4,5-Bis[(triorganotin)thiolato]-1,3-dithiole-2-thione, (R3Sn)2(dmit), 4,5-bis[(triorganotin)thiolato]-1,3-dithiole-2-one, (R3Sn)2(dmio), compounds: Crystal structures of (cyclohexyl3Sn)2(dmio), (Ph3Sn)2(dmit) and (Ph3Sn)2(dmio)

The synthesis and crystal structures of 4,5-bis[(triorganotin)thiolato]-1,3-dithiole-2-thione, (R₃Sn)₂(dmit), 1, and 4,5-bis[(triorganotin)thiolato]-1,3-dithiole-2-one, (R₃Sn)₂(dmio), 2, compounds are reported. Compounds, (1 or 2: R = Ph or cyclohexyl, Cy), have been obtained from reaction of R₃SnCl with Cs₂dmit or Na₂dmio. The presence of the two tin centres in (2: R = Ph) is shown in the ¹³C NMR spectrum by the couplings of both Sn atoms to the dmio olefinic carbons with J values of 29.4 and 24.7 Hz. The δ¹¹⁹ Sn values for (1: R = Ph) and (2: R = Ph) differ by about 30 ppm, values being −20.7 and −50.1 ppm, respectively, in CDCl₃ solution. X-ray structure determinations for (1: R = Ph) and (2: R = Ph or Cy) reveal the compounds to have 4-coordinate, distorted tetrahedral tin centres. The dithiolato ligands, dmit and dmio, act as bridging ligands, in contrast to their chelating roles in R₂Sn(dmit) and R₂Sn(dmio). A further difference between R₂Sn(dmit) and R₂Sn(dmio), on one hand, and 1 and 2 on the other, is that intermolecular Sn-S and Sn-O interactions are absent in 1 and 2. However, weak intermolecular hydrogen bonding interactions are found in (1: R = Ph) [C-H?π] and in (2: R = Ph) [C-H?π and C-H?O].     

Phenylmercury(II) derivatives of tetraorganodichalcogenoimidodiphosphorus acids. Crystal and molecular structure of [PhHg{(OPR2)(SPPh2)N}]2 (R=Me, Ph)

The reactions between PhHgCl or PhHgAc and M[(XPR₂)(YPR′₂)N] (M=Na, K; X, Y=O, S; R, R′=Me, Ph, OEt), in 1:1 molar ratio, have been investigated. PhHg[(XPR₂)(YPR′₂)N] derivatives were isolated as microcrystalline powders and were characterised using IR and NMR (¹H, ¹³C and ³¹P) spectroscopy and mass spectrometry. The molecular structure of PhHg[(OPR₂)(SPPh₂)N] [R=Me (1), Ph (2)] was investigated by X-ray diffraction. In the monomeric unit, PhHg[(OPR₂)(SPPh₂)N], the mercury atom forms the primary bonds with the carbon of the phenyl group and the sulfur atom of the phosphorus ligand [Hg(1)-S(1) 2.405(1) Å for 1, 2.398(2) Å for 2]. These primary bonds are significantly deviated from the expected linear arrangement [C(1)-Hg(1)-S(1) 166.4(2)° for 1, 165.0(2)° for 2]. Both compounds exhibit dimeric associations in the crystal through S,O-bridging organophosphorus ligands [Hg(1)-O(1) 2.556(4) Å for 1, 2.588(4) Å for 2], thus resulting in a distorted T-shaped arrangement of the CHgSO coordination core.. The formation of a 12-membered Hg₂O₂S₂P₄N₂ ring with different conformation in 1 and 2, respectively, results in different additional chalcogen atoms being in the proximity of the metal atom. Weak transannular Hg?O [2.753(4) Å] are also established in 1, leading to a tricyclic ladder structure with a planar central Hg₂O₂ ring.     

