a = 17.168(7), b = 21.612(5), c = 7.508(2) Å, V = 2785(7) Å3. Final R = 0.078 and Rw = 0.091; 1363 reflections were observed. The compound 2 (C26H21N3) crystallizes in the monoclinic space group P21/n with Z = 4. The crystal data for 2 are a = 7.743(1), b = 24.420(1), c = 11.164(1) Å, β = 102.65(1)°, V = 2059.7(3) Å3. Final R = 0.046 and Rw = 0.059; 2701 reflections were observed. Crystals of 3 (C16H17N3) belong to the triclinic space group [Formula: see text] Cell dimensions are a = 14.582(1), b = 7.283(1), c = 7.116(1) Å, α = 110.84(0)°, β = 85.92(0)°, γ = 97.81(1)°, V = 696.9(2) Å3. Final R = 0.047 and Rw = 0.052; 2227 reflections were observed. The cyclohexene ring in 2 and 3 exists as a sofa rather then as a half-chair conformation. Keywords: 1-aminocyclohexenes, α,β-unsaturated nitriles, benzyl cyanide.

Crystal and molecular structure of two C-phenyl pentitol derivatives

1978 ◽  
Vol 56 (23) ◽  
pp. 2915-2921 ◽  
Author(s):  
Douglas C. Rohrer ◽  
Jean-Claude Fischer ◽  
Derek Horton ◽  
Wolfgang Weckerle
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Coupling Constants ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Cell Dimensions ◽  
Palladium Catalyzed ◽  
Discrepancy Index

Grignard addition of phenylmagnesium bromide to 3,5-O-benzylidene-1-deoxy-D-erythro-2-pentulose (1) affords C-phenyl branched-chain pentitols having exclusively either the D-arabino (2) or D-ribo (5) stereochemistry according to the mode of substitution of 1. In order to determine the chirality of these products conclusively, the crystal and molecular structure of the unsubstituted pentitol 6 (from 2) has been determined. Crystals of 1-deoxy-2-C-phenyl-D-arabinitol (6; C11H16O4) are orthorhombic, space group P212121, with cell dimensions a = 8.9420(6), b = 18.910(1), c = 6.4263(6) Å, and Z = 4. The structure was solved by multi-solution direct methods and refined to a final discrepancy index of 5.6%. The molecule has an extended, planar zigzag conformation with the phenyl ring nearly perpendicular to this plane. Compound 6 forms one intramolecular (between 2-OH and O-4) and three intermolecular hydrogen bonds. Palladium-catalyzed hydrogenolysis of the 2-phenylcarbamate of 2 results in deoxygenation of the benzylic center with complete-inversion of configuration, as established by crystal-structure determination of the product 7. Crystals of 2(S)-4-O-acetyl-3,5-O-benzylidene-1,2-dideoxy-2-C-phenyl-D-erytro-pentitol (7; C20H22O4) are monoclinic, space group C2, with cell dimensions a = 19.102(1), b = 6.1925(5), c = 16.098(1) Å, β = 108.325(9)°, and Z = 4. The structure was solved by multi-solution direct methods and refined to a final discrepancy index of 5.9%. The molecule has an almost ideal planar, zigzag backbone conformation which incorporates the 1,3-dioxane ring. Comparison of the conformation observed in the crystal with that calculated from proton–proton coupling constants shows good agreement

Synthesis and crystal structure of 17-deaza-17-methyl thionium isomorphinan (isosulforphanol) perchlorate, an isostere of the opiate isolevorphanol

1985 ◽  
Vol 63 (6) ◽  
pp. 1268-1274 ◽  
Author(s):  
Bernard Belleau ◽  
Ugo Gulini ◽  
Barbara Gour-Salin ◽  
F. R. Ahmed
Keyword(s):  
Ring Closure ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
The Central Nervous System ◽  
Potent Agonist ◽  
Potent Antagonist ◽  
Sulfur Analog

