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A new indium precursor, namely, indium(II) chloride, was tested as a precursor in the synthesis of ternary Ag−In−S and quaternary Ag−In−Zn−S nanocrystals. This new precursor, being in fact a dimer of Cl2In−InCl2 chemical structure, is significantly more reactive than InCl3, typically used in the preparation of these types of nanocrystals. This was evidenced by carrying out comparative syntheses under the same reaction conditions using these two indium precursors in combination with the same silver (AgNO3) and zinc (zinc stearate) precursors. In particular, the use of indium(II) chloride in combination with low concentrations of the zinc precursor yielded spherical-shaped (D = 3.7−6.2 nm) Ag−In−Zn−S nanocrystals, whereas for higher concentrations of this precursor, rodlike nanoparticles (L = 9−10 nm) were obtained. In all cases, the resulting nanocrystals were enriched in indium (In/Ag = 1.5−10.3). Enhanced indium precursor conversion and formation of anisotropic, longitudinal nanoparticles were closely related to the presence of thiocarboxylic acid type of ligands in the reaction mixture. These ligands were generated in situ and subsequently bound to surfacial In(III) cations in the growing nanocrystals. The use of the new precursor of enhanced reactivity facilitated precise tuning of the photoluminescence color of the resulting nanocrystals in the spectral range from ca. 730 to 530 nm with photoluminescence quantum yield (PLQY) varying from 20 to 40%. The fabricated Ag−In−S and Ag−In−Zn−S nanocrystals exhibited the longest, reported to date, photoluminescence lifetimes of ∼9.4 and ∼1.4 μs, respectively. It was also demonstrated for the first time that ternary (Ag−In− S) and quaternary (Ag−In−Zn−S) nanocrystals could be applied as efficient photocatalysts, active under visible light (green) illumination, in the reaction of aldehydes reduction to alcohols.

A semiconducting molecule containing a thiol anchor group, namely 2-(5-mercaptothien-2-yl)-8-(thien-2-yl)-5-hexylthieno[3,4-c]pyrrole-4,6-dione (abbreviated as D-A-D-SH), was designed, synthesized, and used as a ligand in nonstoichiometric quaternary nanocrystals of composition Ag1.0In3.1Zn1.0S4.0(S6.1) to give an inorganic/organic hybrid. Detailed NMR studies indicate that D-A-D-SH ligands are present in two coordination spheres in the organic part of the hybrid: (i) inner in which the ligand molecules form direct bonds with the nanocrystal surface and (ii) outer in which the ligand molecules do not form direct bonds with the inorganic core. Exchange of the initial ligands (stearic acid and 1-aminooctadecane) for D-A-D-SH induces a distinct change of the photoluminescence. Efficient red luminescence of nanocrystals capped with initial ligands (λmax = 720 nm, quantum yield = 67%) is totally quenched and green luminescence characteristic of the ligand appears (λmax = 508 nm, quantum yield = 10%). This change of the photoluminescence mechanism can be clarified by a combination of electrochemical and spectroscopic investigations. It can be demonstrated by cyclic voltammetry that new states appear in the hybrid as a consequence of D-A-D-SH binding to the nanocrystals surface. These states are located below the nanocrystal LUMO and above its HOMO, respectively. They are concurrent to deeper donor and acceptor states governing the red luminescence. As a result, energy transfer from the nanocrystal HOMO and LUMO levels to the ligand states takes place, leading to effective quenching of the red luminescence and appearance of the green one., Efficient red luminescence, characteristic of Ag−In−Zn−S alloyed nanocrystals capped with initial ligands (λmax = 720 nm, quantum yield = 67%) is totally quenched, and green luminescence originating from the donor−acceptor−donor ligands D-A-D-SH appears at 508 nm, exhibiting a 4-fold increase in quantum yield value (10%) as compared to that of free ligands.

