Palladium nitrosyl carboxylate clusters: Synthesis and reactivity. X-ray structures of Pd4(μ-CO)2(μ-NO)(μ-RCO2)5 (R = Pr, Bu)

New palladium nitrosyl carboxylate complexes Pd₈(CO)_4−m(NO)_m(NO₂)₄(RCO₂)₈ (m = 2, 4) were obtained by the treatment of palladium carbonyl carboxylates clusters cyclo-Pd_n(μ-CO)_n(μ-RCO₂)_n (n = 6) (1) with gaseous nitrogen monoxide. These complexes are the products of CO substitution in early described Pd₈(CO)₄(NO₂)₄(RCO₂)₈ clusters. By adding an excess of corresponding acid to reaction mixture Pd₄(CO)₂(NO)(RCO₂)₅ complexes were obtained, their structures were determined by X-ray diffraction analysis. These clusters are intermediate products of transformation of 6-nuclear initial clusters into various 8-nuclear complexes. This fact demonstrates that carboxylate ligands can be used as stabilizers for intermediate unstable polynuclear palladium compounds.     

Bis-phosphine monoxide platinum(II) and palladium(II) cationic complexes as Lewis acid catalysts in Diels-Alder and sulfoxidation reactions

A series of bis-phosphine monoxide (BPMO) palladium(II) and platinum(II) cationic complexes of the type [M(BPMO-κ²-P,O)₂][X]₂ (M = Pd, Pt; BPMO = Ph₂P-(CH₂)_n-P(O)Ph₂ with n = 1 (dppmO), 2 (dppeO), 3 (dpppO); X = BF₄, TfO) were prepared from the corresponding chlorides [MCl₂(BPMO-κ¹-P)₂] upon treatment with 2 equiv. of AgX in wet acetone/CH₂Cl₂ or MeOH solutions. They were characterized by ¹H and ³¹P{¹H} NMR spectroscopies and, in the case of the complex [Pt(dppeO-κ²-P,O)₂][BF₄]₂, also by X-ray crystallography. These complexes were tested as catalysts in some Diels-Alder and oxidation reactions with different substrates. In the latter reaction Pt(II) complexes showed moderate activity, while for the former one, both classes of complexes were active in the C-C coupling, in particular the Pt(II) species showed interesting high endo/exo diasteroselectivity depending on the counteranion.     

Synthesis,characterization and antitumor activity of palladium(II) complexes of monoethyl 8-quinolylmethylphosphonate

The complex-forming properties of monoethyl 8-quinolylmethylphosphonate (8-Hmqmp) towards palladium(II) ion have been investigated by reactions of the hydrochloride, 8-Hmqmp · HCl · H₂O, and sodium salt, Na(8-mqmp) · 2H₂O, of this monoester with palladium(II) halide compounds in aqueous solution over a wide pH range. Depending on pH and initial quinolinium and palladium salts, four types of complexes have been formed. Under acidic solution the ion-pair salt complexes [8-H₂mqmp]₂[PdX₄] (1 and 2, pH < 3) and [8-H₂mqmp]₂[Pd₂X₆] (3 and 4, pH ∼ 3), with protonated quinoline ligand as cation and tetrahalopalladate or hexahalodipalladate complex as anion (X = Cl, Br), were isolated. By heating in methanol the chloro complexes 1 and 3 as well as bromo complexes 2 and 4 were converted into the quinolinium salt complexes, [8-H₂mqmp][Pd(8-Hmqmp)X₃], 5 and 6, respectively, containing as anion the quinoliniummethylphosphonatetrihalopalladate complex with palladium bonded at the phosphonic acid moiety. The chelate complex 7, [Pd(8-mqmp)₂], with ligand bonded through the quinoline nitrogen and the deprotonated phosphonic acid oxygen and forming two seven-membered {N,O} chelate rings, was obtained in neutral and basic media. The complexes were identified and characterized by elemental analysis, magnetic and conductance measurements, spectroscopic studies (IR, ¹H NMR, UV–Vis, positive/negative ion FAB MS) and thermal analysis (TG, DTA). As a preliminary screening for their biological activity, complexes were investigated for their ability to inhibit the cancer growth in vitro in the human KB and murine L1210 cell lines. The results obtained were compared with those obtained for the complexes of diethyl 8-quinolylmethylphosphonate (8-dqmp) and monoethyl 2-quinolylmethylphosphonate (2-Hmqmp), and structural factors that determine the complex activity were discussed.     