Hydrothermal syntheses and structures of the uranyl tellurates AgUO2(HTeO5) and Pb2UO2(TeO6)

Two uranyl tellurates, AgUO₂(HTeO₅) (1) and Pb₂UO₂(TeO₆) (2), were synthesized under hydrothermal conditions and were structurally, chemically, and spectroscopically characterized. 1 crystallizes in space group Pbca, a=7.085(2) Å, b=11.986(3) Å, c=13.913(4) Å, V=1181.5(5) Å³, Z=8; 2 is in P2(1)/c, a=5.742(1) Å, b=7.789(2) Å, c=7.928(2) Å, V=90.703(2) Å³, and Z=2. These are the first structures reported for uranyl compounds containing tellurate. The U⁶⁺ cations are present as (UO₂)²⁺ uranyl ions that are coordinated by O atoms to give pentagonal and square bipyramids in compounds 1 and 2, respectively. The structural unit in 1 is a sheet consisting of chains of edge-sharing uranyl pentagonal bipyramids that are one bipyramid wide, linked through the dimers of TeO₆ octahedra. In 2, uranyl square bipyramids share each of their equatorial vertices with different TeO₆ octahedra, giving a sheet with the autunite-type topology. Sheets in 1 and 2 are connected through the low-valence cations that are located in the interlayer region. The structures of 1 and 2 are compared to those of uranyl compounds containing octahedrally coordinated cations.     

A family of three-dimensional porous coordination polymers with general formula (Kat)2[{M(H2O)n}3{Re6Q8(CN)6}2]·xH2O (Q=S, Se; n=1.5, 2)

The X-ray crystal structures of a series of new compounds (H₃O)₂[{Mn(H₂O)_1.5}₃{Re₆Se₈(CN)₆}₂]·19H₂O (1), (Me₄N)₂[{Co(H₂O)_1.5}₃{Re₆S₈(CN)₆}₂]·13H₂O (2), (Me₄N)₂[{Co(H₂O)_1.5}₃{Re₆Se₈(CN)₆}₂]·3H₂O (3), (Et₄N)₂[{Mn(H₂O)₂}₃{Re₆Se₈(CN)₆}₂]·6.5H₂O (4), (Et₄N)₂[{Ni(H₂O)₂}₃{Re₆S₈(CN)₆}₂]·6.5H₂O (5), and (Et₄N)₂[{Co(H₂O)₂}₃{Re₆S₈(CN)₆}₂]·10H₂O (6) are reported. All six compounds are isostructural crystallizing in cubic space group with four formulae per unit cell. For compounds 1, 3-5 the following parameters were found: (1) a=19.857(2) Å, R1=0.0283; (3 at 150 K) a=19.634(1) Å, R1=0.0572; (4) a=20.060(2) Å, R1=0.0288; (5) a=19.697(2) Å, R1=0.0224. The structures consist three-dimensional cyano-bridged framework formed by cyano cluster anions [Re₆Q₈(CN)₆]⁴⁻, Q=S, Se and transition metal cations, M²⁺=Mn²⁺, Co²⁺, Ni²⁺. Water molecules and large organic cations Me₄N⁺ and Et₄N⁺ are included in cavities of this framework. Porosity of the framework, its ability to accommodate different cations and water molecules by little changes in the structure, as well as distortion of coordination framework under loss of water of crystallization is discussed.     

Experimental and theoretical study of N-(2-hydroxyethyl)morpholine betaine

N-(2-hydroxyethyl)morpholine betaine (HEMB) has been characterized by a single crystal X-ray analysis, FTIR spectroscopy and DFT calculations. The crystals are monoclinic, space group P2₁/c with a=10.273(2), b=9.360(2), c=9.447(2) Å and β=104.72(3)Å. Two molecules of HEMB form a centrosymmetric dimer (X2) connected by a pair of hydrogen bonds between the CH₂CH₂OH and COO⁻ groups, with the O?O distance of 2.672(2) Å. The morpholine ring adopts a chair conformation with the CH₂CH₂OH group in the axial and the CH₂COO⁻ group in the equatorial position. The structures of the dimer, B2, and two monomers, B1a and B1b, have been optimized by the B3LYP approach using the 6-31G(d,p) basis set. The computed structure of B2, agrees well with the experimental X2. From two stable monomeric conformers the more favored is B1a, with the intramolecular hydrogen bond with the O-H?O distance of 2.566 Å. The effects of hydrogen bonding and electrostatic interactions on the conformation of the molecules investigated have been discussed. The FTIR spectrum shows a broad absorption in the 3300-2600 cm⁻¹ region, typical of moderate O-H?O hydrogen bonds.     