To gain a better insight into the factors affecting the enhancement of the energy barrier in single molecule (single ion) magnets, three hexacoordinate cobalt(II) complexes based on the tridentate ligand 2,6-bis(pyrazol-1-yl)pyridine (pypz) and pseudohalide ions have been synthesized and investigated. It was found that dicyanoamido and azido ligands act as bridges to form a one dimensional network based on a single μ1,5-dca bridge [Co(pypz)(dca)(H2O]·dca (1) and dimer [Co2(pypz)2(μ1,1-N3)2(N3)2]·2CH3OH (2), while tcm− counterbalanced the charge of [Co(pypz)2]2+ in [Co(pypz)2](tcm)2 (3), where dca− = dicyanamide ion; tcm− = tricyanomethanide ion, respectively. The DC magnetic data show a sizable magnetic anisotropy, which was confirmed by high-field/high frequency EPR measurements. Two of them are SIMs (1 and 3) and the other one is a SMM (2). All complexes exhibit field induced slow magnetic relaxation with two (1 and 2) or three relaxation channels (3) and an exceptionally long relaxation time for the low-frequency channel upon application of an external field BDC = 0.4, 0.3, and 0.4 T at T = 1.9 K; τ(LF) = 1.9, 2.1 and 0.9 s, respectively. Additionally, the high spin-reversal barriers, U = 103 K for 1 and 95 K for 2, are among the largest for field-induced SIMs for cobalt(II) reported in the literature.

Starting from simple metal precursors (AgNO3 and InCl3), ligands (oleylamine (OLA) and 1-dodecanethiol (DDT)) and popular sulfur precursor S/OLA, we have developed a new method for the preparation of colloidal Ag2S nanocrystals and highly luminescent ternary AgInS2 nanocrystals. The significant advantage of this method is that the nanocrystals can be prepared at room temperature in an ultrasonic bath, without the need for an inert gas atmosphere. In particular, using this method, it was possible to perform the synthesis of the studied nanocrystals in an NMR tube providing direct analytical access to chemical transformations occurring in the reaction mixture during the nanocrystal synthesis. Detailed analysis of the evolution of NMR signals originating from ligands (OLA and DDT) enabled us to identify the nucleation and growth stages as well as the stabilization stage of the nanocrystal formation i.e. the stage in which the ligands were permanently attached to the nanocrystal surface. We also demonstrated that under the analyzed conditions, the reactivities of silver and indium precursors resulting in appropriate cation-to-ligand connections (Ag+–DDT and In3+–OLA) were crucial for the nucleation of ternary AgInS2 nanocrystals exhibiting intense red luminescence.

Alloying of CuFeS2 and CuFeSe2 nanocrystals leads to a new plasmonic nanomaterial in which the plasmon resonance is hypsochromically shifted by ca. 80 nm as compared to the case of CuFeS2, i.e. from 486 nm to 408 nm. Preparation of CuFeS2−xSex facilitates, in addition, the exchange of the hydrophobic ligands for hydrophilic ones, rendering the nanocrystals dispersible in nonpolar and polar (aqueous) media.

Six novel fluoranthene derivatives, namely, three terminally substituted and three bis(fluoranthene) units with fluorene, bithiophene, and carbazole spacers, were obtained through [2+2+2] cycloaddition and characterized completely. Based on the conducted studies, the obtained derivatives can be classified as donor-acceptor (D-A) and acceptor-donor-acceptor (A-D-A) systems, in which the fluoranthene unit acts as an electron-withdrawing unit. The optical results revealed that novel fluoranthene derivatives absorb light in the range λ=236-417 nm, which originates from a π→π* transition within the conjugated system. The compounds exhibit fluorescence that range from deep blue to green, which mainly arises from intramolecular charge transfer (ICT) states. High Stoke shifts and high quantum yields in solution (ϕ=0.22-0.57) and in the solid state (ϕ=0.18-0.44) have been observed for fluoranthene derivatives. All the derivatives display multistep oxidation processes at low potentials. The electronic structure of the presented compounds is additionally supported by time-dependent DFT computations.