A study of β-hydride abstraction from alkanediyl homobimetallic complexes [{Cp(CO)2Fe}2{μ-(CnH2n)}] (n = 4-10, Cp = η-C5H5)

The alkyl-bridged iron(II) complexes [{Cp(CO)₂Fe}₂{μ-(C_nH_2n)}] (n = 6-10, Cp = η⁵-C₅H₅) undergo both single and double hydride abstraction when reacted with one equivalent of Ph₃CPF₆ to give both the monocationic complexes, [{Cp(CO)₂Fe}₂{μ-(C_nH_2n−1)}]PF₆, and the dicationic complexes, [{Cp(CO)₂Fe}₂{μ-(C_nH_2n−2)}](PF₆)₂. The ratios of monocationic to dicationic complexes decrease with the increase in the value of n. The complexes where n = 4 and 5 undergo only single hydride abstraction under similar conditions. When reacted with two equivalents of Ph₃CPF₆, the complexes where n = 6-10 undergo double hydride abstraction to give dicationic complexes only. In contrast, the complex where n = 5 gives equal amounts of the monocationic and the dicationic complexes, while the complex where n = 4 only gives the monocationic complex. ¹H and ¹³C NMR data show that in the monocationic complexes one metal is σ-bonded to the carbenium ion moiety while the other is bonded in a η²-fashion forming a chiral metallacylopropane type structure. In the dicationic complexes both metals are bonded in the η²-fashion. The monocationic complexes where n = 4-6, react with methanol to give η¹-alkenyl complexes[Cp(CO)₂Fe(CH₂)_nCHCH₂] (n = 2-4) as the major products and σ-bonded ether products [{Cp(CO)₂Fe}₂{μ-(CH₂)_nCH(OCH₃)CH₂}] as the minor products. The complex where n = 8 reacted with iso-propanol to give the η¹-alkenyl complex [Cp(CO)₂Fe(CH₂)₆CHCH₂]. The dicationic complexes where n = 5, 8 and 9 were reacted with NaI to give the respective α, ω-dienes and [Cp(CO)₂FeI].     

Preparation and structural characterization of nickel(II), cobalt(II), zinc(II) and tin(IV) complexes of the isatin Schiff bases of S-methyl and S-benzyldithiocarbazates

The molecular structures of the isatin Schiff bases of S-methyldithiocarbazate (Hisasme) and S-benzyldithiocarbazate (Hisasbz) have been determined by X-ray diffraction and their complexes of general formula [ML₂]·n(solvate) [M = Co²⁺, Ni²⁺, Zn²⁺; L = anionic forms of Hisasme or Hisasbz; solvate = DMF, DMSO; n = 1, 2] and [Sn(L)Ph₂Cl]·nMeOH (n = 0, 1) have been synthesized and characterized by a variety of physicochemical techniques and X-ray diffraction. The bis-ligand complexes, [Ni(isasbz)₂]·2DMSO and [Co(isasme)₂]·DMF have a six-coordinate, distorted octahedral geometry with the two uninegatively charged tridentate ONS ligands coordinated to the metal ions meridionally via the amide O-atoms, the azomethine nitrogen atoms and the thiolate sulfur atoms. By contrast, the crystal structure of [Zn(isasbz)₂]·2DMF shows a four-coordinate distorted tetrahedral geometry with the two Schiff bases coordinated as NS bidentate ligands via the azomethine nitrogen atoms and the thiolate sulfur atoms. Steric constraints of the rigid tridentate ligands lead to unusual ‘pseudo-coordination’ of the O-donors which occupy sites close to the metal but too distant to be considered as true coordinate bonds.The crystal structures of the tin(IV) complexes [SnLPh₂Cl]·nMeOH (L = isasme and isasbz; n = 0, 1) also show that the Schiff bases act as monoanionic bidentate NS chelating agents coordinating the tin(IV) ion via the azomethine nitrogen atoms and the thiolate sulfur atoms, the tin atom in each complex is five-coordinate with a highly distorted geometry intermediate of square pyramidal and trigonal bipyramidal. Again Sn?O contacts are weak and do not qualify as coordinate bonds.     

