Nature of coordination bond in silatranes and its formation dynamics according to the ab initio calculations

Quantum-chemical calculations of 1-hydrosilatrane molecule with complete optimization of its geometry and at various fixed Si…N distances (2.0 to 3.7 Å) has been carried out at the MP2/6-31G(d) level. The silatranes coordination bond is formed of different atomic orbitals of Si and N atoms participating in a series of molecular orbitals. With the Si…N distance decreasing, contributions of the atomic orbitals in these molecular orbitals have been changed, number of the molecular orbitals has increased, and total energy of the molecule has decreased. At the coordination centers are getting closer, population of the nitrogen valence s and p _z orbitals have changed due to the corresponding bond angle change; the populations of Si and H orbitals are not significantly changed.     

Copper(II) and lead(II) complexes based on 2,3,5,6-tetrakis(2-pyridyl)pyrazine as a polydentate ligand

The Cu(II) complexes [Cu(Tppz)(Dipic)] · 8H₂O (I) and [Pb₂(Tppz)Cl₄] _n (II), where Tppz, H2Dipic are 2,3,5,6-tetrakis(2-pyridyl)pyrazine, dipicolinic acid, respectively, have been synthesized and characterized by elemental analyses, IR, cyclic voltammetry, and electronic spectral studies. Solid state structures of both complexes have been determined by single crystal X-ray crystallography. An ORTEP drawing of two complexes shows that the coordination geometry around the metal center is a distorted octahedron. There are extensive conventional intermolecular O-H…O, N-H…O, and weaker C-H…O and C-H…Cl non-classical hydrogen bonds, which cause the stability of the crystal structure. Crystal data for I: monoclinic, space group: C2/c, a = 35.421(3), b = 8.422(6), c = 22.824(8) Å, β = 101.69(2)°, V = 6668(5) ų, Z = 8. Crystal data for II: triclinic, space group P \(\bar 1\) , a = 7.9534(4), b = 8.8682(5), c = 9.4245(5) Å, β = 95.086(2)°, V = 655.93(6) ų, Z = 2.     

Molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane)

The molecular structure of 1-methyl-1-fluoroquasisilatrane (2-methyl-2-fluoro-1,3-dioxa-6-aza-2-silacyclooctane) MeFSi(OCH₂CH₂)₂NH (I) is determined by single crystal X-ray diffraction at 100 K. The coordination polyhedron of the silicon atom in this molecule is a slightly distorted trigonal bipyramid with an NH group and a strongly electron-withdrawing fluorine atom in the axial positions, and two endocyclic oxygen atoms and a CH₃ group in three vertices of the equatorial plane. The axial angle N→SiF is 171°. The length of the transannular donor-acceptor bond N→Si (2.058 Å) is as small as in 1-fluorosilatrane. The axial bond F-Si (1.660 Å) is longer than that in 1-fluorosilatrane and tetrahedral silicon compounds.     

Crystal structure refinement for trans-[Pd(NO3)2(H2O)2]

Single crystals of trans-[Pd(NO₃)₂(H₂O)₂] were obtained, and the crystal structure of this complex, previously obtained for polycrystals, was refined. Crystal data (BRUKER X8APEX diffractometer): a = 4.9973(7) Å, b = 10.5982(14) Å, c = 11.7008(17) Å, V = 619.70(15) ų, space group Pbca, Z = 4, d _calc = 2.856 g/cm³. The structure is composed of neutral complexes with a trans configuration. The square plane environment of the Pd atom is formed by four oxygen atoms (Pd-O(NO₃) 1.999(5) Å, Pd-O(H₂O) 2.030(5) Å) and completed to a distorted bipyramid by two intramolecular contacts (Pd…O(NO₃) 2.926 Å). The shortest hydrogen bonds are O…H 2.72 Å.     

