Co(II) Amide, Pyrrolate, and Aminopyridinate Complexes: Assessment of their Manifold Structural Chemistry and Thermal Properties

A series of cobalt(II) (silyl)amides, pyrrolates and aminopyridinates were synthesized. Inspired by the dimeric bis(trimethylsilylamido)cobalt(II) complex ([Co(TMSA)2]2), facile salt metathesis employing the ligand 2,2,5,5-tetramethyl-1,2,5-azadisilolidinyl (TMADS) yielded its congener [Co(TMADS)2]2. Novel, heteroleptic Lewis adducts of the former resulted in unusual three- to four-fold coordination geometry around the metal center. Similarily, the salt [Co(TMADS)3Li(DAD)2] was isolated which demonstrates an ion separated Co(II) anion with silylamide ligation and Li+ counter cation. Transpyrrolylation using [Co(TMSA)2]2 was established for the synthesis of bis[N,N’-2-(dimethylaminomethyl)pyrrolyl]cobalt(II), and bis(N-2-(tert-butyliminomethyl)pyrrolyl)cobalt(II). Treatment of CoCl2 with two equivalents of lithiated N,N-dimethyl(N’-tert-butyl)ethane-1-amino-2-amide and N,N-dimethyl(N’-trimethylsilyl)ethane-1-amino-2-amide resulted in the respective Co(II) amido-amines. Reaction of CoCl2 with lithium 4-methyl-N-(trimethylsilyl)pyridine-2-amide yielded the first binuclear, homoleptic Co(II) aminopyridinate complex with a distorted trigonal bipyramidal coordination environment (τ5 = 0.533) for one central Co(II) ion and a weakly distorted tetrahedral coordination geometry (τ4 = 0.845) for the other. All of the new compounds were thoroughly characterized in terms of composition and structure. Finally, the key thermal characteristics of volatility and thermal stability were assessed using a combination of thermogravimetric analysis and complementary bulk sublimation experiments.

Synthesis, Characterization and Crystal Structures of Zinc(II) and Cobalt(III) Complexes Derived from Tridentate NNO- and NON- Schiff Bases with Antibacterial Activities

Two new polynuclear zinc complexes [Zn2Br2(L1)2] (1) and [Zn(μ1,5-dca)L2]n (2), and two new mononuclear cobalt(III) complexes [CoL1N3(Brsal)] (3) and [CoL2(HL2)] (4), where L1 = 5-bromo-2-(((2-dimethylamino)ethyl)imino)methyl)phenolate, L2 = 5-bromo-2-(((2-hydroxyethyl)imino)methyl)phenolate, dca = dicyanoamide, Brsal = 5-bromo-2-formylphenolate, have been synthesized and characterized. The complexes were characterized by elemental analyses, IR, UVVis spectra, molar conductivity, and single crystal X-ray diffraction. X-ray analysis indicates that the Zn atoms in complex 1 are in distorted square pyramidal coordination, the Zn atoms in complex 2 are in distorted trigonal bipyramidal coordination, and the Co atoms in complexes 3 and 4 are in octahedral coordination. The molecules of the complexes are stacked through π···π interactions and hydrogen bonds. The complexes were assayed for antibacterial activities against three Gram-positive bacterial strains (B. subtilis, S. aureus, and St. faecalis) and three Gram-negative bacterial strains (E. coli, P. aeruginosa, and E. cloacae) by MTT method.

