Heterospin complexes of polynuclear Ni<Superscript>II</Superscript> compounds containing hexafluoroacetylacetonate and pivalate ligands with nitroxides

The heterospin mixed-ligand complex [Ni₆(OH)₄Piv₄(hfac)₄(NIT-Ph)₂] (1) (NIT-Ph is 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide, hfac is hexafluoroacetylacetonate, and Piv is pivalate) was synthesized. The method for the synthesis of complex 1 is based on the replacement of acetone molecules in the hexanuclear complex containing the hexafluoroacetylacetonate and pivalate ligands [Ni₆(OH)₄Piv₄(hfac)₄(Me₂CO)₄] by NIT-Ph molecules. Two monodentate NIT-Ph molecules replace four acetone molecules, because the coordination of the O atom of the nitroxide group results in the blocking of one of the positions in the coordination environment of Ni^II the access to which is hindered by the phenyl ring of NIT-Ph. As a result, these ions are in a square-pyramidal environment unusual of Ni^II. In the low-temperature range, the dependence of the magnetization of 1 on the magnetic field is described by the Brillouin function. The reaction of [Ni₆Piv₄(hfac)₄(OH)₄(Me₂CO)₄] with the nitronyl nitroxide radicals 4,4,5,5-tetramethyl-2-(4-pyridyl)-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide (NIT-p-Py) or 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide (NIT-Iz) containing the pyridine or 1-methylimidazol-5-yl substituent, respectively, in the side chain is accompanied by the decomposition of the polynuclear fragment and affords the mononuclear complexes Ni(hfac)₂(NIT-p-Py)₂ and Ni(hfac)₂(NIT-Iz)₂, respectively. The reaction of 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihyd-ro-1H-imidazol-1-oxyl (Im-Iz), which is the imine analog of NIT-Iz, with [Ni₆Piv₄(hfac)₄(OH)₄(Me₂CO)₄] afforded the decanuclear complex [Ni₁₀(OH)₈Piv₄(hfac)₈(Im-Iz)₂(H₂O)₆]. The molecular and crystal structures of all heterospin compounds were determined, and the magnetic properties of all compounds were investigated in the 2–300 K temperature range.     

Aggregates of the [GaCl<Subscript>4</Subscript>]<Superscript>−</Superscript> anion and the [Ga(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>(NCS)<Subscript>3</Subscript>] complex with 18C6

The complex formation in the system GaCl₃-ROH-MNCS-18K6 is considered (ROH = MeOH, EtOH; M = Na, K; 18C6 is 1,4,7,10,13,16-hexaoxocyclooctadecane). Two modifications of [Na(18C6)][GaCl₄], namely, aggregates [Na(18C6)][GaCl₄](MeOH)_0.9(EtOH)_1.1 and [Ga(H₂O)₃(NCS)₃] · 18C6, are synthesized and identified. The ⁷¹Ga NMR (solutions) and X-ray diffraction studies showed that the compositions and structures of the title compounds are determined by the ratio of the competing acido ligands (Cl^? and NCS^?) in the reaction solution.     

Synthesis and characterization of coordination polymers prepared from Cu<Superscript>II</Superscript> and Ni<Superscript>II</Superscript> cyclam perchlorate and carmosine

Reaction of [Cu^II(cyclam)](ClO₄)₂ or [Ni^II(cyclam)](ClO₄)₂ in DMF with aqueous 4-hydroxy-3-(4-sulfonato-1-naphthylazo)naphthalen-1-sulfonate disodium salt (carmoisine) yielded coordination polymers {[Cu^II(cyclam)](carmoisine dianion)(H₂O)₅}n and powder {[Ni^II(cyclam)](carmoisine dianion)}_n, respectively (cyclam = 1,4,8,11-tetrazacyclotetradecane). They were characterized by powder X-ray diffraction, IR, Raman spectrometry and TGA.     

