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Two morphologically different porous gold layered on Cu-oxide-based electrochemical sensors were developed for the selective detection of dopamine in the presence of uric acid, ascorbic acid or dextrose. The nanoparticles were prepared by layering Au onto either a cubic or octahedron-shaped Cu-oxide crystal via a galvanic reaction. These were characterized with scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy. The porous structure of the gold over layer was clearly visible on the scanning electron microscopy image while the macro morphology was maintained. X-ray photoelectron spectroscopy confirmed the presence of metallic gold while both CuI (CuO) and CuII (Cu2O) were present in the samples. These two Au/Cu-oxide nanocomposites were used to modify glassy carbon electrodes and were tested for their dopamine sensing ability. Differential pulse voltammetry was used to investigate the selectivity towards dopamine in the presence of different interfering molecules uric acid, ascorbic acid and dextrose). From the differential pulse voltammetry, the lowest limit of detection was found to be 1.1 μM, with a sensitivity of 3.4 μA mM−1 mm−2 in the linear range of 10–250 μM for the porous gold layered covering the octahedron Cu-oxide-modified glassy carbon electrode. [ABSTRACT FROM AUTHOR]

Tungsten carbide-based nano-catalysts (Ni-WC, Co-WC and NiCo-WC) and molybdenum carbide-based nano-catalysts (Ni-MoC, Co-MoC and NiCo-MoC) were synthesised using a carbothermal reduction method. X-ray diffraction, scanning electron microscopy coupled with electron dispersive spectroscopy, x-ray photoelectron spectroscopy and cyclic voltammetry were used to evaluate the prepared electrocatalysts. The cyclic voltammetry results showed that Ni-WC coated electrode displayed the best hydrogen evolution reaction catalytic activity with the lowest overpotential of 1.421 V at a current density of 10 mA cm−2, and a Tafel slope of 135 mV dec−1 which is marginally lower than the benchmark Pt/C coated electrodes. Ni-MoC and Co-MoC coated electrocatalysts also produced current more effectively with a change in potential as compared to the Pt/C coated electrode. The durability test showed Co-WC, NiCo-WC and Ni-MoC coated electrodes to have high stability within a wide range of current densities. [ABSTRACT FROM AUTHOR]

Truncated cubic Cu-oxide nanocrystals with edge lengths of ca. 600 nm were prepared employing the low-cost copper (II) chloride as the precursor. XRD revealed that the truncated cubic Cu-oxide nanocrystals are present in both the CuI and Cu0 state. XPS characterisation gives insight into the amount of each state present in the as-prepared, oxidised, reduced and recovered catalyst species. The catalytic activity of the truncated cubic Cu-oxide nanocrystals was tested for the reduction of nitrophenols using NaBH4. After one catalytic cycle of the reduction of 4-nitrophenol, the activity almost halved. The SEM images revealed that the recovered catalyst showed some disfigurement of the structure, and XPS confirmed the reduction of the CuI to metallic Cu0. [ABSTRACT FROM AUTHOR]

Truncated cubic Cu-oxide nanocrystals with edge lengths of ca. 600 nm were prepared employing the low-cost copper (II) chloride as the precursor. XRD revealed that the truncated cubic Cu-oxide nanocrystals are present in both the CuI and Cu0 state. XPS characterisation gives insight into the amount of each state present in the as-prepared, oxidised, reduced and recovered catalyst species. The catalytic activity of the truncated cubic Cu-oxide nanocrystals was tested for the reduction of nitrophenols using NaBH4. After one catalytic cycle of the reduction of 4-nitrophenol, the activity almost halved. The SEM images revealed that the recovered catalyst showed some disfigurement of the structure, and XPS confirmed the reduction of the CuI to metallic Cu0. [ABSTRACT FROM AUTHOR]

In low- to middle-income communities, the lack of affordability of conventional sanitary products during menstrual cycles can cause psychological and health issues, ultimately affecting their quality of life. It is crucial to develop alternative products that are affordable and accessible to all while also promoting menstrual health and hygiene. Super absorbent polymers (SAPs) are a vital component in current disposable sanitary pads and nappies. However, these SAPs are often non-biodegradable and non-biocompatible. Therefore, the use of eco-friendly materials for the production of SAPs is gaining popularity in the hygiene industry, as it offers a means to reduce the carbon footprint and environmental impact associated with traditional SAPs made from non-renewable petroleum-based materials. SAPs made from polysaccharides often have naturally occurring antibacterial properties, making them appealing for commercial applications in sanitary products such as sanitary pads. In addition, the move toward reusable sanitary pads with antibacterial properties can significantly reduce waste generated by single-use products and prevent the growth of bacteria, improving the safety and hygiene of the product. Furthermore, computational modeling and artificial intelligence are now important tools in SAP synthesis, providing advantages such as predicting polymer properties, rationalizing synthesis pathways, and improving quality control. These tools can reduce synthesis costs by eliminating the need for trial-and-error approaches in polymer synthesis, ultimately promoting more affordable products for end users. Overall, these advancements in polymer synthesis and material design can help to create a more sustainable industry and promote menstrual hygiene and product accessibility to those who need it most. [ABSTRACT FROM AUTHOR]

Abstract: A series of metal hexacyanometallate nanoparticles KxMy[M′(CN)6]z·qH2O, with M=M′=Co (1) or Fe (2), M=Co and M′=Fe (3) and M=Fe and M′=Co (4) were prepared by either co-precipitation or reverse micro-emulsion. These nanoparticles were characterised by ATR FTIR, TEM and XPS, which revealed the presence of CoII/III and/or FeII/III within the compounds. The average binding energies found for the Co 2p3/2 photoelectron lines for CoII and CoIII were ca. 781.7 and 782.9 eV respectively, while the binding energies for FeII and FeIII of the Fe 2p3/2 photoelectron lines were located at 709.5 and 711.4 eV. TEM reveal the particle size ranged between 180 and 520 nm. The eight different compounds’ catalytic activity were tested for the solvent-free oxidation of benzyl alcohol using hydrogen peroxide as the oxidant. The progression of the reaction was monitored using ATR FTIR, by following the appearance of the carbonyl stretching frequency of the oxidation products, which showed the formation of not only benzyl aldehyde but also benzyl benzoate, which is the condensation product of benzyl alcohol and benzoic acid (another oxidation product). The TOF of the catalytic oxidation reaction was correlated with the mean particle diameter, % occurrence of CoII/III and/or FeII/III, total metal electronegativity and the degree of covalence of the Co- and Fe-ligand bond.Graphical Abstract: [ABSTRACT FROM AUTHOR]