Synthesis, crystal structure, infrared and Raman spectra of Sr4Cu3(AsO4)2(AsO3OH)4·3H2O and Ba2Cu4(AsO4)2(AsO3OH)3

The two new compounds, Sr₄Cu₃(AsO₄)₂(AsO₃OH)₄·3H₂O (1) and Ba₂Cu₄(AsO₄)₂(AsO₃OH)₃(2), were synthesized under hydrothermal conditions. They represent previously unknown structure types and are the first compounds synthesized in the systems SrO/BaO-CuO-As₂O₅-H₂O. Their crystal structures were determined by single-crystal X-ray diffraction [space group C2/c, a=18.536(4) Å, b=5.179(1) Å, c=24.898(5) Å, β=93.67(3)°, V=2344.0(8) Å³, Z=4 for 1; space group P4₂/n, a=7.775(1) Å, c=13.698(3) Å, V=828.1(2) Å³, Z=2 for 2]. The crystal structure of 1 is related to a group of compounds formed by Cu²⁺-(XO₄)³⁻ layers (X=P⁵⁺, As⁵⁺) linked by M cations (M=alkali, alkaline earth, Pb²⁺, or Ag⁺) and partly by hydrogen bonds. In 1, worth mentioning is the very short hydrogen bond length, D···A=2.477(3) Å. It is one of the examples of extremely short hydrogen bonds, where the donor and acceptor are crystallographically different. Compound 2 represents a layered structure consisting of Cu₂O₈ centrosymmetric dimers crosslinked by As1φ₄ tetrahedra, where φ is O or OH, which are interconnected by Ba, As2 and hydrogen bonds to form a three-dimensional network. The layers are formed by Cu₂O₈ centrosymmetric dimers of CuO₅ edge-sharing polyhedra, crosslinked by As1O₄ tetrahedra. Vibrational spectra (FTIR and Raman) of both compounds are described. The spectroscopic manifestation of the very short hydrogen bond in 1, and ABC-like spectra in 2 were discussed.     

Dibutyltin(IV) complexes of the 5-[(E)-2-(Aryl)-1-diazenyl]-2-hydroxybenzoic acid ligand: an investigation of structures by X-ray diffraction, solution and solid state tin NMR, electrospray ionisation MS and assessment of in vitro cytotoxicity

A series of dibutylbis{5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoato}tin(IV) complexes, Bu₂Sn(LH)₂, have been prepared and characterized by ¹H, ¹³C, ¹¹⁹Sn NMR and ESI mass spectrometry in solution. The structures of the complexes Bu₂Sn(L¹H)₂ (1), Bu₂Sn(L³H)₂ (3), Bu₂Sn(L⁴H)₂ (4), and Bu₂Sn(L⁶H)₂ (6) (L = 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoate: aryl = phenyl (L¹H), 3-methylphenyl (L³H), 4-methylphenyl (L⁴H) and 4-bromophenyl (L⁶H)) were determined by X-ray crystallography and ¹¹⁷Sn CP-MAS NMR spectroscopy in the solid state. In general, the complexes were found to adopt a skew-trapezoidal bipyramidal arrangement around the tin atom. In addition, there are weak bridging intermolecular Sn?O contacts in complexes 1 and 3, but not in 4 and 6, where one of the hydroxy oxygen atoms from a neighboring molecule coordinates weakly with the Sn atom, thereby completing a seventh coordination site in the extended Sn coordination sphere. The Sn?O distance is 3.080(2) and 3.439(2) Å in 1 and 3, respectively, which are significantly shorter than the sum of the van der Waals radii of the Sn and O atoms (∼3.8 Å). In 1, this Sn?O interaction links the molecules into polymeric chains. In 3, these interactions link pairs of molecules into head-to-head dimeric units. The in vitro cytotoxicity of compound 2 indicates better results than cisplatin and etoposide against seven well characterized human tumor cell lines.     

