Mixed ligand complexes of AEE hexafluoroacetylacetonates with diglyme: Synthesis,crystal structure and thermal behavior

The novel mixed ligand complexes [Ca(hfa)₂(diglyme)(H₂O)] (I), [Sr(hfa)₂(diglyme)(H₂O)] (II) and [Ba(hfa)₂(diglyme)₂] (III) (Hhfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, diglyme = 2,5,8-trioxanonane) were synthesized by the reactions of the alkaline earth element (AEE) carbonates in n-hexane with a mixture of Hhfa and diglyme, and they were characterized by elemental analysis, ¹H and ¹³C NMR, and FTIR spectroscopy. The crystal structures of I–III, consisting of mononuclear isolated molecules, have been determined. The thermal behavior and composition of the vapor phase have been studied for I–III by thermal analysis at low pressure and mass spectrometry using a Knudsen cell. The stability of the mixed ligand complexes [M(hfa)₂(diglyme)_n] to the removal of diglyme molecules under heating decreases in the row I > II ≈ III, and only I evaporates as the mixed ligand complex after water removal.     

The synthesis, spectroscopic, electrochemical and X-ray diffraction characterization of novel bridged ferrocene precursors for use in self-assembled monolayers

The synthesis of 1,6-diferrocenylhexane-1,6-dione (I), 1-ferrocenylcarbonyl-2-ferrocenylcyclopentene (II) and 1,6-diferrocenylhexane (III) is reported. All three compounds were characterized by ¹H NMR, ¹³C NMR, and infra-red spectroscopy, mass spectrometry, cyclic voltammetry and chronoamperometry. Compounds I and III each exhibit a single two electron transfer, while compound (II) exhibits two single electron transfers. Compounds (I) and (II) were further studied by single crystal X-ray diffraction. In compound (I), both carbonyl groups are in plane with the adjacent ferrocenyl Cp ring. For compound (II) one of the ferrocenyl Cp rings is coplanar with the carbonyl group, the other with the double bond of the cyclopentene ring, but the CO moiety and the double bond are basically perpendicular to each other.     

New N-heterocyclic carbene mercury(II) complexes: Close mercury-arene interaction

Mononuclear mercury complexes (1, 2, and 3) bearing bis-N-heterocyclic carbene (NHC) ligands of the form [(NHC)₂-μ-Hg]⁺² have been prepared and structurally characterised. The complexes were derived from three bis-imidazolium salts as precursors to NHC; either 1,3-bis(N-methylimidazolium-1-ylmethyl)benzene bis(hexafluorophosphate) (I·2PF₆), 1,3-bis(N-butylimidazolium-1-ylmethyl)benzene bis(hexafluorophosphate) (II·2PF₆) or 3,5-bis(N-butylimidazolium-1-ylmethyl)toluene bis(hexafluorophosphate) (III·2PF₆) treated with mercury(II) acetate. Interestingly X-ray crystal structure analysis revealed a close interaction between the Hg metal centre with one carbon atom of the aryl linker in addition to coordination with two NHCs.     

Temperature dependence on recrystallisation of the magnesium phthalocyanine (MgPc) in triethylamine

Three complexes of magnesium phthalocyaninato(2−) derivatives in the crystalline form, MgPc(H₂O)·(C₂H₅)₃N – (I), MgPc(H₂O)₂·2(C₂H₅)₃N – (II) and MgPc(H₂O)₂ – (III), depending on the thermal recrystallisation conditions were obtained and structurally characterised. In complex I, the Mg center exhibits square-pyramidal (4 + 1) coordination environment, whereas in II and III the Mg center of MgPc the biaxial (4 + 2) coordination. Owing to the interaction of the positively charged Mg center with oppositely charged oxygen atom of water molecule in an axial position in I, the Mg atom is significantly displaced (0.451(2) Å) from the plane defined by four isoindole N atoms and leads to distortion of the planar Pc(2−) macrocycle to the saucer-shape form. In II and III due to the biaxial (4 + 2) coordination of the Mg center of MgPc, the Mg atom lies on a N₄-isoindole plane. The triethylamine solvent molecules in I and II interact with mono or bis(aqua)magnesium phthalocyanine via   O–H?$?$N hydrogen bonds. The axial Mg–O bond in I is significantly shorter than that in the II and III complexes. The strength of the Mg–O bond in these complexes is correlated with their thermal stability. From among the complexes only complex I exhibits an intense near-IR absorption band in the solid-state. The spectra of I, II and III in solution are very similar.     

