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Zwitterionic nickel(II) compounds with a borate-containing anionic bidentate phosphine ligand (PBP − ) have been synthesized and some of them crystallographically characterized. The methyl complex, (PBP − )Ni + CH 3 (NCCH 3 ), reacts with H 2 to form an 12-membered macrocycle containing three Ni nuclei and reacts with carbon monoxide (CO) to afford the acetyl complex (PBP − )Ni + COCH 3 (CO). The square planar acetyl complex is stable in solution under 1 atm of CO but undergoes irreversible decomposition under high CO pressure at room temperature. X-Ray crystallographic characterization of a decomposition product revealed fragmentation of the anionic borate under high pressure. (PBP − )Ni + COCH 3 (CO) is an active catalyst for ethylene-CO copolymerization, but its productivity is low likely due to its instability under high CO pressure. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis, spectroscopic characterization, and theoretical analysis of a linearly conjugated pentacene-fused porphyrin dimer and cross-conjugated quinone-fused dinaphtho[2,3]porphyrins. These multichromophoric systems display non-typical UVvisible absorptions of either porphyrins or pentacenes/quinones. UV-visible, emission and magnetic circular dichroism (MCD) spectroscopy suggest strong electronic interactions among the multichromophores in the system. DFT calculations revealed the delocalization of the HOMOs and LUMOs spanning the entire dimer and linker assembly. The pentacene-fused porphyrin dimer is significantly more stable than both the corresponding pentacene and the heptacene derivatives. The availability of these huge π-extended and electronically highly interactive multichromophoric systems promises unprecedented electronic and photophysical properties. [ABSTRACT FROM AUTHOR]

A series of dimeric ReI(CO)3 compounds have been prepared by means of a one-pot reaction of [Re(CO)5X] (X = Cl, Br), pyridine-2-carboxyaldehyde, and o-, m-, or p-phenylenediamine. For the m- and p-substituted phenylenediamine reactions, phenyl-bridged bis(pyridine-2-carbaldimine) compounds of the formula [Re(CO)3X]2(μ-PPC) [ 3- 7; X = Cl, Br; μ-PPC = m- or p-phenylene bis(pyridine-2-carbaldimine)] were produced, with m-phenylenediamine forming a mixture of isomers. For reactions with o-phenylenediamine, multiple products formed (compounds 8- 11), which ranged from the desired o-phenylene bis(pyridine-2-carbaldimine) adduct to 2-pyridylbenzimidazole and bridging dipyridinylquinoxaline complexes. An example of each complex was structurally elucidated by single-crystal X-ray methods. The dimeric m- and p-phenylene-bridged Re(CO)3X compounds, including a sulfonate derivative designed to improve solubility, were investigated for possible photophysical applications through the use of UV/Vis spectroscopy and cyclic voltammetry; the study revealed coupling between the rhenium centers. [ABSTRACT FROM AUTHOR]

Abstract: A bidentate phosphine ligand with two amide arms, designed to form hydrogen bonds with electron-donating moieties, was synthesized and isolated in high diastereomeric excess (95% de). The hydrogen-bonding abilities of the ligand and its diastereomer were demonstrated with two rhodium complexes containing these ligands. The structures of the rhodium compounds are reminiscent of the well-studied picket-fence porphyrin systems. [Copyright &y& Elsevier]

Abstract: In this Letter, we present a synthetic and structural study into bis-imino substituted diiminoisoindolines, which can be synthesized either via CaCl2 mediated reaction of phthalonitrile with primary amines, or via direct reaction of these amines with unsubstituted diiminoisoindoline. The preferred synthesis does depend on the methodology, and in two cases singly substituted adducts were formed. The single crystal X-ray structures show that, with the exception of the bis-naphthyl compound, the anti conformation is preferred, and that the ionizable hydrogen atom resides on an exocyclic nitrogen rather than the central isoindoline nitrogen atom. [Copyright &y& Elsevier]

In this report we present a study of a series of Re(CO)3 pyridine–imine complexes with pendant phenol groups. We investigated the effects of the position of the phenol hydroxyl group (para, meta or ortho to the imine) on the steric and electronic characteristics of a series of Re(CO)3X(pyca-C6H4OH) compounds, where X = Cl, Br and pyca = pyridine-2-carbaldehyde imine. These compounds can be generated either via ligand synthesis followed by metal chelation (compound 4) or via a one-pot method (compounds 2, 3, 5 and 6). All six compounds show striking differences in pH-dependent UV-visible absorption based on the position of the phenol hydroxyl group. [ABSTRACT FROM AUTHOR]