Heterospin mixed-ligand heterotrinuclear Co<Superscript>II</Superscript>, Gd<Superscript>III</Superscript>, Co<Superscript>II</Superscript> complex with nitronyl nitroxide

A method was developed for the synthesis of mixed-metal heterospin compounds with the direct coordination of the nitroxide fragment based on the replacement of acetonitrile molecules in the heterotrinuclear complex [Co₂Gd(NO₃)Piv₆(CH₃CN)₂] with nitroxide molecules. The molecular and crystal structure of the heterospin mixed-ligand heterotrinuclear Co^II, Gd^III, Co^II complex [Co₂Gd(NO₃)Piv₆(NIT-Me)₂], where NIT-Me is stable nitronyl nitroxide, was established. The magnetic properties of this complex were investigated in the temperature range of 2–300 K. The coordination of nitroxide groups to Co^II ions is responsible for strong exchange interactions between the unpaired electrons in the exchange clusters {>-·O-Co^II}, resulting in the virtually complete spin coupling between each coordinated >N-·O group and one of the unpaired electrons of each Co^II ion at temperatures below 200 K. Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1742–1745, September, 2007.     

Capping [H<Subscript>8−n</Subscript>Ni<Subscript>42</Subscript>C<Subscript>8</Subscript>(CO)<Subscript>44</Subscript>]<Superscript>n−</Superscript> (n = 6, 7, 8) Octa-carbide Carbonyl Nanoclusters with [Ni(CO)] and [CuCl] Fragments

The reactions of [Ni₁₆(C₂)₂(CO)₂₃]^4? and [Ni₃₈C₆(CO)₄₂]^6? with CuCl afforded mixtures of the previously reported [HNi₄₂C₈(CO)₄₄(CuCl)]^7? bimetallic octa-carbide cluster and the new [HNi₄₃C₈(CO)₄₅]^7? and [HNi₄₄C₈(CO)₄₆]^7? homo-metallic octa-carbides. The three species have very similar properties resulting always in co-crystals such as [NMe₄]₇[HNi_42+2xC₈(CO)_44+2x(CuCl)_1?x]·6.5MeCN (x = 0.14) (86% [HNi₄₂C₈(CO)₄₄(CuCl)]^7?, 14%[HNi₄₃C₈(CO)₄₅]^7?/[HNi₄₄C₈(CO)₄₆]^7?) and [NMe₄]₇[HNi_42+2xC₈(CO)_44+2x(CuCl)_1?x]·5.5MeCN (x = 0.30) (70% [HNi₄₂C₈(CO)₄₄(CuCl)]^7?, 30% [HNi₄₃C₈(CO)₄₅]^7?/[HNi₄₄C₈(CO)₄₆]^7?). The new homo-metallic octa-carbides can be obtained free from the Ni–Cu octa-carbido cluster by reacting [Ni₁₀(C₂)(CO)₁₆]^2? in thf with a stoichiometric amount of CuCl, and crystals of [NMe₄]₆[H₂Ni_43+xC₈(CO)_45+x]·6MeCN (x = 0.72), which contain [H₂Ni₄₄C₈(CO)₄₆]^6? (72%) and [H₂Ni₄₃C₈(CO)₄₅]^6? (28%), have been obtained. Despite the different charges and compositions, these anions display almost identical structures, which are also closely related to those previously reported for the bimetallic Ni–Cd octa-carbido clusters [Ni_42+xC₈(CO)_44+x(CdCl)]^7? and [HNi_42+xC₈(CO)_44+x(CdBr)]^6?. Indeed, all these clusters are based on the same Ni₄₂C₈ cage decorated by miscellaneous [CdX]⁺ (X = Cl, Br), [CuCl] and [Ni(CO)] fragments.     