Five oxalato-bridged heterobimetallic compounds of general formula [ReCl4(ox)M(bdmpzm)2].2MeCN [ox = oxalate, bdmpzm = bis(3,5-dimethylpyrazol-1-yl)methane and M = Zn (1),Cu (2), Ni (3), Co (4) and Mn (5)] have been successfully synthesized in self-assembly reactions of the [ReCl4(ox)]2- metalloligand with the coordinatively unsaturated [M(bdmpzm)2]2+ complex generated in situ by the reaction of the suitable metal(II) salt with the bdmpzm ligand. 1-5 are isostructural compounds whose crystal structures consist of neutral heterodinuclear [ReCl4(ox)M(bdmpzm)2] units and free acetonitrile molecules. The magnetic properties of 1-5 were investigated in the temperature range 2.0-300 K. The nature and trend of the magnetic interactions in 2-4 is discussed in the light of the number and symmetry of the magnetic orbitals involved and compared with those reported in previous magneto-structural studies where the [ReCl4(ox)]2- was used as a metalloligand towards first-row transition metal ions.

The presented research is focused on the synthesis of alloyed Ag-In-Zn-S colloidal nanocrystals from a mixture of simple metal precursors such as AgNO3, InCl3, zinc stearate combined with 1-dodecanethiol (DDT), 1-octadecene (ODE), and sulfur dissolved in oleylamine (OLA). In particular, the focus is on the effect of the solvent (ODE vs 1,2-dichlorobenzene (DCB)) and the type of sulfur precursor (S/OLA vs S/ n-octylamine (OCA)) on the metal precursors reactivates and on the chemical composition, crystal structure, and luminescent properties of the resulting nanocrystals. The replacement of ODE by DCB as a solvent lowers the reactivity of metal precursors and results in a 3-fold decrease of the photoluminescence quantum yields (Q.Y.) values (from 67% to 21%). This negative effect can be fully compensated by the use of S/OCA as a source of sulfur instead of S/OLA (Q.Y. increases from 21% to 64%). NMR studies of the isolated organic phase indicate that the S/OLA precursor generates two types of ligands being products of ( Z)-1-amino-9-octadecene (OLA) hydrogenation. These are "surface bound" 1-aminooctadecane (C18H37NH2) and crystal bound, i.e., alkyl chain covalently bound to the nanocrystal surface via surfacial sulfur (C18H37-NH-S crystal). Highly luminescent Ag-In-Zn-S nanocrystals exhibit a cation-enriched (predominantly indium) surface and are stabilized by a 1-aminooctadecane ligand, which shows more flexibility than OLA. These investigations were completed by hydrophilization of nanocrystals obtained via exchange of the primary ligands for 11-mercaptoundecanoic acid, (MUA) with only a 2-fold decrease of photoluminescence Q.Y. in the most successful case (from 67% to 31%). Finally, through ligand exchange, an electroactive inorganic/organic hybrid was obtained, namely, Ag-In-Zn-S/7-octyloxyphenazine-2-thiol, in which its organic part fully retained its electrochemical activity.

Three pentacoordinate complexes of the type [Co(pypz)X2], where pypz is a tridentate ligand 2,6-bis(pyrazol-1-yl)pyridine and X = Cl– (1), NCS– (2), and NCO– (3), have been synthesized, and their structures have been determined by X-ray analysis. The DC magnetic data show a sizable magnetic anisotropy, which was confirmed by high-field high-frequency electron paramagnetic resonance (HF EPR) measurements. Well-resolved HF EPR spectra of high spin cobalt (II) were observed over the microwave frequency range 100–650 GHz. The experimental spectra of both complexes were simulated with axial g tensor components, a very large positive D value, and different E/D ratios. To determine the exact D value for 2 (38.4 cm–1) and 3 (40.92 cm–1), the far-infrared magnetic spectroscopy method was used. Knowledge of the zero field splitting parameters and their signs is crucial in interpreting the single-molecule magnet or single chain magnet behavior. The AC susceptibility data confirm that these complexes exhibit a slow m...

This paper presents the synthesis, X-ray studies, spectroscopic characterization and variable temperature magnetic investigations and DFT calculation of four novel thiocyanato Cu(II) compounds [Cu(mpz)2(NCS)2]n·nH2O (1), {[Cu2(dmpz)4(NCS)4][Cu(dmpz)(NCS)2]}n·2nMeOH (2) [(bdmpzm)CuII(SCN)2(μ1,3-SCN)CuI(bdmpzm)]n (3) and [Cu(bpzpy)(NCS)2] (4). Three of them (1, 2 and 3) display one-dimensional coordination structures while complex (4), incorporating a tridentate N-donor ligand, possesses a 0D molecular structure. Complex 3 belongs to a relatively rare group of mixed-valence CuII/CuI coordination polymers.