Platinum(II) complexes of 8-quinolylmethylphosphonates: Synthesis,characterization and antitumour activity

A series of novel platinum(II) complexes of diethyl (8-dqmp) and monoethyl (8-Hmqmp) ester of 8-quinolylmethylphosphonic acid has been prepared and studied. It was shown that molecular or ionic complexes could be isolated by reaction of these organophosphorus ligands with [PtX₄]²⁻ (X = Cl, Br), depending on the acidity of the reaction solution. In the neutral medium diester formed dihalide adducts, trans-[Pt(8-dqmp)₂X₂] (1 and 2), with N-bonded ligand through the quinoline nitrogen. Under acidic conditions (pH < 3) both ligands gave the quinolinium salt complexes [LH]₂[PtX₄] (3 and 4, L = 8-dqmp; 7 and 8, L = 8-Hmqmp), with protonated quinoline ligand as cation and tetrahalidoplatinate complex as anion. By heating in methanol complexes 3 and 4 were converted into the corresponding dimeric hexahalidodiplatinum complexes, [8-Hdqmp]₂[Pt₂X₆] (5 and 6). The chelate complex [Pt(8-mqmp)₂] (9), with monoester ligand bonded through the quinoline nitrogen and the deprotonated phosphonic acid oxygen and forming two seven-membered {N, O} chelate rings, was obtained in neutral and basic media by reaction of platinum(II) halides either with sodium or hydrochloride salt of this monoester. The complexes were identified and characterized by elemental and thermogravimetric analyses, conductometric measurements, and by spectroscopic studies. In vitro antitumour activity of complexes was evaluated against the human epidermoid KB and murine leukaemia L1210 cell lines. These results were compared with those obtained for the palladium(II) complexes of the same phosphonate ligands and with those of platinum(II) and palladium(II) complexes of diethyl and monoethyl 2-quinolylmethylphosphonate, in order to correlate the structural and biological properties of quinoline-based aminophosphonate compounds.     

New synthesis and thermal studies of palladacycloalkanes and their precursors

A series of new palladacycloalkanes of formula cis-[PdL₂(CH₂)_n] (9. n = 6, L = PPh₃; 10. n = 6, L₂ = dppe; 11. n = 8, L = PPh₃; 12. n = 8, L₂ = dppe) have been prepared by two routes. In the first route, the precursor bis(1-alkenyl) complexes cis-[PdL₂((CH₂)_nCHCH₂)₂] (1. n = 2, L = PPh₃, 2. n = 2, L₂ = dppe, 3. n = 3, L = PPh₃, 4. n = 3, L₂ = dppe) were allowed to react with Grubb’s 2nd generation catalyst to give the palladacycloalkenes, cis-[PdL₂(CH₂)_nCHCH(CH₂)_n] (5. n = 2, L = PPh₃, 6. n = 2, L₂ = dppe, 7. n = 3, L = PPh₃, 8. n = 3, L₂ = dppe), which were then hydrogenated to the palladacycloalkanes, 9-12. In the second route, the di-Grignard reagents BrMg(CH₂)_nMgBr (n = 6, 8) were reacted with the palladium complex [PdCl₂(COD)] followed by immediate ligand displacement to form the respective palladacycloalkanes 10 and 12. The complexes obtained were characterized by a range of spectroscopic and analytical techniques. Thermal decomposition studies were carried out on the palladacycloalkanes 9-12 and the main organic products shown to be 1-alkenes and 2-alkenes.     

