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.

Structure and Synthesis of Dihalogenodicyanoaurate Complexes [Ph3PR][Au(CN)2Hal2], Hal = Cl, R = Me, СH2Ph; Hal = Br, R = cyclo-C6H11; Hal = I, R = Ph

Interaction of organyltriphenylphosphonium halides with potassium dihalogenodicyanoaurates in water followed by recrystallization of reaction products from acetonitrile or DMSO has been used to synthesize gold(III) ionic complexes [Ph3PMe][Au(CN)2Cl2] (1), [Ph3PCH2Ph][Au(CN)2Cl2] (2), [Ph3PC6H11-cyclo][Au(CN)2Br2] (3), and [Ph4P][Au(CN)2I2] (4), which have been structurally characterized by the X-ray analysis method (CIF files CCDC No. 1901681 (1), 1912903 (2), 1912919 (3), 2048146 (4)). According to the X-ray data crystals 1–4 consist of centrosymmetric square-planar [Au(CN)2Hal2]– anions (the Au–Hal average bond lengths are 2.417(3) Å (1), 2.280(2) Å (2), 2.4203(13) Å (3), and 2.6035(10) Å (4); the Au–C average bond lengths are 2.06(2) Å (1), 2.010(7) Å (2), 2.009(7) Å (3,) and 1.998(6) Å (4)); the phosphorus atoms in organyltriphenylphosphonium cations have a slightly distorted tetrahedral coordination (the P–C bond lengths are 1.782(9)-1.806(8) Å (1), 1.788(4)-1.813(5) Å (2), 1.790(5)-1.813(5) Å (3) and 1.793(6)-1.799(5) Å (4)). The structural organization in crystals 2–4 is caused by the interionic С–H∙∙∙N≡C hydrogen bonds (C–HPh∙∙∙N≡C 2.56 Å (2); C–HPh∙∙∙N≡C 2.43–2.59 Å, C–Hcyclohexyl∙∙∙N≡C 2.47 Å (3), C–HPh∙∙∙N≡C 2.63 Å (4)), while in crystals 1 no significant interionic contacts are observed.

Tetrakis(dicyclohexylamido)zirconium(IV)

The reaction of ZrCl4 with three equivalents of LiNCy2 (Cy is cyclohexyl) resulted in the formation of tris(dicyclohexylamido)zirconium chloride and the title compound, [Zr(C12H22N)4]. The latter is isotypic with its cerium(IV) analogue and crystallizes with three independent molecules in the asymmetric unit. One molecule is located about a twofold rotation axis, and the other two on fourfold inversion axes. In each molecule, the ZrIV atom has a distorted tetrahedral coordination environment. The crystal under investigation was twinned by inversion in a 1:1 ratio.

Synthesis and Characterization of Three New Emissive Mononuclear CuI Heteroleptic Complexes with Functionalized 6-Cyano-2,2′-bipyridine Chelating Ligands

A new series of luminescent mononuclear CuI complexes with functionalized 6-cyano-2,2′-bipyridine chelating ligands, [Cu(xantphos)(cbpy)]ClO4 (1), [Cu(xantphos)(4,4’-Me2cbpy)]ClO4·CH2Cl2·H2O (2), and [Cu(POP)(cbpy)]ClO4·CH2Cl2 (3) (xantphos=4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; POP=bis(2-diphenylphosphinophenyl)ether; 4,4’-Me2cbpy=4,4’-dimethyl-6-cyano-2,2′-bipyridine; cbpy=6-cyano-2,2′-bipyridine) have been successfully prepared, and their structures and photophysical properties are investigated. Single crystal structures of the three complexes reveal a distorted tetrahedral coordination geometry around the CuI centres with the P atoms of diphosphane ligands and N donors of 2,2′-bipyridine ring. Luminescence measurements indicate that these CuI complexes display good emission properties both in the solution and solid states at room temperature, which can be well modulated through modifying the structure of 6-cyano-2,2′-bipyridine. It is shown that the introduction of two electron-donating methyl groups at the 4,4’-positions of the 6-cyano-2,2′-bipyridine is favourable to enhance the luminescence properties of the CuI complexes.

Crystal structure and Hirshfeld surface analysis of a zinc xanthate complex containing the 2,2′-bipyridine ligand

In the title compound, (2,2′-bipyridine-κ2 N,N′)bis(2-methoxyethyl xanthato-κS)zinc(II), [Zn(C4H7O2S2)2(C10H8N2)], the ZnII ion is coordinated to two N atoms of the 2,2′-bipyridine ligand and two S atoms from two 2-methoxyethyl xanthate ligands. The ZnII ion lies on a crystallographic twofold rotation axis and has distorted tetrahedral coordination geometry. In the crystal, molecules are linked by weak C—H...O hydrogen bonds, forming supramolecular chains propagating along the a-axis direction. Weak intramolecular C—H...S hydrogen bonds are also observed. The intermolecular contacts in the crystal were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are H...H (36.3%), followed by S...H/H...S (24.7%), C...H/H...C (15.1%), O...H/H...O (14.4%), N...H/H...N (4.1%) and C...C (2.9%).