Tris(Para-Tolyl)Bismuth Bis(Bromodifluoroacetate). Synthesis and Structure Features

The interaction of tri(para-tolyl)bismuth with tert-butyl hydroperoxide and bromodifluoroacetic acid in diethyl ether have synthesized tris(para-tolyl)bismuth bis(bromodifluoroacetate). The X-ray diffraction pattern for the crystal has been obtained at 293 K on an automatic diffractometer D8 Quest Bruker (MoKα-radiation, λ = 0.71073 Å, graphite monochromator), the results are [C25H21O4F4Br2Bi, M 830.22, the triclinic syngony, the symmetry group P–1; cell parameters: a = 10.292(8), b = 11.752(9), c = 12.693(9) Å, α = 89.42(2) degrees, β = 78.04(3) degrees, γ = 78.04(3) degrees; V = 1424.8(18) Å3; the crystal size is 0.73×0.57×0.41 mm; intervals of reflection indexes are –13 ≤ h ≤ 13, –15 ≤ k ≤ 15, –16 ≤ l ≤ 16; total reflections 45443; independent reflections 7096; Rint 0.1030; GOOF 1.049; R1 = 0.0739, wR2 = 0.1834; residual electron density 2.11/–2.78 e/Å3], the bismuth atom have a distorted trigonal-bipyramidal coordination. The OBiO axial angle is 172.2(3) degrees; the sum of the CBiC angles in the equatorial plane is 360.6. The Bi–O and Bi–C bond lengths are 2.275(8), 2.295(8) Å and 2.187(10)–2.212(13) Å. The Bi•••O=С distances are 3.127(10) and 3.159(10) Å, which is less than the sum of the van der Waals radii of bismuth and oxygen (3.59 Å). There are no intermolecular contacts H∙∙∙Hal in the crystal. Complete tables of coordinates of atoms, bond lengths and valence angles for the structure are deposited at the Cambridge Structural Data Bank (no. 1923097; [email protected]; http: //www.ccdc.cam.ac.uk).

Synthesis and Structure Features of Tetraphenylantimony 2,3-Difluoro- and 2,3,4,5,6-Pentafluorobenzoate

Tetraphenylantimony 2,3-difluorobenzoate (1) and tetraphenylantimony 2,3,4,5,6-pentafluorobenzoate (2) was obtained by the interaction of pentaphenylantimony with 2,3-difluorobenzoic and 2,3,4,5,6-pentafluorobenzoic acids in benzene with a yield of up to 98 %. The compounds were also synthesized by the ligand redistribution reaction between pentaphenylantimony and triphenylantimony dicarboxylates. The compounds have been identified by IR spectroscopy and X-ray diffraction analysis. According to the X-ray diffraction data, the antimony atoms in compounds 1 and 2 have a distorted trigonal-bipyramidal coordination with the oxygen atom in axial positions. X-ray diffraction analysis was performed on a D8 QUEST diffractometer (Bruker). The crystallographic parameters of the unit cell of the compounds: 1 space group Р1 ̅, а = 9.857(5), b = 10.154(7), c = 14.362(11) Å, α = 83.74(4)°, β = 82.59(3), γ = 68.34(2)°, V = 1321.9(16) Å3, ρcalc = 1.475 g/cm3, Z = 2; 2 space group Р21/с, а = 16.186(9), b = 8.771(6), c = 20.413(13) Å, α = 90.00°, β = 113.073(17), γ = 90.00°, V = 2666(3) Å3, ρcalc = 1.597 g/cm3, Z = 4. The OSbO axial angles are slightly different and amount to 177.90(5)º in 1 and 179.00(5)º in 2. The sums of the CSbC equatorial angles are 356.89(9)º (1), 355.85(7)º (2). The Sb–Ceq distances in compounds 1 and 2 are 2.116(2), 2.119(2), 2.118(2) and 2.1073(17), 2.1158(18), 2.1152(19) Å respectively, which are significantly shorter than the Sb–Сax bond lengths (2.169(2) and 2.1617(19) Å). The organization of molecules in the crystals of compounds is due to hydrogen bonds and CHπ-interactions of the aryl and carboxyl ligands. The main difference between structures 1 and 2 is the different Sb–O bond lengths (2.2864(18) and 2.3168(18) Å), which is due to an increase in the electronegativity of the carboxyl ligand in 2, caused by the presence of five electronegative fluorine atoms in the benzoate substituent. Complete tables of atom coordinates, bond lengths and valence angles are deposited at the Cambridge Crystallographic Data Center (No. 1980908 (1); 1977189 (2); [email protected]; http://www.ccdc.cam.ac.uk/data_request/cif).

