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Vol 44, No 8 (2018)
- Year: 2018
- Articles: 7
- URL: https://journals.rcsi.science/1070-3284/issue/view/13325
Article
Formation of Polynuclear Cadmium Pivalates in Exchange Reactions
Abstract
The exchange reaction of CdCl2 ⋅ 2H2O with KPiv affords cadmium(II) trimethyl acetate complexes (K[Cd6(Piv)12Cl] ⋅ 2MeCN (I), [K2Cd3(Piv)8(H2O)6] (II), and [Cd(Piv)2(Н2О)2] (III) as a mixture with complex II and [K3Cd2(Piv)7(MeCN)2]n (IV) (HPiv is trimethylacetic acid). The exchange reaction of CdSO4 ⋅ 8/3H2O with Ba(Piv)2 makes it possible to obtain complex III in a quantitative yield. Complex III can also be isolated by the recrystallization of {Cd(Piv)2} from water. The recrystallization of complex III or {Cd(Piv)2} from MeCN affords hexanuclear complex [Cd6(Piv)12(MeCN)2] (V), which transforms into complex III upon recrystallization from water. All new compounds are characterized by the data of single-crystal X-ray diffraction analysis (CIF files CCDC no. 1572202–1572206), IR spectroscopy, and C,H,N analysis.
473-482
Magnetic Properties of Adducts of Trinuclear Heterometallic Complexes with Acetonitrile: Quantum Chemical Study
Abstract
Computational modeling (DFT UTPSSh/6-311++G(d,p)) of heterometallic complexes comprising the transition metal bis(chelate) as a linker with coordinated acetonitrile molecules and 2,6-di(pyrazolyl)pyridine iron complexes in the terminal moieties is performed. The variation of the central metal atom (Co, Ni) and donor centers (NH, O) in the linker makes it possible to find compounds capable of undergoing one- and two-step spin-crossover of the iron ions. The character of exchange interactions is shown to be determined by the properties of the bis(chelate) linker. The calculated energy and magnetic characteristics of the studied compounds allow one to regard them as candidates for the design of molecular electronics and spintronics devices.
483-488
Synthesis and Spin State of the Cobalt(II) Complexes with Substituted 2,6-Bis(pyrazol-3-yl)pyridine Ligands
Abstract
The direct template reactions afford the cobalt(II) complexes (I–III) with the hydroxy- and acetyl-substituted 2,6-bis(pyrazol-3-yl)pyridine ligands containing the phenyl and 4-tert-butylphenyl group in position 1. All compounds are isolated in the individual state and characterized by elemental analysis and NMR spectroscopy. The X-ray diffraction data obtained for crystals of compound I (СIF file CCDC 1577238) and the data for solutions (using the proposed approach to analysis of paramagnetic NMR shifts on the basis of quantum chemical calculations) show that in the complexes the metal ion exists in the high-spin state (S = 3/2) and undergoes no temperature-induced spin transition in a temperature range of 120–300 K.
489-495
Unexpected Product of the Reaction of Iron(II) Dichloroclathrochelate with the [Fe2(μ-S)2(CO)6]2– Cluster Dianion: Synthesis and X-ray Diffraction Structure of the First Cage Complex with Thiol Groups Inherently Bonded to a Macrobicyclic Framework
Abstract
An attempt to prepare a hybrid clusteroclathrochelate by nucleophilic substitution of iron(II) dichloroclathrochelate by substitution of its chlorine atoms with the [Fe2(μ-S)2(CO)6]2– cluster dianion as a nucleophilic agent generated in situ by the reduction of Fe2(μ-S2)(CO)6 with lithium triethylborohydride unexpectedly gave the macrobicyclic complex with two inherent thiol groups as the single clathrochelate product. Obviously, the initial iron-sulfide cluster underwent a complete decomposition during the reaction, thus acting only as a source of HS– and S2– anions. The composition and the structure of the complex obtained were confirmed by elemental analysis, MALDI-TOF mass spectrometry, 1H and 13C{1H} NMR spectroscopy, and single crystal X-ray diffraction (CIF file CCDC 1585112). The encapsulated iron(II) ion is located at the centre of its FeN6 coordination polyhedron possessing the geometry intermediate between a trigonal prism (the distortion angle φ = 0°) and a trigonal antiprism (φ = 60°) with φ ≈ 25°; the height of this polyhedron is 2.33 Å. The presence of two thiol groups in the vicinal positions of the same ribbed moiety of the macrobicyclic molecule substantially affects the crystal packing of the molecular crystal containing clathrochelate dimers formed by four hydrogen bonds of two types (i.e., two S–H···O and two S–H···N bonds). The obtained cage complex and its deprotonated forms seem to be promising cis-disulfide bridging or chelating ligand synthons for the synthesis of new types of polynuclear complexes and coordination polymers as well.