New catalytically or high pressure activated reactions and routes, including coupling, double bond migration in allylic systems, and various types of cycloaddition and dihydroamination have been used for the synthesis of novel bithiophene derivatives. Thanks to the abovementioned reactions and routes combined with non-catalytic ones, new acetylene, butadiyne, isoxazole, 1,2,3-triazole, pyrrole, benzene, and fluoranthene derivatives with one, two or six bithiophenyl moieties have been obtained. Basic sources of crucial substrates which include bithiophene motif for catalytic reactions were 2,2'-bithiophene, gaseous acetylene and 1,3-butadiyne.

Here we report the preparation of 3,6- bis(bithenyl)-N-decylcarbazole with low oxidation potential due to extended conjugation that underwent facile electrochemical polymerization to form stable electroactive polymer. We extended the conjugation of the monomers in comparison to the carbazole and large decrease were observed in the oxidation potential at which polymerization occurs. To lower the oxidation potential of the monomer and control the optical and electronic properties of the polycarbazole, we attached the thiophene, bithiophene and 3,4-ethylenedioxythiophene (EDOT) at both the 3 and 6 positions of N-substituted carbazole. The monomers and their polymers were compared through electron paramagnetic resonance (EPR) and UV-Vis-NIR spectroelectrochemistry resulting in interesting properties. As optically active materials the CIE L*a*b chromaticity and other optical properties were observed.

Through varying the auxiliary N-donor ligands under similar synthetic conditions nine new compounds: [Cu(C2O4)(pz)]n (1), [Cu(C2O4)(apz)2]n·(3H2O)n (2), [Cu2(μ-C2O4)2(H2O)2(ampz)4] (3), [Cu(C2O4)(mpz)2]n (4), [Cu(C2O4)(aind)2]n (5), [Cu2(C2O4)2(bpzm)2]n·(3.5H2O)n (6), [Cu(C2O4)(ampy)(H2O)]n (7) {[Cu2(μ-C2O4)(aepy)2][Cu(C2O4)2(H2O)2]}n·(2H2O)n (8) and [Cu4(μ-C2O4)3(aepy)4(H2O)2]Cl2 (9) (pz = pyrazole, apz = 3(5)-aminopyrazole, mpz = 3(5)-methylpyrazole, ampz = 3(5)-amino-5(3)-methylpyrazole, aind = 7-azaindole, bpzm = bis(pyrazol-1-yl)methane, ampy = 2-aminomethylpyridine and aepy = 2-(2-pyridyl)ethylamine) have been synthesized and characterised structurally (by single crystal X-ray analysis) and spectroscopically. On the basis of structural data, the influence of neutral N-donor ligands on the control of the final complex structures and the role of weak intermolecular interactions in the creation of molecular architectures have been discussed in detail. The two independent oxalate anions in 1, adopting μ3-oxalato-1κ2O1,O2:2κO1:3κO2a and a relatively rare μ4-oxalato-1κ2O1,O2:2κO1:3κO1a,O2a:4κO2a coordination mode, connect the Cu centers into a two-dimensional net extending along the crystallographic plane (100). Simultaneous existence of both amino and methyl groups in the ampz ligand results in the formation of a 0D dimeric structure of 3. Compounds 2 and 4–8 display one-dimensional coordination structures, and the most significant differences between these structures concern the geometry around the copper(II) center and the coordination mode of the oxalate bridge. The structures of 2–9 are stabilized by the extensive hydrogen-bonding interactions that give rise to the supramolecular architectures. Additionally, the magnetic properties of the complexes 1–9 have been investigated and discussed in the context of their structures.

