C6 H5 Research Articles

Electronically Strongly Coupled Divinylheterocyclic-Bridged Diruthenium Complexes.

Complexes [{Ru(CO)Cl(PiPr3 )2 }2 (μ-2,5-(CH-CH)2 -(c) C4 H2 E] (E=NR; R=C6 H4 -4-NMe2 (10 a), C6 H4 -4-OMe (10 b), C6 H4 -4-Me (10 c), C6 H5 (10 d), C6 H4 -4-CO2 Et (10 e), C6 H4 -4-NO2 (10 f), C6 H3 -3,5-(CF3 )2 (10 g), CH3 (11); E=O (12), S (13)) are discussed. The solid state structures of four alkynes and two complexes are reported. (Spectro)electrochemical studies show a moderate influence of the nature of the heteroatom and the electron-donating or -withdrawing substituents R in 10 a-g on the electrochemical and spectroscopic properties. The CVs display two consecutive one-electron redox events with ΔE°'=350-495 mV. A linear relationship between ΔE°' and the σp Hammett constant for 10 a-f was found. IR, UV/Vis/NIR and EPR studies for 10(+) -13(+) confirm full charge delocalization over the {Ru}CH-CH-heterocycle-CH-CH{Ru} backbone, classifying them as Class III systems according to the Robin and Day classification. DFT-optimized structures of the neutral complexes agree well with the experimental ones and provide insight into the structural consequences of stepwise oxidations.

Ansa-Complexes of [Mn(η(5) -C5 H5 )(η(6) -C6 H6 )]: Preparation, Characterization, and Reactivity of [n]Manganoarenophanes (n=1, 2, 3).

We report the synthesis of [n]manganoarenophanes (n=1, 2) featuring boron, silicon, germanium, and tin as ansa-bridging elements. Their preparation was achieved by salt-elimination reactions of the dilithiated precursor [Mn(η(5) -C5 H4 Li)(η(6) -C6 H5 Li)]⋅pmdta (pmdta=N,N,N',N',N''-pentamethyldiethylenetriamine) with corresponding element dichlorides. Besides characterization by multinuclear NMR spectroscopy and elemental analysis, the identity of two single-atom-bridged derivatives, [Mn(η(5) -C5 H4 )(η(6) -C6 H5 )SntBu2 ] and [Mn(η(5) -C5 H4 )(η(6) -C6 H5 )SiPh2 ], could also be determined by X-ray structural analysis. We investigated for the first time the reactivity of these ansa-cyclopentadienyl-benzene manganese compounds. The reaction of the distannyl-bridged complex [Mn(η(5) -C5 H4 )(η(6) -C6 H5 )Sn2 tBu4 ] with elemental sulfur was shown to proceed through the expected oxidative addition of the Sn-Sn bond to give a triatomic ansa-bridge. The investigation of the ring-opening polymerization (ROP) capability of [Mn(η(5) -C5 H4 )(η(6) -C6 H5 )SntBu2 ] with [Pt(PEt3 )3 ] showed that an unexpected, unselective insertion into the Cipso -Sn bonds of [Mn(η(5) -C5 H4 )(η(6) -C6 H5 )SntBu2 ] had occurred.

Ansa-bridged bis(benzene) titanium complexes.

Taking advantage of an improved synthesis of [Ti(η(6) -C6 H6 )2 ], we report here the first examples of ansa-bridged bis(benzene) titanium complexes. Deprotonation of [Ti(η(6) -C6 H6 )2 ] with nBuLi in the presence of N,N,N',N'',N''-pentamethyldiethylenetriamine (pmdta) leads to the corresponding 1,1'-dilithio salt [Ti(η(6) -C6 H5 Li)2 ]⋅pmdta that enables the preparation of the first one- and two-atom-bridged complexes by simple salt metathesis. The ansa complexes were fully characterized (NMR spectroscopy, UV/Vis spectroscopy, elemental analysis, and X-ray crystallography) and further studied electrochemically and computationally. Moreover, [Ti(η(6) -C6 H6 )2 ] is found to react with the Lewis base 1,3-dimethylimidazole-2-ylidene (IMe) to give the bent sandwich complex [Ti(η(6) -C6 H6 )2 (IMe)].