Polynuclear Ni<Superscript>II</Superscript> and Co<Superscript>II</Superscript> hexafluoroacetylacetonates

Hydrolysis of [M₄(hfac)₄(MeO)₄(MeOH)₄] (М = Сo, Ni and hfac is hexafluoroacetylaceton ate) is a convenient way of obtaining polynuclear complexes [Ni₇(hfac)₆(OH)₈(H₂O)₆]?2H₂O, [Co₁₂(hfac)₁₀(OH)₁₄(H₂O)₈]?2H₂O?2MePh, [Co₁₂(hfac)₁₀(OH)₁₄(H₂O)₄(Me₂CO)₄]?3PhMe, and [Co₁₂(hfac)₁₀(OH)₁₄(H₂O)₆(Me₂CO)₂]?2H₂O?2Me₂CO, whose structures were confirmed by X-ray analysis.     

New antiferromagnetic tetranuclear pivalate complex containing Fe<Superscript>III</Superscript> and Fe<Superscript>II</Superscript> atoms

The interaction of [K₂Fe^III ₄(O)₂(OOCCMe₃)₁₀(HOOCCMe₃)₂(H₂O)₂]_n with 2-pyridinecarboxaldehyde results in a mixed-valence complex Fe^IIFe^III ₃(μ₃-O)₂(μ₂-OOCCMe₃)₇L₂··2.5MeCN·3H₂O (L = 2-NC₅H₄COOH_0.75K_0.25). The structure of the complex was established by X-ray analysis. The magnetic properties of the complex were studied. Dedicated to Academician A. L. Buchachenko on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2145–2148, September, 2005.     

Synthesis and study of N-(1-phenylethylidene)-N-(4H-1,2,4-triazol-4-yl)amine, N′-(4H-1,2,4-triazol-4-yl)benzamidine, and cobalt(ii), nickel(ii), and copper(ii) complexes based on these ligands

Methods were developed for the synthesis of complexes of Co^II, Ni^II, and Cu^II nitrates and chlorides with N-(1-phenylethylidene)-N-(4H-1,2,4-triazol-4-yl)amine (L¹) and N′-(4H-1,2,4-triazol-4-yl)benzamidine (L²). The Co^II and Ni^II complexes have a linear trinuclear structure. The Cu^II complexes are polynuclear. Both ligands are coordinated to the metal ions in a bidentate-bridging mode through the N(1) and N(2) atoms of the heterocycle. In all compounds, the coordination polyhedron can be described as a distorted octahedron. The molecular and crystal structure of the [Ni₃(L¹)₆(EtOH)₂(H₂O)₄](NO₃)₆·2EtOH·4H₂O complex was established.     

Polynuclear Co<Superscript>II,III</Superscript> compounds containing pivalate and hexafluoroacetylacetonate anions in the ligand shell and their heterospin complexes with nitroxides

