Tautomeric behaviour and isotopic multiplets in the 13C NMR spectra of partially deuterated 5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones and 5‐arylazo‐2‐thioxo‐pyrimidine (1H,3H,5H)‐4,6‐diones—evidence for elucidation of tautomeric forms

NMR spectra of the synthesized azo dyes, 5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones (5a–g), 1,3‐dimethyl‐5‐arylazo‐pyrimidine (1H,3H,5H)‐2,4,6‐triones (6a–g), and 5‐arylazo‐2‐thioxo‐pyrimidine (1H,3H,5H)‐4,6‐diones (7a–g) were studied in (CD₃)₂SO (three drops of CD₃OD were added into solutions of the dyes in two different concentrations). All dyes showed intramolecular hydrogen bonding. Dyes 5a–7a showed bifurcated intramolecular hydrogen bonds. Tautomeric behaviours of some of N‐methylated azo dyes (6a‐g) were studied in two different concentrations. The solvent–substrate proton exchange of dyes 5a–d, 6a and 7a–e was examined in presence of three drops of CD₃OD. The dyes which were soluble in (CD₃)₂SO containing CD₃OD showed isotopic splitting (β‐isotope effect) in the ¹³C NMR spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,characterization and in vitro antitumor activity of some arylantimony ferrocenecarboxylates and crystal structures of C5H5FeC5H4CO2SbPh4 and (C5H5FeC5H4CO2)2Sb(4‐CH3C6H4)3

A series of arylantimony ferrocenecarboxylates with the formula (C₅H₅FeC₅H₄CO₂)_nSbAr_(5?n) (n = 1, 2; Ar = C₆H₅, 4‐CH₃C₆H₄, 3‐CH₃C₆H₄, 2‐CH₃C₆H₄, 4‐ClC₆H₄, 4‐FC₆H₄) were synthesized and characterized by elemental analysis, IR, ¹H NMR and mass spectra. The crystal structures of (C₅H₅FeC₅H₄CO₂)₂Sb(4‐CH₃C₆H₄)₃ and C₅H₅FeC₅H₄CO₂SbPh₄ were determined by X‐ray diffraction. Four human neoplastic cell lines (HL‐60, Bel‐7402, KB and Hela) were used to screen these compounds. The results indicate that these compounds at 10 µM show certain in vitro antitumor activities. Copyright © 2003 John Wiley & Sons, Ltd.     

N—H...O and N—H...N interactions in three pyran derivatives

The three pyran structures 6‐methylamino‐5‐nitro‐2,4‐diphenyl‐4H‐pyran‐3‐carbonitrile, C₁₉H₁₅N₃O₃, (I), 4‐(3‐fluorophenyl)‐6‐methylamino‐5‐nitro‐2‐phenyl‐4H‐pyran‐3‐carbonitrile, C₁₉H₁₄FN₃O₃, (II), and 4‐(4‐chlorophenyl)‐6‐methylamino‐5‐nitro‐2‐phenyl‐4H‐pyran‐3‐carbonitrile, C₁₉H₁₄ClN₃O₃, (III), differ in the nature of the aryl group at the 4‐position. The heterocyclic ring in all three structures adopts a flattened boat conformation. The dihedral angle between the pseudo‐axial phenyl substituent and the flat part of the pyran ring is 89.97 (1)° in (I), 80.11 (1)° in (II) and 87.77 (1)° in (III). In all three crystal structures, a strong intramolecular N—H...O hydrogen bond links the flat conjugated H—N—C=C—N—O fragment into a six‐membered ring. In (II), molecules are linked into dimeric aggregates by N—H... O(nitro) hydrogen bonds, generating an R₂²(12) graph‐set motif. In (III), intermolecular N—H...N and C—H...N hydrogen bonds link the molecules into a linear chain pattern generating C(8) and C(9) graph‐set motifs, respectively.     

Synthesis,Crystal Structure and Magnetic Properties of a 1‐D Polymer, [Cu(NITpPy)2(H2TCB)(H20)]·2H2O

A novel complex [Cu(NnpPy)₂(H_lTCB)(H₁O)]·2H₂O (NITpPy = 2‐(pyrid‐4′‐yl)‐4,4,5,5‐tetramethyl‐1, 3‐dioxoimidazoline; H₂TCB = 1, 5‐dicarboxybenzene carboxylic‐2, 4‐diacid) has been synthesized and characterized by X‐ray crystallography analysis. The crystal structure consists of infinite chains of Cu‐(NITpPy)₂(H₂O) units linked by H₂TCB ligands. The complex crystallizes in triclinic system with space group PI. Crystal data: a = 1.0594(2) nm, b = 1.3830(3) nm, c = 1.5551(3) nm, a = 67.75(3)°, β = 89.83(3)°, γ = 70.54(3)°. The variable magnetic susceptibility studies lead to magnetic coupling constant values of J₁= ?11.18 cm‐¹ (Cu—Rad) and J₂ = ?4.06 cm^?1 (Cu—Cu).     