Two isotypic diphosphates LiM2H3(P2O7)2 (M=Ni, Co) containing ferromagnetic zigzag MO6 chains

Two new isotypic phosphates LiNi₂H₃(P₂O₇)₂ (1) and LiCo₂H₃(P₂O₇)₂ (2) have been hydrothermally synthesized and structurally characterized by the single-crystal X-ray diffraction technique. They crystallize in the monoclinic space group C2/c with the lattice: a=10.925(2) Å, b=12.774(3) Å, c=8.8833(18) Å, β=123.20(3)° for 1 and a=10.999(2) Å, b=12.863(3) Å, c=8.9419(18) Å, β=123.00(3)° for 2. The transition metal atoms are octahedrally coordinated, whereas the lithium and phosphorus atoms are all tetrahedrally coordinated. As the lithium-induced derivatives of MH₂P₂O₇ (M=Ni, Co), 1 and 2 possess the same structure with MH₂P₂O₇ in terms of topology, comprising the MO₆ zigzag chains and P₂O₇ as the interchain groups. The magnetisms of 1 and 2 could be interpreted by adopting a quasi-one-dimensional (1D) zigzag chain model as that in their parent compounds: both 1 and 2 have ferromagnetic (FM) NiO₆/CoO₆ chains; 1 shows a FM cluster glass behavior at low temperatures, which is originated from the possible antiferromagnetic (AFM) next-nearest-neighbour intrachain interactions; 2 shows a AFM ordering at T_N=2.6 K and a metamagnetic transition at H_C=4.2 kOe at 1.8 K.     

New organomercury(II) compounds containing intramolecular N → Hg interactions: crystal and molecular structure of [2-(Me2NCH2)C6H4]HgCl and [2-(Me2NCH2)C6H4]Hg[S(S)PPh2]

[2-(Me₂NCH₂)C₆H₄]HgCl (1) was prepared by reacting HgCl₂ with [2-(Me₂NCH₂)C₆H₄]Li in diethyl ether. The reactions of 1 with the sodium or ammonium salt of the appropriate thiophosphinato ligand, in 1:1 molar ratio, afford the isolation of [2-(Me₂NCH₂)C₆H₄]Hg[S(S)PR₂] [R=Me (2), Et (3), Ph (4)], [2-(Me₂NCH₂)C₆H₄]Hg[S(O)PPh₂] (5) and [2-(Me₂NCH₂)C₆H₄]Hg[S(S)P(OⁱPr)₂] (6). The compounds were investigated by IR and multinuclear NMR (¹H, ¹³C and ³¹P) spectroscopy. The molecular structures of 1 and 4 were determined by single-crystal X-ray diffraction. Due to the strong intramolecular coordination of the N atom of the pendant CH₂NMe₂ arm [Hg(1)-N(1) 2.764(6) and 2.725(4) Å in 1 and 4, respectively] both compounds exhibit a T-shaped (C,N)HgX core in the molecular unit, with almost linear arrangement of the covalent bonds [C(1)-Hg(1)-Cl(1) 176.93(18)° in 1, and C(1)-Hg(1)-S(1) 169.54(16)° in 4]. The crystals of 1 contain discrete monomeric molecules, while the crystals of 4 contain dimer associations built through asymmetric bridging dithiophosphinato ligands [Hg(1)-S(1) 2.3911(16) Å, Hg(1)?S(2a) 3.102(2) Å], thus resulting in an overall pseudo-trigonal bipyramidal (or seesaw) (C,N)HgS₂ core, with the nitrogen atom and the weekly bonded sulfur atom in equatorial positions [N(1)-Hg(1)?S(2a) 82.01(10)°].     