Synthesis of allylamides from allyl halides, carbon monoxide, and titanium-nitrogen complexes prepared from molecular nitrogen

4-Phenylbut-3-enamide could be synthesized from corresponding 3-chloroprop-2-enylbenzene, carbon monoxide (1 atm), and titanium-nitrogen complexes, prepared from Ti(OⁱPr)₄, Li, TMSCl, and molecular nitrogen (1 atm), using a palladium catalyst. The reaction proceeds via transmetalation of the titanium-nitrogen complex to an acylpalladium complex. P^tBu₃ as a ligand of the palladium catalyst, afforded a good result, and the amounts of Li and TMSCl affected the yield of amide. When the reaction was carried out using a bidentate ligand on the palladium complex under an atmosphere of argon instead of carbon monoxide, an allylamine derivative was obtained.     

Cu(II) and Pd(II) complexes of N-(2-hydroxybenzyl)aminopyridines

N-(2-Hydroxybenzyl)aminopyridines (Lⁱ) react with Cu(II) and Pd(II) ions to form complexes in the compositions Cu(Lⁱ)₂(CH₃COO)₂ · nH₂O (n = 0, 2, 4), Pd(Lⁱ)₂Cl₂ · nC₂H₅OH (n = 0, 2) and Pd(L²)₂Cl₂ · 2H₂O. In the complexes, the ligands are neutral and monodentate which coordinate through pyridinic nitrogen. Crystal data of the complexes obtained from 2-amino pyridine derivative have pointed such a coordinating route and comparison of the spectral data suggests the validity of similar complexation modes of other analog ligands. Cu(II) complex of N-(2-hydroxybenzyl)-2-aminopyridine (L¹), [Cu(L¹)₂(CH₃COO)₂] has slightly distorted square planar cis-mononuclear structure which is built by two oxygen atoms of two monodentate carboxylic groups disposed in cis-position and two nitrogen atoms of two pyridine rings. The remaining two oxygen atoms of two carboxylic groups form two Cu and H bridges containing cycles which joint at same four coordinated copper(II) ion. IR and electronic spectral data and the magnetic moments as well as the thermogravimetric analyses also specify on mononuclear octahedric structure of complexes [Cu(L²)₂(CH₃COO)₂ · 2H₂O] and [Cu(L³)₂(CH₃COO)₂ · 4H₂O] where L² and L³ are N-(2-hydroxybenzyl)-2- or 3-aminopyridines, respectively.     

Synthesis, structure, and bridge-terminal alkyl exchange kinetics of pyrazolate-bridged dialuminum complexes containing bridging n-alkyl groups

Treatment of triethylaluminum with 3,5-diphenylpyrazole in a 2:1 stoichiometry afforded the ethyl-bridged complex Et₂Al(μ-Ph₂pz)(μ-Et)AlEt₂ (79%) as a colorless crystalline solid. Treatment of tri-n-propylaluminum with 3,5-di-tert-butylpyrazole in a 2:1 stoichiometry afforded the n-propyl-bridged complex (nPr)₂Al(μ-tBu₂pz)(μ-nPr)Al(nPr)₂ (63%) and the dimeric complex [(nPr)₂Al(μ-tBu₂pz)]₂ (3%), respectively, as colorless crystalline solids. Treatment of tri-n-propylaluminum (1 equiv.) or triisobutylaluminum (1 or 2 equiv.) with 3,5-di-tert-butylpyrazole afforded exclusively the dimeric complexes [(nPr)₂Al(μ-tBu₂pz)]₂ (68%) or [(iBu)₂Al(μ-tBu₂pz)]₂ (96%), respectively, as colorless crystalline solids. The solid state structures of Et₂Al(μ-Ph₂pz)(μ-Et)AlEt₂ and (nPr)₂Al(μ-tBu₂pz)(μ-nPr)Al(nPr)₂ consist of 3,5-disubstituted pyrazolato ligands with a di-n-alkylalumino group bonded to each nitrogen atom. An ethyl or n-propyl group acts as a bridge between the two aluminum atoms. The kinetics of the bridge-terminal exchange was determined for the bridging n-alkyl complexes by ¹³C NMR spectroscopy, and afforded ΔH^‡ = 1.5 ± 0.1 kcal/mol, ΔS^‡ = −46.8 ± 39.0 cal/K mol, and for Et₂Al(μ-Ph₂pz)(μ-Et)AlEt₂ and ΔH^‡ = 1.7 ± 0.1 kcal/mol, ΔS^‡ = −46.6 ± 43.4 cal/K mol, and for (nPr)₂Al(μ-tBu₂pz)(μ-nPr)Al(nPr)₂. The negative values of ΔS^‡ imply ordered transition states relative to the ground states, and rotation along the N-AlR₃ vector without aluminum-nitrogen bond cleavage is proposed.     