496-501
Mono- and Binuclear Chloride and Bromide Complexes of Bi(III) with Double-Charged Cations Based on Pyridine: Syntheses and Crystal Structures
Abstract
The reactions of solutions obtained by the reactions of Bi2O3 with 2 M HCl and HBr with the salts containing bis(pyridyl)alkane cations afford mono- and binuclear halide complexes (Py-(CH2)3-Py)3[Bi2Br9]2 (I), (H3O)(Py-(CH2)4-Py)[BiCl6] ⋅ 3H2O (II), and (H2Bpp)2[Bi2Br10] ⋅ 2H2O (Bpp is 1,3-bis(4-pyridyl)propane) (III). The structures of the synthesized compounds are determined by X-ray diffraction analysis (СIF files CCDC no. 1583338–1583340, respectively).
502-506
Iron(II) Bis-α-Benzyldioximate Complexes with 3- and 4-Pyridine Hemiacetals as Axial Ligands: Synthesis, Structure, and Physicochemical Properties
Abstract
The coordination compounds [Fe(DfgH)2(HL1)2] and [Fe(DfgH)2(HL2)2], where DfgH = is the α-benzyldioxime monoanion, HL1 = 3-pyridine hemiacetals: methoxy(pyridin-3-yl)methanol (I), ethoxy(pyridin-3-yl)methanol (II); HL2 = 4-pyridine hemiacetal: methoxy(pyridin-4-yl)methanol (III), ethoxy(pyridin-4-yl)methanol (IV), and propoxy(pyridin-4-yl)methanol (V), were synthesized and studied by X-ray diffraction and IR and Mössbayer spectrosopy. According to X-ray diffration data (CIF files CCDC 1578217–1578221 for I–V, respectively), all of these Fe(II) complexes are molecular. The metal coordination polyhedron is an octahedron formed by four equatorial nitrogen atoms of two monodeprotonated α-benzyldioxime residues coordinated in the bidentate chelating fashion and by two axial nitrogen atoms of two neutral 3- or 4-pyridine hemiacetal molecules coordinated in the monodentate fashion. The DfgH– ligands in complexes I–V are joined by intramolecular O–H···O hydrogen bonds to form a pseudomacrocyclic system. The ligands HL1 and HL2 are generated in the reaction of the corresponding alcohols with 3- or 4-pyridinecarboxaldehyde. The IR and Mössbauer spectra of the products were studied. The Mössbauer spectral parameters of compounds I–V correspond to low-spin iron(II) ions.
507-517
Chemisorption Synthesis of the Ion-Polymeric Heteronuclear Gold(III)–Bismuth(III) Complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n Based on [Bi2{S2CN(C3H7)2}6]: 13C MAS NMR, Supramolecular Structure, and Thermal Behavior
Abstract
Chemisorption synthesis on the basis of the binuclear compound [Bi2{S2CN(C3H7)2}6] (I) and preparative isolation of the ion-polymeric heteronuclear gold(III)–bismuth(III) complex ([Au{S2CN(C3H7)2}2]3[Bi2Cl9])n (II) are carried out. Compounds I and II are characterized in comparison by IR spectroscopy and 13C CP-MAS NMR. According to the X-ray diffraction analysis data (CIF file CCDC no. 1407705), the cationic moiety of compound II exhibits an unusually complicated supramolecular structure including six isomeric noncentrosymmetric complex cations [Au{S2CN(C3H7)2}2]+ (hereinafter A–F) and two binuclear anions [Bi2Cl9]3– as conformers. The isomeric gold(III) cations perform various structural functions. Owing to pair secondary interactions Au···S, cations B, C, E, and F form centrosymmetric ([E···E], [F···F]) and noncentrosymmetric ([B···C]) binuclear aggregates [Au2{S2CN(C3H7)2}4]2+, whereas cations A and D are not involved in dimerization. The strongest secondary Au···S bonds are formed between the binuclear and mononuclear cations, resulting in the formation of supramolecular cation-cationic polymer chains of two types: (⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅A⋅⋅⋅[B⋅⋅⋅C]⋅⋅⋅)n and (D⋅⋅⋅[E⋅⋅⋅E]⋅⋅⋅D⋅⋅⋅[F⋅⋅⋅F]⋅⋅⋅])n. In both chains, the gold atoms of the binuclear cations are characterized by a distorted octahedral coordination [S6], whereas in the mononuclear cations the gold atoms retain the square environment [S4]. The cation-anionic interactions are provided by secondary bonds Cl⋅⋅⋅S involving the terminal chlorine atoms of isomeric [Bi2Cl9]3– and the sulfur atoms of the binuclear cations [Au2{S2CN(C3H7)2}4]2+. The character of the thermal behavior of compounds I and II is studied by simultaneous thermal analysis with the identification of intermediate and final products of the thermal transformations. The thermolysis of compound I at 193–320°C is accompanied by the formation of Bi2S3 with an impurity of reduced metallic bismuth particles. The final products of the thermal transformations of compound II are reduced elemental gold and Bi2O3, and the thermal transformation intermediates are BiCl3 and Bi2S3.
518-531