Facile synthesis of pyridinium aryltetrachlorotellurates: crystal and molecular structure of [C5H6N][RTeCl4] (R = m‐O2NC6H4, p‐NCC6H4)

Arylation of TeCl₄ with arylboroxine–pyridine complexes [(RBO)₃·C₅H₅N, where R = m‐O₂NC₆H₄ ( 1 ), p‐O₂NC₆H₄ ( 2 ), m‐NCC₆H₄ ( 3 ), p‐NCC₆H₄ ( 4 )] and advantageous moisture provided good yields of the pyridinium aryltetrachlorotellurates [C₅H₆N][RTeCl₄] [R = m‐O₂NC₆H₄ ( 5 ), p‐O₂NC₆H₄ ( 6 ), m‐NCC₆H₄ ( 7 ), p‐NCC₆H₄ ( 8 )]. Compounds 5 and 8 have been investigated by X‐ray crystallography. Key features of both crystal structures are intermolecular secondary Te???Cl interactions between the aryltetrachlorotellurate anions and weak association of the cations and anions. Electrospray mass spectra of compound 5 reveal that the associative interactions also play a role in solution. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and Characterization of 2‐Mono‐ and 1,2‐Diaminocarba‐closo‐dodecaborates M[1‐R‐2‐H2N‐closo‐CB11H10] (R=H,Ph, H2N,CyHN)

The first primary 2‐aminocarba‐closo‐dodecaborates [1‐R‐2‐H₂N‐closo‐CB₁₁H₁₀]^? (R=H ( 1 ), Ph ( 2 )) have been synthesized by insertion reactions of (Me₃Si)₂NBCl₂ into the trianions [7‐R‐7‐nido‐CB₁₀H₁₀]^3?. The difunctionalized species [1,2‐(H₂N)₂‐closo‐CB₁₁H₁₀] ( 3 ) and 1‐CyHN‐2‐H₃N‐closo‐CB₁₁H₁₀ (H‐ 4 ) have been prepared analogously from (Me₃Si)₂NBCl₂ and 7‐H₃N‐7‐nido‐CB₁₀H₁₂. In addition, the preparation of [Et₄N][1‐H₂N‐2‐Ph‐closo‐CB₁₁H₁₀] ([Et₄N]‐ 5 ) starting from PhBCl₂ and 7‐H₃N‐7‐nido‐CB₁₀H₁₂ is described. Methylation of the [1‐Ph‐2‐H₂N‐closo‐CB₁₁H₁₀]^? ion ( 2 ) to produce 1‐Ph‐2‐Me₃N‐closo‐CB₁₁H₁₀ ( 6 ) is reported. The crystal structures of [Et₄N]‐ 2 , [Et₄N]‐ 5 , and 6 were determined and the geometric parameters were compared to theoretical values derived from DFT and ab initio calculations. All new compounds were studied by NMR, IR, and Raman spectroscopy, MALDI mass spectrometry, and elemental analysis. The discussion of the experimental NMR chemical shifts and of selected vibrational band positions is supported by theoretical data. The thermal properties were investigated by differential scanning calorimetry (DSC). The pK_a values of 2‐H₃N‐closo‐CB₁₁H₁₁ (H‐ 1 ), 1‐H₃N‐closo‐CB₁₁H₁₀ (H‐ 7 ), and 1,2‐(H₃N)₂‐closo‐CB₁₁H₁₀ (H₂‐ 3 ) were determined by potentiometric titration and by NMR studies. The experimental results are compared to theoretical data (DFT and ab initio). The basicities of the aminocarba‐closo‐dodecaborates agree well with the spectroscopic and structural properties.     