Cooperative Ge-N Bond activation in aluminium-functionalised aminogermanes and spontaneous imine elimination via an intermediate germyl cation.

Hydrometallation of iPr2 N-Ge(CMe3 )(C≡C-CMe3 )2 with H-M(CMe3 )2 (M=Al, Ga) affords alkenyl-alkynylgermanes in which the Lewis-acidic metal atoms are not coordinated by the amino N atoms but by the α-C atoms of the ethynyl groups. These interactions result in a lengthening of the Ge-C bonds by approximately 10 pm and a comparably strong deviation of the Ge-CC angle from linearity (154.3(1)°). This unusual behaviour may be caused by steric shielding of the N atoms. Coordination of the metal atoms by the amino groups is observed upon hydrometallation of Et2 N-Ge(C6 H5 )(C≡C-CMe3 )2 , bearing a smaller NR2 group. Strong M-N interactions lead to a lengthening of the Ge-N bonds by 10 to 15 pm and a strong deviation of the M atoms from the MC3 plane by 52 and 47 pm, for Al and Ga, respectively. Dual hydrometallation is achieved only with HAl(CMe3 )2 . In the product, there is a strong Al-N bond with converging Al-N and Ge-N distances (208 vs. 200 pm) and an interaction of the second Al atom to the phenyl group. Addition of chloride anions terminates the latter interaction while the activated Ge-N bond undergoes an unprecedented elimination of EtN=C(H)Me at room temperature, leading to a germane with a Ge-H bond. State-of-the-art DFT calculations reveal that the unique mechanism comprises the transfer of the amino group from Ge to Al to yield an intermediate germyl cation as a strong Lewis acid, which induces β-hydride elimination, with chloride binding being crucial for providing the thermodynamic driving force.

Strongly phosphorescent neutral rhenium(i) isocyanoborato complexes: synthesis, characterization, and photophysical, electrochemical, and computational studies.

A new series of neutral isocyanoborato rhenium(I) diimine complexes [Re(CO)3 (N^N)(CNBR3 )], where N^N=bpy, 4,4'-Me2 bpy, phen, 4,7-Me2 phen, 2,9-Me2 phen, 3,4,7,8-Me4 phen; R=C6 F5 , C6 H5 , Cl, 4-ClC6 H4 , 3,5-(CF3 )2 C6 H3 , with various isocyanoborate and diimine ligands of diverse electronic and steric nature have been synthesized and characterized. The X-ray crystal structures of six complexes have also been determined. These complexes displayed intense bluish green to yellow phosphorescence at room temperature in dichloromethane solution. The photophysical and electrochemical properties of these complexes had been investigated. To elucidate the electronic structures and transitions of these complexes, DFT and TD-DFT calculations have been performed, which revealed that the lowest-energy electronic transition associated with these complexes originates from a mixture of MLCT [dπ(Re)→π*(N^N)] and LLCT [π(CNBR3 )→π*(N^N)] transitions.

Measuring oxygen yields of a thermal conversion/elemental analyzer-isotope ratio mass spectrometer for organic and inorganic materials through injection of CO.

The thermal conversion/elemental analyzer-isotope ratio mass spectrometer (TC/EA-IRMS) is widely used to measure the δ(18) O value of various substances. A premise for accurate δ(18) O measurement is that the oxygen in the sample can be converted into carbon monoxide (CO) quantitatively or at least proportionally. Therefore, a precise method to determine the oxygen yield of TC/EA-IRMS measurements is needed. Most studies have used the CO peak area obtained from a known amount of a solid reference material (for example, benzoic acid) to calibrate the oxygen yield of the sample. Although it was assumed that the oxygen yield of the solid reference material is 100%, no direct evidence has been provided. As CO is the analyte gas for δ(18) O measurement by IRMS, in this study, we use a six-port valve to inject CO gas into the TC/EA. The CO is carried to the IRMS by the He carrier gas and the CO peak area is measured by the IRMS. The CO peak area thus obtained from a known amount of the injected CO is used to calibrate the oxygen yield of the sample. The oxygen yields of commonly used organic and inorganic reference materials such as benzoic acid (C6 H5 COOH), silver phosphate (Ag3 PO4 ), calcium carbonate (CaCO3 ) and silicon dioxide (SiO2 ) are investigated at different reactor temperatures and sample sizes. We obtained excellent linear correlation between the peak area for the injected CO and its oxygen atom amount. C6 H5 COOH has the highest oxygen yield, followed by Ag3 PO4 , CaCO3 and SiO2 . The oxygen yields of TC/EA-IRMS are less than 100% for both organic and inorganic substances, but the yields are relatively stable at the specified reactor temperature and for a given quantity of sample.