The complexes [Ru(bpy)2(pyESO)](PF6)2 and [Os(bpy)2(pyESO)](PF6)2, in which bpy is 2,2′-bipyridine and pyESO is 2-((isopropylsulfinyl)ethyl)pyridine, were prepared and studied by 1H NMR, UV-visible and ultrafast transient absorption spectroscopy, as well as by electrochemical methods. Crystals suitable for X-ray structural analysis were grown for [Ru(bpy)2(pyESO)](PF6)2. Cyclic voltammograms of both complexes provide evidence for S→O and O→S isomerization as these voltammograms are described by an ECEC (electrochemical-chemical electrochemical-chemical) mechanism in which isomerization follows Ru2+ oxidation and Ru3+ reduction. The S- and O-bonded Ru3+/2+ couples appear at 1.30 and 0.76 V versus Ag/AgCl in propylene carbonate. For [Os(bpy)2(pyESO)](PF6)2, these couples appear at 0.97 and 0.32 V versus Ag/AgCl in acetonitrile, respectively. Charge-transfer excitation of [Ru(bpy)2(pyESO)](PF6)2 results in a significant change in the absorption spectrum. The S-bonded isomer of [Ru(bpy)2(pyESO)]2+ features a lowest energy absorption maximum at 390 nm and the O-bonded isomer absorbs at 480 nm. The quantum yield of isomerization in [Ru(bpy)2(pyESO)]2+ was found to be 0.58 in propylene carbonate and 0.86 in dichloroethane solution. Femtosecond transient absorption spectroscopic measurements were collected for both complexes, revealing time constants of isomerizations of 81 ps (propylene carbonate) and 47 ps (dichloroethane) in [Ru(bpy)2(pyESO)]2+. These data and a model for the isomerizing complex are presented. A striking conclusion from this analysis is that expansion of the chelate ring by a single methylene leads to an increase in the isomerization time constant by nearly two orders of magnitude. [ABSTRACT FROM AUTHOR]

The ortho-phenylenes are a simple class of helical oligomers and representative of the broader class of sterically congested polyphenylenes. Recent work has shown that o-phenylenes fold into well-defined helical conformations (in solution and, typically, in the solid state); however, the specific causes of this folding behavior have not been determined. Here, we report the effect of substituents on the conformational distributions of a series of o-phenylene hexamers. These experiments are complemented by dispersion-corrected DFT calculations on model oligomers (B97-D/TZV(2d,2p)). The results are consistent with a deterministic role for offset arene–arene stacking interactions on the folding behavior. On the basis of the experimental and computational results, we propose a model for o-phenylene folding with two simple rules. (1) Conformers are forbidden if they include a particular sequence of biaryl torsional states that causes excessive steric strain. These "ABA" states correspond to consecutive dihedral angles of -55°/+130°/-55° (or +55°/-130°/+55). (2) The stability of the remaining conformers is determined by offset arene–arene stacking interactions that are easily estimated as an additive function of the number of well-folded torsional states (±55°) along the backbone. For the parent, unsubstituted poly(o-phenylene), each interaction contributes roughly 0.5 kcal/mol to the helix stability (in chloroform), although their strength is sensitive to substituent effects. The behavior of theo-phenylenes as a class is discussed in the context of this model. They are analogous to α-helices, with axial aromatic stacking interactions in place of hydrogen bonding. The model predicts that the overall folding propensity should be quite sensitive to relatively small changes in the strength of the arene–arene stacking. In a broader sense, these results demonstrate that polyphenylenes may exhibit folding behavior that is amenable to simple models, and validate the use of diffusion-corrected DFT methods in predicting their three-dimensional structures. [ABSTRACT FROM AUTHOR]

Abstract: In this communication, we present a study that probes the middle and late first row transition metal chemistry of 1,3-bis(2-thiazolylimino)isoindoline, adding to the known Fe and Cu compounds. Complexes of this ligand with Mn, Co, Zn and a new Fe form are presented and all are structurally characterized by single crystal X-ray methods. The 1,3-bis(2-thiazolylimino)isoindoline ligand can potentially bind via the thiazolyl nitrogen or sulfur atoms; in all of the complexes presented in this report, the N,N,N binding mode is observed exclusively. The ligands bind in a planar configuration, similar to that seen for bis(2-iminopyridyl)isoindoline. [Copyright &y& Elsevier]