Synthesis of novel 5H‐Pyrimido[5,4‐b]mdole‐(1H,3H)2,4‐diones as potential ligands for the cloned α1‐adrenoceptor subtypes

A new series of 3‐[ω‐[4‐(4‐substituted phenyl)piperazin‐1‐yl]alkyl]‐5H‐pyrimido[5,4‐b]indole‐(1H,3H)‐2,4‐diones ( 3–10 and 12–13 ) were synthesized from the N‐(2‐chloroethyl)‐N'‐[3‐(2‐ethoxycarbonyl)indolyl] urea ( 1 ) or the N‐(3‐chloropropyl)‐N'‐[3‐(2‐ethoxycarbonyl)indolyl] urea ( 2 ) and a number of 1‐(4‐substi‐tuted‐phenyl)piperazines. 3‐[2‐[4‐(4‐Aminophenyl)piperazin‐1‐yl]ethyl]‐5H‐pyrimido[5,4‐b]indole‐(1H,3H)2,4‐dione ( 14 ) was obtained by reduction of the parent nitro compound 8 . The obtained 5H‐pyrimido[5,4‐b]indole‐(1H,3H)2,4‐dione derivatives were tested towards cloned α_1A, α_1B and α_1D adrenergic receptors subtypes in binding assays. Some compounds showed good affinity and selectivity for the α_1D‐adrenoceptor subtype.     

Reduction of 3‐Aminoquinoline‐2,4(1H,3H)‐diones and Deamination of the Reaction Products

3‐Aminoquinoline‐2,4‐diones were stereoselectively reduced with NaBH₄ to give cis‐3‐amino‐3,4‐dihydro‐4‐hydroxyquinolin‐2(1H)‐ones. Using triphosgene (=bis(trichloromethyl) carbonate), these compounds were converted to 3,3a‐dihydrooxazolo[4,5‐c]quinoline‐2,4(5H,9bH)‐diones. The deamination of the reduction products using HNO₂ afforded mixtures of several compounds, from which 3‐alkyl/aryl‐2,3‐dihydro‐1H‐indol‐2‐ones and their 3‐hydroxy and 3‐nitro derivatives were isolated as the products of the molecular rearrangement.     

Synthesis and Crystal Structure of the Binuclear Complex [Pr2(C10H8N2O4)2(C10H9N2O4)2(H2O)4]·3H2O·C6H6

The binuclear praseodymium(III) complex with N‐(1‐carboxyethylidene)‐salicylhydrazide (C₁₀H₁₀N₂O₄, H₂L) was prepared in H₂O‐C₂H₅OH mixed solution, and the crystal structure of [Pr₂L₂(HL)₂(H₂O)₄]·3H₂O·C₆H₆ was determined by X‐ray single crystal diffraction. The crystal complex crystallizes in the triclinic system with space group P‐1, and in the structure each Pr atom is 9‐coordinated by carboxyl O and acyl O and azomethine N atoms of two tridentate ligands to form two stable five‐membered rings sharing one side in keto‐mode and two water molecules. The coordination polyhedron around Pr³⁺ was described as a monocapped square antiprism geometry. In an individual molecule, four tridentate ligands were coordinated by two negative univalent (HL) and two bivalent forms (L) respectively. Two negative univalent ligands were coordinated via μ₂‐bridging mode.     

Barium bis­[6‐amino‐3‐methyl‐5‐nitro­so­pyrimidine‐2,4(1H,3H)‐dionate] trihydrate: coordination polymer chains linked by hydrogen bonds

The title complex, catena‐poly[[triaquabarium(II)]‐di‐μ‐6‐amino‐3‐methyl‐5‐nitro­so­pyrimidine‐2,4(1H,3H)‐dionato], [Ba(C₅H₅N₄O₃)₂(H₂O)₃]_n, forms a coordination polymer chain in which the two distinct anions use different ligating atoms to bridge pairs of cations. Adjacent pairs of cations are also linked by pairs of bridging water mol­ecules. The chains are linked into a single three‐dimensional framework by an extensive series of hydrogen bonds.     

3D Coordination Polymers with Chiral Structures, [Ln2(tda)2(H2O)3]·5H2O: Hydrothermal Synthesis,Structural Characterization,and Luminescent Properties

Reactions of H₃tda (H₃tda = 1H‐1, 2, 3‐triazole‐4, 5‐dicarboxylic acid) with Sm(NO₃)₃ · 6H₂O, Eu(NO₃)₃ · 6H₂O, and Tb(NO₃)₃ · 6H₂O, in the presence of NaOH under hydrothermal conditions, produced three new coordination polymers, [Ln₂(tda)₂(H₂O)₃] · 5H₂O [Ln = Sm ( 1 ), Eu ( 2 ), Tb ( 3 )]. These compounds were structurally characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), PXRD and single‐crystal X‐ray diffraction. The single‐crystal X‐ray diffraction studies of compounds 1 – 3 reveal that all compounds are three‐dimensional porous structures with chiral frameworks. Furthermore, the luminescence studies of compound 2 and 3 in the solid state reveal that they are potential luminescent materials at room temperature.     