Synthesis and characterization of some organotin(IV) adducts containing a related series of pyridines: Crystal structure of [SnMe2Cl2(bu2bpy)]

Organotin(IV) complexes of [SnR_(4−n)Cl_n] (n = 2, R = Me, ⁿBu; n = 1, R = Ph) react with the bidentate pyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine (bu₂bpy) to give hexa-coordinated adducts with the general formula [SnR_(4−n)Cl_n(bu₂bpy)]. However, the reaction of these organotin(IV) complexes with the corresponding monodentate ligand 4-tert-butylpyridine (bupy) resulted in the formation of the hexa-coordinated complex [SnMe₂Cl₂(bupy)₂] and the penta-coordinated complexes [SnR_(4−n)Cl_n(bupy)] (n = 2, R = ⁿBu; n = 1, R = Ph). Moreover, the reaction of the above organotin(IV) complexes with 4,4′-trimethylenedipyridine (tmdp) yields hexa-coordinated adducts with the general formula [SnR₂Cl₂(tmdp)] (R = Me, ⁿBu) and the penta-coordinated complex [ClPh₃Sn-μ-(tmdp)SnPh₃Cl] in the solid state. The resulting complexes have been characterized by multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and elemental analysis. NMR data shows that the triphenyltin(IV) adducts are not stable in solution and dissociate to give tetra-coordinated tin(IV) complexes. The X-ray crystal structure determination of [SnMe₂Cl₂(bu₂bpy)] reveals that the tin atom is hexa-coordinated in an octahedral geometry with a trans-[SnMe₂] configuration.     

Ru(II)–DMSO complexes containing aromatic and heterocyclic acid hydrazides: Structure,electrochemistry and biological activity

The reaction of cis-[RuCl₂(DMSO)₄] with a family of aromatic and heterocyclic acid hydrazides yielded new complexes of the general formula trans-[RuCl₂(DMSO)₂(hydrazide)] · nH₂O (n = 0; 1–6; n = 1; 7). The new complexes have been characterized by IR, UV–Vis and ¹H NMR spectroscopic methods. In addition, the structure of one of the complexes, [RuCl₂(DMSO)₂(tcah)] · H₂O (tcah = thiophene-2-carboxylic acid hydrazide), has been determined by single crystal X-ray diffraction. All the studies reveal the neutral bidentate coordination of the hydrazide ligands through the acyl oxygen and amine nitrogen atoms. The electron transfer properties of the complexes were studied by cyclic voltammetry and all the complexes except one show an irreversible/quasi-reversible reduction wave (Ru^II/Ru^I) and an uncoupled oxidation peak (Ru^III/ Ru^II). The preliminary DNA-binding ability of the complexes, studied with herring sperm DNA, shows the binding of the complexes with DNA with a lesser affinity than classical intercalators. The complexes have also been screened for their antibacterial activity against five pathogenic bacteria.     