The reaction of diiminoisoindoline with amine-terminated polyethers results in the formation of phthalocrown macrocycles. For n = 1 (where n is the number of ether units), a 2 + 2 condensation takes place, but for n = 2 and 3, a 1 + 1 macrocyde formation occurs. The n = 2 phthalocrown is particularly stable due to a strong intramolecular hydrogen bond, but the n = 3 ring hydrolyzes to form a 3-imino-l-oxoisoindoline derivatized crown ether species. For the n = 1 phthalocrown, we observed dynamic behavior in the ¹H NMR spectrum, and using VTNMR were able to measure a ΔG = 44.6 kJ/mol for proton exchange. [ABSTRACT FROM AUTHOR]

Cobalt complexes of N-confused porphyrins and benziphthalocyanine, which both feature organometallic bonds at the macrocycle cores, catalyze the cyclopropanation of styrene with a higher trans-selectivity than the corresponding porphyrin and phthalocyanine complexes. [ABSTRACT FROM AUTHOR]

The crystal structures of six cobalt sandwich complexes—four in the η5-cyclopentadienyl/η4-cyclobutadiene family, two from the related η5-cyclopentadienyl/η4-cyclopentadienone family—are presented and discussed alongside related structural precedents. In each of the complexes an undecorated cyclopentadienyl ligand is present whereas the partner cyclobutadiene or cyclopentadienone ligand bears four identical aromatic substituents (phenyl, p-tolyl, p-fluorophenyl, 2-thienyl or 2,2′-bithienyl). This range of substituents allows for detailed structural comparison between members of the families of sandwich complexes presented here, and with previously reported structures. Crystal structures of members of the η5-cyclopentadienyl/η4-tetraarylcyclobutadiene (left) and η5-cyclopentadienyl/η5-cyclopentadienone (right) families of sandwich complexes are presented. [ABSTRACT FROM AUTHOR]

An addition to the article "The Role of Arene-Arene Interactions in the Folding of ortho-Phenylenes" published in 2013 is presented and concerns the addition of an ASCII file for the Cartesian coordinates for optimized computational geometries which can be found online at http://pubs.acs.org.

We present the synthesis of several azadipyrromethenes with four peripheral arene units which can be readily generated via the well-established chalcone synthetic method. The stability and yields of these azadipyrromethenes is highly dependent on the nature of the arene substituent, with the bis-pyridine systems exhibiting the highest degree of instability. The structures of several of the compounds and their BF 2 adducts are presented; intramolecular hydrogen bonding is observed in the free base ADPMs. We also present a study into the absorption and emission properties of the ADPMs and their BF 2 adducts and observe that they are also highly dependent on the identity of the substituents. [ABSTRACT FROM AUTHOR]

Irradiation of [Ru(bpy)2(bpSOp)](PF6)2 (where bpy is 2,2'-bipyridine and bpSOp is 1,3-bis(phenylsulfinyl)-propane) results in the formation of two new isomers, namely the S,O- and O,O-bonded species. The crystal structure of the bis-thioether and bis-sulfoxide complexes are reported. NMR spectroscopy of the bis-thioether complex in solution is consistent with the molecular structure determined by diffraction methods. Further, NMR spectroscopy of the bis-sulfoxide complex reveals two conformers in solution, one that is consistent with the solid state structure and a second conformer showing distortion in the aliphatic portion of the chelate ring. Time-resolved visible absorption spectroscopy reveals isomerization time constants of 91 ps in dichloroethane (DCE) and 229 ps in propylene carbonate (PC). Aggregate isomerization quantum yields of 0.57 and 0.42 have been determined in DCE and in PC, respectively. The kinetics of the thermal reversion from the O,O- to S,O-bonded isomer are strongly solvent dependent, occurring with rates of 2.41 × 10-3 and 4.39 × 10-5 s-1 in DCE, and 4.68 × 10-4 and 9.79 × 10-6 s-1 in PC. The two kinetic components are assigned to the two isomers identified in solution. [ABSTRACT FROM AUTHOR]

