Cl Moiety Research Articles

Bis(diethylamino)(pentafluorophenyl)phosphane – a Push–Pull Phosphane Available for Coordination

A facile large-scale synthesis of the “push–pull”-substituted ligand bis(diethylamino)(pentafluorophenyl)phosphane is reported. A selenophosphorane as well as complexes with CuI and PdCl2, can be formed almost quantitatively from suitable starting materials. The PdII complex shows a square-planar coordination with significant distortions of the Cl–Pd–Cl moiety in the solid state. In contrast, the phosphane ligand exhibits a large flexibility in the trigonal-planar coordination of the Cu salt, as proven by X-ray crystallography. C–C cross-coupling reactions and 1,3-dipolar cycloadditions have been tested for the PdII and CuI complexes, respectively. Whereas the reactivity of the PdII complex is good at low temperature, the CuI complex reveals remarkable reaction rates at temperatures up to 130 °C. Furthermore, the CuI-catalyzed azide/alkyne 1,3-dipolar cycloaddition was successfully adapted for flow conditions.

Light induced photoreactions with plasmid DNA by Cu/Ru and Cu/Ru/Pt multi-metallic porphyrins

Coordination of two [Ru(bipy)(2)Cl](+) moieties (where bipy = 2,2'-bipyridine) to the pyridyl nitrogens in the 5,10-positions of meso-5,10,15-(4-Pyridyl)-20-(pentafluorophenyl)porphyrin gives the diruthenium porphyrin complex II. Insertion of copper(II) into the porphyrin center allows for the third pyridyl nitrogen to coordinate to Pt(dmso)Cl(2). Electronic transitions associated with the ruthenium porphyrin include an intense Soret band and four less intense Q-bands in the visible region of the spectrum. An intense π-π* transition in the UV region associated with the bipyridyl groups and a metal to ligand charge transfer (MLCT) band appearing as a shoulder to the Soret band are also observed. A slight blue shift of the Soret band and collapse of the Q-bands into one band is observed upon insertion of Cu(II) into the porphyrin center. No change in the electronic spectrum is observed upon coordination of the Pt(dmso)Cl(2) moiety. Electrochemical properties associated with the complexes include a redox couple in the cathodic region attributed to the porphyrin and a redox couple in the anodic region due to the Ru(III/II) couple. DNA titrations of the Cu/Ru and Cu/Ru/Pt porphyrins indicate that both complexes interact strongly with DNA potentially through a partial intercalation mechanism. Gel electrophoresis studies indicate that the Cu/Ru/Pt porphyrin has a greater effect on DNA migration through the gel than the well known DNA binding agent cis-platin. Irradiation of aqueous solutions of the Cu/Ru porphyrin and supercoiled DNA at a 5:1 base pair to complex ratio (in the absence of oxygen) with visible light above 400 nm shows a nicking of the DNA. Repeat experiments in the presence of oxygen show that the Cu/Ru porphyrin photocleaves the DNA, giving the linear form, as evidenced by gel electrophoresis.

A new Os,Rh bimetallic with O2 independent DNA cleavage and DNA photobinding with red therapeutic light excitation

Many Ru and Os systems display photoactive (3)MLCT states. Systems activated by therapeutic window light in the absence of O(2) remain elusive. [(bpy)(2)Os(dpp)RhCl(2)(phen)](3+) photobinds and photocleaves DNA under red light in an oxygen independent manner, due to molecular design involving one Os chromophore coupled to a photoactive cis-Rh(III)Cl(2) moiety.