The reaction of cobalt(II) bis(hexafluoroacetylacetonate) (Co(hfac)₂) with polynuclear Co^II or Co^II,III pivalates, [Na₂Co₄(OH)₂(Piv)₈(EtOH)₄], [Co₂(H₂O)(Piv)₄(HPiv)₄], and [Co^III ₂Co^II ₄(O)₂(Piv)₁₀(H₂O)(THF)₃]·1.5THF (Piv is pivalate), affords the previously unknown cobalt compounds containing coordinated Piv and hfac anions in the ligand shell, viz., the dinuclear complex [Na₂Co₂(hfac)₄(Piv)₂(Me₂CO)₄], the tetranuclear complex [Co₄(Piv)₄(hfac)₂(OH)₂(HPiv)₄]·HPiv, and the tetradecanuclear complex [Co^III ₄Co^II ₁₀(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(HPiv)₄]·2HPiv·2H₂O·3C₇H₁₆, respectively. The tetradecanuclear complex has an unusual ability to precipitate nitroxides from solution, due to which the following new heterospin crystalline solids were synthesized: [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(H₂O)₂(HPiv)₂]·2NIT-Me·2HPiv·C₆H₁₄, [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(HPiv)₄]·2NIT-Et·2CHCl₃, [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(HPiv)₄]·2NIT-Ph·2C₆H₁₄, [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(HPiv)₄]·2L¹·2CH₂Cl₂, and [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(HPiv)₄]·2L²·C₆H₁₄, where NIT-Me, NIT-Et, and NIT-Ph are 2-imidazoline nitroxides, L¹ is 3-imidazoline nitroxide, and L² is di-tert-butyl nitroxide. The X-ray diffraction study showed that the efficient binding of nitroxides is provided by the specific arrangement of the μ₃-OH groups in the [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(HPiv)₄] molecule, which is spatially complementary for the formation of numerous hydrogen bonds with the nitroxide moiety. The coordination of the nitroxides by terminal cobalt ions is impossible because this would lead to the impermissible spatial overlap of the atoms of the tetradecanuclear moiety and the nitroxide. The spatial characteristics of only NIT-H containing the H atom in position 2 of the 2-imidazoline ring are suitable for the direct coordination of the nitroxide, which made it possible to synthesize the complex [Co₁₄(Piv)₁₀(hfac)₄(OH)₁₄(O)₂(H₂O)₄(NIT-H)₂]·4HPiv·2H₂O.     

Increasing the π–π Interactions in Trinuclear NiII3 Triplesalophen Complexes

The new triplesalophen ligand H₆kruse^Br was synthesized as a variation of the triplesalophen ligands H₆baron^R by replacing a phenyl by a methyl group at the terminal ketimine in order to allow closer contacts of trinuclear complexes due to less steric hindrance by the smaller methyl group. The ligand H₆kruse^Br was used to synthesize the trinuclear complex [(kruse^Br)Ni^II₃], which is insoluble in organic solvents despite the coordinating solvent pyridine. Recrystallization from pyridine results in the complex [(kruse^Br){Ni₂(Ni(py)₂)}], which was characterized by single‐crystal X‐ray diffraction. Two Ni^II ions are four‐coordinate by the salophen‐like subunits while the third Ni^II ion is six‐coordinate by two additional pyridine donors. The analysis of the molecular and crystal structure in comparison to that of Ni^II₃ complexes of (baron^R)^6– reveals that the methyl group in [(kruse^Br){Ni₂(Ni(py)₂)}] results in less ligand folding and in closer contact distance of two Ni^II₃ complexes by π–π interactions of 3.2 Å. This indicates that trinuclear complexes of H₆kruse^Br are more suitable than complexes of H₆baron^R as molecular building blocks for the anticipated synthesis of nonanuclear single‐molecule magnets.     

Replacement of carboxylate bridges in polynuclear nickel pivalates with 2-hydroxy-6-methylpyridine anions

The reaction of 2-hydroxy-6-methylpyridine (HL, 1) with nonanuclear nickel trimethyl-acetate Ni₉(OH)₆(OOCCMe₃)₁₂(HOOCCMe₃)₄ (2) in MeCN with a ratio M: L = 1: 1 under mild conditions (20 °C, 15 min) led to degradation of the metal core to form the hexanuclear complex (HL)₂(μ ₂-HL)₂Ni₆(μ₃-OH)₂(μ₂-H₂O)₂(μ-OOCCMe₃)₈(η-OOCCMe₃)₂ (3). Further heating of 3 in acetonitrile at 80 °C for 4 h afforded the (HL)Ni₆(μ ₃-OH)(μ₃,η²-L)₃(μ,η²-L)(μ₃-L)(μ ₃-OOCCMe₃)(μ-OOCCMe₃)₄(η²-OOCCMe₃) complex. The reaction with the use of a 2: 1 THF-EtOH mixture instead of acetonitrile at 50 °C gave the decanuclear complex [Ni₁₀(μ ₃-O)₂(μ₃-OH)₄(μ-OOCCMe₃)₆(μ₃,η ²-L)₆(EtOH)₆](H₂O)₂, which is also produced from compounds 1 and 2 in ethanol. The structures of the resulting complexes were established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 908–917, May, 2007.     