Univalent gallium complexes of simple and ansa-arene ligands: effects on the polymerization of isobutylene.

Using [Ga(C6 H5 F)2 ](+) [Al(OR(F))4 ](-) (1) (R(F) =C(CF3)3) as starting material, we isolated bis- and tris-η(6) -coordinated gallium(I) arene complex salts of p-xylene (1,4-Me2 C6 H4), hexamethylbenzene (C6 Me6 ), diphenylethane (PhC2 H4 Ph), and m-terphenyl (1,3-Ph2 C6 H4): [Ga(1,4-Me2 C6 H4 )2.5 ](+) (2(+)), [Ga(C6 Me6 )2 ](+) (3(+)), [Ga(PhC2 H4 Ph)](+) (4(+)) and [(C6 H5 F)Ga(μ-1,3-Ph2 C6 H4)2 Ga(C6 H5 F)](2+) (5(2+)). 4(+) is the first structurally characterized ansa-like bent sandwich chelate of univalent gallium and 5(2+) the first binuclear gallium(I) complex without a Ga-Ga bond. Beyond confirming the structural findings by multinuclear NMR spectroscopic investigations and density functional calculations (RI-BP86/SV(P) level), [Ga(PhC2 H4 Ph)](+) [Al(OR(F))4](-) (4) and [(C6 H5 F)Ga(μ-1,3-Ph2 C6 H4)2 Ga(C6 H5 F)](2+) {[Al(OR(F) )4] (-)}2 (5), featuring ansa-arene ligands, were tested as catalysts for the synthesis of highly reactive polyisobutylene (HR-PIB). In comparison to the recently published 1 and the [Ga(1,3,5-Me3 C6 H3)2](+) [Al(OR(F))4](-) salt (6) (1,3,5-Me3 C6 H3 =mesitylene), 4 and 5 gave slightly reduced reactivities. This allowed for favorably increased polymerization temperatures of up to +15 °C, while yielding HR-PIB with high contents of terminal olefinic double bonds (α-contents=84-93 %), low molecular weights (Mn =1000-3000 g mol(-1)) and good monomer conversions (up to 83 % in two hours). While the chelate complexes delivered more favorable results than 1 and 6, the reaction kinetics resembled and thus concurred with the recently proposed coordinative polymerization mechanism.

Univalent Gallium Complexes of Simple and ansa-Arene Ligands: Effects on the Polymerization of Isobutylene.

Using [Ga(C6 H5 F)2 ]+ [Al(ORF )4 ]- (1) (RF =C(CF3 )3 ) as starting material, we isolated bis- and tris-η6 -coordinated gallium(I) arene complex salts of p-xylene (1,4-Me2 C6 H4 ), hexamethylbenzene (C6 Me6 ), diphenylethane (PhC2 H4 Ph), and m-terphenyl (1,3-Ph2 C6 H4 ): [Ga(1,4-Me2 C6 H4 )2.5 ]+ (2+ ), [Ga(C6 Me6 )2 ]+ (3+ ), [Ga(PhC2 H4 Ph)]+ (4+ ) and [(C6 H5 F)Ga(μ-1,3-Ph2 C6 H4 )2 Ga(C6 H5 F)]2+ (52+ ). 4+ is the first structurally characterized ansa-like bent sandwich chelate of univalent gallium and 52+ the first binuclear gallium(I) complex without a GaGa bond. Beyond confirming the structural findings by multinuclear NMR spectroscopic investigations and density functional calculations (RI-BP86/SV(P) level), [Ga(PhC2 H4 Ph)]+ [Al(ORF )4 ]- (4) and [(C6 H5 F)Ga(μ-1,3-Ph2 C6 H4 )2 Ga(C6 H5 F)]2+ {[Al(ORF )4 ] - }2 (5), featuring ansa-arene ligands, were tested as catalysts for the synthesis of highly reactive polyisobutylene (HR-PIB). In comparison to the recently published 1 and the [Ga(1,3,5-Me3 C6 H3 )2 ]+ [Al(ORF )4 ]- salt (6) (1,3,5-Me3 C6 H3 =mesitylene), 4 and 5 gave slightly reduced reactivities. This allowed for favorably increased polymerization temperatures of up to +15 °C, while yielding HR-PIB with high contents of terminal olefinic double bonds (α-contents=84-93 %), low molecular weights (Mn =1000-3000 g mol-1 ) and good monomer conversions (up to 83 % in two hours). While the chelate complexes delivered more favorable results than 1 and 6, the reaction kinetics resembled and thus concurred with the recently proposed coordinative polymerization mechanism.