Distorted tetrahedral copper(I)′complexes of 2,2′bi-4,5-dihydrothiazine and 2,2′-bi-2-thiazoline

The copper(I) complexes [Cu(btz)₂](BPh]₄(I) and [Cu₂(bt)₄][ClO₄]₂ (II) have been prepared (btz = 2,2′-bi-4,5-dihydrothiazine and bt = 2,2′-bi-2-thiazoline). Crystals of (I) are orthorhombic with a = 10.927(8), b = 11.743(8), c = 15.000(6) A, Z = 2, spacegroup P2₁2₁2. Crystals of (II) are monoclinic with a = 21.928(11), b = 11.925(8), c = 14.716(11) A, β = 103.6(1), Z = 8, spacegroup C2/c. 2121 and 2204 independent reflections have been measured on a diffractometer and the structures refined R 0.061 to R 0.063 respectively. In the cation of (I) the two btz ligands are coordinated via the α-di-imine groups (Cu-N 2.010(6), 2.024(6)Å). The resulting CuN₄ coordination geometry is a flattened tetrahedron with a dihedral angle of 68.9° between the two “CuN₂” planes. It is suggested that this distortion is an intrinsic property of the molecule associated with metal-to-ligand d_π-p_π* charge transfer rather than a consequence of lattice packing effects. In the dimeric cation (II), each copper(I) ion is bonded to the α-di-imine group of one bt molecule (A) but with appreciably different CuN bond lengths (2.277(6), 1.999(5)Å), to one nitrogen atom of a second ligand molecule (B) in the trans configuration (CuN 1.961(5)Å) and to one sulphur atom (CuS 2.428(2)Å) of a third ligand molecule (C). The coordination geometry is a very distorted tetrahedron if a very weak interaction (Cu…S 3.039(2)Å) with a sulphur atom of ligand B is discounted. It is suggested that the different structure arise from the different “bites” of the two ligands.     

Synthesis and crystal structure of a trinuclear copper(II) complex derived from N,N′-Bis(4-methoxysalicylidene)-1,3-pentanediamine

A trinuclear copper(II) complex [Cu₃Cl₂L₂], where L is the dianionic form of N,N′-bis(4-methoxysalicylidene)-1,3-pentanediamine, has been synthesized and characterized by means of spectroscopic methods and single crystal X-ray structure determination. The complex crystallizes in the orthorhombic space group Pnma with unit cell dimensions a = 15.301(2), b = 23.226(2), c = 12.089(1)Å, V = 4296.2(8) ų, Z = 4, R ₁ = 0.0682, and wR ₂ = 0.1590. The molecule of the complex possesses a crystallographic mirror plane symmetry with the mirror plane passes through the three Cu atoms and the two Cl atoms. The two terminal Cu atoms adopt distorted square pyramidal coordination, and the middle one adopts square planar coordination. The intramolecular Cu…Cu distances are 2.900(1) and 2.916(1) Å. The complex was tested for its antibacterial activity to assess its inhibiting potential.     

Supramolecular hydrogen‐bonding patterns in the organic–inorganic hybrid compound bis(4‐amino‐5‐chloro‐2,6‐dimethylpyrimidinium) tetrathiocyanatozinc(II)–4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–water (1/2/2)

Zinc thiocyanate complexes have been found to be biologically active compounds. Zinc is also an essential element for the normal function of most organisms and is the main constituent in a number of metalloenzyme proteins. Pyrimidine and aminopyrimidine derivatives are biologically very important as they are components of nucleic acids. Thiocyanate ions can bridge metal ions by employing both their N and S atoms for coordination. They can play an important role in assembling different coordination structures and yield an interesting variety of one‐, two‐ and three‐dimensional polymeric metal–thiocyanate supramolecular frameworks. The structure of a new zinc thiocyanate–aminopyrimidine organic–inorganic compound, (C₆H₉ClN₃)₂[Zn(NCS)₄]·2C₆H₈ClN₃·2H₂O, is reported. The asymmetric unit consist of half a tetrathiocyanatozinc(II) dianion, an uncoordinated 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidinium cation, a 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine molecule and a water molecule. The Zn^II atom adopts a distorted tetrahedral coordination geometry and is coordinated by four N atoms from the thiocyanate anions. The Zn^II atom is located on a special position (twofold axis of symmetry). The pyrimidinium cation and the pyrimidine molecule are not coordinated to the Zn^II atom, but are hydrogen bonded to the uncoordinated water molecules and the metal‐coordinated thiocyanate ligands. The pyrimidine molecules and pyrimidinium cations also form base‐pair‐like structures with an R₂²(8) ring motif via N—H…N hydrogen bonds. The crystal structure is further stabilized by intermolecular N—H…O, O—H…S, N—H…S and O—H…N hydrogen bonds, by intramolecular N—H…Cl and C—H…Cl hydrogen bonds, and also by π–π stacking interactions.     