No morphinan analog carrying a heteroatom other than nitrogen at position 17 has yet been synthesized. The synthesis of the position 17 sulfur analog of the perchlorate salt of (±)-isolevorphanol is described. The strategy adopted is based on the classical Grewe synthesis of morphinans and, under narrowly defined conditions, the title compound isosulforphanol (3a) and an intermediate by-product 13 resulting from an unusual non-bridged head ring closure of 11a were obtained. The X-ray structures of both 3a and 13 were determined. Crystals of 13 (C17H22OS) are monoclinic, space group P21/a, a = 17.080(2), b = 9.372(1), c = 9.327(1) Å, β = 108.67(1), V = 1414.4 Å3, Z = 4. Final R = 0.034 for 2545 reflections. The crystals of 3a(C17H23OS+•ClO4−)are orthorhombic, space group Pna21,a = 10.934(1), b = 9.219(1), c = 17.131(2) Å, V = 1726.8 Å3, Z = 4. Final R = 0.053 for 1018 reflections. The C17H23OS+ molecule has been identified by this X-ray analysis as S-methyl isosulforphanol (Fig. 2). The structure of 13 is shown in Fig. 1. The stereochemical outcome of the Grewe-like synthesis is thus established as proceeding in a reversed manner when sulfur replaces the nitrogen in the final cyclization step. Preliminary pharmacological studies showed that 3a is a potent agonist in the central nervous system but a potent antagonist on the guinea-pig ileum.

Supramoleküle aus Kronenethern und geminalen Sulfonen: Synthese von vier binären Komplexen und Kristallstruktur von (CH2CH2O)4·2H 2C(SO2C2H5)2/Supramolecules of Crown Ethers with Geminal Sulfones: Synthesis of Four Binary Complexes and Crystal Structure of (CH2CH2O )4·2H2C(SO2C2H5)2

1995 ◽  
Vol 50 (7) ◽  
pp. 1018-1024 ◽  
Author(s):  
Axel Michalides ◽  
Dagmar Henschel ◽  
Armand Blaschette ◽  
Peter G. Jones
Keyword(s):  
Monoclinic Space Group ◽  
Triclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Binary Complexes ◽  
Cyclic Polyethers ◽  
Adjacent Unit ◽  
Methylene Group

In a systematic search for supramolecular complexes involving all combinations of the cyclic polyethers 12-crown-4 (12C4), 15-crown-5 (15C 5), 18-crown-6 (18C 6) and dibenzo- 18-crown-6 (DB -18C6), and the geminal di- or trisulfones H2C(SO 2Me)2, H2C (SO2Et)2 and HC (SO2Me)3-n (SO2Et)n (n = 0 -3 ) , only the following four complexes could be isolated and unequivocally characterized by elemental analysis and 1H NMR spectroscopy: [(12C4){H2C (SO2Et)2}2] (3), [(18C6){H2C (S O2Me)2}] (4), [(DB -18C 6){H2C (SO2Et)2}] (5) and [(D B -18C 6)2{HC (SO2Me )(SO2Et)2}3] (6). The structure of 3 (triclinic, space group P1̄) consists of crystallographically centrosymmetric formula units, in which the disulfone molecules are bonded on each side of the ring by two C -H ··· O(crown) interactions originating from the central methylene group (H···O 213 pm) and from the methylene group of one EtSO2 moiety ( H ··· O 237 pm). Formula units related by translation are connected into parallel strands by a third type of reciprocal C -H ···O bond (H ···O 232 pm) between the second H atom of the central methylene group and a sulfonyl oxygen atom of the adjacent unit. The structure of 4 (monoclinic, space group C2/c) showed severe disorder of the crown ether and could not be refined satisfactorily. Compounds 5 and 6 crystallized as long and extremely thin fibres, indicative of linear-polymeric supramolecular structures; single crystals for X-ray crystallography were not available.

Strukturuntersuchungen an Diaryldichalkogeniden: Die Molekülstrukturen von [2,4,6-(CF3)3C6H2S]2,[2,4,6-Me3C6H2Te]2 und [2-Me2N-4,6-(CF3)2C6H2Te]2 / Structural Investigations of Diaryl Dichalcogenides: The Molecular Structures of [2,4,6-(CF3)3C6H2S]2, [2,4,6-Me3C6H2Te]2 and [2-Me2N-4,6-(CF3)2C6H2Te]2

1992 ◽  
Vol 47 (3) ◽  
pp. 305-309 ◽  
Author(s):  
Anja Edelmann ◽  
Sally Brooker ◽  
Norbert Bertel ◽  
Mathias Noltemeyer ◽  
Herbert W. Roesky ◽  
...  
Keyword(s):  
Molecular Structures ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Structural Investigations ◽  
Space Group ◽  
X Ray

Abstract The Molecular Structures of [2,4,6-(CF3)3C6H2S]2 (1) [2,4,6-Me3C6H2Te]2 and [2-Me2N-4,6-(CF3)2C6H2Te]2 (3) have been determined by X-ray diffraction. Crystal data: 1: orthorhombic, space group P212121, Z = 4, a = 822.3(2), b = 1029.2(2), c = 2526.6(5) pm (2343 observed independent reflexions, R = 0.042); 2: orthorhombic, space group Iba 2, Z = 8, a = 1546.5(2), b = 1578.4(2), c = 1483.9(1) pm (2051 observed independent reflexions, R = 0.030); 3: monoclinic, space group P 21/c, Z = 4, a = 1118.7(1), b = 1536.5(2), c = 1492.6(2) pm, β = 98.97(1)° (3033 observed independent reflexions, R = 0.025).