Five novel thiocyanate complexes [Mn(bpzm)2(NCS)2] (1), [Mn(bdmpzm)2(NCS)2] (2), [Co(bpzm)2(NCS)2] (3), [Co(bdmpzm)2(NCS)2] (4) and [Co(bdmpzm)(NCS)2] (5) (bpzm = bis(pyrazol-1-yl)methane and bdmpzm = bis(3,5-dimethylpyrazol-1-yl)methane) were synthesized and characterized structurally (by single X-ray analysis) and spectroscopically. The studies showed influence of central metal ion and organic co-ligands on the geometry of the thiocyanate Co(II) and Mn(II) complexes. Variable-temperature magnetic susceptibility measurements revealed occurrence of ferromagnetic interactions in 1 and the antiferromagnetic ones for the remaining complexes. The fluorescence properties of the Co(II) complexes were examined in solution and compared with the free ligands.

The p-tolyldiazenido ruthenium(II) complexes [RuCl3(PPh3)2(N2PhCH3)]� CH3OH (1), [RuCl3(PPh3) (N2PhCH3)(HPz)] (2) and [RuCl3(PPh3)(N2PhCH3)(Im)]� CH3OH (3) were synthesized and characterized by IR, 1 H, 13 C, 31 P NMR, electronic absorption and emission spectroscopy, and X-ray crystallography. In the molecular structure of complex (1) some p–p stacking interactions are observed, whereas in the structure of the imidazole complex (3) graph set analysis shows intermolecular hydrogen bonded rings. The electronic structures of the complexes were calculated by DFT based on their crystal structures. The spin-allowed singlet–singlet electronic transitions of the complexes were calculated by time-dependent DFT and the UV–Vis spectra have been discussed on this basis. The emission properties of the complexes were also studied.

An excellent, selective and very convenient method for the synthesis of hydroxyalkyl vinyl ethers of HO–A–O–CH CHCH3 type via isomerization of appropriate readily available allylic substrate of HO–A–O–CH2CH CH2 type mediated by various soluble ruthenium complexes under solvent-free conditions has been presented. Our research has demonstrated that (CH2)n or (CH2CH2O)n or ortho-phenylene, but neither –CH2C CCH2– nor –CH2CH CHCH2– can play a role of an A linker. The use of detailed screening experiments allowed discovering new, efficient catalysts for a highly selective isomerization of allyloxyalcohols such as [RuH2(CO)(PPh3)3], [RuH2(PPh3)4] or [Ru(CO)3(PPh3)2]. For these ruthenium complexes, the only reaction products were enol ethers, and an intra- and/or intermolecular addition of an OH group to the double bond has not been observed. The use of the complexes containing Cl ligand as catalysts precursors ([RuClH(CO)(PPh3)3], [RuCl2(PPh3)3], RuCl3·3H2O and other) and surprisingly also [Ru3(CO)12] led to a consequent cyclization and/or polymerization of enol ethers. The addition to the catalytic system of trialkyl amines, K2CO3, CaH2 and others as scavengers of HCl (generated in situ from Ru–Cl complexes) has also allowed to eliminate fully consequent reactions. The scale-up of the selected method of isomerization has been successfully performed and the best results were obtained for [RuH2(CO)(PPh3)3] and [RuCl2(PPh3)3] + 5 K2CO3. Finally, several pathways of the reaction between allyloxyalcohols and the ruthenium complexes of various structures have been proposed. The double bond migration and addition of the OH group to the allyl or the vinyl ether moiety could proceed according to the transition metal catalysis mechanisms and tandems the transition metal catalysis-Lewis acid catalysis or the transition metal catalysis-Bronsted acid catalysis.

The hydridecarbonyl ruthenium(II) [RuH(CO)(MeImCOO)(PPh3)2]·CH3OH 1 and [RuH(CO)(BImCOO)(PPh3)2] 2 complexes were synthesized and characterized by IR, 1H, 31P NMR, UV–Vis spectroscopy and X-ray crystallography. The experimental studies were completed by quantum chemical calculations which were used to identify the nature of the interactions between the ligands and the central ion and the orbital compositions in the frontier electronic structures. Based on a molecular orbital scheme, the calculated results allowed the interpretation of the UV–Vis spectra obtained at an experimental level. The luminescence properties of the complexes were determined. The catalytic activity for both of the complexes was tested in the reaction of the double bond migration in O-allyl systems. Complex 1 was significantly more active than complex 2, because of the longer Ru–H bond distance in complex 1 in comparison with complex 2.