Synthesis,crystal structure,and properties of a novel coordination polymer constructed from a trinickel string core of [Ni<Subscript>3</Subscript>(Dpa)<Subscript>4</Subscript>]<Superscript>2+</Superscript> and pyrazine-2,3-dicarboxylate

A novel 1D coordination polymer constructed from the trinickel cluster [Ni₃(Dpa)₄]²⁺ and pyrazine-2,3-dicarboxylate (Pzdc), [Ni₃(Dpa)₄(Pzdc)] _n , where Dpa is 2,2′-dipyridylamine anion, was synthesized and characterized by X-Ray, IR, elemental analysis, and fluorescence and TG analysis. The axial bridging ligand led to the change in Ni-Ni distances and fluorescence property compared with those for [Ni₃(Dpa)₄Cl₂], indicating that the axial modification can tune the structural parameters and properties.     

Synthesis and spectral characterization of macrocyclic Ni<Superscript>II</Superscript> complexes derived from various diamines,Ni<Superscript>II</Superscript> perchlorate and 1,4-bis(2-carboxyaldehydephenoxy)butane

Six new macrocyclic complexes were synthesized by reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane with various diamines. Then, their nickel(II) perchlorate complexes were synthesized by the template effect by reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane, Ni(ClO₄)₂ · 6H₂O and various diamines. The metal-to-ligand ratio of Ni^II metal complexes was found to be 1:1. The compounds are coordinated to the central metal as tetradentate O₂N₂ ligands The Ni^II complexes are proposed to exhibit tetrahedral geometry. Ni^II metal complexes are 1:2 electrolytes as shown by their molar conductivities (Λ_M) in DMF (dimethyl formamide) at 10⁻³ m. The structure of Ni^II metal complexes is proposed from elemental analysis, f.t.-i.r., u.v.-vis., magnetic susceptibility measurements, molar conductivity measurements and mass spectra.     

Heteronuclear 3 d/DyIII Coordination Clusters as Catalysts in a Domino Reaction

Three isoskeletal tetranuclear coordination clusters with general formula [M^II₂Dy^III₂L₄(EtOH)₆](ClO₄)₂?2 EtOH, (M=Co, 1 ; M=Ni, 2 ) and [Ni^II₂Dy^III₂L₄Cl₂(CH₃CN)₂]?2 CH₃CN ( 3 ), have been synthesized and characterized. These air‐stable compounds, and in particular 3 , display efficient homogeneous catalytic behavior in the room‐temperature synthesis of trans‐4,5‐diaminocyclopent‐2‐enones from 2‐furaldehyde and primary or secondary amines under a non‐inert atmosphere.     

Synthesis and Structural Characterization of a Binuclear Mixed‐Ligand (Salicylate and N,N‐diethylnicotinamide) Nickel(II) Complex,Its Magnetic Properties. [Ni2(µ‐Sal)4(Dena)2]H2O

The title complex of [Ni₂(µ‐Sal)₄(Dena)₂]H₂O, [( µ‐tetrakissalicylato‐κ‐O,O)(bis‐N,N‐diethylnicotinamide‐κ‐N)(binickel(II))]hydrate, C₄₈H₅₂Ni₂N₄O₁₆, has been synthesized and explained as structural using some elemental analysis, FT‐IR spectra, UV‐Vis reflectance, magnetic measurements, thermal analysis and x‐ray diffraction methods. The analysis results showed that the unit cell of complex includes two molecules Ni^II cation, four molecules salicylates as bridge and two molecules N,N‐diethylnicotinamide ligands, also there is one molecule hydrated aqua. The compound crystallizes in the monoclinic space group P2₁/c with the following unit‐cell parameters: a =13.6776(6) Å, b =10.5238(3) Å, c =21.8165(9), α=90.00°, β=126.546(3)°, γ=90.00º and Z=2. The compound [Ni₂(µ‐Sal)₄(Dena)₂]H₂O is a typical paddle‐wheel complex structure. Two Ni^II ions are bridged by four salicylate ligands (O2, O2ⁱ, O3, O3ⁱ, O5, O5ⁱ, O6 and O6ⁱ) using a µ‐COO^? coordination mode [symmetry code: (i) 1‐x, 1‐y, 1‐z]. Each Ni^II also coordinates to one nitrogen atom (N1 and N1ⁱ) from one N,N‐diethylnicotinamide ligand molecule in the axial position. The complex has strong paramagnetic properties.     