Diiminoisoindoline (DII) can be modified with primary amines to afford bis-substituted heterocycles. Although the metal binding chemistry of isoindoline-based macrocycles and chelates has been explored, the corresponding chemistry of hydrocarbon substituted diiminoisoindolines remains open. The reaction of the bis(benzylimino)isoindoline with AgNO 3 affords a Ag 6 cluster complexed by four equivalents of ligand. The cluster exhibits a previously unknown argentophilic geometry. The Ag 6 unit forms a compressed hexagon, comprised of two Ag 3 triangles that are linked together to form a parallelogram. The argentophilic interactions range from ~ 2.76 to ~ 3.17 Å. [ABSTRACT FROM AUTHOR]

Phlorins bearing different substituents at the sp³-hybridized meso-position were investigated. The extent to which different substituents at this unique position can influence phlorin spectroscopic properties, structure, and stability is of interest given that such substituents are not in direct conjugation with the phlorin macrocycle. While the effect of various substituents at the sp2-hybridized positions has been the subject of prior investigations, the impact of different substituents at the saturated carbon atom has not been systematically examined. In this study, phlorins with different combinations of geminal methyl and phenyl substituents were prepared in yields of 24-49% via dipyrromethane + dipyrromethanedicarbinol routes, and their NMR spectra, UV-vis spectra, X-ray crystal structures, and stability toward light and air were compared. The nature of the substituents at the sp³-hybridized position was found to impact spectroscopic properties, structure, and stability to varying degrees. Thus, the choice of substituents at the sp³-hybridized meso-position provides a further option for altering phlorin properties. [ABSTRACT FROM AUTHOR]

The new fluorescent chromophore BOPHY can be readily synthesized in two steps from commercially available reagents via the coupling of pyrrole-2-carbox-aldehyde with hydrazine followed by reaction with BF3. The resultant symmetric and dimeric tetracycle is composed of two BF2 units in six-membered chelate rings appended with pyrrole units on the periphery. The quantum yields of fluorescence for the unmodified compound and the tetramethyl variant are near unity, with values of 95 and 92%, respectively, in CH2Cl2. We have probed the electronic structure of this compound via cyclic voltammetry and density functional theory analysis. [ABSTRACT FROM AUTHOR]

Abstract: The new pyridine-2-carboxaldehyde adduct, Re(CO)3(NC6H5C(O)H)Cl 1, and previously reported complex Re(CO)3(NC6H5C(O)H)Br 2 react with aniline derivatives sulfanilamide or 4-aminofluorescein in methanol giving Schiff base conjugates Re(CO)3(pyca-R)X (pyca = pyridinecarbaldehyde imine, X = Cl, Br), 3–6. Pre-isolation of compounds 1 and 2 provides a convenient method for preparing conjugate complexes in addition to the known methods of ligand synthesis and one-pot reactions. All new compounds were completely characterized, and compound 1 and the sulfanilamide derivatives 3 and 4 were structurally elucidated by X-ray crystallography. [Copyright &y& Elsevier]

The formal replacement of one or two pyrrole groups in meso-tetraphenylporphyrin by oxazole moieties is described, generating inter alia the bacteriochlorin-type chromophores oxazolobacteriochlorins (oxabacteriochlorins) and bisoxazolobacteriochlorins (dioxabacteriochlorins). The key step is the conversion of a β,β'-dihydroxy-functionalized pyrroline group into an oxazolone or (substituted) oxazole. Depending on the substitution pattern on the oxazole or oxazoline moieties, mono- and dioxabacteriochlorins may have chlorin- or bacteriochlorin-like spectra. The optical properties (as measured by UV-vis and fluorescence spectroscopies) of the novel oxa- and dioxabacteriochlorins are described and contrasted against benchmark chlorins and bacteriochlorins. The conformations of a representative number of mono- and dioxabacteriochlorins, as their free bases or ZnII complexes, were determined by single-crystal X-ray diffractometry. They proved to be essentially planar, showing that the modulation of their optical properties is primarily due to their intrinsic electronic structures and electronic substituent effects and are not largely affected by conformational effects. The mono- and bisoxazolobacteriochlorins are a novel class of readily prepared and oxidatively stable chlorin and bacteriochlorin analogues with tunable optical spectra that, in part, reach into the NIR. [ABSTRACT FROM AUTHOR]