Synthesis,crystal structure,and catalytic properties of a one-dimensional nickel(II) polymer

The title complex [Ni₂(C₁₀H₉N₃)₂(C₁₄H₈O₅)₂] _n , which has an inversion center, midway between two Ni(II) atoms forms a one-dimensional polymer bridged by 4,4′-oxydibenzoate ligands with a Ni…Ni separation of 14.4705(11) Å. The Ni(II) atom is six-coordinated by two N atoms of a bis(2-pyridyl)amine ligand and four O atoms from two 4,4′-oxydibenzoate ligands, to form a distorted octahedron coordination geometry and then are linked via N-H…O and C-H…O hydrogen bonding into a polymeric ribbon structure. The activity and selectivity profiles of the polymer indicate that the optimization temperature and time span are 175°C and 30–40 min for the dehydration of cyclohexanol, respectively.     

Structures of the silver complexes with lutidines according to the NMR data. Crystal structure of [AgNO3(3,5-Lut)2]

The silver(I) nitrate complexes with 2,3-, 2,4-, 2,6-, and 3,5-lutidine (Lut, dimethylpyridine C₇H₉N), [AgNO₃(Lut)₂], are synthesized and studied by multinuclear NMR (¹H, ¹³C, and ¹⁵N) in various solvents (chloroform, dimethyl sulfoxide, and acetonitrile). The influence of steric and electronic factors of the organic ligand on the parameters of the NMR spectra is revealed. It is shown that the ¹⁵N NMR spectra are the most informative. The structure of complex [AgNO₃(3,5-Lut)₂] is determined. The crystals are monoclinic, space group C2/c, a = 14.599(1) Å, b = 8.422(1) Å, c = 12.954(1) Å, β = 99.60(1)°, V = 1570(2) ų, ρ_calcd = 1.625 g/cm³, Z = 4. The structure is built of discrete neutral complexes [AgNO₃(3,5-Lut)₂]. The coordination mode of the Ag⁺ ion includes two nitrogen atoms of two crystallographically equivalent lutidine ligands (Ag-N 2.194(5) Å, angle NAgN 147.6(3)°). The nitrate ion behaves as a weak chelating ligand with respect to the Ag⁺ ion (Ag…O 2.674(6) Å).     

Low‐dimensional compounds containing cyano groups. XVI. (Dicyanamido‐κN1)bis(1,10‐phenanthroline‐κ2N,N′)copper(II) tetrafluoridoborate

The title compound, [Cu{N(CN)₂}(C₁₂H₈N₂)₂]BF₄, was prepared as part of our study of the shape of coordination polyhedra in five‐coordinated copper(II) complexes. Single‐crystal X‐ray analysis reveals that the structure consists of [Cu{N(CN)₂}(phen)₂]⁺ cations (phen is 1,10‐phenanthroline) and BF₄⁻ anions. The Cu centre is five‐coordinated in a distorted trigonal bipyramidal manner by four N atoms of two phen ligands and one N atom of a dicyanamide anion, which is coordinated in the equatorial plane at a distance of 1.996 (2) Å. The two axial Cu—N_phen distances have similar values [average 1.994 (6) Å] and are shorter than the two equatorial Cu—N_phen bonds [average 2.09 (6) Å]. This work demonstrates the effect of ligand rigidity on the shape of coordination polyhedra in five‐coordinated copper(II) complexes.     