Why p-Cymene? Conformational effect in asymmetric hydrogenation of aromatic ketones with a η(6) -arene/ruthenium(II) catalyst.

The global reaction route mapping (GRRM) methods conveniently define transition states in asymmetric hydrogenation and transfer hydrogenation of aromatic ketones via the [RuH{(S,S)-TsNCH(C6 H5 )CH(C6 H5 )NH2 }(η(6) -p-cymene)] intermediate. Multiple electrostatic CH/π interactions are the common motif in the preferred diastereometric structures.

Influence of cyclopentadienyl ring-tilt on electron-transfer reactions: redox-induced reactivity of strained [2] and [3]ruthenocenophanes.

In contrast to ruthenocene [Ru(η(5) -C5 H5 )2 ] and dimethylruthenocene [Ru(η(5) -C5 H4 Me)2 ] (7), chemical oxidation of highly strained, ring-tilted [2]ruthenocenophane [Ru(η(5) -C5 H4 )2 (CH2 )2 ] (5) and slightly strained [3]ruthenocenophane [Ru(η(5) -C5 H4 )2 (CH2 )3 ] (6) with cationic oxidants containing the non-coordinating [B(C6 F5 )4 ](-) anion was found to afford stable and isolable metalmetal bonded dicationic dimer salts [Ru(η(5) -C5 H4 )2 (CH2 )2 ]2 [B(C6 F5 )4 ]2 (8) and [Ru(η(5) -C5 H4 )2 (CH2 )3 ]2 [B(C6 F5 )4 ]2 (17), respectively. Cyclic voltammetry and DFT studies indicated that the oxidation potential, propensity for dimerization, and strength of the resulting RuRu bond is strongly dependent on the degree of tilt present in 5 and 6 and thereby degree of exposure of the Ru center. Cleavage of the RuRu bond in 8 was achieved through reaction with the radical source [(CH3 )2 NC(S)SSC(S)N(CH3 )2 ] (thiram), affording unusual dimer [(CH3 )2 NCS2 Ru(η(5) -C5 H4 )(η(3) -C5 H4 )C2 H4 ]2 [B(C6 F5 )4 ]2 (9) through a haptotropic η(5) -η(3) ring-slippage followed by an apparent [2+2] cyclodimerization of the cyclopentadienyl ligand. Analogs of possible intermediates in the reaction pathway [C6 H5 ERu(η(5) -C5 H4 )2 C2 H4 ][B(C6 F5 )4 ] [E=S (15) or Se (16)] were synthesized through reaction of 8 with C6 H5 EEC6 H5 (E=S or Se).

Enhancement of spin relaxation in an FeDy2 Fe coordination cluster by magnetic fields.

Two [FeLn2 Fe(μ3 -OH)2 (teg)2 (N3 )2 (C6 H5 COO)4 ] compounds (where Ln=Y(III) and Dy(III) ; teg=triethylene glycol anion) have been synthesized and studied using SQUID and Mössbauer spectroscopy. The magnetic measurements on both compounds indicate dominant antiferromagnetic interactions between the metal centers. Analysis of the (57) Fe Mössbauer spectra complement the ac magnetic susceptibility measurements, which show how a static magnetic field can quench the slow relaxation of magnetization generated by the anisotropic Dy(III) ions.

Synthesis of unsymmetrically substituted phosphane oxides (R(1)R(2)P(O)H) and phosphinous acids (R(1)R(2)POH).