A systematic analysis of the XPS Fe 2p 3/2 core-level photoelectron lines and their satellite structures gave insight into the electronic properties of a series of ferrocenyl-containing chalcones with the structure Fc CO CH CH C 6 H 4 R, where R is in the para -position on the phenyl ring and R OCH 3 ( 1 ), CH 3 ( 2 ), C 6 H 5 ( 3 ), t Bu ( 4 ), H ( 5 ), Br ( 6 ) and CF 3 ( 7 ). A V-shaped correlations obtained between the binding energy of the Fe 2p 3/2 photoelectron line and Hammett constants (σ R ) of the R-groups as well as the oxidation potential of the Fe II /Fe III couple, E pa , indicates that there are different modes of zwitterion formation, of electron-donating and electron-withdrawing R-substituents, after photoemission of an electron during the XPS measurements. The intensity of the satellite peak ( I ratio ) within the substructure of the photoelectron line is an indication of the amount of charge being transfer from the donor (ferrocenyl-fragment) to the acceptor fragments. The link between the Gordy group electronegativities, λ R , and I ratio show that more charge is being transfer from Fc in chalcone with more electron withdrawing R-groups. During electron transfer processes (like electrochemical oxidation or photoemission) the chalcone undergoes inner-sphere reorganisation to compensate for the positively charged species which is formed. The I ratio is also an indication of the degree of inner-sphere reorganisation, while the carbonyl stretching frequency ( v CO as measured by ATR FTIR) is a measure of the amount of energy of required for this inner-sphere reorganisation. The link between I ratio and v CO showed that as the degree of inner-sphere reorganisation increases, more energy is required for this inner-sphere reorganisation. [ABSTRACT FROM AUTHOR]

A series of ferrocenyl-functionalized β-diketonato manganese(III) complexes, [Mn(FcCOCHCOR)3] with R = CF3, CH3, Ph (phenyl) and Fc (ferrocenyl) was subjected to a systematic XPS study of the Mn 2p3/2 and Fe 2p3/2 core-level photoelectron lines and their satellite structures. A charge-transfer process from the β-diketonato ligand to the Mn(III) metal center is responsible for the prominent shake-up satellite peaks of the Mn 2p photoelectron lines and the shake-down satellite peaks of the Fe 2p photoelectron lines. Multiplet splitting simulations of the photoelectron lines of the Mn(III) center of [Mn(FcCOCHCOR)3] resemble the calculated Mn 2p3/2 envelope of Mn3+ ions well, indicating the Mn(III) centers are in the high spin state. XPS spectra of complexes with unsymmetrical β-diketonato ligands (i.e., R not Fc) were described with two sets of multiplet splitting peaks representing fac and the more stable mer isomers respectively. Stronger electron-donating ligands stabilize fac more than mer isomers. The sum of group electronegativities, ΣχR, of the β-diketonato pendant side groups influences the binding energies of the multiplet splitting and charge transfer peaks in both Mn and Fe 2p3/2 photoelectron lines, the ratio of satellite to main peak intensities, and the degree of covalence of the Mn-O bond. [ABSTRACT FROM AUTHOR]

A new synthetic route involving ligand exchange towards a series of ruthenocenyl-containing β-diketonato titanocene complexes of the type [Ti IV (C 5 H 5 ) 2 (RcCOCHCOR)][ClO 4 ] with Rc = Ru II (C 5 H 5 )(C 5 H 4 ) and R = C 10 F 21 ( 1 ), CF 3 ( 2 ), C 6 F 5 ( 3 ), C 10 H 21 ( 4 ), CH 3 ( 5 ), Rc ( 6 ) and Fc = Fe II (C 5 H 5 )(C 5 H 4 ) ( 7 ) are described. The complex [Ti IV (C 5 H 5 ) 2 (RcCOCHCOCH 3 )][ClO 4 ], 5 , (Z = 4) crystallised in the monoclinic space group P2 1 /n. A cyclic voltammetric electrochemical study in CH 2 Cl 2 /0.1 M [NBu 4 ][B(C 6 F 5 ) 4 ] showed the one-electron transfer redox processes of the Ti III /Ti IV and Rc/Rc + couples exhibited irreversible electrochemical behaviour. In CH 3 CN/0.1 M [N( n Bu) 4 ][PF 6 ], the ruthenocenyl couple switched to an electrochemically and chemically irreversible two-electron transfer redox couple, Rc/Rc 2+ , involving the Ru IV redox centre. The redox potentials of the Ti III /Ti IV , Rc/Rc + and Rc/Rc 2+ couples were in the range −642 < E o′ < −1479 mV (both solvents), 1016 mV < E o′ < 1034 mV (CH 2 Cl 2 ) and 609 mV < E o′ < 832 mV (CH 3 CN) vs . the free ferrocene couple, FcH/FcH + , respectively. The Fc/Fc + redox process associated with 7 was observed at E o′ = 0.259 (CH 3 CN) and 0.235 V (CH 2 Cl 2 ). The cytotoxicity of [Ti IV (C 5 H 5 ) 2 (RcCOCHCOCF 3 )][ClO 4 ], 2 , against CoLo DM320 and HeLa cells, IC 50 = 10.2 and 9.7 μmol dm −3 respectively, was found to be in the same order of magnitude as those of the free ligand, RcCOCH 2 COCF 3 . [ABSTRACT FROM AUTHOR]

A rhodium(I) dicarbonyl on HY zeolite prepared from [Rh(CH 3 COCHCOCH 3 )(CO) 2 ] were charaterised by Attenuated Total Reflectance Fourier Transformed Infrared (ATR FTIR) and X-ray Photoelectron Spectroscopy (XPS). The ATR FTIR spectra of the anchored rhodium complex showed that [Rh(CH 3 COCHCOCH 3 )(CO) 2 ] reacted with the HY zeolite by loosing the [CH 3 COCHCOCH 3 ] − ligand to form Rh(CO) 2 /HY zeolite and [CH 3 COCHCOCH 3 ]/HY zeolite. The sharpness of the v (CO) bands measured by the ATR FTIR showed that the rhodium(I) dicarbonyl complex are distributed fairly uniform over the zeolite support. This heterogeneous catalyst was monitored for the oxidative addition of methyl iodide in the liquid phase, followed by reductive elimination of acetyl iodide upon treatment with CO gas. These reactions were monitored by following the carbonyl stretching frequencies from ATR FTIR measurements and the change in binding energy of the Rh 3d 5/2 photoelectron line as measured by XPS, observed rate constants determined were mutually consistent with each other. [ABSTRACT FROM AUTHOR]