A Systematic Exploration of Nickel–Pyrazolinato Chemistry with Alkali Metals: New Cages From Serendipitous Assembly

The preparation and properties of fourteen novel paramagnetic [Ni^II_x] aggregates bridged by pivalate, pyrazolinolate and in most cases hydroxide are reported. A rich structural diversity has been achieved by changing the nature of the alkali of the base used during the synthesis, leading to the nuclearities [Ni^II₄Na^I₄] ( 2, 3, 4 ), [Ni^II₅Na^I₄] ( 5, 6, 7 ), [Ni^II₅Li^I₆] ( 8 ), [Ni^II₈M^I₂] (M=K ( 9, 10 ), Rb ( 11, 12 ), Cs ( 13, 14 ) and [Ni^II₈] ( 15 ). All compounds have been characterised by single‐crystal Xray diffraction; however, full crystallographic details are given only for the representative molecules [Ni₄Na₄(fpo)₄(piv)₈(Hpiv)₈] ( 2 ), [Ni₅Na₄(OH)₂(mpo)₄(piv)₈(Hpiv)₂(MeCN)₂] ( 5 ), [Ni₅Li₆(OH)₂(fpo)₂(piv)₁₂(Hpiv)₄] ( 8 ), [Ni₈K₂(OH)₄(ppo)₄(piv)₁₀(Hppo)₂(Hpiv)₂(MeCN)₂] ( 9 ), [Ni₈Rb₂(OH)₄(ppo)₄(piv)₁₀(Hppo)₂(Hpiv)₂(MeCN)₂] ( 11 ), [Ni₈Cs₂(OH)₄(ppo)₄(piv)₁₀(Hppo)₂(Hpiv)₂(MeCN)₂] ( 13 ) and [Ni₈(OH)₄(mpo)₂(PhCH₂CO₂)₁₀(Hmpo)₈] ( 15 ). Variable‐temperature bulk magnetisation measurements have been performed for each type of complex. The [Ni^II₄Na^I₄] clusters show intramolecular antiferromagnetic coupling and a spin ground state of S=0. Complexes of the type [Ni^II₅Na^I₄] also display antiferromagnetic superexchange, leading to an S=1 spin ground state. The molecule with nuclearity [Ni^II₅Li^I₆], in contrast, exhibits ferromagnetic interactions, resulting in the presence of low energy states with high multiplicity, and a spin ground state S>1. The [Ni^II₈M^I₂] and [Ni^II₈] clusters have the same topology of spin carriers, which display predominantly antiferromagnetic interactions to yield a diamagnetic ground state. The coupling within these octanuclear Ni^II clusters is rationalised in terms of the nature of the Ni‐O‐Ni angles within the core.     