Copper Halide-Incorporated Tellurium−Iron Carbonyl Complexes: Transformation, Electrochemical Properties, and Theoretical Calculations

When the tellurium-capped tri-iron carbonyl cluster [Et(4)N](2)[TeFe(3)(CO)(9)] was treated with 1 equiv of CuX in THF at 0 degrees C, CuX-incorporated clusters [Et(4)N](2)[TeFe(3)(CO)(9)CuX] (X = Cl, [Et(4)N](2)[1a]; Br, [Et(4)N](2)[1b]; I, [Et(4)N](2)[1c]) were formed, respectively. X-ray analysis showed that 1a-1c each exhibited a TeFe(3) core with one Fe-Fe bond bridged by one CuX fragment. When the reactions were carried out at a molar ratio of 1:2 (X = Cl, Br) or 1:3 (X = I) in tetrahydrofuran (THF) or MeCN at 0 degrees C, Cu(2)X(2)-incorporated clusters [Et(4)N](2)[TeFe(3)(CO)(9)Cu(2)X(2)] (X = Cl, [Et(4)N](2)[2a]; Br, [Et(4)N](2)[2b]; I, [Et(4)N](2)[2c]) were obtained, respectively. Cluster 2a was structurally characterized by X-ray analysis to display a TeFe(3) core, in which one TeFe(2) plane was asymmetrically bridged and capped by one mu(3)-CuCl and another mu(4)-CuCl with two Cu atoms bonded. Complexes 1a-1c underwent skeleton expansion to form Cu(3)X-incorporated di-TeFe(3) clusters [{TeFe(3)(CO)(9)}(2)Cu(3)X](2-) (X = Cl, 3a; Br, 3b; I, 3c), respectively, upon treatment with 1 equiv of [Cu(MeCN)(4)][BF(4)] at 0 degrees C. X-ray analysis showed that 3b and 3c each consisted of two TeFe(3) clusters that were linked by a Cu(3)X moiety. However, a similar reaction for 1a and 1b with 1 equiv of [Cu(MeCN)(4)][BF(4)] at room temperature produced Cu(4)X(2)-linked di-TeFe(3) clusters [{TeFe(3)(CO)(9)}(2)Cu(4)X(2)](2-) (X = Cl, 4a; Br, 4b). Cluster 4a was shown by X-ray analysis to have two TeFe(3) cores linked by a Cu(4)Cl(2) moiety. Clusters 4a and 4b were also produced directly from the reaction of [Et(4)N](2)[TeFe(3)(CO)(9)] with 4 equiv of CuX (X = Cl, Br) in THF. Furthermore, the nature, the formation, the cluster transformation, and the electrochemistry of the CuX-incorporated mono- or di-TeFe(3) clusters are explained in terms of the effects of tellurium, copper halide, and the size of the metal skeleton, all of which are elucidated by molecular calculations at the B3LYP level of density functional theory.

Heterobimetallic Re–Pd, Re–Au and Re–Cu complexes derived from diphenylphosphino cyrhetrene: Synthesis and X-ray structure

Diphenylphosphinecyrhetrene ligand (η 5-C 5H 4PPh 2)Re(CO) 3 ( 1) reacts with 1 equiv. of PdCl 2(NCPh) 2 to form, after workup, the square-planar trans-[(η 5-C 5H 4PPh 2)Re(CO) 3]PdCl 2(NCMe) ( 2). Similarly, reaction of 1 with (tetrahydrothiophene)AuCl produces, in excellent yield, the bimetallic complex [(η 5-C 5H 4PPh 2)Re(CO) 3]AuCl ( 3) with a linear P–Au–Cl moiety. From the reaction of 2 equiv. of 1 with CuBr(SMe 2) the planar-trigonal complex [(η 5-C 5H 4PPh 2)Re(CO) 3] 2CuBr ( 4) was obtained. 31P NMR and X-ray crystallography demonstrate, for the three cases, that (η 5-C 5H 4PPh 2)Re(CO) 3 acts as a monodentate ligand. The structural parameters of the bimetallic complexes are compared with related diphenylphosphinoferrocene metal complexes, described in the literature.