Hydrogallierungsreaktionen mit den Monoalkinen H5C6‐C≡C‐SiMe3 und H5C6‐C≡C‐CMe3 – cis/trans‐Isomerie und Substituentenaustausch

Hydrogallation Reactions Involving the Monoalkynes H₅C₆‐C≡C‐SiMe₃ and H₅C₆‐C≡C‐CMe₃ – cis/trans Isomerisation and Substituent Exchange Phenyl‐trimethylsilylethyne, H₅C₆‐C≡C‐SiMe₃, reacted with different dialkylgallium hydrides, R₂Ga‐H (R = Me, Et, nPr, iPr, tBu), by the addition of one Ga‐H bond to its C≡C triple bond (hydrogallation). The gallium atoms attacked selectively those carbon atoms, which were also attached to trimethylsilyl groups. The cis arrangement of Ga and H across the resulting C=C double bonds resulted only for the sterically most shielded di(tert‐butyl)gallium derivative, while in all other cases spontaneous cis/trans rearrangement occurred with the quantitative formation of the trans addition products. The diethyl compound Et₂Ga‐C(SiMe₃)=C(H)‐C₆H₅ ( 2 ) gave by substituent exchange the secondary products EtGa[C(SiMe₃)=C(H)‐C₆H₅]₂ ( 7 , Z,Z) and Ga[C(SiMe₃)=C(H)‐C₆H₅]₃ ( 8 ). Interestingly, compound 8 has two alkenyl groups with a Z configuration, while the third C=C double bond has the cis arrangement of Ga and H (E configuration). The reversibility of the cis/trans isomerisation of hydrogallation products was observed for the first time. tert‐Butyl‐phenylethyne gave the simple addition product, R₂Ga(C₆H₅)=C(H)‐CMe₃ ( 9 ), only with di(n‐propyl)gallium hydride.     

Seven 3‐methylidene‐1H‐indol‐2(3H)‐ones related to the multiple‐receptor tyrosine kinase inhibitor sunitinib

The solid‐state structures of a series of seven substituted 3‐methylidene‐1H‐indol‐2(3H)‐one derivatives have been determined by single‐crystal X‐ray diffraction and are compared in detail. Six of the structures {(3Z)‐3‐(1H‐pyrrol‐2‐ylmethylidene)‐1H‐indol‐2(3H)‐one, C₁₃H₁₀N₂O, (2a); (3Z)‐3‐(2‐thienylmethylidene)‐1H‐indol‐2(3H)‐one, C₁₃H₉NOS, (2b); (3E)‐3‐(2‐furylmethylidene)‐1H‐indol‐2(3H)‐one monohydrate, C₁₃H₉NO₂·H₂O, (3a); 3‐(1‐methylethylidene)‐1H‐indol‐2(3H)‐one, C₁₁H₁₁NO, (4a); 3‐cyclohexylidene‐1H‐indol‐2(3H)‐one, C₁₄H₁₅NO, (4c); and spiro[1,3‐dioxane‐2,3′‐indolin]‐2′‐one, C₁₁H₁₁NO₃, (5)} display, as expected, intermolecular hydrogen bonding (N—H...O=C) between the 1H‐indol‐2(3H)‐one units. However, methyl 3‐(1‐methylethylidene)‐2‐oxo‐2,3‐dihydro‐1H‐indole‐1‐carboxylate, C₁₃H₁₃NO₃, (4b), a carbamate analogue of (4a) lacking an N—H bond, displays no intermolecular hydrogen bonding. The structure of (4a) contains three molecules in the asymmetric unit, while (4b) and (4c) both contain two independent molecules.     