U(IV)/Ln(III) unexpected mixed site in polymetallic oxalato complexes. Part I. Substitution of Ln(III) for U(IV) from the new oxalate (NH4)2U2(C2O4)5·0.7H2O

A new ammonium uranium (IV) oxalate (NH₄)₂U₂(C₂O₄)₅·0.7H₂O (1) and three mixed uranium (IV)-lanthanide (III) oxalates, (N₂H₅)_2.6U_1.4M_0.6(C₂O₄)₅·xH₂O (M=Nd (2) and M=Sm (3)), Na_2.56U_1.44Nd_0.56(C₂O₄)₅·7.6H₂O (4) and Na₃UCe(C₂O₄)₅·10.4H₂O (5), have been prepared. The crystal structures of compounds 1, 4 and 5 have been determined by single-crystal X-ray diffraction. The crystal structures were solved by the direct methods and Fourier difference techniques, and refined by a least square method on the basis of F² for all unique reflections. Compounds 2 and 3 are isotypic with 1. Crystallographic data: 1, hexagonal, space group P6₃/mmc, a=19.177(3), c=12.728(4) Å, Z=6, R₁=0.0575 for 52 parameters with 1360 reflections with I?2σ(I); 2, hexagonal, space group P6₃/mmc, a=19.243(4), c=12.760(5) Å, Z=6; 3, hexagonal, space group P6₃/mmc, a=19.211(3), c=12.274(4) Å, Z=6; 4, orthorhombic, space group Pbcn, a=18.79(3), b=11.46(1), c=12.77(2) Å, Z=4, R₁=0.0511 for 183 parameters with 3026 reflections with I?2σ(I); 5, monoclinic, space group C2/c, a=18.878(6), b=11.684(4), c=12.932(4) Å, β=95.97(1)°, Z=4, R₁=0.0416 for 213 parameters with 4060 reflections with I?2σ(I). The honeycomb-like structure of the five compounds is built from the same three-dimensional arrangement of metallic and oxalate ions. Similar hexagonal rings of alternating metallic and oxalate ions form layers parallel to the (001) plane that are pillared by another oxalate ion. Indeed, some torsions or rotations of the bridging oxalate ligands led to modifications of the network symmetry. The monovalent cations and the water molecules occupy the hexagonal tunnels running down the [001] direction. Starting from the uranium (IV) compound A₂U₂(C₂O₄)₅·0.7H₂O with A=NH₄⁺ (1), the mixed U(IV)/Ln(III) oxalates are obtained by partial substitution of U(IV) by Ln(III) in a ten-coordinated site, the charge deficit being compensated by intercalation of supplementary monovalent ions within the tunnels. The distortion of the arrangement in the [001] direction for the Na-containing compounds allows the accommodation of a greater number of water molecules that insure an octahedral coordination of the Na atoms.     

Syntheses, structure and magnetic properties of pillared layered diphosphonates: M2(O3PC6H4PO3)(H2O)2 (M=Co, Ni)

This paper describes the hydrothermal syntheses of two isostructural metal bisphosphonates: M₂(O₃PC₆H₄PO₃)(H₂O)₂ [M=Co^II (1), Ni^II (2)]. Single-crystal structure determination of compound 1 revealed a pillared layered structure in which the phenyl groups connect the inorganic layers of cobalt phosphonate. Crystal data for 1: orthorhombic, space group Pnnm, a=19.306(5), b=4.8293(12), c=5.6390(14) Å, V=525.7(2) Å³, Z=2. Magnetic susceptibility data indicate that antiferromagnetic interactions are mediated in both cases.     

New binuclear vanadium(III) and (IV) squarate species: synthesis, structure and characterization of [V(OH)(H2O)2(C4O4)]2·2H2O and (NH4)[(VO)2(OH)(C4O4)2(H2O)3]·3H2O

Two new vanadium squarates have been synthesized, characterized by infrared and thermal behavior and their structures determined by single crystal X-ray diffraction. Both structures are made of discrete, binuclear vanadium entity but in 1, [V(OH)(H₂O)₂(C₄O₄)]₂·2H₂O the vanadium atom is trivalent and the entity is neutral while in 2, (NH₄)[(VO)₂(OH)(C₄O₄)₂(H₂O)₃]·3H₂O, the vanadium atom is tetravalent and the entity is negatively charged, balanced by the presence of one ammonium ion. Both molecular anions are bridged by two terminal μ₂ squarate ligands. 1 crystallizes in the triclinic system, space group P-1, with lattice constants a=7.5112(10) Å, b=7.5603(8) Å, c=8.2185(8) Å, α=106.904(8)°, β=94.510(10)°, γ=113.984(9)° while 2 crystallizes in the monoclinic system, space group C2/c, with a=14.9340(15) Å, b=6.4900(9) Å, c=17.9590(19) Å and β=97.927(12)°. From the magnetic point of view, V(III) binuclear species show ferromagnetic interactions at low temperatures. However, no anomalies pointing to magnetic ordering are observed down to 2 K.     