Silanol-Based Pincer Pt(II) Complexes: Synthesis, Structure, and Unusual Reactivity

Aiming at the generation of a silanone intramolecularly bound to platinum, we prepared pincer-type PSiP silanol Pt(II) complexes. While a stable silanone complex was not isolated, unusual reactivity modes, involving its possible intermediacy, were observed. Treatment of the new PSiH 2P-type ligand ( o-IPr 2PC 6H 4) 2SiH 2 ( 7) with (Me 2S) 2Pt(Me)Cl yields the pincer-type hydrosilane complex [{( o- iPr 2PC 6H 4) 2SiH}PtCl] ( 8), which upon Ir(I)-catalyzed hydrolytic oxidation gives the structurally characterized silanol complex [{( o- iPr 2PC 6H 4) 2SiOH}PtCl] ( 3). Complex 3, comprising in its structure the nucleophilic silanol fragment and electrophilic Pt(II)-Cl moiety, exhibits dual reactivity. Its reaction with the non-nucleophilic KB(C 6F 5) 4 in fluorobenzene leads to the ionic complex [{( o- iPr 2PC 6H 4) 2SiOH}Pt] (+) [(C 6F 5) 4B] (-) ( 9), which reacts with CO to yield the structurally characterized [{( o- iPr 2PC 6H 4) 2SiOH}PtCO] (+) [(C 6F 5) 4B] (-) ( 10). Treatment of 3 with non-nucleophilic bases leads to unprecedented rearrangement and coupling, resulting in the structurally characterized, unusual binuclear complex 11. The structure of 11 comprises two different fragments: the original O-Si-Pt(II)-Cl pattern, and the newly formed silanolate Pt(II)-H pattern, which are connected via a disiloxane bridge. Complex 9 undergoes a similar hydrolytic rearrangement in the presence of iPr 2NEt to give the mononuclear silanolate Pt(II)-H complex 17. Both these rearrangement-coupling reactions probably involve the inner-sphere generation of an intermediate silanone 14, which undergoes nucleophilic attack by the starting silanol 3 to yield complex 11, or adds a water molecule to yield complex 17. X-ray diffraction studies of 3, 10, and 11 exhibit a very short Si-Pt bond length (2.27-2.28 A) in the neutral complexes 3 and 11 that elongates to 2.365 A in the carbonyl complex 10. A significantly compressed geometry of the silanolate platinum(II)-hydride fragment B of the binuclear complex 11 features a Pt(2)-O(2)-Si(2) angle of 100.4 (3) degrees and a remarkably short Pt(2)...Si(2) [2.884 (3) A] distance.

Suggestion of an Organometallic Intermediate in an Intramolecular Dechlorination Reaction Involving Copper(I) and a ArCH2Cl Moiety

A copper(I)-mediated reductive dechlorination reaction involving an "internal" chloromethylene substrate at the pyridyl 6-position of one TMPA arm (TMPA triple bond TPA triple bond tris(2-pyridylmethyl)amine) leads to a 1:1 ratio of the starting ligand 6ClCH2-TMPA and a new methyl-TMPA product, 6CH2H-TMPA. On the basis of observed product distributions and a kinetic study, a reaction mechanism involving intramolecular oxidative insertion of Cu(I) to the C-Cl substrate is suggested. The resulting organometallic intermediate is then protonated, leading to the observed products.

μ‐Coordination Chemistry of NO Ligands: Adducts of trans‐Mo(dmpe)2(Cl)(NO) with Lithium Salts

AbstractReaction of trans‐Mo(dmpe)2(Cl)(NO) (1) [dmpe = bis(dimethylphosphanyl)ethane] with lithium triethylborohydride and lithium bis(trimethylsilyl)amide affords the adducts [Mo(dmpe)2(Cl)(NO)(LiHBEt3)]n (2) and {Mo(dmpe)2(Cl)(NO)[LiN(SiMe3)2]2}n (3), respectively, and the reaction of 1 with n‐butyllithium and iodomethane generates the complex [Mo(dmpe)2(Cl)(NO)]3(LiI)2 (4). Complexes 2–4 have been characterized by elemental analysis, IR spectroscopy, NMR spectroscopy, and single‐crystal X‐ray diffraction analysis. The structure of 2 shows an infinite one‐dimensional “zigzag” chain constructed from an alternating arrangement of Mo(dmpe)2(Cl)(NO) and LiHBEt3 moieties, whereas the structure of 3 exhibits an infinite linear chain generated by the alternating arrangement of the Mo(dmpe)2(Cl)(NO) moiety and the dimeric [LiN(SiMe3)2]2 unit. In both compounds, the Mo(dmpe)2(Cl)(NO) moieties act as bridging ligands by coordination of the nitrosyl oxygen atom and the chlorine atom to the lithium ions. Complex 4 displays a discrete structure formed by two separate monomeric LiI units that are bridged by the nitrosyl oxygen atoms of three Mo(dmpe)2(Cl)(NO) moieties. The chlorine atoms of 4 are not involved in coordination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Phosphole-Containing Hybrid Calixpyrroles: New Multifunctional Macrocyclic Ligands for Platinum(II) Ions