Crystal structure of tetrakis[μ-3-carboxy-1-(1,2,4-triazol-4-yl)adamantane-κ2 N 1:N 2]tetrafluoridodi-μ2-oxido-dioxidodisilver(I)divanadium(V) tetrahydrate

The crystal structure of the title molecular complex, [Ag2{VO2F2}2(C13H17N3O2)4]·4H2O, supported by the heterofunctional ligand tr-ad-COOH [1-(1,2,4-triazol-4-yl)-3-carboxyadamantane] is reported. Four 1,2,4-triazole groups of the ligand link two AgI atoms, as well as AgI and VV centres, forming the heterobimetallic coordination cluster {AgI 2(VVO2F2)2(tr)4}. VV exists as a vanadium oxofluoride anion and possesses a distorted trigonal–bipyramidal coordination environment [VO2F2N]. A carboxylic acid functional group of the ligand stays in a neutral form and is involved in hydrogen bonding with solvent water molecules and VO2F2 − ions of adjacent molecules. The extended hydrogen-bonding network is responsible for the crystal packing in the structure.

Crystal structure of chlorido{tris[2-(isopropylsulfanyl)phenyl]phosphane-κ4 P,S,S′,S′′}nickel(II) trifluoromethanesulfonate

The complex cation of the title compound, [NiCl{P(C6H4-2-S-i-Pr)3}](CF3SO3), has a slightly distorted trigonal–bipyramidal coordination geometry in which three S atoms are located in the equatorial plane, and one P and one Cl atom in the apical positions. In the cation, there are two intramolecular C—H...S hydrogen bonds. In the crystal, there are some intermolecular C—H...O and C—H...F hydrogen bonds formed between the cation and the anion. The trifluoromethanesulfonate anion and one of the methyl groups are both disordered over two sets of sites with occupancies of 0.629 (17):0.371 (17) and 0.786 (14):0.214 (14), respectively.

μ2-Chlorido-chlorido(μ2-4-{[2-(diethylamino)ethyl]imino}pent-2-en-2-olato)bis(tetrahydrofuran-κO)cobalt(II)lithium

The crystal structure of the title compound, [CoLi(C11H21N2O)Cl2(C4H8O)2], has monoclinic symmetry and comprises one heterometallic binuclear complex molecule in the asymmetric unit. The Co2+ cation is bonded to one oxygen and two nitrogen atoms of a β-ketoiminato ligand and to two chlorido ligands, leading to a distorted trigonal-bipyramidal coordination sphere. One of the Cl ligands and the oxygen atom of the β-ketoiminato ligand are bridging to a Li+ cation, which is further bonded to oxygen atoms of two THF molecules. The resulting coordination sphere is distorted tetrahedral. In the crystal, weak intermolecular C—H...Cl hydrogen bonds are identified that link the complex molecules into a three-dimensional network structure.

Crystal structure of [{FeCl3}2(μ-PCHP)2] [PCHP = 1,3-bis(2-diphenylphosphanylethyl)-3H-imidazol-1-ium] with an unknown solvent

The crystal structure of the title compound, bis{μ-1,3-bis[2-(diphenylphosphanyl)ethyl]-1H-imidazole-κ2 P:P′}bis[trichloridoiron(III)], [Fe2Cl6(C31H31N2P2)2] or [{FeCl3}2(μ-PCHP)2] (PCHP = C31H31N2P2), consists of dinuclear complexes that are located about centres of inversion. The FeIII cation is in a distorted trigonal–bipyramidal coordination with three chloride ligands located in the trigonal plane and two P atoms of symmetry-related PCHP ligands occupying the axial positions. Within the centrosymmetric complex, a pair of intramolecular C—H...Cl hydrogen bonds between aromatic CH groups and chloride ligands are found. Individual complexes are linked into layers parallel to (\overline{1}01) by intermolecular C—H...Cl hydrogen bonds. No pronounced intermolecular interactions occur between these layers. This arrangement leaves space for disordered solvent molecules. Electron density associated with these additional solvent molecules was removed with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s).