This paper describes the synthesis of unsymmetrically substituted phosphinous acids and phosphane oxides featuring at least one electron-withdrawing pentafluoroethyl group. The presence of a diethylamino function as a protecting group allows a selective reaction of RClPNEt2 (R=CF3 , C6 F5 , C6 H5 ) with LiC2 F5 . On treatment with para-toluenesulfonic acid the isolated aminophosphanes R(C2 F5 )PNEt2 are readily converted into the corresponding phosphinous acids or phosphane oxides, respectively. Investigation of the tautomeric equilibrium between oxide and acid tautomer revealed (CF3 )(C2 F5 )POH as a stable phosphinous acid, whereas the pentafluorophenyl and phenyl derivatives constitute a solvent dependent equilibrium between the acid and the oxide tautomer.

Gas‐Phase Synthesis of the Benzyl Radical (C6H5CH2)

Dicarbon (C2 ), the simplest bare carbon molecule, is ubiquitous in the interstellar medium and in combustion flames. A gas-phase synthesis is presented of the benzyl radical (C6 H5 CH2 ) by the crossed molecular beam reaction of dicarbon, C2 (X(1) Σg (+) , a(3) Πu ), with 2-methyl-1,3-butadiene (isoprene; C5 H8 ; X(1) A') accessing the triplet and singlet C7 H8 potential energy surfaces (PESs) under single collision conditions. The experimental data combined with ab initio and statistical calculations reveal the underlying reaction mechanism and chemical dynamics. On the singlet and triplet surfaces, the reactions involve indirect scattering dynamics and are initiated by the barrierless addition of dicarbon to the carbon-carbon double bond of the 2-methyl-1,3-butadiene molecule. These initial addition complexes rearrange via multiple isomerization steps, leading eventually to the formation of C7 H7 radical species through atomic hydrogen elimination. The benzyl radical (C6 H5 CH2 ), the thermodynamically most stable C7 H7 isomer, is determined as the major product.

Triamidoamine–Uranium(IV)‐Stabilized Terminal Parent Phosphide and Phosphinidene Complexes

Reaction of [U(Tren(TIPS) )(THF)][BPh4 ] (1; Tren(TIPS) =N{CH2 CH2 NSi(iPr)3 }3 ) with NaPH2 afforded the novel f-block terminal parent phosphide complex [U(Tren(TIPS) )(PH2 )] (2; U-P=2.883(2) Å). Treatment of 2 with one equivalent of KCH2 C6 H5 and two equivalents of benzo-15-crown-5 ether (B15C5) afforded the unprecedented metal-stabilized terminal parent phosphinidene complex [U(Tren(TIPS) )(PH)][K(B15C5)2 ] (4; UP=2.613(2) Å). DFT calculations reveal a polarized-covalent UP bond with a Mayer bond order of 1.92.

Monocyclometalated Gold(III) Monoaryl Complexes—A New Class of Triplet Phosphors with Highly Tunable and Efficient Emission Properties

Highly tunable and rich phosphorescent emission properties based on the stable monocyclometalated gold(III) monoaryl structural motif are reported. Monochloro complexes of the type cis-[(N^C)Au(C6 H2 (CF3)3)(Cl)] N^C=2-phenylpyridine (ppy)] (1), [N^C=benzo[h]quinoline (bzq)] (2), [N^C=2-(5-Methyl-2-thienyl)pyridine (5m-thpy)] (3) were successfully prepared in modest to good yields by reacting an excess of 2, 4, 6-tris(trifluoromethyl)phenyl lithium (LiFmes) with the corresponding dichloride complexes cis-[(N^C)AuCl2]. Subsequent replacement of the chloride ligand in 1 with strong ligand field strength such as cyanide and terminal alkynes resulted in complexes of the type cis-[(ppy)Au(Fmes)(R)] R=CN (4), I (5), C≡C-C6 H5 (6) and C≡C-C6 H4 N(C6 H5)-p (7). Single crystal X-ray diffraction studies of all the complexes except 7 were performed to further corroborate their chemical identity. Thermogravimetric analysis (TGA) studies of the uncommon cis configured aryl alkyne complex 7 confirmed the high stability of this complex. Detailed photophysical investigations carried out in solution at room temperature, at 77 K (2-MeTHF) in rigidified media, solid state and 5 wt % PMMA revealed the phosphorescent nature of emission in these complexes. Additionally, their behavior was found to be governed based on both the nature of the cyclometalated ligand and the electronic properties of the ancillary ligands. Highly efficient interligand charge transfer in complex 7 provides access to a wide range of emission colors (solvent-dependent) from deep blue to red with phosphorescence emission quantum yield of 30 % (441 nm) and 39 % (622 nm) in solution and solid state, respectively, and is the highest reported for any Au(III) complexes. DFT and TDDFT calculations carried out further validated the observations and assignments based on the photophysical experimental findings.