Phosphole-containing hybrid calixpyrroles have been prepared by acid-promoted condensation reactions. σ3-Calix[1]phosphole[1]thiophene[2]pyrrole reacts with PtCl2(COD) to afford an unusual type of macrocyclic Pt(II)−monophosphine complex bearing a η3-cyclooctadienyl ligand, in which the phosphole and pyrrole units bind the Pt−Cl moiety through cooperative, noncovalent bonding interactions.

Charge exchange between TiO 2 and a polyfunctional chemisorbed molecule – the involvement of electrophilic groups

A chemisorbed polyfunctional molecule containing both a S atom and a Cl atom, (2-chloroethylethyl sulfide, 2-CEES) is able to abstract electrons which reside near the bottom of the conduction band in TiO 2. By using analogous model compounds containing either the S moiety or the Cl moiety, it is found that electron transfer from TiO 2 occurs only into the molecule containing the Cl moiety. This suggests that a specific electron transfer pathway involving the Cl atom is involved in the electron transfer interaction of 2-CEES with TiO 2. Small coverages of adsorbed electron acceptor molecules are found to cause electron depletion of individual TiO 2 crystallites.

Electron exchange on TiO2–SiO2 photocatalysts during O2 and organic molecule adsorption – the role of adsorbate electrophilicity

The mixed oxide photocatalyst, TiO2–SiO2 has been observed to contain trapped conduction band electrons after annealing in vacuum. These electrons are consumed by adsorption of particular electrophilic molecules. It is found that O2 and an adsorbed organic molecule containing a Cl moiety can remove trapped electrons, whereas a similar organic molecule, not containing Cl, is ineffective in charge removal. The measurement of trapped electronic charge is made by observation of the intensity of the background IR absorption in the 4000 to 1400 cm−1 region, which originates from trapped electron excitation into a continuum of excited electronic states by IR photons.

New phosphino-oxazoline and related phosphino-iminolate palladium complexes; structure of an unusual zwitterionic dinuclear Pd(ii) complex

Reaction of the phosphino-oxazoline chiral ligand (4-(R)-phenyl-2-oxazoline-2-ylmethyl)diphenylphosphine) (abbreviated (R)-PCH2oxPh) with [Pd(dmba-C,N)(μ-Cl)]2 or [PdCl2(cod)] (cod = 1,5-cyclooctadiene) led to the formation of [Pd(dmba-C,N){(R)-PCH2oxPh-κ2P,N}]Cl 1 and [PdCl2{(R)-PCH2oxPh-κ2P,N}] 5, respectively. Deprotonation of the palladium phosphino-oxazoline complex 1 occurred at the PCH2 group and resulted in the formation of an anionic P,N chelate with a prochiral carbon atom in [Pd(dmba-C,N){(R)-PCHoxPh-κ2P,N}] 2. Reaction of 2 with [Pd(dmba-C,N)(μ-Cl)]2 led to the unexpected and diastereoselective formation of the dinuclear complex [{Pd(dmba-C,N)Cl}-(R)-{CHPPh2-(R)-oxPh}Pd(dmba-C,N)] 4 in which a Pd(dmba-C,N)Cl moiety is directly bonded to the carbon α to the P atom of the anionic P,N chelate of 2. This results in an unsual zwitterionic structure. In the course of this work, crystals of [(dmba-C,N)Pd(μ-OH)(μ-Cl)Pd(dmba-C,N)]·1/2[Pd(dmba-C,N)(μ-Cl)]27 were obtained and the single crystal X-ray analyses of complexes 2, 4·2THF, 5·CH2Cl2, [PdCl(Me){(R)-PCH2oxPh-κ2P,N}] 6 and 7 are presented.