Synthesis,crystal structure and some properties of new perrhenate and pertechnetate complexes of Nd and Am with 2,6-bis(tetramethylfurano)-1,2,4-triazin-3-yl)-pyridine,tris(2-pyridylmethyl)amine and N,N′-tetraethylmalonamide

The coordination complexes of trivalent f-element pertechnetates and perrhenates with some N-donor ligands were determined by using X-ray structural analysis: Nd³⁺ perrhenate with 2,6-bis(tetramethylfurano)-1,2,4-triazin-3-yl)-pyridine ([Nd(FBTP)₃ReO₄](ReO₄)₂ · 2H₂O (I)), tris(2-pyridylmethyl)amine ([Nd(TPA)(ReO₄)₃] (II)) and N,N′-tetraethylmalonamide ([Nd(TEMA)₄](ReO₄)₃ (III)). The coordination number of Nd is 10 in I, 9 in II and 8 in III. The complexes of Nd³⁺ pertechnetate and Am³⁺ pertechnetate with TPA have been also synthesized (Nd(TPA)(TcO₄)₃ (IV) and Am(TPA)(TcO₄)₃ (V)). The structure II does not change on replacement of perrhenate by pertechnetate and neodymium by americium.     

Syntheses, electrochemical and spectroelectrochemical properties of novel ball-type and mononuclear Co(II) phthalocyanines substituted at the peripheral and non-peripheral positions with binaphthol groups

Mononuclear cobalt phthalocyanine (CoPc) substituted at the non-peripheral 8 and peripheral positions 9 with 1,1′-binaphthyl-8,8′-diol and ball-type dinuclear Co₂Pc₂ substituted at the non-peripheral 10 and peripheral 11 positions with the same substituent are reported. The complexes with 1,1′-binaphthol-bridges were prepared from the corresponding phthalonitriles 4-7. The effects of the position of substituent on spectral, electrochemical and spectroelectrochemical properties of these complexes were also explored. The mononuclear complexes 8 and 9 exhibited one metal reduction, one ring reduction and one ring oxidation. The redox properties of the ball-type complexes 10 and 11 exhibited two reduction processes assigned to [(Co^IPc⁻²)₂]²⁻/[(Co^IPc⁻³)₂]⁴⁻ (I), (Co^IIPc⁻²)₂/[(Co^IPc⁻²)₂]²⁻ (II) and one oxidation process assigned to [(Co^IIIPc⁻²)₂]²⁺/Co^IIPc⁻²)₂ (III). The ball-type complexes are much easier to oxidize and more difficult to reduce than the corresponding monomers 8 and 9.     

Syntheses and crystal structures of copper mixed-ligand complexes of multidentate enaminones and acetate anions

Reactions of ferrocenoylacetone with 2-(aminomethyl)pyridine and N-(2-hydroxyethyl)-1,2-diaminoethane afford the multidentate enaminones HL¹ and H₃L², respectively. Reactions of copper acetate with the two enaminones generate the corresponding mixed-ligand complexes I and II, which are formulated as [CuL¹(OAc)] and [Cu(H₂L²)(OAc)], respectively. The structures of HL¹, I and II have been determined by single-crystal X-ray crystallography. In complex I, HL¹ acts as a monoanionic tridentate donor via the carbonyl oxygen, deprotonated enamine nitrogen and pyridyl nitrogen atoms, the acetate anion is monodentate and the coordination geometry of the central metal is square planar. In complex II, H₃L² is a monoanionic tetradentate ligand via the carbonyl oxygen, deprotonated enamine nitrogen, secondary amine nitrogen and hydroxy oxygen atoms, the acetate anion is monodentate and the coordination geometry of the central metal is a distorted trigonal bipyramid.     