Reaction of [Mn3(OAc)6O•3H2O]+ (1) with ferrocenyl β-diketones of the type FcCOCH2COR with R = CF3 (2a) and CH3 (2b), Ph = C6H5 (2c), and Fc = FeII(η5-C5H4)(η5-C5H5) (2d) yielded a series of ferrocene-functionalized β-diketonato manganese(III) complexes 3a-3d, respectively, of general formula [Mn(FcCOCHCOR)3]. The mixed-ligand β-diketonato complex [Mn(FcCOCHCOFc)2(FcCOCHCOCH3)] (4) was obtained by reacting mixtures of diketones 2b and 2d with 1. A single-crystal X-ray structure determination of 3b (Z = 2, triclinic, space group P1̅) highlighted a weak axial elongating Jahn-Teller effect and a high degree of bond conjugation. An X-ray photoelectron spectroscopic study, by virtue of linear relationships between group electronegativities of ligand R groups, χR, or ∑χR, and binding energies of both the Fe 2p3/2 and Mn 2p3/2 photoelectron lines, confirmed communication between molecular fragments of 2a-2d as well as 3a-3d. This unprecedented observation allows prediction of binding energies from known β-diketonato side group χR values. [ABSTRACT FROM AUTHOR]

The electrochemical behaviour of a series of rhodium(I) complexes of the type [Rh(CH 3 COCHCOCH 3 )CO(Ph 2 POPh- p -R)], where R = H ( 1 ), CH 3 ( 2 ), t Bu( 3 ) and Cl( 4 )] revealed an irreversible oxidation of Rh(I) to Rh(III), an irreversible oxidation of the phosphorus atom followed by the decomposition of the phosphinite ligand. An unexpected reaction occurred between the electrochemical internal standard, free ferrocene, in its ferricinium ion form and the radical cation of the oxidised diphenyl phosphinite, leading to uncharacteristic electrochemical behaviour. Electronic communication between different molecular fragment was confirmed by the linear relationships obtained between the Gordy group electronegativities of the R-groups on the phosphinites ( χ R ) and the E pa of Rh and the phosphorus atoms as well as the binding energy (eV) (measured by XPS) of the Rh 3d and P 2p peak positions. V-shape correlations were found between the Hammett constants of the R-groups on the phosphinites ( χ R ) and the oxidation potentials and binding energies. This shows the difference in stabilisation either resonance or inductive between the electrondonating and electronwithdrawing substituents. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance measurements confirm that, as expected, the mer isomer of tris(β-diketonato) cobalt(III) complexes is more stable (mer isomers are more stable because they are less affected by steric hindrance and they have lower dipoles). An excess of the mer isomer or only the mer isomer is experimentally observed. The existence of both fac and mer isomers is predicted by density functional theory calculations. At room temperature, the nuclear magnetic resonance peaks of phenyl-containing mer complexes are broad due to the intermediate rotation of bulky phenyl groups resulting in only the average orientation of the non-equivalent protons in the mer complexes. However, upon heating to 55°C (thus speeding up the rotation) or cooling to −50°C (slowing down the rotation), this broad peak is resolved into three sets of carbon peaks appearing in the 13C NMR spectrum, as well as splitting of the ¹H NMR peaks for the non-equivalent protons in the mer isomer. In solid-state 13C NMR the aromatic rings do not rotate, resulting in the splitting of all the 13C NMR peaks. Two sets of well-defined peaks are observed for the fluorine-containing compound [Co(CF3COCHCOCPh)3] in both the 13C and 19F NMR spectra, indicating that both the fac and mer isomers are present with a ratio of fac:mer = 0.1:1. The X-ray photoelectron spectroscopy measured binding energy of the Co 2p3/2 photoelectron lines are influenced by the subtle electronic (electron-donating or electron-withdrawing) properties of the R groups on the β-diketonato ligands. Various relationships are established between the binding energy of Co 2p3/2 and several physical and density functional theory–calculated properties, confirming good electronic communication (the measurable electronic effect that a molecular fragment has on the physical properties of another molecular fragment in the molecule) of the substituent groups through the pseudo aromatic system of the β-diketonato backbones to the metal. [ABSTRACT FROM AUTHOR]

Ruthenocene-containing β-diketones, RcCOCH2COR with Rc = ruthenocenyl and R = C10F21 (1), CF3 (2), C6F5 (3), C10H21 (4), CH3 (5) and C6H5 (6), were synthesised by Claisen condensation of the appropriate methyl ester with acetylruthenocene, and their spectroscopic, electrochemical and thermal properties were compared. A new synthetic route utilising 1,2,3-benzotriazol-1-ylethanone (9) or 1,2,3-benzotriazol-1-yl(ruthenocenyl)methanone (10) as a reactant, rather than the conventional esters, was found to be more efficient for β-diketone synthesis. The apparent acid dissociation constants, pKa′, of the new ruthenocene-containing β-diketones are 7.14(4) (1, R = C10F21), 9.92(3) (3, R = C6F5) and 10.06(2) (4, R = C10H21). Peak anodic potentials of the ruthenocenyl group of 1–6, pKa′ values and the FTIR ν(C=O) stretching frequencies of the precursor esters, RCOOCH3, correlated linearly with the Gordy scale group electronegativity, χR, of the C10F21 (χC10F21 = 3.04), C6F5 (χC6F5 = 2.46), C10H21 (χC10H21 = 2.43) and other R-groups. An electrochemical study in the non-interacting solvent and electrolyte system CH2Cl2/0.1 mol dm−3 [N(nBu4)][B(C6F5)4] revealed electrochemically irreversible one-electron transfer Rc/Rc+ couples in the potential range 650 ＜ Epa ＜ 1110 mV. Strikingly, reduction of the unstable monomeric 17 electron species, [Rc+(C5H5)(C5H4COCH2COR)], was clearly observed for all β-diketones possessing fluorinated R-groups, even at slow (100 mV s−1) scan rates. The enol isomer of the fluorinated β-diketones had ＞90% abundance under the conditions of study and the first order rate constant of enol to keto conversion varied between 220 and 50 000 s−1 depending on solvent (CDCl3 or CD3CN) and R-groups. Thermal analysis (DSC) of 1 and 4 showed no liquid crystalline mesophase behaviour but definite polymorphism was observed. β-diketones 1 and 4 exist as low temperature polymorphs below 42 °C or 12 °C respectively. The high temperature polymorphs converted to isotropic liquids at 83 °C (compound 1) or 52 °C (compound 4). [ABSTRACT FROM AUTHOR]