Die Kristallstruktur des 1 : 1-Adduktes zwischen Antimontrichlorid und Diphenylammoniumchlorid,SbCl3 · (C6H5)2NH2+Cl−

The Crystal Structure of the 1:1 Addition Compound between Antimony Trichloride and Diphenylammonium Chloride, SbCl₃ · (C₆H₅)₂NH₂⁺Cl^? The 1:1 addition compound between antimony trichloride and diphenylammoniumchloride SbCl₃ · (C₆H₅)₂NH₂⁺Cl^? crystallizes in the monoclinic space group P2₁/n with a = 5.668(8), b = 20.480(12), c = 14.448(17) Å, β = 110.4(1)° and Z = 4 formula units. Chains of SbCl₃ molecules and anion cation chains are bridged by Cl ions and form square tubes. The coordination of the Sb atoms by Cl atoms by Cl atoms and Cl ions is distorted octahedral. Mean distances are Sb? Cl = 2.37 Å for Sb? Cl (3×), 3.09 Å for Sb…Cl^? (2×) and 3.42 Å for Sb…Cl (1×). The Sb…Cl^? contacts and hydrogen bonds NH…Cl^? at 3.15 Å generate tetrahedral coordination of the Cl ions.     

Coordination polymer of uranyl nitrate with 4,4,10,10-Tetramethyl-1,3,7,9-Tetraazaspiro[5.5]undecane-2,8-dione (Spirocarbone, Sk): Synthesis and study of molecular and crystal structures

The coordination polymer {[UO₂(NO₃)₂(C₁₁H₂₀N₄O₂)] · 2H₂O} _n (I) was obtained and examined by X-ray diffraction. The crystals are monoclinic, space group C2/c; a = 23.1386(13), b = 5.41575(15), c = 19.7769(11) Å, β = 125.285(8)°, V = 2023.01(17) ų, ρ_calcd = 2.20 g/cm³, Z = 4. The U atom occupies a special position in the center of inversion. Its coordination polyhedron is a distorted hexagonal bipyramid with axial oxo ligands. In the equatorial plane, the U(1) atom is coordinated by four O atoms of two bidentate nitrate anions and two O atoms of two carbonyl groups of organic spirocarbone (Sk) molecules, which are related by the symmetry operation (0.5 ? x, 0.5 ? y, ?z). In the crystal, polymer chains are parallel to the direction (101). Water molecules are hydrogen-bonded to the N(1) atom of ligand Sk; in addition, they are linked together by the intermolecular hydrogen bonds O(6)-H(6d)…O(6)ⁱ(ⁱ1/2 ? x, ?1/2 + y, 1/2 ? z); H…O 2.11 Å angle O-H…O 160°) and to the nitrate anions by the hydrogen bonds O(6)-H(6e)…O(3)ⁱ; H…O 2.29 Å; the angle O-H…O 149°). In the crystal, hydrogen-bonded water molecules form chains along the axis y that are perpendicular to the coordination polymers. To verify the purity of complex I, the Rietveld refinement of its X-ray powder diffraction pattern was performed. At room temperature, the unit cell parameters are a = 23.2965(6), b = 5.51225(15), c = 19.8588(6) Å, β = 125.6063(17)°, V = 2073.40(10) ų.     

Reactions of 2,2′-Pyridyl with the cadmium(II) compounds: Synthesis,crystal structure,and luminescence properties of [Cd(Pic)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>] · H<Subscript>2</Subscript>O

The reactions of 2,2'-pyridyl, (2-Py)C(O)C(O)(2-Py), with the Cd(II) compounds under various conditions are studied. The medium and nature of the anions exert a decisive effect on the compositions and structures of the formed cadmium complexes. The reaction of cadmium diacetate with 2,2'-pyridyl in an aqueous-alcohol medium in air affords coordination compound [Cd(Рic)₂(H₂O)₂] · H₂O (I) (Pic^? is picolinate ion, CO₂C₅H₄N), and its crystal structure is determined. The crystals are monoclinic: space group P2₁/c, a = 7.499(1), b = 15.676(1), с = 12.719(1) Å, β = 94.79(1)°, V = 1490.0(2) Å3, Z = 4, ρ_calcd = 1.502 g/cm³. The molecular packing of compound I is a supramolecular 3D framework consisting of discrete complexes [Cd(Pic)₂(H₂O)₂] linked by hydrogen bonds O–H…O. The coordination sphere of Cd²⁺ contains two O atoms and two N atoms of the ligand and two water molecules. The coordination polyhedron of Cd²⁺ is a distorted octahedron.     