A “sodium trap” based on benzo-15-crown-5 with an exocyclic N-(thiophosphoryl)thiourea moiety

For N-(thio)phosphorylthioureas of the common formula RC(S)NHP(X)(OiPr)₂HL^I (R = N-(4′-aminobenzo-15-crown-5), X = S), HL^II (R = N-(4′-aminobenzo-15-crown-5), X = O), HL^III (R = PhNH, X = S), HL^IV (R = PhNH, X = O), and (N,N′-bis-[C(S)NHP(S)(OiPr)₂]₂-1,10-diaza-18-crown-6) H₂L^V, salts LiL^I,III,IV, NaL^I–IV, KL^I–IVM₂L^V (M = Li⁺, Na⁺, K⁺), Ba(L^I,III,IV)₂, and BaL^V have been synthesized and investigated. Compounds NaL^I,II quantitatively drop out as a deposit in ethanol medium, allowing the separation of Na⁺ and K⁺ cations. This effect is not displayed for the other compounds. The crystal structures of HL^III and the solvate of the composition [K(Me₂CO)L^III] have been investigated by X-ray crystallography.     

Synthesis, structures and some chemical and electrochemical properties of E-1,2-diferrocenyl-3-methylthioprop-2-enone and its ketals

2,3-Diferrocenyl-1-methylthiocyclopropenylium iodide reacts with water, metal alkoxides, phenolates and with alcohols in the presence of Et₃N to give E-1,2-diferrocenyl-3-methylthioprop-2-enone or its ketals. Their structures were established based on data from ¹H and ¹³C NMR spectroscopy and X-ray diffraction analysis. The mechanistic aspects of these reactions are discussed. Electrochemical properties of 8 and 13b have been studied. The compounds present two oxidation processes (I-II), attributed to the oxidations of the ferrocenes groups, E^0′(I), E^0′(II), ΔE^0′(II-I) and comproportionation constant K_com are reported.     

Regioselectivity in the rhodium catalysed 1,4-hydrosilylation of isoprene. Aspects on reaction conditions and ligands

The regioselectivity in the Rh catalysed 1,4-hydrosilylation of isoprene was investigated. Variation of solvents and temperature did not significantly affect the isomer distribution between tail-product (I) and head-product (II). The choice of ligands had the greater influence, where Rh^I-based catalysts with the strong electron withdrawing ligand CO favoured production of isomer II, while Rh^I catalysts with strong electron donating ligands (for example triarylphosphines) gave isomer I as the main product. In contrast to the square planar carbonyl complex RhCl(CO)(PPh₃)₂, the square planar thiocarbonyl complex RhCl(CS)(PPh₃)₂, gave I as the major isomer.     

Two tantalum fluorides templated with tren: [H4tren](TaF7)2·H2O and [H4tren](TaF7)2

Using tris(2-aminoethyl)amine [(C₂H₄NH₂)₃N] (tren) as a template, two new tantalum fluorides are obtained by slow evaporation of solutions: [H₄tren](TaF₇)₂·H₂O (I) and [H₄tren](TaF₇)₂ (II). The structure determinations are performed by single crystal X-ray technique. Structures of I and II are built up from isolated TaF₇ distorted monocapped trigonal prisms or pentagonal bipyramids; charge balance is achieved by tetraprotonated [H₄tren]⁴⁺ cations which possess a “scorpion” configuration. In I and II, TaF₇ polyhedra, connected by hydrogen bonds with water molecules in I, lie in corrugated layers; hydrogen bond networks ensure the cohesion between these layers and [H₄tren]⁴⁺cations.     

Synthesis and electrochemical properties of new cobalt and manganese phthalocyanine complexes tetra-substituted with 3,4-(methylendioxy)-phenoxy