Two lithium tricyanomethanide compounds: syntheses and single-crystal structure determination of LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO

2015 ◽  
Vol 70 (3) ◽  
pp. 191-196 ◽  
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Structure Determination ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Cell Parameters ◽  
New Compounds

AbstractThe new compounds LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO were synthesized and their crystal structures were determined. Li[C(CN)3]·½ (H3C)2CO crystallizes in the orthorhombic space group Ima2 (no. 46) with the cell parameters a=794.97(14), b=1165.1(2) and c=1485.4(3) pm, while LiK[C(CN)3]2 adopts the monoclinic space group P21/c (no. 14) with the cell parameters a=1265.7(2), b=1068.0(2) and c=778.36(12) pm and the angle β=95.775(7)°. Single crystals of K[C(CN)3] were also acquired, and the crystal structure was refined more precisely than before corroborating earlier results.

Gemischte Alkalimetall-Oxidosulfidomolybdate A2[MoOxS4– x] (x = 1, 2, 3; A = K, Rb, Cs, NH4). Synthesen, Kristallstrukturen und Eigenschaften / Mixed Alkali Oxidosulfidomolybdates A2[MoOxS4−x] (x = 1, 2, 3; A = K, Rb, Cs, NH4).Synthesis, Crystal Structure and Properties

2012 ◽  
Vol 67 (2) ◽  
pp. 127-22
Author(s):  
Anna J. Lehner ◽  
Korina Kraut ◽  
Caroline Röhr
Keyword(s):  
Bathochromic Shift ◽  
Structure Type ◽  
Structure Theory ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Coordination Numbers ◽  
Preparation Conditions ◽  
Vis Spectroscopy ◽  
Type Orthorhombic

Mixed sulfido/oxidomolybdate anions [MoOxS4−x]2− (x = 1, 2, 3) have been prepared by passing H2S gas through a solution of oxidomolybdates. The alkali salts of K+, Rb+, Cs+, and NH+4 precipitate as crystalline salts from these solutions depending on the pH, the polarity of the solvent, the educt concentrations and the temperature. Their structures have been determined by means of X-ray single-crystal diffraction data. All trisulfidomolybdates A2[MoOS3] (A = NH4/K/Rb/Cs) are isotypic with the tetrasulfido salts, exhibiting the β -K2[SO4] type (orthorhombic, space group Pnma, Z = 4; for A = Rb: a = 940.62(4), b = 713.32(4), c = 1164.56(5) pm, R1 = 0.0281). In contrast, the disulfidomolybdates exhibit a rich crystal chemistry, forming three different structure types depending on the preparation conditions and the size of the A cation: All four cations form salts crystallizing with the (NH4)2[WO2S2] structure type (monoclinic, space group C2/c, Z = 4, for A = Rb: a = 1144.32(11), b = 732.60(4), c = 978.99(10) pm, β = 120.324(7)°, R1 = 0.0274). For the three alkali metal cations a second polymorph with a new structure type (monoclinic, space group P21/c, Z = 4) is observed in addition (for A = Rb: a = 674.83(2), b = 852.98(3), c = 1383.10(9) pm, β = 115.19(1)°, R1 = 0.0216). The cesium salt also crystallizes with a third modification of another new structure type (orthorhombic, space group Pbcn, Z = 4, a = 915.30(6), b = 777.27(7), c = 1120.02(7) pm, R1 = 0.0350). Only for K, an anhydrous monosulfidomolybdate could be obtained (K2[MoO4] structure type, monoclinic, space group C2/m, Z = 4, a = 1288.7(3), b = 615.7(2), c = 762.2(1) pm, β = 109.59(1)°, R1 = 0.0736). The intramolecular chemical bonding in the molybdate anions is discussed and compared with the respective vanadates. Hereby aspects like bond lengths, bond strengths and force constants derived from Raman spectroscopy, are taken into account. Especially for the polymorphic disulfido salts, in-depth analyses of the local coordination numbers and the packing of the ions are presented. The gradual bathochromic shift of the crystal color with increasing S content and increasing size of the counter cations A and molar volumes (for the polymorphic forms), respectively, is in accordance with the increase of the experimental (UV/Vis spectroscopy) and calculated (FP-LAPW band structure theory) band gaps.

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