Synthesis and crystal structure of hexakis(isothiocyanato)erbium(III) thiocyanate bis(18-crown-6)dipotassium bis[(18-crown-6)ethanolpotassium]

A new complex compound, [K₂(18-crown-6)₂[K(18-crown-6)(EtOH)]₂[Er(NCS)₆](SCN) (I), was synthesized and its crystal structure was studied by X-ray diffraction. In this work, the synthes and X-ray difraction stady of the crystals of a new complex, hexakis (isothiocyanato) erbiu(III) thiocyanate bis(18-crown-6) dipotassium bis(18-crown-6) ethanolpotassium], [K₂(18-crown-6)₂][K(18-crown-6)(ETON)]₂[Er(NCS)₆(SCN)(I)] are described. In crystal I, the alternating [Er(NCS)₆]^3? anions and binuclear complex cation [K(18-crown-6)₂]²⁺ from infinite chains via the F-S bonds, while two complex cations [K(18-crown-6)(ETON)]⁺ and the statistically disordered SCN^? anion between them are linked by the hydragen bonds O-H…S and O-H…N. Complex I contains the host-guest complex cations [K₂(18-crown-6)₂)]²⁺ and [K(18-crown-6)(ETON)]⁺ [1]. The alternating octabedral [Er(NCS)₆]^3? anions and binuclear complex cations [K₂(18-crown-6)₂]²⁺of crystal I form infinite chains via the K-S bonds, while two complex cations [K(18-crown-6)(EtOH)]⁺ and the statistically disordered SCN^? anion lying between them are linked by interionic hydrogen bonds O-H…S and O-H…N. Complex I contains the host-guest complex cations [K₂(18-crown-6)₂]²⁺ and [K(18-crown-6)(EtOH)]⁺ [1].     

Zinc(II) and Nickel(II) Complexes Based on Schiff Base Ligands: Synthesis,Crystal Structure,Luminescent and Magnetic Properties

Three new phenolate oxygen bridged transition metal complexes [Zn₃(HL¹)₃(μ₃‐CH₃O)]·(ClO₄)₂(H₂O)₃ ( 1 ), [Ni₂(HL¹)₂(μ_1,1‐N₃)(o‐vanillin)]·H₂O ( 2 ), [Ni₃(HL²)₂(PhCOO)₂(PhCOOH)₂(EtOH)₂] ( 3 ) have been synthesized by metal ions and potentially multidentate Schiff base ligands (H₂L¹ = 2‐((1‐hydroxy‐2‐methylpropan‐2‐ylimino) methyl)‐6‐methoxyphenol; H₃L² = (E)‐1‐((2‐hydroxy‐3‐methoxy‐benzylidene)amino)ethane‐1,2‐diol). All the three complexes 1 , 2 , and 3 have been characterized by elemental analysis, FT‐IR spectroscopy, and single‐crystal X‐ray diffraction studies. Crystal structures reveal that complex 1 is a trinuclear incomplete cubane‐like zinc cluster whereas complex 2 is a dinuclear nickel complex bridged by azide, and compound 3 is a trinuclear nickel complex. The luminescent property for complex 1 and magnetic behaviors for complexes 2 and 3 have been investigated.     

Structural Investigation of Small Nickel-Ethanol Clusters Using Vibrational Spectroscopy in a Molecular Beam

The structural identification of small nickel clusters with ethanol can help to understand fundamental steps for heterogenous catalysis. We investigate the rows [Ni_x(EtOH)₁]⁺ with x=1–4, and [Ni₂(EtOH)_y]⁺ with y=1–3 via IR photodissociation spectroscopy in a molecular beam experiment. Analyzing the CH- and OH-stretching frequencies and comparing these experimental results with density functional theory (DFT) calculations on the PW91/6-311+G(d,p) level leads to the identification of intact motifs for all clusters and hints for C−O cleavage of the ethanol in two particular cases. Furthermore, we analyze the effects of frequency shifts with the increasing clusters sizes using the results of natural bond orbitals (NBO) analyses and an energy decomposition method.     

Complex formation of maleic acid with the Zn<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> in aqueous solution

The process of complex formation of maleic acid (H₂L) with the ions Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO₃). The moieties ZnL, CoL, NiL, NiL ₂ ^2? , CuL, and CuL ₂ ^2? were detected and their stability constants were determined.