The synthesis and electrochemical properties of new cobalt and manganese phthalocyanine complexes, tetra-substituted with 3,4-(methylendioxy)-phenoxy at the peripheral (complexes 3 and 5) and non-peripheral (complexes 4 and 6) positions, are reported. Complexes 3 and 4 showed Q-band absorption, in DMF, at 668 and 686 nm, respectively while Q-band due to complexes 5 and 6 appeared at 732 and 760 nm, respectively in CHCl₃. All the complexes showed well resolved redox processes attributed to both metal and ring based processes. Complexes 3 and 4 showed four redox processes, labeled I, II, III and IV. For complex 3, process I (Co^IPc⁻²/Co^IPc⁻³) was observed at −1.45 V, II (Co^IIPc⁻²/Co^IPc⁻²) at −0.38 V, III (Co^IIIPc⁻²/Co^IIPc⁻²) at +0.49 V and IV (Co^IIIPc⁻¹/Co^IIIPc⁻²) at +0.97 V versus Ag|AgCl. Similar processes were observed for complex 4 at −1.36 V, −0.27 V, +0.56 V, +1.03 V versus Ag|AgCl, respectively. Complexes 5 and 6 showed two redox processes (I and II). For complex 5, these processes appeared at −0.79 V (Mn^IIPc⁻²/Mn^IIPc⁻³, I) and −0.07 V versus Ag|AgCl (Mn^IIIPc⁻²/Mn^IIPc⁻², II), while for complex 6, they were observed at −0.86 V and −0.04 V versus Ag|AgCl. Spectroelectrochemistry was used to probe and confirm the origin of these processes.     

Synthesis and structural characterisation of the palladium N-heterocyclic carbene cluster complexes [Pd3(μ-CO)3(NHC)3] and [Pd3(μ-SO2)3(NHC)3]

The reduction of trans-[Pd(NHC)₂Cl₂] (NHC = IMes, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; IⁱPr₂ = 1,3-bis-isopropylimidazol-2-ylidene) with potassium graphite under an atmosphere of CO affords the palladium NHC carbonyl clusters [Pd₃(μ-CO)₃(NHC)₃] (NHC = IMes, 1; IⁱPr₂, 3). Treatment of 1 with SO₂ at room temperature yields the bridging SO₂ complex [Pd₃(μ-SO₂)₃(IMes)₃] (4) in quantitative yield. Complexes 1, 3 and 4 have been structurally characterised by X-ray crystallography.     

Synthesis and characterization of Ru/Au,Pd/Au,Pd/2Au,Pt/2Au and Cu/2Au heterometallic complexes of cyclodiphosphazane cis-{(o-MeOC6H4O)P(μ-NBu)}2

Mononuclear complexes of cyclodiphosphazane with an uncoordinated phosphorus centre [RuCl₂(η⁶-cymene){l-κP}] (1a) (L = cis-{(o-MeOC₆H₄O)P(μ-N^tBu)}₂) and [PdCl₂(PEt₃){l-κP}] (1b) react with 1 equiv. of [AuCl(SMe₂)] to afford Ru^II/Au^I and Pd^II/Au^I heterodinuclear complexes [RuCl₂(η⁶-cymene){μ-l-κP,κP}AuCl] (2) and [PdCl₂(PEt₃){μ-l-κP,κP}AuCl] (3), respectively. Heterotrinuclear complexes [PdCl₂{μ-l-κP,κP}₂(AuCl)₂] (4), [PtCl₂{μ-l-κP,κP}₂(AuCl)₂] (5) and [CuI{μ-l-κP,κP}₂(AuCl)₂] (6) containing Pd^II/2Au^I, Pt^II/2Au^I and Cu^I/2Au^I metal centers have been synthesized from the reactions of trans-[PdCl₂{l-κP}₂] (1c), cis-[PtCl₂{l-κP}₂] (1d) and [CuI{{l-κP}₂] (1f) respectively, with 2 equiv. of [AuCl(SMe₂)]. Molecular structures of complexes 2, 3 and 4 were established by single crystal X-ray diffraction studies.     

Synthesis and characterization of Pd(IMe)2, and its reactivity by C-S oxidative addition of DMSO

Two-electron reduction of PdX₂(NHC)₂ with Groups 1, 2 metals (K, Mg) is a convenient route to Pd(NHC)₂ complexes including Pd(IMe)₂ (2a), isolated and crystallographically characterized as the least sterically encumbered d¹⁰ M(0)L₂ species to date. 2a exhibits a regular linear geometry and modest Lewis acidity to coordinating solvents and additional IMe. In contrast to its analogs with bulkier NHC = I^tBu and IPr, 2a undergoes cleanly net oxidative addition of the Me-S(O)Me bond of DMSO, forming trans-PdMe(S(O)Me)IMe₂ (3) at RT. DFT calculations suggest this reaction to proceed by substitution of IMe by κS-DMSO followed by concerted C-S oxidative addition to Pd with a single IMe, with a preference of ca. 10 kcal/mol in the effective ΔG_s^‡ over the direct pathway. Calculations also identify two facile intramolecular pathways for racemization of Pd(II) methylsulfinyl complexes at sulfur.     