Sn(OTf)2 catalysed regioselective styrene oxide ring opening with aromatic amines

Sn(OTf)₂ is an efficient and versatile catalyst for the highly regioselective opening of styrene oxide with aromatic amines, which allowed for the preparation of fourteen 2-arylamino-2-phenylethanols, some of them described here for the first time (6g, 6i, 6j, 6k and 6m). Sn(OTf)₂ also catalyses the opening of styrene oxide with aliphatic amines in moderate to high yields but with a lower degree of regioselectivity. 2-Akylamino-1-phenylethanols are the predominant products when moderate to high regioselectivity is observed (compounds 4b, 4c and 4d). This is the first report of the use of Sn(OTf)₂ to catalyse the opening of an epoxide by aliphatic amines.     

Self-assembly of diorganotin(IV) 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetates: An investigation of structures by X-ray diffraction, solution and solid-state tin NMR, and electrospray ionization MS

The diorganotin(IV) compounds, [Me₂SnL²(OH₂)]₂ (1), [ⁿBu₂SnL²(OH₂)]₂ (2), [ⁿBu₂SnL¹]₃ · 0.5C₃H₆O (3), [ⁿBu₂SnL³]₃ · 0.5C₆H₆ (4) and [Ph₂SnL³]_n · 0.5C₆H₆ (5) (L = carboxylic acid residue, i.e., 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetate), were synthesized by treating the appropriate diorganotin(IV) dichloride with the potassium salt of the ligand in anhydrous methanol.The reaction of Ph₂SnL² (L = 2-{[(E)-1-(2-oxyphenyl)ethylidene]amino}acetate) with 1,10-phenanthroline (Phen) yielded a 1:1 adduct of composition, [Ph₂SnL²(Phen)] (6).The crystal structures of 1-6 were determined.The crystal of 1 is composed of centrosymmetric dimers of the basic Me₂SnL²(OH₂) moiety, where the two Sn-centres are linked by two asymmetric Sn-O?Sn bridges involving the carboxylic acid O atom of the ligand and a long Sn?O distance of 3.174(2) Å.The dimers are further linked into columns by hydrogen bonds.The coordination geometry about the Sn atom is a distorted pentagonal bipyramid with the two methyl groups in axial positions.The structure of 2 is similar.The same Sn atom coordination geometry is observed in compound 3, which is a cyclic trinuclear[ⁿBu₂SnL¹]₃ compound. Each Sn atom is coordinated by the phenoxide O atom, one carboxylate O atom and the imino N atom from one ligand and both the exo- and endo-carboxylate O atoms (mean Sn-O(exo): 2.35 Å; Sn-O(endo): 2.96 Å) from an adjacent ligand to form the equatorial plane, while the two butyl groups occupy axial positions. Compound 4 was found to crystallize in two polymorphic forms. The Sn-complex in both forms has a trinuclear [ⁿBu₂SnL³]₃ structural motif similar to that found in 3. In compound 5, distorted trigonal bipyramidal Ph₂SnL³ units are linked into polymeric cis-bridged chains by a weak Sn?O interaction (3.491(2) Å) involving the exocyclic O atom of the tridentate ligand of a neighboring Sn-complex unit. This interaction completes a highly distorted octahedron about the Sn atom, where the weakly coordinated exocyclic O atom and one phenyl group are trans to one another. In contrast, a monomeric distorted pentagonal bipyramidal geometry is found for adduct 6 where the Sn-phenyl groups occupy the axial positions. The solution and solid-state structures are compared by using ¹¹⁹Sn NMR chemical shift data. Compounds 1-6 were also studied using ESI-MS and their positive- and negative-ions mass fragmentation patterns are discussed.     