The complex [Ru(bpy)2(bpSO)](PF6)2, where bpy is 2,2'-bipydine and bpSO is l,2-bis(phenylsulfinyl)ethane, exhibits three distinct isomers which are accessible upon metal-to-ligand charge-transfer (MLCT) irradiation. This complex and its parent, [Ru(bpy)2(bpte)](PF6)2, where bpte is 1,2-bis(phenylthio)ethane, have been synthesized and characterized by UV--visible spectroscopy, NMR, X-ray crystallography, and femtosecond transient absorption spectroscopy. A novel method of 2-color Pump-Repump-Probe spectroscopy has been employed to investigate all three isomers of the bis-sulfoxide complex This method allows for observation of the isomerization dynamics of sequential isomerizations of each sulfoxide from MLCT irradiation of the S,S-bonded complex to ultimately form the 0,0-bonded metastable complex. One-dimensional (l-D) and two-dimensional (2-D) (COSY, NOESY, and TOCSY) 'H NMR data show the thioether and ground state S,S-bonded sulfoxide complexes to be rigorously C2 symmetric and are consistent with the crystal structures. Transient absorption spectroscopy reveals that the S,S to S,0 isomerization occurs with an observed time constant of 56.8 (±7.4) ps. The S,0 to 0,0 isomerization time constant was found to be 59 (±4) ps by pump-repump-probe spectroscopy. The composite S,S- to 0,0-isomer quantum yield is 0.42. [ABSTRACT FROM AUTHOR]

The formal replacement of a pyrrole moiety of meso-tetraarylporphyrin 1 by an oxazole moiety is described. The key step is the conversion of porpholactones 4 (prepared by a known two-step oxidation procedure from 1) by addition of alkyl Grignard reagent to form meso-tetraaryl-3-alkyl-2-oxachlorins 9 (alkyloxazolochlorins; alkyl = Me, Et, iPr). Hemiacetal 9 can be converted to an acetal, reduced to an ether, or converted to bis-alkyloxazolochlorins 11. The optical properties (UV-visible and fluorescence spectroscopy) are described. The chlorin-like optical properties of the alkyloxazolochlorins are compared to regular chlorins, such as 2,3-dihydroxychlorins and nonalkylated oxazolochlorins made by reduction from porpholactone 4. The conformations of the mono- and bis-alkylated 2-oxachlorins, as determined by single crystal X-ray diffractometry, are essentially planar, thus proving that their optical properties are largely due to their intrinsic electronic properties and not affected by conformational effects. The mono- and bis-3-alkyl-2-oxachlorins are a class of readily prepared and oxidatively stable chlorins. [ABSTRACT FROM AUTHOR]

A new zwitterionic nickel(II) catalyst that comprises a partially fluorinated tetrakis(aryl)borate center in a bidentate phosphine ligand and a cationic Ni center has been developed and studied for CO-ethylene copolymerization in the context of comparison with a previously reported zwitterionic catalyst that carries a nonfluorinated borate anion. The crystal structures of several zwitterionic and related nickel compounds are characterized. Partial fluorination of the tetrakis(aryl)borate only brings a modest increase in productivity (2700 vs 1600 g of polyketone per gram of Ni, g (g of Ni)-1). Like the nonfluorinated catalyst, the fluorinated zwitterionic catalyst is extremely active at the beginning of the polymerization but deactivates rapidly. Deactivation of the two catalysts apparently follows different mechanisms. Stoichometric decomposition studies show that the partially fluorinated tetrakis(aryl)borate in the Ni compounds is stable under acidic conditions either directly introduced by addition of an acid or created by a CO atmosphere. In contrast, the nonfluorinated tetrakis(aryl)borate is readily decomposed by an acid or under acidic conditions created by CO. For the new catalyst system with the partially fluorinated tetrakis(aryl)borate anion, the deactivation likely involves initially redox processes and eventually ligand redistribution around Ni, as inferred from the stoichiometric decomposition studies. It turns out that such a process allows the deactivated catalyst to be reactivated by H2. When the polymerization is carried out in the presence of H2, the productivity of the new zwitterionic catalyst can reach 6400 g (g of Ni)-1. The zwitterionic catalyst with the nonfluorinated tetrakis(aryl)borate anion cannot be reactivated by H2. A cationic analogue of the zwitterionic catalysts is also studied for comparison. Its productivity for CO-ethylene copolymerization (230 g (g of Ni)-1) is about 1 order of magnitude lower than that of the zwitterionic catalysts, demonstrating the critical role of the zwitterionic character in attaining the aforementioned high productivity. At the productivity level of the zwitterionic catalysts, which to our knowledge is among the highest observed for Ni catalysts, an unacceptable amount of residual Ni(II) species is left in the product, causing the alternating CO-ethylene copolymer to begin to decompose near its melting temperature and hence making melt processing difficult. [ABSTRACT FROM AUTHOR]