The ruthenium(II) complexes [RuH(CO)(6-OH-py-2-COO)(PPh 3 ) 2 ] ( 1 ) and [Ru(3-OH-py-2-COO) 2 (PPh 3 ) 2 ] ( 2 ) have been prepared in the reactions of [RuHCl(CO)(PPh 3 ) 3 ] and [RuCl 2 (PPh 3 ) 3 ] with 6-hydroxy- and 3-hydroxypyridine-2-carboxylic acids. The complexes have been characterized by IR, UV–Vis, NMR spectroscopy and X-ray crystallography. Based on the crystal structures, computational investigations were carried out in order to determine the electronic structures of the complexes. The electronic spectra were calculated with the use of time-dependent DFT methods, and correlated with the molecular orbitals of the complexes. The emission properties of the complexes have been examined and quantum efficiencies equal to 0.084 for the hydride carbonyl complex ( 1 ) and 0.046 for complex ( 2 ) have been determined. The catalytic activity in the reaction of the double bond migration in 4-allyloxybutan-1-ol for both the complexes was tested. Under properly selected reaction conditions, complex ( 1 ) selectively catalyzes double bond migration leading to 1-propenyloxyalcohol.

The paper presents a combined experimental and computational study for two novel Cu(II) complexes of 2,6-bis(benzimidazolyl)pyridine. The compounds [Cu(bbp)(NCS)(SCN)]·MeOH (1) and [Cu(bbp)(SCN)Cl]·MeOH·H2O (2) have been studied by IR, UV–Vis spectroscopy and single crystal X-ray analysis. The electronic spectra of 1 and 2 were analyzed and bands were assigned through the DFT/TDDFT procedures. Simultaneous existence of N- and S-coordinated thiocyanate groups makes the complex 1 a rare example of [Cu(N–N–N)(SCN)2] structures. The energetically unfavorable S-binding of the thiocyanate group is stabilized by inter-molecular hydrogen bonds between the N atom of the apical SCN− and the N–H proton of L ligand of an adjacent molecule.

The paper presents a combined experimental and computational study of novel oxorhenium(V) complexes incorporating 2-(hydroxymethyl)benzimidazole and 2-(2-hydroxyphenyl)-1H-benzimidazole ligands, namely [ReO(hmbzim)2(py)]Cl·H2O (1) and [ReO(hpbzim)2(Hhpbzim)]Cl (2). Both complexes have been characterised structurally (by single-crystal X-Ray diffraction) and spectroscopically (by IR, NMR, UV–Vis). The experimental studies on the Re(V) complexes have been accompanied computationally by the density functional theory (DFT) and time-dependent DFT calculations. Additional information about binding between the rhenium atom and oxo ligand in the complexes 1 and 2 has been obtained by NBO analysis.

Addition of alcohols and phenols to allyl ethers catalyzed mainly by ruthenium complexes was studied. Complexes of ruthenium generated in situ from precursors such as {[RuCl 2 (1,5-COD)] x } or [Ru 3 (CO) 12 ] and from external ligands such as phosphines (e.g. PPh 3 , PBu 3 , BINAP) or phosphites (e.g. P(OPh) 3 , P(OMe) 3 ) were found to be particularly efficient catalysts of the studied reactions. Transacetalization reaction could be practically completely eliminated by the addition of a base (particularly Na 2 CO 3 ) to the catalytic systems. It was observed that the selectivity of mixed acetals formation increases with increasing value of Θ parameter of phosphines. Especially interesting results (0–5% of transacetalization) have been obtained for catalytic systems generated from {[RuCl 2 (1,5-COD)] x } or [Ru 3 (CO) 12 ], phosphines (PPh 3 , BINAP, dppe, tris(2,4,6-tri-metylphenyl)phosphine, or dppf) and Na 2 CO 3 . The mechanism of mixed acetals formation has been investigated using deuterated reagents. It is postulated that the examined reaction is a nucleophilic addition of ROH to a hydrido-π-allyl complex formed during oxidative addition of allyl substrate to metal complex. As a result, a new, selective, and convenient method of the synthesis of symmetrical and, in particular, unsymmetrical (mixed) acetals has been developed. Mixed acetals CH 3 CH 2 CH(OR 1 )(OR 2 ) may be obtained in the reaction of R 1 - O -allyl with R 2 OH or R 1 OH with R 2 - O -allyl, depending on the structure of R 1 and R 2 .