Compromise between conjugation length and charge-transfer in nonlinear optical η-monocyclopentadienyliron(II) complexes with substituted oligo-thiophene nitrile ligands: Synthesis, electrochemical studies and first hyperpolarizabilities

A systematic series of η⁵-monocyclopentadienyliron(II) complexes with substituted oligo-thiophene nitrile ligands of general formula [FeCp(P_P)(NC{SC₄H₂}_nNO₂)][PF₆] (P_P = dppe, (+)-diop; n = 1-3) has been synthesized and characterized. The electrochemical behaviour of the new compounds was explored by cyclic voltammetry. Quadratic hyperpolarizabilities (β) of the complexes with dppe coligands have been determined by hyper-Rayleigh scattering (HRS) measurements at two fundamental wavelengths of 1.064 and 1.550 μm, to uncover the two-photon resonance effect and to estimate static β values. The obtained overall results are found to be better than for the related η⁵-monocyclopentadienyliron(II) complexes with p-benzonitrile derivatives. Although an increase of the resonant β at 1.064 μm with increasing number of thiophene units in the conjugated ligand was found (up to 910 × 10⁻³⁰ esu), the static values β₀ remain practically unchanged, as shown by the 1.550 μm measurements. Combined with the electrochemical and spectroscopic data (IR, NMR, UV-vis), this remarkable evolution of β shows that the increase of conjugation length is balanced by a decrease in charge-transfer efficiency.     

Novel phosphite palladium complexes and their application in C-P cross-coupling reactions

A mono- and a 1,3-bis-phosphite arene ligand based on 2,2′-biphenol have been synthesized in order to study the synthesis of the corresponding palladium(II) complexes starting from different Pd precursors. Novel bis-phosphite palladium complex 1 [PdCl₂(L)₂] (L = dibenzo[d,f][1,3,2]dioxaphosphepin, 6-phenoxy), C,P-chelate bonded monophosphite palladium complex 2 [Pd(κ₂-L)(μ-Cl)]₂, and PCP-pincer palladium complex 3 have been prepared from these ligands in promising to excellent yields (50-95%). Additionally, complexes 1 and 3 have been characterized by X-ray crystal structure determinations. The application of 2,6-bis-phosphite pincer palladium(II) complex 3 in C-P cross-coupling between diphenylphosphine-borane and a wide range of various aryl iodides under very mild conditions is reported. Kinetic investigations indicate that 3 merely acts as a pre-catalyst and that Pd nanoparticles are the actual catalytically active species.     

Synthesis and electrochemical studies of η-monocyclopentadienylruthenium(II) complexes with substituted thiophene nitrile ligands. Crystal structure of [Ru(η-C5H5)(dppe)(NC{SC4H2}2NO2)][PF6]

A systematic series of η⁵-monocyclopentadienylruthenium(II) complexes with substituted thiophene nitrile ligands of general formula [Ru(η⁵-C₅H₅)(P_P)(NC{SC₄H₂}_nNO₂)][PF₆] (P_P = dppe, (+)-diop; n = 1-3) has been synthesized and characterized. Spectroscopic and electrochemical data were used in order to get an insight on the molecular nonlinear optical properties of these complexes when compared to those found for the reported thiophene iron(II) and p-benzonitrile or 1,2-di-(2-thienyl)-ethene derived iron(II)/ruthenium(II) related complexes. The compound [Ru(η⁵-C₅H₅)(dppe)(NC{SC₄H₂}₂NO₂)][PF₆] was also characterized by X-ray diffraction. The solid state nonlinear optical properties of the chiral compounds were also evaluated by Kurtz powder technique with a Nd:YAG laser emitting at 1064 nm.     

New N,N-amino-diphosphonate-containing methacrylic derivatives, their syntheses and radical copolymerizations with MMA

Hydroxy-amino-diphosphonates HO-C_n-NH₂, with 2 ? n ? 11, have been successfully synthesized via the Kabachnick-Field reaction at 70 °C with high yields. These hydroxy compounds are then reacted with methacryloyl chloride to lead to novel amino-diphosphonate methacrylates MAC_nNP₂ (with 2 ? n ? 11). These highly pure methacrylate monomers were obtained with yields higher than 75%. Radical copolymerizations of MAC_nNP₂ (with 2 ? n ? 11) with MMA have been conducted and the r₁ values (related to MAC_nNP₂) are in the range of 1.1-1.3, and r₂ values (related to MMA) about 0.8; this shows that the diphosphonate groups are statistically bonded to the methacrylic backbone.     