Crystal Structure of Mercury 7-Amylthio-8-mercaptoquinolinate Hg[C9H5(SC5H11)NS]2 and the Structure of the 7-Amylthio-8-mercaptoquinoline Ligand

Mercury 7-amylthio-8-mercaptoquinolinate Hg[C9H₅(SC5H₁₁)NS]₂ has been synthesized and studied by X-ray diffraction. The crystals are triclinic: a = 8.980(2) Å, b = 9.298(2) Å, c = 18.909(4) Å, α = 93.66(2)°, β = 98.00(2)°, γ = 62.25(2)°, V = 1383.7(5) ų, ρ_calcd = 1.74 g/cm³, Z = 2, space group P1?. The structure is formed by neutral asymmetric complexes in which two 7-amylthio-8-mercaptoquinoline ligands coordinate, in a bidentate fashion (N,S), a mercury atom (Hg-S, 2.363(2) and 2.376(2) Å; Hg-N, 2.436(6) and 2.466(7) Å). The coordination polyhedron of mercury, which is a “swing” (2S+2N), has an SHgS bond angle equal to 173.5(1)°. Some structural features of the ligands in mercury, zinc and copper 7-amylthio-8-mercaptoquinolinates are discussed.     

X-ray diffraction study of the monoclinic modification of [Cu(NH<Subscript>3</Subscript>)<Subscript>4</Subscript>](ReO<Subscript>4</Subscript>)<Subscript>2</Subscript> in the range 100-410 K

The monoclinic modification of [Cu(NH₃)₄](ReO₄)₂ complex salt in the range 100-410 K is studied by single crystal X-ray diffraction. The crystallographic data for 300 K are as follows: a = 10.6123(3) Å, b = 7.5443(2) Å, c = 15.2261(4) Å, β = 108.406(1)°, V = 1156.67(5) ų, space group Р2₁/n, Z = 4, d_x = 3.623 g/cm³. The coordination environment of the Cu atom, being a distorted square formed by four nitrogen atoms with Cu–N of 1.997-2.018 Å, is completed by the contacts with two oxygen atoms Cu…O of 2.472 Å and 2.598 Å. The comparative crystal chemical analysis with the triclinic modification of [Cu(NH₃)₄](ReO₄)₂ known in the literature is performed.     

Malonatobenzhydrazidediaquacobalt(II) hydrate: Synthesis,crystal and molecular structures

The coordination compound [Co(L)(Mal)(H₂O)₂]H₂O (I) (L is benzhydrazide, H₂Mal is malonic acid) has been synthesized and studied by IR spectroscopy, thermogravimetry, and X-ray diffraction. Crystals are triclinic, a = 7.610(4) Å, b = 7.854(2) Å, c = 12.751(2) Å, α = 75.12(3)°, β = 88.01(3)°, γ = 80.26(3)°, Z = 2, space group \(P\bar 1\). The structure is molecular. The Co²⁺ atom has a distorted octahedral coordination. The Co-O and Co-N bond lengths are 2.031-2.129(4) and 2.157(5) Å, respectively. The endocyclic O1Co1N1 bond angles are 77.3(2)° and 90.0(2)° in the five- and six-membered chelate rings, respectively. Molecules of complex I are linked via a great number of hydrogen bonds. The C…C contacts between phenyl rings additionally strengthen the structure.     

The crystal structures of m-trifluoromethylphenylsilatranone and p-fluorophenylsilatranone

The crystal structures of two silatranone derivatives are reported. The close N → Si approach (2.106(3) Å in m-trifluoromethylphenyl-, and 2.129(3) Å in p-fluorophenyl-silatranone) indicates strong dative acceptor bonds. For various silatrane derivatives and inverse relation has been revealed between the mean group electronegativity of the substituent R attached to silicon and the N → Si dative bond distance. In both structures there are long (1.72 Å) SiO bonds in the SiOCO moiety. The m-trifluoromethylphenyl derivative contains a disordered CF₃ group.     