Nano γ-alumina-supported transition metal-based mono- (Pd 0/γ-Al2O3 or Co111/γ-Al2O3) and bimetallic catalysts (Pd0 Co111 /γ-Al2O3), were prepared by wet impregnation, oxidation and in situ reduction of the palladium. The palladium(II) acetate [Pd113 (OOCCH3)6], cobalt(II) acetate [Co11 (OOCCH3)2]•4H2O and palladium, cobalt bridging tetraacetate [Pd11 Co11 (OOCCH3)4]•H2O•2CH3COOH, were used as catalyst precursors to prepare a 7.4 % mol catalyst/support loading. The oxidation states of these activated catalysts were studied by XPS. These catalysts were evaluated for hydrogenation of cinnamaldehyde in a biphasic reaction under 3 MPa of hydrogen at 80°C. The Pd0/-Al2O3 selectively catalyzed the hydrogenation of C=C bond in cinnamaldehyde to form phenylpropanol (100%). In contrast, catalysiswith Pd0 Co111/γ-Al2O3 hydrogenated both C=C and C=O bonds consecutively, forming 65 % phenylpropanal and 35 % phenylpropanol with TOF = 47.2 h-1 . No reaction occurred when Co111/γ-Al2O3 was used. [ABSTRACT FROM AUTHOR]

The bimetallic paddlewheel catalyst precursor, [PdIICoII(μ-OOCCH3)4] H2O·2CH3COOH (1), prepared from[Pd3(μ-OOCCH3)6] and [Co(OOCCH3)2], was used as a single source precursor to prepare,after binding to a surface-hydroxylated silicon wafer and oxidation,the bimetallic oxides of PdIVCoIII/SiO2catalyst supported on a model planar (i.e., two-dimensional) siliconwafer. This catalyst catalyzes the aerobic oxidation of alcohols toits corresponding carbonyl compounds. The bimetallic tetracarboxylatocatalyst precursor was bonded to the surface-hydroxylated siliconwafer by spin-coating and also by grafting. X-ray photoelectron spectroscopy(XPS) revealed that one of the four μ-acetato bridging ligandswas substituted by Si–O fragments in a covalent bond formationprocess during grafting of 1onto the wafer. In contrast,during the spin-coating process, all four acetato ligands remainedintact during fixation on the silicon surface. Upon oxidation andworkup, the grafted sample’s Pd:Co ratio remained unchanged(1.0:1.3), whereas the spin-coated sample’s Pd content decreasedwith respect to Co content. XPS determined binding energies were interpretedto imply that after oxidation in an oxygen/argon mixture of the graftedsample both PdIIand CoIIwere oxidized to producePdO2(337.5 eV) and CoIII2O3(781.1 eV) which most probably interacts with the silicon surfacevia PdIV–O–Si and CoIII–O–Sibonds. Solvent free aerobic oxidation of octadecanol to its correspondingcarbonyl compound was achieved on this oxidized PdIVCoIII/SiO2model catalyst using molecular oxygen asoxidant under solvent-free conditions. The use of the single sourcecatalyst precursor, 1, resulted in a PdIVCoIII/SiO2catalyst with superior catalytic activitytoward the oxidation of octadecanol over a catalyst prepared froma physical mixture of the separate reactant compounds tripalladium(II)hexaacetate and cobalt(II) diacetate. [ABSTRACT FROM AUTHOR]

Abstract: Aerobic oxidation of a thin film of octadecanol at 105°C and ambient pressures to its corresponding carbonyl derivatives (a mixture of aldehyde and carboxylic acid) was for the first time performed over a flat-model (i.e. two-dimensional), silicon wafer-supported metallic silver catalyst. The experimental set-up was extraordinary simple. An open-to-the-atmosphere glass beaker was used as reactor. Just enough octadecanol was placed on the silicon-supported catalytic surface to cover it with a thin film when melted. Reaction progress was monitored by ATR-FTIR analyses to identify the appearance of octadecanal and octadecanoic acid carbonyl stretching peaks at 1730 and 1710cm−1 respectively. The successful demonstration of this simple approach in studying catalysed small-molecule condensed organic reactions opens a new avenue towards simplified catalytic mechanistic studies of such processes. The catalyst was prepared by spin coating silver nitrate on a flat silicon wafer with (100) surface orientation, pretreated to have 4−5 silanol (ph name="sbnd" />OH) groups per nm2. Reduction by hydrogen at 350°C afforded metallic silver particles on the two-dimensional support at a nominal surface concentration of ca. 21–23 silver atoms/nm2. XPS differentiation between the catalyst precursor, AgNO3, and the metallic silver catalytic surface required use of the Auger MNN kinetic energies. TEM studies of the active catalyst showed no serious aggregation of metallic Ag particles occurred during reduction. [Copyright &y& Elsevier]

Abstract: Chalcones of the type Mc-CO–CH-CO–CH Mc-CO–CHh Mc=Fc=ferrocenyl or Rc=ruthenocenyl, and Ph=phenyl were synthesized. Synthesis was achieved by base catalyzed Claisen–Schmidt condensation of the appropriated acetyl and aldehyde in ethanol. Cyclic voltammetry in CH3CN in the presence of 0.1moldm−3 [N(Bu)4][PF6] revealed chemical and electrochemical reversible behaviour for the Fc/Fc+ couple and irreversible electrochemistry for the two electron Rc/Rc2+ couple. The potential ranges for the Fc/Fc+ couple varied in the range 138⩽ E°′⩽302mV while E pa for Rc/Rc2+ couple was between 358 and 510mV vs. FcH/FcH+, the internal standard. Chalcones with the carbonyl group adjacent to the metallocene, are more difficult to oxidize. [Copyright &y& Elsevier]

Abstract: The synthesis of a variety of tetrahedral β-diketonato titanium(IV) complexes of the type with R=CF3, OCH3, C6H5, CH3 and Fc is described. The TiIII/TiIV couples and the Fc/Fc+ couple exhibited chemically and electrochemically reversible cyclic voltammetric behaviour. The formal reduction potential of the TiIII/IV couple increased as the group electronegativity of the R group of the β-diketonato ligand increased. Bulk electrolysis showed that one electron was transferred in the TiIII/IV couple and one electron in the ferrocenyl/ferrocenium redox couple in the ligand. The crystal structure for the R=OCH3 complex showed that this β-keto-ester binds through the carbonyl oxygen of the ester group and not the ether oxygen. [Copyright &y& Elsevier]