Bis(sulfonylimide)ruthenium(VI) Porphyrins: X‐ray Crystal Structure and Mechanism of CH Bond Amination by Density Functional Theory Calculations

The X-ray crystal structure of [Ru(VI) (NMs)2 (tmp)] (Ms=SO2 - p-MeOC6 H4 ; tmp=5,10,15,20-tetramesitylporphyrinato(2-)), a metal sulfonylimide complex that can undergo alkene aziridination and C-H bond amination reactions, shows a Ru=N distance of 1.79(3) Å and Ru-N-S angle of 162.5(3)°. Density functional theory (DFT) calculations on the electronic structures of [Ru(VI) (NMs)2 (tmp)] and model complex [Ru(VI) (NMs)2 (por(0) )] (por(0) =unsubstituted porphyrinato(2-)) using the M06L functional gave results in agreement with experimental observations. For the amination of ethylbenzene by the singlet ground state of [Ru(VI) (NMs)2 (por(0))], DFT calculations using the M06L functional revealed an effectively concerted pathway involving rate-limiting hydrogen atom abstraction without a distinct radical rebound step. The substituent effect on the amination reactivity of ethylbenzene by [Ru(VI) (NX)2 (por(0) )] (X=SO2 -p-YC6 H4 with Y=MeO, Me, H, Cl, NO2 ) was examined. Electron-withdrawing Y groups lower the energy of the LUMOs of [Ru(VI) (NX)2 (por(0))], thus facilitating their interaction with the low-lying HOMO of the ethylbenzene C-H bond and hence increasing the reactivity of [Ru(VI) (NX)2 (por(0) )]. DFT calculations on the amination/aziridination reactions of [Ru(VI) (NSO2 C6 H5 )2 (por(0) )] with pent-4-enal, an aldehyde substrate bearing acyl, homoallylic, and allylic C-H bonds and a C=C bond, revealed a lower reaction barrier for the amination of the acyl C-H bond than for both the amination of the other C-H bonds and aziridination of the C=C bond in this substrate.

Synthesis and Characterization of Gold Clusters Ligated with 1,3-Bis(dicyclohexylphosphino)propane.

In this multidisciplinary study the chemical reduction synthesis of novel gold clusters in solution was combined with high-resolution analytical mass spectrometry (MS) to gain insight into the composition of the gold clusters and how their size, ionic charge state, and ligand substitution influences their gas-phase fragmentation pathways. Ultrasmall cationic gold clusters ligated with 1,3-bis(dicyclohexylphosphino)propane (dcpp) were synthesized for the first time and introduced into the gas phase using electrospray ionization (ESI). Mass-selected cluster ions were fragmented by employing collision-induced dissociation (CID) and the product ions were analyzed using MS. The solutions were found to contain the multiply charged cationic gold clusters Au9 L4 3+ , Au13 L5 3+ , Au6 L3 2+ , Au8 L3 2+ , and Au10 L4 2+ (L=dcpp). The gas-phase fragmentation pathways of these cluster ions were examined systematically by employing CID combined with MS. In addition, CID experiments were performed on related gold clusters of the same size and ionic charge state but capped with 1,3-bis(diphenylphosphino)propane (dppp) ligands containing phenyl functional groups at the two phosphine centers instead of cyclohexane rings. It is shown that this relatively small change in the molecular substitution of the two phosphine centers in diphosphine ligands (C6 H11 versus C6 H5 ) exerts a pronounced influence on the size of the species that are preferentially formed in solution during reduction synthesis as well as the gas-phase fragmentation channels of otherwise identical gold cluster ions. The mass spectrometry results indicate that in addition to the length of the alkyl chain between the two phosphine centers, the substituents at the phosphine centers also play a crucial role in determining the composition, size, and stability of diphosphine-ligated gold clusters synthesized in solution.