Two new Re(iv) compounds of formulae H2tppz[ReCl6] (1) and [Cu(bpzm)2(μ-Cl)ReCl3(μ-ox)Cu(bpzm)2(μ-ox)ReCl3(μ-Cl)]n (2) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine and bpzm = bis(pyrazolyl-1-yl)methane] have been prepared and their crystal structures determined by X-ray diffraction on single crystals. Compound 1 is a mononuclear species whose structure consists of octahedral hexachlororhenate(iv) anions and diprotonated H2tppz(2+) cations which are arranged in the unit cell as alternating anionic and cationic layers, held together by electrostatic forces. The structure of 2 is made up of alternating [Cu(1)(bpzm)2](2+) and [(ox)ReCl3(μ-Cl)Cu(2)(bpzm)2(μ-Cl)ReCl3(ox)](2-) entities interlinked by oxalate bridges to afford a neutral heterobimetallic chain. The oxalate group adopts the didentate (at Re)/monodentate (at Cu) bridging mode. The magnetic behavior of 1 and 2 has been investigated over the temperature range 1.9-295 K. 1 is a magnetically diluted Re(iv) complex, the relatively large value of the zero-field splitting of the ground level [D = -15.8(2) cm(-1)] accounting for the variation of χMT in the low temperature range. Weak intrachain ferromagnetic interactions between Re(iv) and Cu(ii) through oxalate (J1 = +0.15 cm(-1)) and single chloro (J2 = +4.9 cm(-1)) bridges occur in 2 which are obscured by the large zero-field splitting of the Re(iv) ion (DRe = 42 cm(-1)). In addition, interchain antiferromagnetic interactions are also involved in 2 which are responsible for the metamagnetic behavior observed, the value of the critical dc magnetic field (Hc) being 20 kOe.

The synthesis of unsymmetrical alkyl acetals via addition of primary alcohols to allyl ethers mediated by various ruthenium complexes is described.

A comprehensive review of the reports concerning the synthesis of symmetrical and, particularly, mixed acetals and orthoesters with transition metal compounds and complexes as catalysts is presented. The following methods for the synthesis of symmetric and mixed acetals are discussed: acetalization of aldehydes or ketones with alcohols or diols; transacetalization; synthesis from vinyl and allyl ethers; synthesis via intra- or intermolecular addition of OH group to a triple bond; oxidation of primary alcohols; tetrahydropyranylation of alcohols or phenols; synthesis from epoxides and aldehydes or ketones; formation of 1,3-dioxanes by Prins cyclization of olefins with paraformaldehyde; oxidative cyclization-carbonylation of ynones; acetalization of ene-diol under Wacker-type catalysis. Reviewed is also the synthesis of mixed orthoesters via addition of alcohols and phenols to acrolein acetals. Presented are methods of the isolation of pure products, recycling of the catalysts (if applicable) and the advantages of the metal complexes compared to classical catalysts, Bronsted acids in particular. The relationship between the structure and reactivity was analyzed and the mechanisms of the reactions of acetal formation catalyzed by transition metal compounds and complexes were discussed.

Ru-catalyzed synthesis of mixed alkyl–alkyl acetals via addition of primary alcohols to allyl ethers has been extended to include long-chain and/or functionalized substrates. The catalytic systems for these reactions were generated from RuCl2(PPh3)3 and [RuCl2(1,5-COD)]x and phosphines [PPh3 or P(p-chlorophenyl)3] or SbPh3. Of particular importance is the almost quantitative elimination of transacetalization. The addition proceeds through allyl complexes, not via isomerization of allyl ethers––subsequent addition of ROH to vinyl ethers. Graphical Abstract