Nitric Oxide Insertion Reactivity with the Bismuth–Carbon Bond: Formation of the Oximate Anion, [ON(C6H2tBu2O)]−, from the Oxyaryl Dianion, (C6H2tBu2O)2−

The first example of NO insertion into a Bi?C bond has been found in the direct reaction of NO with a Bi³⁺ complex of the unusual (C₆H₂tBu₂‐3,5‐O‐4)^2? oxyaryl dianionic ligand, namely, Ar′Bi(C₆H₂tBu₂‐3,5‐O‐4) [Ar′=2,6‐(Me₂NCH₂)₂C₆H₃] ( 1 ). The oximate complexes [Ar′Bi(ONC₆H₂‐3,5‐tBu₂‐4‐O)]₂(μ‐O) ( 3 ) and Ar′Bi(ONC₆H₂‐3,5‐tBu₂‐4‐O)₂ ( 4 ) were formed as a mixture, but can be isolated in pure form by reaction of NO with a Bi³⁺ complex of the [O₂C(C₆H₂tBu₂‐3‐5‐O‐4]^2? oxyarylcarboxy dianion, namely, Ar′Bi[O₂C(C₆H₂tBu₂‐3‐5‐O‐4)‐κ²O,O’]. Reaction of 1 with Ph₃CSNO gave an oximate product with (Ph₃CS)^1? as an ancillary ligand, (Ph₃CS)(Ar′)Bi(ONC₆H₂‐3,5‐tBu₂‐4‐O) ( 5 ).     

New Borate‐citrate: Synthesis,Structure, and Properties of Sr[B(C6H5O7)2](H2O)4·3H2O

Single crystals of Sr[B(C₆H₅O₇)₂](H₂O)₄ · 3H₂O, a new borate‐citrate material, were grown with sizes up to 8 × 6 × 2 mm by slow evaporation of water at room temperature. The structure of Sr[B(C₆H₅O₇)₂](H₂O)₄ · 3H₂O was determined by single‐crystal X‐ray diffraction. It crystallizes in the monoclinic space group P2₁/c, with a = 11.363(3) Å, b = 18.829(4) Å, c = 11.976(3) Å, β = 110.736(3)°, and Z = 4. The SrO₈ dodecahedra, BO₄ tetrahedra and citrate groups are linked together to form chains. The compound was characterized by IR and UV/Vis/NIR transmittance spectroscopy as well as thermal analysis.     

Design and Synthesis of Novel 3‐(Phenyl)‐2‐(3‐substituted propylthio) Quinazolin‐4‐(3H)‐ones as a New Class of H1‐Antihistaminic Agents

A series of novel 3‐(phenyl)‐2‐(3‐substituted propylthio) quinazolin‐4‐(3H)‐ones were synthesized by the reaction of 2‐(3‐bromopropylthio)‐3‐(phenyl) quinazolin‐4‐(3H)‐one with various amines. The starting material, 2‐(3‐bromopropylthio)‐3‐(phenyl) quinazolin‐4‐(3H)‐one was synthesized from aniline. When tested for their in vivo H₁‐antihistaminic activity on conscious guinea pigs, all the test compounds protected the animals from histamine‐induced bronchospasm significantly. Compound 2‐(3‐(4‐methylpiperazin‐1‐yl) propylthiothio)‐3‐(phenyl) quinazolin‐4(3H)‐one ( Ph5 ) emerged as the most active compound (73.23% protection) of the series when compared with the reference standard chlorpheniramine maleate (70.09% protection). Compound Ph5 shows negligible sedation (5.01 %) compared with chlorpheniramine maleate (29.58%). Therefore, compound Ph5 can serve as the leading molecule for further development into a new class of H₁‐antihistaminic agents.     

[{Er(NC5H4COOH)(H2O)2}2(H5O2)(HgCl5)(HgCl4)2(H2O)2]n – Synthesis,Crystal Structure and Properties

The first heterometallic 4f‐5d inorganic‐organic metal‐isonicotinic acid hybrid [{Er(NC₅H₄COOH)(H₂O)₂}₂(H₅O₂)(HgCl₅)(HgCl₄)₂(H₂O)₂]_n ( 1 ) has been synthesized via hydrothermal reaction and structurally characterized. Complex 1 crystallizes in the space group C2/c of the monoclinic system with four formula units per unit cell: a = 24.194(3), b = 20.792(3), c = 15.289(4) Å, β = 128.39(2)°, V = 6028(2) ų, C₃₆H₄₇Cl₁₃Er₂Hg₃N₆O₂₀, M_r = 2280.94, D_c = 2.513 g/cm³, S = 0.929, μ(MoKα) = 11.017 mm^?1, F(000) = 4248, R = 0.0425 and wR = 0.0739. The crystal structure analysis reveals that the title complex is characteristic of a one‐dimensional chain‐like structure. Photoluminescent investigation reveals that the title complex displays interesting emissions. Optical absorption spectra of 1 reveal the presence of an optical gap of 3.45 eV. The magnetic properties show that complex 1 exhibits antiferromagnetic interactions.     