Solvent-dependent formation of two different Cd(II) complexes with p-BrC6H4C(S)NHP(O)(OiPr)2 (HL). Crystallographic modification of Cd(HL)2L2

Reaction of the potassium salt of N-(diisopropoxyphosphoryl)-p-bromothiobenzamide p-BrC₆H₄C(S)NHP(O)(OiPr)₂ (HL) with Cd(II) cations in freshly dried and distilled EtOH leads exclusively to the complex [Cd(p-BrC₆H₄C(S)NH₂-S)(L-O,S)₂] ([Cd(L^I)L₂]), while the same reaction in H₂O leads to the complex [Cd(HL-O)₂(L-O,S)₂] ([Cd(HL)₂L₂]). The corresponding reactions with Zn(II) always lead to the complex [Zn(L-O,S)₂] ([ZnL₂]) regardless of the solvent. The crystal structure of [Cd(HL)₂L₂]^.2/3H₂O reveals to be a polymorph to the previously reported anhydrous [Cd(HL)₂L₂].     

Thermal fragmentation of the guanidinato aluminum amide precursor [Me2NC(NPr)2]Al(NMe2)2: An investigation of reactive species by matrix-isolation FTIR spectroscopy and time-of-flight mass spectrometry

The gas-phase thermolysis of the guanidinato aluminum amide precursor [Me₂NC(NⁱPr)₂]Al(NMe₂)₂ (1) in the oven temperature range of ambient temperatures to 600 °C has been investigated with matrix-isolation FTIR spectroscopy and time-of-flight mass spectrometry (argon as carrier gas). Precursor 1 fragments above 300 °C to form iPrCNCiPr (2) and monomeric Al(NMe₂)₃ (3m). Independent thermolysis series with 2 and the aluminum amide dimer 3d, [Al(NMe₂)₃]₂, were conducted and been used to interpret the results of the fragmentation of precursor 1. Compound 3m was present in the thermolysis range of 350–450 °C and has been identified for the first time. Through a comparison of measured FTIR spectra with the calculated spectrum of 3m (D₃ point group symmetry; B3LYP/6-31G(d) level of theory) all expected IR bands were found and could be assigned to normal modes. At thermolysis temperatures of ?500 °C signals indicative for H₂CNCH₃ (4) were found, showing that 3m fragments further at higher temperature. The thermolysis product 2 (iPrCNCiPr) withstands the higher thermolysis temperatures. From our study one can conclude that precursor 1 cleanly delivers the monomeric aluminum alane 3m, which then acts as the reactive material forming species.     

Reverse Kocheshkov reaction - Redistribution reactions between RSn(OCH2CH2NMe2)2Cl (R = Alk, Ar) and PhSnCl3: Experimental and DFT study

A series of organotin compounds bearing two intramolecular N → Sn coordination bonds RSn(OCH₂CH₂NMe₂)₂Cl (R = Me (4), n-Bu (5), Mes (6)) were synthesized in good yields. These compounds as well as 2 (R = Ph) react with PhSnCl₃ to give redistribution products RPhSnCl₂ and (Me₂NCH₂CH₂O)₂SnCl₂ (3). The direction of redistribution reactions is reverse to Kocheshkov reaction. DFT calculations have shown that the driving force of the reactions is formation of intramolecular N → Sn coordination bonds in (RO)₂SnCl₂ (3), the Lewis acid stronger than RSn(OR)₂Cl (2, 4-6). The mechanism of the redistribution reaction between 2 and PhSnCl₃ consists of two steps: (1) initial exchange of OCH₂CH₂NMe₂ and Cl to give PhSn(OCH₂CH₂NMe₂)Cl₂ (7) followed by (2). Ph and OCH₂CH₂NMe₂ exchange.     