To improve understanding of copper at the active site of Type 1 copper proteins, CuI and CuII complexes of 1,8-dithia-4,11-diazacyclotetradecane, shown in FIGREFFig. 1/FIGREF, have been successfully isolated and structurally characterized by X-ray crystallography. In these compounds, both CuI and CuII are centered in the plane of the macrocycle containing two sulphur and two nitrogen heteroatoms comprising the distorted tetrahedral/square planar coordination geometry. The UV/VIS spectra, electrochemistry and EPR properties have been obtained for the CuII complex 2. Three absorption bands at 295 nm, 354 nm, and 545 nm are observed in aqueous solution at a pH of 5. These bands have been assigned to the N → CuII and S → CuII charge transfer bands and the d–d transitions respectively. The CuI/II redox midpoint potential of complex 2 in CH3CN is +403 mV versus NHE. [ABSTRACT FROM AUTHOR]

The reaction of [Re(CO)3(H2O)3]Br or [Re(CO)5Cl] with two peptides, glycylglycine, or glycylalanine were investigated. Each reaction produced a unique, well-defined product. Structural elucidation showed the formation of chiral compounds with the formula [Re(CO)3(Gly-Xxx-O)]2, Xxx = Gly ( 1), Ala ( 2). Each dimer displays C2 symmetry and a nearly rectangular shape. The ligands are bound through the amine and amide carbonyl at a rhenium center and through the pendant carboxylate to the adjacent rhenium center. Both products are fully characterized by X-ray structure elucidation. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of 1,8-dithia-4,11-diazacyclotetradecane L3 , a member of a series of [14]aneN2S2 ligands, has been synthesized and characterized. The crystal structures of [1,8-dithia-4,11-diazacylotetradecane] L3 and [1,8-dithia-4,11-diazayclotetradecane dihydrochloride] L3·2HCl are presented. [Copyright &y& Elsevier]

The rational syntheses of meso-tetraaryl-3-oxo-2-oxaporphyrins 5, known as porpholactones, via Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed-mediated oxidations of the corresponding meso-tetraaryl-2,3- dihydroxychlorins (7) is detailed. Since chlorin 7 is prepared from the parent porphyrin 1, this amounts to a 2-step replacement of a pyrrole moiety in 1 by an oxazolone moiety. The stepwise reduction of the porpholactone 5 results in the formation of chlorin analogues, meso-tetraaryl-3-hydroxy-2- oxachlorin (11) and meso-tetraaryl-2-oxachlorins (12). The reactivity of 11 with respect to nucleophilic substitution by O-, N-, and S-nucleophiles is described. The profound photophysical consequences of the formal replacement of a pyrrole with an oxazolone (porphyrin-like chromophore) or (substituted) oxazole moiety (chlorin-like chromophore with, for the parent oxazolochlorin 12, red-shifted Qx band with enhanced oscillator strengths) are detailed and rationalized on the basis of SAC--CI and MNDO-PSDCI molecular orbital theory calculations. The single crystal X-ray structures of the porpholactones point at a minor steric interaction between the carbonyl oxygen and the flanking phenyl group. The essentially planar structures of all chromophores in all oxidation states prove that the observed optical properties originate from the intrinsic electronic properties of the chromophores and are not subject to conformational modulation. [ABSTRACT FROM AUTHOR]

Abstract: Complexes of the type [Ru(bpy)2(OSOBnR)](PF6) where bpy is 2,2′-bipyridine and OSOBnR is a 4-substituted benzylsulfinylbenzoate with R=NO2, F, Cl, H, CH3, CF3 and OCH3, have been prepared and investigated by 1H NMR spectroscopy, cyclic voltammetry and UV–vis spectroscopy. Despite the distance of the R group from ruthenium, the Ru3+/2+ reduction potential and charge transfer absorption maximum vary predictably with the electron withdrawing nature of the group. [ABSTRACT FROM AUTHOR]