[Display omitted] Three different classes of ferrocenyl-containing β-keto compounds Fc-CO-CH 2 -CO-R were synthesised to obtain two β-diketones with R = CH 3, 3 , and R = Fc (ferrocenyl = FeII(C 5 H 5)(C 5 H 4)), 4 , a β-ketoester, 5 , with R = OEt and a β-ketoamide, 6 , with R = NH 2. The β-diketones exhibited keto ⇌ enol tautomerization with the enol form Fc-CO-CH=C(OH)-R as the dominant isomer. Both the β-ketoester and β-ketoamide primarily existed in the keto form. FTIR and 1H NMR measurements could distinguish between keto and enol isomers. Dilute CHCl 3 solutions of 3 and 4 exhibited FTIR ѵ C=O keto vibrations between 1627 and 1712 cm−1 and ѵ C=O enol vibrations between 1590 and 1660 cm−1. X-ray photoelectron spectroscopic (XPS) measurements showed keto isomer Fe 2p 3/2 photoelectron lines at smaller binding energies than enol isomers. Significantly lower calculated molecular energies of the keto form of the β-ketoester 5 and β-ketoamide 6 utilising the Gaussian09 suite of programs at the B3LYP (uB3LYP for open-shell species), confirmed that 5 and 6 almost exclusively exists in the keto conformation. Cyclic voltammetry also distinguished between keto and enol isomers, and it was found that the electrochemical reversible ferrocenyl formal oxidation potential, E °ꞌ, of keto isomers of compounds can be estimated with the equation E °ꞌ keto = 170.99χ R –57.57 where χ R is the group electronegativities of R in FcCOCH 2 COR. This result complements earlier research that enables calculation of the ferrocenyl formal oxidation potentials of enol isomers of β-diketones. Computational studies further showed that the HOMO orbitals of 3 – 6 is exclusively on the Fe centre and computed Mulliken spin densities on the d xy orbital of the oxidised iron species approached 1 e−. [ABSTRACT FROM AUTHOR]

p-Cresol as additive to the Grubbs second generation catalyst (GII) allows the cross-metathesis of acrylates with prop-1-en-1-ylbenzenes under conditions that only give the prop-1-en-1-ylbenzene self-metathesis product in the absence of cresol. NMR and IR spectroscopy, MALDI-TOF MS and XPS supported the formation of a ruthenium benzylidene with hydrogen bonds between p-cresol and the chloride ligands of GII. XPS furthermore confirmed p-cresol to increase the binding energies of the GII Ru 3d5/2, 3d3/2, 3p3/2 and 3p1/2 photoelectron lines, whereas 1H NMR spectroscopy indicated the carbene carbon and hydrogen to be shielded. It is thus postulated that p-cresol allows for more facile interaction between electron-deficient compounds and the ruthenium benzylidene by decreasing the electron density on the metal center and increasing the electron density on the carbene. [ABSTRACT FROM AUTHOR]

Palladium-based heterometallic complexes are important because of their interesting physical properties and excellent catalytic activity. In this study, four monometallic trinuclear palladium long chain carboxylates and four palladium-based bimetallic bridging tetracarboxylate complexes were synthesised. These complexes were characterised by different techniques, including DSC, TGA-MS, X-Ray diffraction and IR spectroscopy. [ABSTRACT FROM AUTHOR]

The electrochemical analysis, theoretical examination, as well as the first X-ray photoelectron spectroscopic (XPS) study on molybdenum(0) Fischer carbene complexes are presented. The intramolecular communication between the carbene ligand, molybdenum metal centre, and the ancillary ligands is illustrated by linear relationships and trends obtained between experimentally measured redox and XPS binding energy values and theoretically calculated energies and charges. The ease of oxidation of the three series of Mo(0) Fischer carbene complexes presented, namely four pentacarbonyl Mo(0) Fischer carbene complexes of general formula [(CO) 5 MoC(OEt)(Ar)], with Ar = 2-thienyl ( 1 ), 2-furyl ( 2 ), 2-(N-methyl)pyrrolyl ( 3 ), 2,2'-bithienyl ( 4 ), four triphenylphosphine-substituted tetracarbonyl Mo(0) Fischer carbene complexes of general formula [(CO) 4 (PPh 3 )MoC(OEt)(Ar)], with Ar = 2-thienyl ( 5 ), 2-furyl ( 6 ), 2-(N-methyl)pyrrolyl ( 7 ), 2,2'-bithienyl ( 8 ), and four triphenylarsine-substituted tetracarbonyl Mo(0) Fischer carbene complexes of general formula [(CO) 4 (AsPh 3 )MoC(OEt)(Ar)], with Ar = 2-thienyl ( 9 ), 2-furyl ( 10 ), 2-(N-methyl)pyrrolyl ( 11 ), 2,2'-bithienyl ( 12 ), all showed the same trend, namely (most difficult to oxidize at a higher potential): 2-thienyl ≈ 2,2'-bithienyl > 2-furyl > 2-(N-methyl)pyrrolyl. The pentacarbonyl complexes [(CO) 5 MoC(OEt)(Ar)] have the highest oxidation potentials, followed by the oxidation potential of [(CO) 4 (PPh 3 )MoC(OEt)(Ar)], while [(CO) 4 (AsPh 3 )MoC(OEt)(Ar)] oxidized at a potential 0.12 − 0.15 V lower than the PPh 3 substituted complexes [(CO) 4 (PPh 3 )MoC(OEt)(Ar)]. Substitution of carbonyl ligand(s) in the pentacarbonyl complexes 1 – 4 , by one (complexes 5 – 12 ) or two ([(dppe)(CO) 3 MoC(OEt)(2-furyl)] complex ( 13 ), dppe = 1,2-bis(diphenylphosphino)ethane) weaker π-acceptor ligands (phosphines/arsines) in Fischer carbene complexes leads to a decrease in the binding energy of the Mo 3d 5/2 photoelectron lines of the X-ray photoelectron spectra of the Fischer carbene complexes and an increase in the binding energy of the carbene carbon C 1 s photoelectron lines. [ABSTRACT FROM AUTHOR]

Abstract: A comparative investigation of seven ferrocene-containing chalcones (Fc–CO–CH;C6H4R, with R=OCH3, CH3, Ph, t Bu, H, Br and CF3) has been performed based on their electrochemical and spectroscopical behavior as well as with DFT calculations. These compounds were prepared by Claisen-Schmidt condensation of acetylferrocene and the appropriate benzaldehyde derivative. All compounds exhibited reversible chemical and electrochemical behavior, as confirmed by ΔE =83−93mV and i pc/i pa =0.93−1.00. The formal reduction potential E°′ for the compounds ranged between 231.0 and 261.5mV versus FcH/FcH+ as an internal standard. The UV–Vis spectra of all ferrocene-containing chalcones showed the characteristic peaks for aromatic systems at ±380nm and a peak in the visible region at ±490nm, which is attributed to the ferrocene moiety. FTIR of all the ferrocene-containing chalcones showed a characteristic CO stretching peak at ±1650cm−1. DFT calculated HOMO energies and ionization potentials correlate well with experimentally measured E°′ values. [Copyright &y& Elsevier]