Crystal structure and Hirshfeld surface analysis of aquabis(nicotinamide-κN1)bis(2,4,6-trimethylbenzoato-κO)zinc

The asymmetric unit of the title complex, [Zn(C10H11O2)2(C6H6N2O)2(H2O)], contains one half of the complex molecule, and the ZnIIcation and the water O atom lie on a twofold rotation axis. The ZnIIcation is coordinated by two carboxylate O atoms of the two symmetry-related 2,4,6-trimethylbenzoate (TMB) anions and by the water O atom at distances of 2.0311 (16) and 2.076 (2) Å to form a slightly distorted trigonal–planar arrangement, while the distorted trigonal–bipyramidal coordination sphere is completed by the two pyridine N atoms of the two symmetry-related monodentate nicotinamide (NA) ligands at distances of 2.2066 (19) Å in the axial positions. In the crystal, molecules are linkedviaintermolecular N—H...O and O—H...O hydrogen bonds withR22(12),R33(10) andR33(16) ring motifs, forming a double-column structure running along thec-axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (58.4%), H...C/C...H (20.3%) and H...O/O...H (18.3%) interactions.

Copper(II) bromide, nitrate and perchlorate complexes with sterically demanding N-(6-methylpyridin-2-yl)acetamide ligands

Functionalized acid amides are widely used in biology, medicine, environmental chemistry and many other areas. Among them, pyridine-substituted amides, in particular N-(pyridin-2-yl)acetamide and its derivatives, play an important role due to their excellent chelating properties. The donor properties of these ligands can be effectively modified by introducing electron-donating substituents (e.g. alkyl groups) into the heterocycle. On the other hand, substituents in the α-position of the pyridine ring can create steric hindrance, which significantly influences the coordination number and geometry. To achieve a better understanding of these effects, copper(II) complexes with sterically demanding N-(6-methylpyridin-2-yl)acetamide ligands (L) and monoanions of different size, shape and coordination ability have been chosen as model compounds. The crystal structures of three new compounds, bromidobis[N-(6-methylpyridin-2-yl-κN)acetamide-κO]copper(II) bromide, [CuBr(C8H10N2O)]Br, (I), aquabis[N-(6-methylpyridin-2-yl-κN)acetamide-κO]copper(II) dinitrate, [Cu(C8H10N2O)(H2O)](NO3)2, (II), and aquabis[N-(6-methylpyridin-2-yl-κN)acetamide-κO]copper(II) bis(perchlorate), [Cu(C8H10N2O)(H2O)](ClO4)2, (III), have been determined by single-crystal X-ray diffraction analysis. It has been shown that the presence of the 6-methyl group results in either a distorted square-pyramidal or a distorted trigonal–bipyramidal coordination geometry around the CuII centres instead of the typical octahedral geometry observed when the methyl substituent is absent or occupies any other position on the pyridine ring. Moreover, due to the steric hindrance provided by the L ligands, only the bromide ligand, the smallest of the series, enters into the first coordination sphere of the CuII ion in (I). In (II) and (III), the vacant coordination site of the CuII ion is occupied by a water molecule, while the nitrate and perchlorate anions are not involved in coordination to the metal centre. The structures of (I)–(III) are characterized by the presence of one-dimensional infinite chains formed by hydrogen bonds of the types N—H...Br [in (I)], N—H...O and O—H...O [in (II) and (III)] between the amide groups of the L ligands, the coordinated water molecules and the uncoordinated anions. The hydrogen-bonded chains are further interconnected through π–π stacking interactions between the pyridine rings of the L ligands, with approximate interplanar separations of 3.5–3.6 Å.