Chemistry of silicon-nitrogen compounds. 165. On the crystalline products from the reaction of silicon tetrachloride with nitrogen in a glow discharge. Single crystal X-ray structure determination of N(SiCl3)3 and Cl3SiN(SiCl2)2NSiCl3

Of the two crystalline products obtained by reacting a silicon tetrachloride/nitrogen mixture in a glow discharge tube, the more volatile (m. p. 78°C) has been confirmed to be tris(trichlorosilyl)amine NSi₃Cl₉ whereas the less volatile component (m. p. 66°C) has been identified as N,N′-bis(trichlorosilyl)-Si,Si′-tetrachloro-cyclodisildiazane N₂Si₄Cl₁₀. These conclusions are supported by mass and vibrational spectroscopy and single crystal X-ray structures. NSi₃Cl₉ possesses a nearly planar NSi₃ skeleton with average N? Si distances of 1.734(2) Å. The N₂Si₄ fragment of N₂Si₄Cl₁₀ is roughly planar with endocyclic N? Si? N and Si? N? Si angles of 89.2(1) and 90.8(1)°, respectively, and mean N? Si distances of 1.731(3) (endocyclic) and 1.687(3) Å (exocyclic).     

Synthesis,X-ray structure and spectroscopy of Cu(II) complexes derived from diacetylazine dioxime

Complexes of Cu(II) with the polydentate diacetylazine dioxime ligand C₈H₁₄N₄O₂ have been synthesized by template and non-template reactions. The crystal structure of [Cu(C₈H₁₃N₄O₂)]₂[ClO₄]₂(C₂H₅OH)₂ has been determined to establish the conformation of the ligand and the coordination of the oxime function. The structural analysis shows that the nearly planar [C₈H₁₃N₄O₂]^? group behaves as a bridging tetradentate ligand. The distorted square-pyramidal coordination about each Cu atom includes three N donors from two oxime and azine and one O donor from the other oxime, the ethanol molecule occupying the apical position. A perchlorate anion is loosely bonded to Cu. The intramolecular Cu…Cu separation is 3.725(2) Å. The compound crystallizes in the centrosymmetric space group P$\text{1}$ triclinic lattice with refined lattice parameters of a = 11.963(8) Å, b = 9.784(7) Å, c = 7.501(6) Å, α = 90.69(4)°, β = 104.53(4)°, γ = 90.83(4)°, V = 849.7 ų and Z = 2. Full-matrix least-squares refinement of 1490 independent reflexions led to final discrepancy indices, R = 0.059, and R_w = 0.065. The Cu centres are highly coupled as indicated by the ESR spectrum. There is no evidence that the C₈H₁₄N₄O₂ ligand stabilizes unusual oxidation states of Cu.     

Structure of arsenic 8-mercaptoquinolinate: Synthesis and crystal structure of arsenic 4-methoxy-8-mercaptoquinolinate As[C<Subscript>9</Subscript>H<Subscript>5</Subscript>(OCH<Subscript>3</Subscript>)NS]<Subscript>3</Subscript>

Arsenic 4-methoxy-8-mercaptoquinolinate As[C₉H₅(4-OCH₃)NS]₃ (I) was synthesized and studied by X-ray diffraction. Crystals are trigonal: space group R3, a = b = 13.9867(4) Å, c = 12.4991(5) Å, γ = 120°, V = 2117.58(12) ų, ρ = 1.519 g/cm³, Z = 3. An arsenic atom in the crystal structure occupies a special position on axis 3. The structural unit of the crystal (neutral complex I) has symmetry C3. 4-Methoxy-8-mercaptoquinoline acts as a bidentate (N,S-) ligand. The coordination polyhedron of the arsenic atom is a symmetric octahedron (3S + 3N) or, with allowance for the lone electron pair, ψ-one-capped octahedron (3S + 3N + E). Bond lengths are as follows: As-S, 2.3179(7)Å; As…N 2.688(3) Å. The geometries of coordination polyhedra of arsenic atoms are compared in the crystal structures of As(C₉H₆NS)₃, As[C₉H₅(2-CH₃)NS]₃, and As[C₉H₅(4-CH₃)NS]₃.