Abstract: Enhanced electrochemical resolution of anodic processes is possible in the presence of [N( n Bu)4][B(C6F5)4], 1, as supporting electrolyte over that obtained in the presence of [N( n Bu)4][PF6]. By changing the anion of the supporting electrolyte to a salt having [B(C6F5)4]−, anions, electrochemical processes of especially cationic analytes can benefit. Thus, the redox chemistry of 0.5mmoldm−3 solutions of [Ru2(μ-FcCOO)4·(CH3CH2OH)2][PF6], 2, Fc=ferrocenyl, in CH2Cl2/[N( n Bu)4][B(C6F5)4] were found to involve four well-resolved ferrocenyl-based electrochemical reversible redox processes as well as reduction of RuIII–RuII. At 1.0mmoldm−3 concentrations of 2, or in the presence of [N( n Bu)4][PF6], the four ferrocenyl processes coalesced into only two waves as a result of (Fc+)⋯() ion paring. Seventeen of the possible 18 one-electron transfer processes of the biscadmium trisphthalocyaninato complex [Cd2{Pc(C6H13)8}3], 3, could be observed in THF/[N( n Bu)4][B(C6F5)4], but the electrochemical window of CH2Cl2/[N( n Bu)4][B(C6F5)4] only allowed detection of 15 of these processes. Although reduction processes were unaffected, THF solvation leading to species such as (3 n +)(THF) x with 1⩽ n ⩽4 and x ⩾1 as well as ion pair formation of the type (3 n +)⋯() prevented good resolution of oxidation processes. The CH2Cl2/[N( n Bu)4][B(C6F5)4] system also allowed detection of reversible one-electron transfer ferrocenyl (Fc/Fc+) and ruthenocenyl-based (Rc/Rc+) processes for both enol and keto isomers of the β-diketone FcCOCH2CORc, 4, Rc=ruthenocenyl. In CH3CN/[N( n Bu)4][PF6], the ruthenocenyl moiety was oxidised to a RuIV species. [Copyright &y& Elsevier]

The metathesis of 1-hexene and (E)-anethole in the presence of Grubbs 2nd generation catalyst was monitored by in situ 1H NMR spectroscopy at different temperatures (15 °C, 25 °C, and 45 °C) and anethole mol fractions (XAnethole ≈ 0.17, 0.29, 0.5, 0.71, 0.83). Time traces confirmed the instantaneous formation of (E)-1-(4-methoxyphenyl)-1-hexene, the cross-metathesis product. A maximum concentration of (E)-1-(4-methoxyphenyl)-1-hexene is reached fairly fast (the time depending on the reaction conditions), and this is followed by a decrease in the concentration of (E)-1-(4-methoxyphenyl)-1-hexene due to secondary metathesis. The maximum concentration of (E)-1-(4-methoxyphenyl)-1-hexene was more dependent on the XAnethole than the temperature. The highest TOF (3.46 min−1) was obtained for the reaction where XAnethole was 0.16 at 45 °C. The highest concentration of the cross-metathesis product was however achieved after 6 min with an anethole mol fraction of 0.84 at 25 °C. A preliminary kinetic study indicated that the secondary metathesis reaction followed first order kinetics. [ABSTRACT FROM AUTHOR]

In methanol solutions, [Rh(FcCOCHCOR)(CO)(PPh 3)] and [Rh(FcCOCHCOR)(CO) 2 ] complexes do not undergo substitution or oxidative addition by MeOH. In contrast, when the same compounds are spin-coated on (OH)-capped silicon wafers, XPS measurements showed that, in the solid state, both ligand substitution and oxidative addition by Si-OH functionalities occur. Rh XPS binding energies are linearly related to RhI oxidation potentials and group electronegativities of the R-groups (CF 3 , CH 3 , phenyl and ferrocenyl). [Display omitted] A series of rhodium β-diketonato complexes [Rh(FcCOCHCOR)(CO) 2 ] and [Rh(FcCOCHCOR)(CO)(PPh 3)] with R = CF 3 , CH 3 , Ph = C 6 H 5 and Fc (ferrocenyl = FeII(C 5 H 5)(C 5 H 4)) were spin-coated on two-dimensional silanol-functionalised silicon wafers. Chemical reactions were observed that do not occur in ethanol solutions. Si-OH fragments on the wafers substituted ligands and oxidatively added to the Rh(I) centres. A multitude of different surface species could be identified with X-ray photoelectron spectroscopy (XPS). These included the parent spin-coated rhodium(I) complexes and rhodium(I) species that resulted from β-diketonato displacement from parent rhodium complexes by surface silanol OH's to generate [wafer-(O) 2 -Rh-(CO) 2 ]⊝ and [wafer-(O) 2 -Rh-(CO)(PPh 3)]⊝ units. Several RhIII surface species that inter alia resulted from oxidative addition of surface Si-OH groups to surface-coordinated RhI core atoms were also identified. Efficacy of β-diketonato ligand substitution by the silanol surfaces is a kinetically driven process and can be related to the rate of solution-phase β-diketonato substitution by 1,10-phenanthroline from parent [Rh(FcCOCHCOR)(CO) 2 ] and [Rh(FcCOCHCOR)(CO)(PPh 3)] complexes. The binding energies of the RhI and RhIII 3 d 5/2 photoelectron lines were found to be functions of Gordy scale R-group electronegativities and they are also linearly related to electrochemically determined RhI oxidation potentials. [ABSTRACT FROM AUTHOR]