The product branching and dynamics of the reaction of chlorine atoms with methylamine

Nascent rotational level population distributions have been measured for the HCl and DCl products of photo-initiated reaction of Cl atoms with CH3NH2, CD3NH2, CH3ND2 and CD3ND2. The use of the different isotopomers of methylamine enables the dynamics of abstraction of H/D atoms from carbon or nitrogen atoms to be distinguished, and the former channel is found to produce HCl or DCl with greater rotational excitation than the latter channel. Mean HCl rotational energies for the two reactions Cl + CH3ND2 → HCl + CH2ND2 and Cl + CD3NH2 → HCl + CD3NH are, respectively, 501 ± 84 and 122 ± 12 cm−1. Fits of the HCl and DCl rotational distributions for reaction of Cl atoms with the CH3NH2 and CD3ND2 molecules with distributions obtained from reactions of the two partially deuterated isotopomers yield branching ratios for C–H ∶ N–H and C–D ∶ N–D abstraction of 0.48 ∶ 0.52 and 0.58 ∶ 0.42, respectively. Ab initio electronic structure theory calculations of the energetics and geometries of transition states and molecular complexes along the reaction pathways for the two competing channels provide key insights to aid the interpretation of the experimental data. The computed bond angle of the N–H–Cl moiety (142.0°) in the transition state for the CH3NH forming channel deviates more from linearity than the C–H–Cl bond angle (171.1°) in the competing transition state, but leads to lower rotational excitation of the nascent HCl products. This counter-intuitive outcome is explained in terms of dipole–dipole interactions between the HCl and organic radical products as they separate.

Preparation of isospecific metallocene catalysts for olefin polymerization that are covalently tethered on solid surface

Novel methodology was developed for preparation of isospecific metallocene catalysts for olefin polymerization that are tethered on silica surfaces with covalent bonds. A racemic ansa-zirconocene complex that has a Si–Cl moiety on its bridge was immobilized on SiO2 by the reaction of the Si–Cl anchor with Si–OH on the solid surface. The prepared solid catalyst was found to be effective for isospecific propene polymerization (catalyst A). Pretreatment of silica surfaces with Me3SiCl improved the catalyst performance (catalyst B). An ansa-zirconocene complex with a BH group reacted with “vinyl-coated” silica gel to afford another immobilized catalysts (catalyst C). This catalyst achieved satisfactorily high catalytic activity and high isotacticity in its produced polypropene.

Reactions between Li Atoms and HX (X = F, Cl) Molecules: Semiempirical SCF MO and Matrix Isolation ESR Studies

Examination of reaction between the Li atom and the HX (X = F, Cl) molecule by a semiempirical molecular orbital method (AM1) revealed the spontaneous formation of the Li:HCl and Li:HF complexes with the respective heats of complexation of 75 and 84 kJ/mol. The calculations yielded totally different structures for the two complexes, however. In the Li:HCl complex, the unpaired electron is in the antibonding σ orbital of the H−Cl moiety and the elongated H−Cl is sided by the Li atom bearing a substantial positive charge (+0.47). For the Li:HF complex, a linear Li−F−H structure was predicted. The unpaired electron resides in a s−p hybridized orbital of the Li atom directed away from the F atom, and the complex is formed by the dative interaction of the fluorine electrons with vacant Li orbitals. A substantial net negative charge (−0.18) is thus borne by the Li atom of the complex. Examination by ESR of argon matrixes in which Li atoms and HCl (and HF) molecules had been co-condensed indeed revealed the spontaneous formation of complexes exhibiting the ESR spectra which were in total accord with the structures and the SOMOs (singly occupied molecular orbitals) predicted above. In the case of Li/HCl/Ar system, the formation of the second complex, Li2Cl, was observed and was ascribed to the reaction between Li atoms and LiCl molecules inadvertently formed during deposition (Li + HCl → H + LiCl). An examination of the Li:LiCl system by the AM1 method revealed a spontaneous formation of the complex with the heat of complexation of 121 kJ/mol. The complex has an isosceles triangular form, and the unpaired electron renders a bent, one-electron bond between the two Li atoms.