SYNTHESIS AND STRUCTURE OF TRIPHENYLBUT-2-ENYL- AND TRIPHENYLMETOXYMETHYLPHOSPHONIUM HEXACHLOROZIRCONATES

Triphenylbut-2-enyl- (1a) and triphenylmetoxymethylphosphonium (1b) hexachlorozirconates have been synthesized by the reactions of zirconium tetrachloride with the triphenylalkylphosphonium chlorides in acetonitrile for the first time and characterized by the IR, NMR spectroscopy and X-ray analysis. The most intensive bands in IR spectra correspond to the valence vibrations of the CAr-H and the СAr-СAr bonds in the triphenylalkylphosphonium cations. The splitting of carbon atoms signals is observed due to the presence of 13C – 31P coupling. SSCC for carbon atoms directly connected with phosphorus are about 48–85 Hz. According to the X-Ray data, compound 1a crystallizes in the monoclinic crystal lattice (the P21/c space symmetry group). Hexachlorozirconate 1b forms the triclinic crystals belong to the P-1 space symmetry group. Crystals of compound 1a is characterized by the less dense molecular packing in the crystal lattice in comparison with compound 1b. Calculated densities for the structures 1a,b are 1.355 g/cm3 and 1.466 g/сm3, respectively. Structural organization of the complexes in crystals is caused by the formation of hydrogen bonds between chlorine atoms of the anion and hydrogens of phenyl and alkyl groups of the cations. The phosphorus atoms in the triphenylalkylphosphonium cations have distorted tetrahedral coordination (CPC 107.01(4)°-114.10(6)° for 1а, 107.38(9)°-112.06(7)° for 1b, the P-С bonds are 1.790(14)-1.865(14) Å for 1а, 1.7838(12)-1.8293(18) Å for 1b). In centrosymmetric octahedral anions [ZrCl6]2− (trans-ClZrCl 180°) the Zr-Cl distances are 2.4654(15)-2.4952(17) Å for 1а and 2.4641(14)-2.4711(12) Å for 1b.

A heterometallic Cd/Ag/Se complex incorporating 3-ferrocenyl-5-(2-pyridyl)pyrazolato (fcpp) ligands: synthesis and structure of [Cd2{Ag(SePh)}2(μ3-OH2)2(μ2,η3-fcpp)4]·2C3H6O

A self-assembly reaction of Cd(NO3)2 · 4H2O, 3-ferrocenyl-5-(2-pyridyl)-pyrazole (Hfcpp), [Ag(SePh)]n, and Et3N in a mixed acetone-water solvent resulted in the formation of a heterometallic complex [Cd2{Ag(SePh)}2 (μ3-OH2)2(μ2,η3-fcpp)4] · 2C3H6O (1) with a phenylselenolate ligand. The two cadmium and two silver centers are linked by four [μ2,η3-fcpp]− ligands and two μ3-OH2 water molecules. Each Cd atom is in a slightly distorted octahedral coordination environment, while each Ag atom shows a distorted tetrahedral coordination geometry, which is composed of two pyrazolyl nitrogen atoms, one selenium atom, and one oxygen atom.

Steric control of supramolecular association in structures of Zn(S2COR)2 with N,N′-bis(pyridin-4-ylmethyl)oxalamide

The crystal and molecular structures of the one-dimensional coordination polymer [Zn(S2COEt)2(4LH2)]n (1) and binuclear [Zn(S2COCy)2]2(4LH2) (2) are described, where 4LH2 is N,N′-bis(pyridin-4-ylmethyl)ethanediamide. In 1, the Zn(S2COEt)2 entities are linked by bidentate bridging 4LH2 ligands through the pyridyl-N atoms to generate a twisted supramolecular chain. As a result of monodentate xanthate ligands, the N2S4 donor set defines a distorted tetrahedral coordination geometry and, crucially, allows the participation of the non-coordinating sulfur atoms in supramolecular association. Thus, in the crystal amide-N–H···O(amide) and amide-N–H···S(thione) hydrogen bonds link chains into a three-dimensional architecture. The substitution of the ethyl group in the xanthate ligand with a cyclohexyl group results in very different structural outcomes. In 2, a binuclear molecule is observed with the coordination geometry for zinc being defined by chelating xanthate ligands and a pyridyl-N atom with the NS4 donor set defining a highly distorted geometry. In the molecular packing, amide-N–H···S(thione) hydrogen bonds stabilise a supramolecular chain along the a-axis and these are connected into a three-dimensional arrangement by methylene-C–H···O and methylene-C–H···π(pyridyl) interactions. The relative importance of the specified intermolecular interactions and weaker, contributing contacts has been revealed by an analysis of the calculated Hirshfeld surfaces of 1 and 2.

Crystal structures of two stilbazole derivatives: bis{(E)-4-[4-(diethylamino)styryl]-1-methylpyridin-1-ium} tetraiodidocadmium(II) and (E)-4-[4-(diethylamino)styryl]-1-methylpyridin-1-ium 4-methoxybenzenesulfonate monohydrate

The title molecular salts, (C18H23N2)2[CdI4], (I), and C18H23N2 +·C7H7O4S−·H2O, (II), are stilbazole, or 4-styrylpyridine, derivatives. The cation, (E)-4-[4-(diethylamino)styryl]-1-methylpyridin-1-ium, has a methyl group attached to pyridine ring and a diethyl amine group attached to the benzene ring. The asymmetric unit of salt (I), comprises one cationic molecule and half a CdI4 dianion. The Cd atom is situated on a twofold rotation axis and has a slightly distorted tetrahedral coordination sphere. In (II), the anion consists of a 4-methoxybenzenesulfonate and it crystallizes as a monohydrate. In both salts, the cations adopt an E configuration with respect to the C=C bond and the pyridine and benzene rings are inclined to each other by 10.7 (4)° in (I) and 4.6 (2)° in (II). In the crystals of both salts, the packing is consolidated by offset π–π stacking interactions involving the pyridinium and benzene rings, with centroid–centroid distances of 3.627 (4) Å in (I) and 3.614 (3) Å in (II). In the crystal of (II), a pair of 4-methoxybenzenesulfonate anions are bridged by Owater—H...Osulfonate hydrogen bonds, forming loops with an R 2 4(8) motif. These four-membered units are then linked to the cations by a number of C—H...O hydrogen bonds, forming slabs lying parallel to the ab plane.