Reaction of (η5‐C5H5)Fe(CO)2I with Anionic Bidentate Phosphine Ligands PPh2(o‐C6H4NHLi) or PPh2(o‐C6H4OLi)

The o‐substituted hybrid phenylphosphines, PPh₂(o‐C₆H₄NH₂) and PPh₂(o‐C₆H₄OH), could be deprotonated with LDA or n‐BuLi to yield PPh₂(o‐C₆H₄NHLi) and PPh₂(o‐C₆H₄OLi), respectively. When added to a solution of (η⁵‐C₅H₅)Fe(CO)₂I at room temperature, these two lithiated reagents produce a chelated neutral complex 1 (η⁵‐C₅H₅)Fe(CO)[C(O)NH(o‐C₆H₄)PPh₂‐C,P‐η²] for the former and mainly a zwitterionic complex 2 , (η⁵‐C₅H₅)Fe⁺(CO)₂[PPh₂(o‐C₆H₄O^?)] for the latter. Complex 1 could easily be protonated and then decarbonylated to give 4 [(η⁵‐C₅H₅)Fe(CO){NH₂(o‐C₆H₄)PPh₂‐N,P‐η²}⁺]. Complexes 1 and 4‐I have been crystallographically characterized with X‐ray diffraction.     

Discrete [Yb(NCS)3(H2O)5] Molecules in Pentaaquatriisothiocyanatoytterbium(III) Monohydrate

Single crystals of [Yb(NCS)₃(H₂O)₅] · H₂O were synthesized from a salt‐metathesis reaction between stoichiometric amounts of aqueous solutions of Yb₂(SO₄)₃ · 8H₂O and Ba(NCS)₂ · 3H₂O driven by the precipitation of Ba(SO₄), followed by isothermic evaporation of the filtered‐off solution at room temperature under atmospheric conditions. These crystals of the title compound came as transparent, colorless and hygroscopic needles. According to the X‐ray diffraction structure analysis [Yb(NCS)₃(H₂O)₅] · H₂O crystallizes in the monoclinic space group P2₁ with the lattice parameters a = 845.38(5), b = 719.26(4), c = 1219.65(7) pm, β = 103.852(3)° for Z = 2. The acentric crystal structure contains crystallographically unique Yb³⁺ cations, each surrounded by three thiocyanate anions, all grafting with their nitrogen atoms, and five water molecules forming a neutral [Yb(NCS)₃(H₂O)₅] complex with square antiprismatic shape, completed by a sixth interstitial water molecule. ATR‐FT infrared and single‐crystal Raman spectra of [Yb(NCS)₃(H₂O)₅] · H₂O confirm these findings.     

Syntheses,Crystal Structures,and Properties of the Isotypic Pair [Cr(H2O)6]2[B12H12]3·15H2O and [In(H2O)6]2[B12H12]3·15H2O

Single crystals of [Cr(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O and [In(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O were obtained by reactions of aqueous solutions of the acid (H₃O)₂[B₁₂H₁₂] with chromium(III) hydroxide and indium metal shot, respectively. The title compounds crystallize isotypically in the trigonal system with space group R$\bar{3}$ c (a = 1157.62(3), c = 6730.48(9) pm for the chromium, a = 1171.71(3), c = 6740.04(9) pm for the indium compound, Z = 6). The arrangement of the quasi‐icosahedral [B₁₂H₁₂]^2– dianions can be considered as stacking of two times nine layers with the sequence …ABCCABBCA… and the metal trications arrange in a cubic closest packed …abc… stacking sequence. The metal trications are octahedrally coordinated by six water molecules of hydration, while another fifteen H₂O molecules fill up the structures as zeolitic crystal water or second‐sphere hydrating species. Between these free and the metal‐bonded water molecules, bridging hydrogen bonds are found. Furthermore, there is also evidence of hydrogen bonding between the anionic [B₁₂H₁₂]^2– clusters and the free zeolitic water molecules according to B–H^δ– ··· ^δ+H–O interactions. Vibrational spectroscopy studies prove the presence of these hydrogen bonds and also show slight distortions of the dodecahydro‐closo‐dodecaborate anions from their ideal icosahedral symmetry (I_h). Thermal decomposition studies for the example of [Cr(H₂O)₆]₂[B₁₂H₁₂]₃ · 15H₂O gave no hints for just a simple multi‐stepwise dehydration process.