The Crystal Structure and Raman Spectrum of Ge(5)Cl(12).GeCl(4) and the Vibrational Spectrum of Ge(2)Cl(6).

The Raman spectrum of Ge(2)Cl(6) shows close analogies with that of the isoelectronic [Ga(2)Cl(6)](2)(-). A band at 262 cm(-)(1) is assigned as principally a Ge-Ge stretching mode. The compound is very moisture-sensitive and decomposes readily in vacuo to give GeCl(4) as one of the products. A sealed sample stored at room temperature gave colorless cuboidal crystals shown by X-ray crystallography to be Ge(5)Cl(12).GeCl(4). The Ge-Ge distance in the neopentyl-like Ge(5) skeleton is 2.420(6) Å, and the Ge-Cl distance in the Ge(5)Cl(12) moiety is 2.119(5) Å whereas in the case of the GeCl(4) molecule it is 2.082(7) Å. The symmetric stretching frequency of the Ge(5) tetrahedron is assigned to the band at 224 cm(-)(1).

Biodehalogenation: Oxidative and Hydrolytic Pathways in the Transformations of Acetonitrile, Chloroacetonitrile, Chloroacetic Acid, and Chloroacetamide by Methylosinus trichosporium OB-3b

Resting cell suspensions of the soil methylotroph Methylosinus trichosporium OB-3b rapidly metabolize acetonitrile (ACN) and chloroacetonitrile (CCN) to bicarbonate. Formate, a natural substrate for this organism, is a major metabolite in both cases. The first step in these processes, established with 13C-labeled substrates and NMR analysis, is an oxygen insertion into the C−H bond to yield the corresponding cyanohydrins. With acetonitrile, the loss of HCN from the initially formed cyanohydrin (HOCH2CN) produces formaldehyde. The latter is rapidly converted to formate and CO2. With chloroacetonitrile, the first formed cyanohydrin [HOCHCl(CN)] may lose HCN to produce formyl chloride or lose HCl to yield formyl nitrile. The generation of CO, in addition to formate, implicates formyl chloride and/or formyl nitrile as intermediates. With neither ACN nor CCN is the nitrile moiety directly attacked or hydrolyzed. In particular, the nitrile hydrolysis products from CCN, chloroacetamide (CAM), and chloroacetic acid (CA) are not detected. In addition, hydrolysis of the C−Cl moiety of CCN does not occur. In contrast, incubation of CAM and CA with this organism does result in the corresponding hydroxy amide and acid directly. The slower dehalogenation of the amide and acid entail a direct microbial hydroxylation of the C−Cl bond. Based upon this study and related work with methylene and ethylene halides, it may be concluded that in the series ClCH2X (X = Cl, Br, CN) oxygen insertion is the initial step in dehalogenation by this organism. However, in the series ClCH2Y (Y = CH2Cl, CO2H, CONH2), the dehalogenation is the result of a direct hydrolysis of the C−Cl bond. This organism also transforms cyanide ion, but incubations with K13CN resulted in no detectable products.

Perturbation of the Electronic Structure of a Copper(II) ion by a Cu(I)Cl Moiety in a Class I Mixed Valence Copper Complex, Cu(II)(Me(5)dien)Cl(2)(Cu(I)Cl).