• A series of deep eutectic solvents (DESs) catalysts with varying ratios were successfully synthesized. • The DES with a composition of [TEA-12][OH]:[Q-COOH]- 0.9: 0.1 had the lowest melting point of 100.17 °C. • The efficiency of the catalysts for CO 2 fixation was evaluated and [TEA-12][OH]:[Q-COOH]−0.9:0.1 proved to be the most effective catalyst with a TOF of 1466 h−1. • Exceptional conversions were observed for epoxides with electron-withdrawing function groups, while electron-donating functional groups showed lower activity. The accumulation of greenhouse gases (GHG) in the atmosphere, with carbon dioxide being the most significant contributor, is a major environmental problem as it impacts significantly on climate change. The development of new catalysts and chemical reactions that incorporate CO 2 are needed to reduce its further emission significantly. Deep eutectic solvents (DES) have garnered increasing attention as environmentally friendly catalysts in the cycloaddition of carbon dioxide (CO 2) with epoxide substrates to produce cyclic carbonates. Their appeal stems from their facile synthesis, cost-effectiveness, low vapour pressure, and thermal stability. In this study, we present a convenient solvent-free synthesis method for nine deep eutectic solvents (DES), utilizing varying compositions of quaternary amine salts (N,N,N -triethyldodecan-1-aminium hydroxide, [TEA-12][OH]) and quinaldic acid [Q-COOH]. These deep eutectic solvents were thoroughly characterized using several techniques, including FTIR, NMR, DSC, and TGA. Moreover, their efficacy for the solvent-free fixation of CO 2 to cyclic carbonates were evaluated. Among the tested compositions, [TEA-12]:[Q-COOH] (0.9:0.1) exhibited the lowest melting point (100.17 °C) and highest catalytic activity, showcasing an optimized Turn-Over Frequency (TOF) of 1466 h−1. This remarkable result represents a significant advancement in the application of DES for CO 2 fixation, exceeding the previous highest catalytic activity observed with TBAB:Citric acid (2.5:1) by more than tenfold. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphical abstract The electrochemical behavior of the Fc/Fc+ of ferrocenyl-terpyridine coordination metal complexes is related to the charge transfer and binding energy of the Fe 2p photoelectron lines as measured by XPS, giving insight into the electronic properties of the complexes. Highlights • Preparation of coordinated ferrocenyl-terpyridine complexes. • Electrochemical study of the coordinated ferrocenyl-terpyridine complexes. • X-ray photoelectron spectroscopy of ferrocenyl-terpyridine coordination complexes. • The intensity of satellite structures in XPS indicated the amount of charge transferred. • Single crystal structure of [Rh(Fctpy) 2 ][PF 6 ] 3. Abstract A series of 4′-ferrocenyl-2,2′:6′,2′'-terpyridine coordination metal complexes, [M(Fctpy) 2 ][PF 6 ] x with M = Co (2), Fe (3), and Rh (4) and x = 2 (for 2 and 3) or 3 (for 4), was subjected to an electrochemical and X-ray photoelectron spectroscopic study. The formal reduction potential of the Fc/Fc+ couple of the ferrocenyl-moiety (FeII) is related to the Allred Rochow electronegativities of the different coordinated metals, as well as with binding energies of the Fe 2p 3/2 photoelectron lines (as measured by XPS). The binding energy position of the main Fe 2p 3/2 photoelectron line, spin–orbit splitting between the main and satellite structure (charge transfer band) of the Fe 2p 3/2 photoelectron line as well as the intensity ratio between the of the main and satellite structure of the Fe 2p 3/2 photoelectron line (I ratio , this gives the relative amount of charge being transferred) gave insight in the electronic structure of these ferrocenyl-terpyridine coordination metal complexes, 2 – 4. A single crystal X-ray structure determination of 4 highlighted the disorder of the PF 6 counter anions as well as double occupancy of the central metal atom of Rh (in 4) with Fe, the Fe:Rh ratio is 0.14:0.85. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of the first triphenylstibine-containing Fischer carbene complexes of Mo(0) with general formula [(SbPh 3 )(CO) 4 MoC(OEt)(Ar)] with Ar = 2-thienyl ( 1 ), 2-furyl ( 2 ), 2-(N-methyl)pyrrolyl ( 3 ), and 2,2′-bithienyl ( 4 ) are reported. The solid state crystal structures of these complexes show a syn conformation of the 2-thienyl and 2,2′-bithienyl groups relative to the ethoxy group, and an anti conformation of the 2-furyl group relative to the ethoxy group. Density functional theory calculations using natural bonding orbital (NBO) and quantum theory of atoms in molecules (QTAIM) calculations gave insight into the electronic structure and preferred conformations of these novel complexes. X-ray photoelectron spectroscopy measurements show that the binding energy of the Mo 3d 5/2 photoelectron line for the 2-(N-methyl)pyrrolyl-containing Fischer carbene complex, 3 , is the smallest; followed by 2 and then 1 . This implies that the Mo metal centre is more electron rich in 3 , relative to the 2-furyl or 2-thienyl containing Fischer carbene complexes, 2 and 1 , respectively. [ABSTRACT FROM AUTHOR]

The electrochemical behaviour of triphenylstibine-containing Fischer carbene complexes of Mo(0) of the type [(SbPh 3 )(CO) 4 MoC(OEt)(Ar)] with Ar = 2-thienyl ( 1 ), 2-furyl ( 2 ), 2-(N-methyl)pyrrolyl ( 3 ) or 2,2'-bithienyl ( 4 ) is reported. Results are compared to the related complexes [(L,L')(CO) 3 MoC(OEt)(Ar)] where L,L' = CO,CO; PPh 3 ,CO; AsPh 3 ,CO; or dppe (1,2-bis(diphenylphosphino)ethane). Linear trends and relationships obtained between HOMO/LUMO energies, oxidation/reduction potentials, ionization energies/electron affinities and X-ray photoelectron spectroscopic binding energies of the Mo 3d 5/2 photoelectron lines, show that the electronic influences of the heteroaryl carbene substituent and pnictogen ligands in Mo(0) Fischer ethoxycarbene complexes are transmitted well through the bonds to the Mo metal centre. [ABSTRACT FROM AUTHOR]

Ethoxy chromium (0) Fischer carbene pentacarbonyl complexes [(CO) 5 CrC(OEt)R]; R = 2-thienyl ( 1 ), 2-furyl ( 2 ) were covalently anchored onto aminopropyltrimethoxysilane-functionalized silicon-wafers to form Cr-grafted Si-wafers S1 and S2 that were characterized by X-ray photoelectron spectroscopy (XPS). X-ray photoelectron spectroscopy determined that binding energy of the Cr 2p 3/2 photoelectron line of the thienyl-containing complexes were smaller than that of the furyl-containing complexes. The binding energy of the Cr 2p 3/2 photoelectron line of the ethoxycarbene complexes was smaller than that of aminocarbenes. The binding energy of the Cr 2p 3/2 photoelectron line of the Cr-grafted Si-wafers were ca. 1 eV higher than that of the related aminocarbenes. A 25–33% anchoring of the Cr-complexes 1 and 2 on the aminopropyltrimethoxysilane-functionalized silicon-wafers was achieved. [ABSTRACT FROM AUTHOR]