Reactivity Studies of Iridium Pyridylidenes [TpMe2Ir(C6H5)2(C(CH)3C(R)NH] (R=H, Me, Ph)

The reactivity of a series of iridiumpyridylidene complexes with the formula [Tp(Me2) Ir(C6 H5 )2 (C(CH)3 C(R)NH] (1 a-1 c) towards a variety of substrates, from small molecules, such as H2 , O2 , carbon oxides, and formaldehyde, to alkenes and alkynes, is described. Most of the observed reactivity is best explained by invoking 16 e(-) unsaturated [Tp(Me2) Ir(phenyl)(pyridyl)] intermediates, which behave as internal frustrated Lewis pairs (FLPs). H2 is heterolytically split to give hydridepyridylidene complexes, whilst CO, CO2 , and H2 CO provide carbonyl, carbonate, and alkoxide species, respectively. Ethylene and propene form five-membered metallacycles with an IrCH2 CH(R)N (R=H, Me) motif, whereas, in contrast, acetylene affords four-membered iridacycles with the IrC(CH2 )N moiety. C6 H5 (CO)H and C6 H5 CCH react with formation of IrC6 H5 and IrCCPh bonds and the concomitant elimination of a molecule of pyridine and benzene, respectively. Finally the reactivity of compounds 1 a-1 c against O2 is described. Density functional theory calculations that provide theoretical support for these experimental observations are also reported.

Effects of in ovo injection of electrolyte solutions on the pre- and posthatch physiological characteristics of broilers ,

Effects of the automated in ovo injection of various concentrations and volumes of physiological electrolyte solutions and a carbohydrate–electrolyte solution (CEN) on broiler embryo development and posthatch chick performance were investigated in 5 individual consecutive trials to test potential diluents for commercial injection. A 200-µL saline solution (117 mM) injection treatment and a noninjected control were included in all trials. For the first 4 trials, solutions were injected into the amnion of embryos on d 16 of incubation, and subsequent percentage incubational egg weight loss, embryo mortality, proportional embryo BW, embryo moisture content, proportional yolk sac weight, and yolk moisture content were evaluated on d 18. In trial 5, solutions were injected into the amnion on d 18, and subsequent hatchability and posthatch performance were investigated. In trial 1, a 200-μL injection of 5 mM tripotassium citrate (C6 H5 K3 O7) and a 200-μL injection of CEN at 1:400 and 1:8,000 concentrations had no detrimental effect on proportional embryo BW. However, embryo moisture content was increased by the injection of either solution at all concentrations. In trial 2, 200-μL injections of saline, potassium chloride (KCl), or sodium dihydrogen phosphate (NaH2 PO4) solution at various physiological concentrations did not affect any of the parameters examined. In trial 3, the injection of 2,000 µL of 117 mM saline reduced 0 to 18 d percentage egg weight loss. In trial 4, percentage egg weight loss was reduced and embryo moisture was increased by a 200-μL saline (117 mM) injection, but not by 200 μL of solutions of CEN (1:400), C6 H5 K3 O7 (5.0 mM), or NaH2 PO4 (1.0 mM) in 5.5 mM KCl. Compared with controls in trial 5, plasma refractive index was increased by CEN–KCl (1:400–5.5 mM) and saline (117 mM) injections, but not by C6 H5 K3 O7–KCl (5 mM–5.5 mM). The current study indicated that 5.5 mM KCl and 5 mM C6 H5 K3 O7 have the greatest potential for use individually or in combination for the commercial injection of broiler hatching eggs.

Sterically encumbered lithium dialkynidoalanates Li[R2Al([sbnd]C[tbnd]C[sbnd]R')2] [R = CH(SiMe3)2

Bis[bis(trimethylsilyl)methyl]aluminium chloride, [(Me3 Si)2 CH]2 Al–Cl, reacted with two equivalents of the lithium alkynides Li–C≡C–R (R=CMe3 , C6 H5 ) and formed the corresponding alanates Li{[(Me3 Si)2 CH]2 Al(–C≡C–R’)2 } (1: R=C6 H5 ; 2: R=CMe3