Synthesis and characterization of some novel cadmium(II) complexes with 3-hydroxypicolinic acid (3-OHpicH): Crystal and molecular structures of [CdI(3-OHpic)(3-OHpicH)(H2O)]2, [Cd(3-OHpic)2(H2O)2] and [Cd(3-OHpic)2]n

Cadmium(II) complexes of 3-hydroxypicolinic acid, namely [CdI(3-OHpic)(3-OHpicH)(H₂O)]₂ (1), [Cd(3-OHpic)₂(H₂O)₂] (2) and [Cd(3-OHpic)₂]_n (3) were prepared and characterized by spectroscopic methods (IR, NMR) and their molecular and crystal structures were determined by X-ray crystal structure analysis. Complexes 1 and 2 were prepared in similar reaction conditions using different cadmium(II) salts: cadmium(II) iodide and cadmium(II) acetate dihydrate, respectively, while 3 was prepared by recrystallization of 2 from N,N-dimethylformamide solution. Various coordination modes of 3-OHpicH in 1–3 were established in the solid state: bidentate N,O-chelated mode in 1 and 2, monodentate mode through the carboxylate O atom from zwitterionic ligand in 1 and bidentate N,O-chelated and bridging mode in 3. In the DMF solution of all prepared complexes, only monodentate mode of 3-OHpicH binding to cadmium(II) through the carboxylate O atom was established by ¹H, ¹³C, ¹⁵N and ¹¹³Cd NMR spectroscopy.     

Two layered gallophosphates assembled about the chiral metal complexes: Co(en)3·Ga3P4O16·5H2O and trans−Co(dien)2·Ga3P4O16·3H2O

Two new layered gallophosphates Co(en)₃·Ga₃P₄O₁₆·5H₂O (1) and trans-Co(dien)₂·Ga₃P₄O₁₆·3H₂O (2) have been hydrothermally synthesized using the racemic mixture of chiral metal complex Co(en)₃Cl₃ and Co(dien)₂Cl₃ as the structure-directing agent, respectively. Their structures are determined by single-crystal X-ray diffraction analysis and further characterized by X-ray power diffraction, ICP, elemental, and TG analyses. The structures of 1 and 2 consist of vertex-linking GaO₄ and PO₃(=O) tetrahedral units forming macroanionic [Ga₃P₄O₁₆]³⁻ sheets with a 4.6-net. The 4.6-net is characteristic of chiral [3.3.3] propellane-like structural motifs. The sheets of 1 stack in an ABAB sequence, with a pair of enantiomers of chiral Co(en)₃³⁺ cations residing in the interlayer region. The sheets of 2 array in a helical fashion with an ABCDEF stacking sequence, with only one enantiomer of chiral Co(dien)₂³⁺ cations residing in the interlayer region. Structural elucidation of 1 and 2 reveals that there exist stereo-specific correspondence between the metal complex template and the structure of the inorganic host. Crystal data: 1, Co(en)₃·Ga₃P₄O₁₆·5H₂O, orthorhombic, Pnna (No. 52), a=8.6618(2) Å, b=21.6071(5) Å, c=13.7426(4) Å, Z=4, R₁=0.0337 (I>2σ(I)), wR₂=0.0985 (all data); 2, Co(dien)₂·Ga₃P₄O₁₆·3H₂O, hexagonal, P6₅22 (No. 179), a=8.5152(7) Å, b=8.5152(7) Å, c=63.278(8) Å, R₁=0.1183 (I>2σ(I)), wR₂=0.2864 (all data) and Z=6.     

Redistribution reactions of heteroleptic barium iodide derivatives: Synthesis and structures of trans-BaI2(DME)(triglyme), cis-BaI2(DME)(tetraglyme) and [Ba(tetraglyme)2]I2 · C7H8

The reaction between BaI₂ · 2H₂O and NaHFIP [HFIP = OCH(CF₃)₂] in a 1:1 stoichiometry gave the heterometallic compound NaBaI₂(HFIP)(H₂O)(THF)_0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI₂(DME)₃ (2), trans-BaI₂(DME)(triglyme) (3) and cis-BaI₂(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI₂ · 2H₂O and NaTFA (TFA = O₂CCF₃) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)₂]I₂ · C₇H₈ (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and ¹H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 Å for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 Å for 4.