It is illustrated that the electrochemical redox potentials of chromium(0) Fischer carbene complexes containing a heteroaromatic substituent can be determined to a high degree of accuracy from the gas phase density functional theory (DFT) optimized frontier orbital energies, with a mean average error of the calculated redox potentials of 0.047 V for the chromium-based oxidation potential and 0.057 V for the carbene ligand based reduction potential. For the first time it was possible to distinguish between the Cr 0/I oxidation peaks of the E and the Z -isomer of a cyclohexylamino pentacarbonyl chromium Fischer carbene complex, namely [(CO) 5 CrC(NHCy)(2-thienyl)]. The linear relationship obtained between the oxidation potential and the DFT calculated highest molecular orbital energies, made it possible to assign the oxidation peak at the lower less positive oxidation potential to the oxidation of the E isomer, and the peak at the slightly higher (more positive) oxidation potential to the oxidation of the Z isomer of [(CO) 5 CrC(NHCy)(2-thienyl)]. [ABSTRACT FROM AUTHOR]

Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, 1a) tetrabenzomonoazaporphyrin (2H-TBMAP, 2a), tetrabenzo-cis-diazaporphyrin (2H-TBDAP, 3a), tetrabenzotriazaporphyrin (2H-TBTAP, 4a), and phthalocyanine (2H-Pc, 5a), as well as their copper complexes (1b-5b), were synthesized. As the number of meso nitrogen atoms increases from zero to four, λmax of the Q-band absorption peak becomes red-shifted by almost 100 nm, and extinction coefficients increased at least threefold. Simultaneously the blue-shifted Soret (UV) band substantially decreased in intensity. These changes were related to the relative electron-density of each macrocycle expressed as the group electronegativity sum of all meso N and CH atom groups, ∑χR. X-ray photoelectron spectroscopy differentiated between the three different types of macrocyclic nitrogen atoms (the Ninner, (NH)inner, and Nmeso) in the metal-free complexes. Binding energies of the Nmeso and Ninner,Cu atoms in copper chelates could not be resolved. Copper insertion lowered especially the cathodic redox potentials, while all four observed redox processes occurred at larger potentials as the number of meso nitrogens increased. Computational chemical methods using density functional theory confirmed 1b to exhibit a Cu(II) reduction prior to ring-based reductions, while for 2b, Cu(II) reduction is the first reductive step only if the nonperipheral substituents are hydrogen. When they are methyl groups, it is the second reduction process; when they are ethyl, propyl, or hexyl, it becomes the third reductive process. Spectro-electrochemical measurements showed redox processes were associated with a substantial change in intensity of at least two main absorbances (the Q and Soret bands) in the UV spectra of these compounds. [ABSTRACT FROM AUTHOR]

Surface-hydroxylated silicon wafers, 8, were reacted with 3-aminopropyltrimethoxysilane, 9, to create wafers with amine-functionalized surfaces, 10. The metallocenylaldehydes FcCHO, 1 (Fc = ferrocenyl = FeII(C5H5)(C5H4)), RcCHO, 2 (Rc = ruthenocenyl = RuII(C5H5)(C5H4)), and OcCHO, 3 (Oc = osmocenyl = OsII(C5H5)(C5H4)) as well as the carboxylic acids FcCOOH, 4, RcCOOH, 5, OcCOOH, 6, and Cc+COOH·PF6 −, 7 (Cc+ = cationic cobaltocenium = [CoIII(C5H5)(C5H4)]+), were reacted with 10 to covalently anchor the metallocenes on the wafers either via an imine (–CH N–) or amide (–NHCO–) bond. The aldehydes were anchored more effectively than the carboxylic acids. Binding energies of all important atoms in all seven systems were determined by XPS measurements. Metal binding energies of the amide-bonded metallocenes were consistently larger (up to 0.6 eV) than those of the imine-anchored systems. AFM and SEM measurements showed that the covalently anchored metallocenes aggregate into nano-islets of diameter between 40 and 100 nm depending on the metallocene and type of anchoring bond. Up to seven additional layers of unreacted metallocenylaldehyde or -acid further stacked on top of the main layer of metallocene to form each islet. These additional layers of metallocene of each islet are stabilized by a large network of secondary and/or tertiary bonding forces. The main film surfaces have average thicknesses ranging between 2 and 6 nm, while film roughness, which is mostly associated with the islets, was with one exception (that of the Oc–CONH– surface 14) between 17% and 68% of the film thickness. The crystal structures for OcCHO, 3, and Cc+COOH·PF6 −, 7, was determined and the observed tertiary and secondary intermolecular interactions between independent molecules explains the formation of the nano-islets of each metallocene when anchored onto the aminated silicon wafers. [ABSTRACT FROM AUTHOR]

The ferrocenylthiophenes 2,3-Fc2-cC4H2S (9), 2,4-Fc2-cC4H2S(10), and 2,3,4-Fc3-cC4HS (11) have been prepared by a 2-or 3-fold Negishi cross-coupling reaction of the appropriate bromothiophenes 5–7with FcZnCl (8; Fc = Fe(η5-C5H4)(η5-C5H5)) in the presence of either [Pd(PPh3)4] or [Pd(CH2CMe2PtBu2)(μ-Cl)]2as catalyst.Concerning electron transfer studies on ferrocenyl-substituted aromaticheterocycles, the electrochemistry as well as in situ UV–vis–near-IRspectroelectrochemistry highlight the electrochemical properties ofthese compounds in a series of mono-, di-, tri-, and tetraferrocenylthiophenes,including 2-Fc-cC4H3S (1), 3-Fc-cC4H3S (2), 2,5-Fc2-cC4H2S (3), 3,4-Fc2-cC4H2S(4), 2,3,5-Fc3-cC4HS (12), and 2,3,4,5-Fc4-cC4S (13). These organometalliccompounds display one (1, 2), two (3, 4, 9, 10), three(11, 12), or four (13) well-resolvedelectrochemically reversible one-electron-transfer processes using[NnBu4][B(C6F5)4] as the supporting electrolyte. The spectroelectrochemicalstudies reveal that ferrocenyl units placed in the α-positionof the thiophene ring interact more strongly with the heterocyclethan those in the β-position. Thus, the intensity of the ligand-to-metalcharge transfer (LMCT) absorptions, caused by interactions betweenthe thiophene core and the ferrocenyl moieties, decreases from 1 2. Furthermore, in the series of diferrocenylthiophenes theinteraction between the iron centers in the mono-oxidized compoundsdecreases in the series 3> 9> 10> 4. Thestructural properties of 10were investigated by single-crystalX-ray diffraction studies, indicating that 10possessesa syn conformation in the solid state with respect to the orientationof the two ferrocenyl units along the central thiophene core. Compound 10is isomorphic with 3. [ABSTRACT FROM AUTHOR]