A new mixed valence copper complex Cu(II)(Me(5)dien)Cl(2)(Cu(I)Cl) (2) was obtained from the reaction of CuCl with Cu(II)(Me(5)dien)Cl(2) (1) in acetonitrile. The structures of 1 and 2 have been determined by single-crystal X-ray diffraction analyses. Compound 1 crystallizes in the monoclinic space group P2(1)/n with a = 8.374(5) Å, b = 17.155(3) Å, c = 23.806(5) Å, beta = 94.40(4) degrees, Z = 8, and V = 3398(1) Å(3) while compound 2 crystallizes in orthorhombic space group Pbcn with a = 14.71(1) Å, b = 16.06(2) Å, c = 13.38(1) Å, Z = 8, and V = 3159(5) Å. The Cu(II)(Me(5)dien)Cl(2) unit in both compounds has a similar distorted square-pyramidal geometry. The Cu(I)Cl moiety in 2 is attached to the Cu(II) unit via two bridging chlorine atoms and has a distorted trigonal planar geometry. UV-vis and EPR spectroscopic studies and molecular orbital calculations established the presence of significant perturbation of the Cu(I)Cl unit to the electronic structure of the Cu(II) ion in compound 2.

Synthesis and characterization ofSchiff bases derived from 1:1 and 1:2 condensations of benzoylacetylacetone with N-benzylethylenediamine. Complexes with some divalent metal ions

The synthesis and characterization of two new ligands derived from the 1:1 and 1:2Schiff base condensation of benzoylacetylacetone with N-benzylethylenediamine as well as some of their metal complexes are reported. The 1:1Schiff base1 is a potential tetradentate, binucleating ligand with two adjacent coordination sites NNO(X) (X=Cl, NO3) and OO(XY), whereX andY are exogenic donor atoms. The reaction of1 with PdCl 4 2− affords a mononuclear, square-planar complex3a with the metal atom coordinated to the NNO site of1 and to Cl−. The X-ray structure of this complex shows that the coordination of the Pd atom by an NNO (Cl) moiety reduces the available space in OO(XY) site for coordinating another metal atom; moreover, the small distance between the two oxygen atoms of the “hard base” site OO(XY) suggests the presence of hydrogen bonding and therefore this proton is not easily displaced by a typical soft acid such as Pd2+. When the same ligand reacts with Ni(II) or Cu(II) nitrates, again only mononuclear complexes3b and3c are obtained with the same donor atoms as for the Pd(II) complex but withX=NO3. The 1:2Schiff base4, a potentially binucleating ligand with two non-equivalent coordination sites NNO(X), was not isolated as a free ligand. However, it gave the binuclear Hg(II) complex5 by the reaction of benzoylacetylacetone and N-benzylethylenediamine in the presence of HgCl2.

Characterization of Gold(I) in NaY Zeolite and Acidity Generation

Au(I) ions were incorporated into NaY zeolite via solid-vapor reaction between Au 2Cl 6 vapor and partially dehydrated zeolite in high vacuum. The process involved the evolution of HCl, as monitored by temperature-programmed desorption-mass, resulting in the reduction of Au(III) into Au(I). X-ray photoelectron spectroscopy characterization of Au n+ /NaY revealed the Au 4 f 7/2 peak exhibited a chemical shift by +1.95 eV relative to that of Au 0, implying the formation of surface AuCl or like species. Upon the introduction of Au 2Cl 6 into NaY zeolite, the IR OH band at 3690 cm −1 due to cation-water interaction in NaY zeolite declined. On the other hand, a strong hydroxyl band at 3640 cm −1 was delivered due to polarization of H 2O in zeolite by the electrostatic potential associated with the Au n+ ( n > 1) ions. Adsorption of D 2O onto Au 2Cl 6/NaY at room temperature produced a peak at 2656 cm −1 due to OD species associated with Au n+ ( n > 1). Degassing of D 2O at 333 K reduced this peak in favor of a new band at 2690 cm −1 which is assigned to O-D stretching mode in the Au (OD)Cl moiety. The CO chemisorption onto Au(I)/NaY at 77 K followed by evacuation to reduced pressures showed a unique carbonyl band at 2188 cm −1, which is characteristic of Au(I) ions. The evolution of HCl during the solid-vapor reaction produced protonic sites, which were detected by Fourier transform infrared of pyridine adsorption. The concentration of these sites increased up to 353 K, where the solid-vapor reaction leveled off. The subsequent pyridine-Cl 2 adsorption did not lead to changes in the oxidation state of Au(I) ions, indicating that NaY zeolite stabilized their structure.