Coordination studies of 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine towards Cu cation. X-ray studies,spectroscopic characterization and DFT calculations

The reactions of 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine with CuCl₂ · 2H₂O, Cu(NO₃)₂ · 3H₂O and CuSO₄ · 5H₂O have been examined, and four [CuCl₂(dppt)] (1), [CuCl₂(dppt)₂] · 2MeOH (2), [Cu(dppt)₂(H₂O)₂](NO₃)₂ (3) and [Cu(SO₄)(dppt)(H₂O)]_n · nH₂O (4) complexes have been obtained. All the complexes have been structurally and spectroscopically characterized, and compound 4 has been additionally studied by magnetic measurements. The electronic structure of 1 has been calculated with the density functional theory (DFT) method, and the time-dependent DFT calculations have been employed to calculate the electronic spectrum of 1.     

A study of the formation and application of new chiral water soluble lanthanoid benzoates using real-time infrared spectroscopy

A range of water soluble lanthanoid benzoate complexes of composition [Ln(Bz)₃(H₂O)_n] (Ln = La, Gd, Ho and Yb; Bz = 3,5-bis((R)-2,3-dihydroxypropoxy)benzoate and 3,4,5-tris((R)-2,3-dihydroxypropoxy)benzoate) have been prepared by reaction of lanthanoid bicarbonates with three equivalents of the corresponding optically active benzoic acid in water. Application of [Ln(Bz)₃(H₂O)_n] as asymmetric catalysts for epoxide ring opening reactions has been investigated using styrene oxide, showing complete conversion after 20 h, albeit with no significant enantiomeric excess observed. The formation of the lanthanoid complexes and subsequent catalytic conversion of styrene oxide to phenylethane-1,2-diol were monitored using real-time infrared (RTIR) spectroscopy, yielding information about reaction pathways and intermediates.     

Palladium(I) carbonyl carboxylate clusters cyclo-[Pd2(μ-CO)2(μ-OCOR)2]n (n = 2 or 3): Structure and reactivity

The interaction of palladium(+1) cluster Pd₄(μ-CO)₄(μ-OAc)₄ with saturated and unsaturated carboxylic acids was studied. It was found, that the substitution of acetates groups on others carboxylates leads to the clusters with different nuclearity. Palladium(+1) carbonyl carboxylate complexes of composition [Pd(μ-CO)(μ-OCOR)]_n, where R = CF₃, CCl₃, CH₂Cl, MeCH = CMe, Me, Prⁱ, Bu, Buⁱ, Bu^tert, n-C₅H₁₁ and n = 4 or 6 were synthesized. According to X-ray data all clusters possess cyclic planar metal cores with alternate pairs of μ-carbonyl and μ-carboxylate ligands. The presence of bulky alkyl fragments in the carboxylate ligand increases the nuclearity of the cluster compared to that of the starting palladium(+1) carbonyl acetate of composition Pd₄(μ-CO)₄(μ-OAc)₄ due, apparently, to steric hindrance.     

Synthesis of mono and doubly alkynyl substituted ferrocene and its crystal engineering using -C-H···O supramolecular synthon

Mono and doubly alkynyl substituted ferrocene complexes, [Fc(CH₂OCH₂CCH)_n], 2-3 (2: n = 1; 3: n = 2; Fc = ferrocene) have been synthesized from the room temperature reaction of mono and 1,1′-dihydroxymethyl ferrocene, Fc(CH₂OH)_n , 1a-b (1a: n = 1; 1b: n = 2) and propargyl bromide, in modest to good yields. These new ferrocene derivatives have been characterized by mass, IR, ¹H, ¹³C NMR spectroscopy, and molecular structures of compound 2 and 3 were unequivocally established by single crystal X-ray diffraction study. The crystal structure analysis revealed that 2 and 3 consist of infinite 1D zig-zag hydrogen bonded chains and 2D microporous hydrogen bonded network of molecules, linked by intermolecular C-H···O hydrogen bonding. The molecular structures of both 2 and 3 are further stabilized by C-H···π interactions.