Copper(II) complexes of tetradentate N2S2 donor sets: Synthesis,crystal structure characterization and reactivity

Two mononuclear and one dinuclear copper(II) complexes, containing neutral tetradentate NSSN type ligands, of formulation [Cu^II(L¹)Cl]ClO₄ (1), [Cu^II(L²)Cl]ClO₄ (2) and [Cu^II₂(L³)₂Cl₂](ClO₄)₂ (3) were synthesized and isolated in pure form [where L¹ = 1,2-bis(2-pyridylmethylthio)ethane, L² = 1,3-bis(2-pyridylmethylthio)propane and L³ = 1,4-bis(2-pyridylmethylthio)butane]. All these green colored copper(II) complexes were characterized by physicochemical and spectroscopic methods. The dinuclear copper(II) complex 3 changed to a colorless dinuclear copper(I) species of formula [Cu^I₂(L³)₂](ClO₄)₂,0.5H₂O (4) in dimethylformamide even in the presence of air at ambient temperature, while complexes 1 and 2 showed no change under similar conditions. The solid-state structures of complexes 1, 2 and 4 were established by X-ray crystallography. The geometry about the copper in complexes 1 and 2 is trigonal bipyramidal whereas the coordination environment about the copper(I) in dinuclear complex 4 is distorted tetrahedral.     

A study of the physico-chemical properties of 1,3,5-trihydroxy-1,3,5-triazin-2,4,6[1H,3H,5H]-trione

Acetyl (Ia) and pivaloyl (Ib) triesters of the 1N,3N,5N-trihydroxy-1,3,5-triazin-2,4,6[1H,3H,5H]-trione (I) were synthesised. The spectrophotometric and potentiometric investigation of I revealed a weak acidic properties of triprotonic acid (pK_a1=5.23, pK_a2=6.32, and pK_a3=7.93). The MS and TGA analyses of I indicated on hydroxyisocyanate as possible degradation product. The chelating ability of I with Fe(III)-ion was preliminary explored. IR measurements of aqueous solutions of I in the presence of Fe(III) ion showed the possible chelating ability of all hydroxamic moieties. The chemical structures and properties of investigated compounds were derived from the results of IR, ¹H and ¹³C NMR, UV and MS spectrometric data, as well as thermogravimetric and potentiometric analysis.     

Preparation and reactivity of polyfunctional six- and eight-membered cyclic silicates

Six- and eight-membered cyclic silicates with reactive SiH or Si-vinyl functional groups have been prepared: hexakis(dimethylsiloxy)cyclotrisiloxane (I), hexakis(vinyldimethylsiloxy)cyclotrisiloxane (II), octakis(dimethylsiloxy)cyclotetrasiloxane (III) and octakis(vinyldimethylsiloxy)cyclotetrasiloxane (IV). Reaction of pseudo wollastonite (Ca₃Si₃O₉) with dimethylchlorosilane or vinyldimethylchlorosilane gives I and II, respectively. IV has been prepared similarly by reaction of octakis[chloro calcium oxy]cyclotetrasilicate [Ca₈Si₄O₁₂Cl₈] with vinyldimethylchlorosilane. On the other hand, acid catalyzed siloxane exchange between tetramethyldisiloxane and octakis(trimethylsiloxy)cyclotetrasiloxane (V) gave III. Cyclic silicates (I-VI) are surprisingly resistant to acid catalyzed ring opening polymerization. In addition, II, IV, V and hexakis(trimethylsiloxy)cyclotrisiloxanes (VI) are resistant to phosphazene P₄-t-Bu superbase catalyzed ring opening polymerization.