Mixed ligand complexes of [Pd(terpy)(H2O)]2+ with some selected amino acids,peptides, DNA and related ligands

Stability constants of the ternary palladium(II) complexes of triamine 2,2′:6′,2″-terpyridine (terpy) and some amino acids, peptides, DNA constituents or thiols were determined at 25 °C and at constant 0.1 mol dm⁻³ ionic strength, adjusted using NaNO₃. The coordination sites are pH-dependent. The results show the formation of binuclear species, 210. The speciation diagrams of various complex species were evaluated as a function of pH. Good correlations were found between the stability constants of the complexes and basicity of ligands.     

Mixed-Ligand Complexes of 2-(Aminomethyl)benzimidazole Palladium(II) with Various Biologically Relevant Ligands

cis-Dichloro(2-(aminomethyl)benzimidazole)palladium(II), [Pd(AMBI)Cl₂], was synthesized and characterized. The stoichiometry and stability constants of the complexes formed between [Pd(AMBI)(H₂O)₂]²⁺ with various biologically relevant ligands containing different functional groups are investigated. The ligands used are dicarboxylic acids, amino acids, peptides and DNA constitutents. The results show the formation of 1:1 complexes with amino acids and dicarboxylic acids. The effect of the chelate ring size of the dicarboxylic acid complexes on their stability constants is examined. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. Structural effects of the peptide on the amide deprotonation are investigated. DNA pyrimidinic constituents such as uracil, uridine, thymidine and thymine form 1:1 and 1:2 complexes, whereas purinic constituents such as inosine 5′-monophosphate (5′-IMP) and guanosine 5′-monophosphate (5′-GMP) form only 1:1 complexes. The concentration distribution of the complexes in solution was evaluated. The effect of increasing chloride ion concentration on the formation constant of CBDCA with Pd(AMBI)²⁺ was reported.     

Complex formation reactions of palladium(II)-1,3-diaminopropane with various biologically relevant ligands. Kinetics of hydrolysis of glycine methyl ester through complex formation

The interaction of [Pd(DAP)(H₂O)₂]²⁺ (DAP = 1,3-diaminopropane) with some selected bio-relevant ligands, containing different functional groups, were investigated. The ligands used are dicarboxylic acids, amino acids, peptides and DNA constituents. Stoichiometry and stability constants of the complexes formed are reported at 25°C and 0.1 M ionic strength. The results show the formation of 1:1 complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants is examined. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. DNA constituents form 1:1 and 1:2 complexes. The effect of dioxane on the acid dissociation constants of CBDCA and the formation constant of its complex with Pd(DAP)²⁺ was reported. The kinetics of hydrolysis of glycine methyl ester bound to [Pd(DAP)(H₂O)₂]²⁺ was studied at 25°C and 0.1M ionic strength.      

Synthesis of palladium–biscarbene complexes derived from 1,1′-methylenebis(1,2,4-triazole) functionalized in the methylene bridge

Palladium–biscarbene complexes derived from N,N′-bis(1,2,4-triazol-1-yl)methane, which bear an alkyl chain functionalized with a hydroxyl group, have been synthesized ([Pd(L1)Br₂] (6) and [Pd(L1)I₂] (7) [L1 = 1,1′-(3-hydroxypropylidene)bis(4-butyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)]). Each product is obtained as a non-equimolecular mixture of two conformers. The hydroxyl group has been replaced by bromide and methanesulphonate and ( [Pd(L2)Br₂] [L2 = 1,1′-(3-bromopropylidene)bis(4-butyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)] (9)) and ([Pd(L3)Br₂] [L3 = 1,1′-(3-methanesulphonyloxypropylidene)-bis(4-butyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene)] (10)) were obtained, respectively, as mixtures of conformers. All compounds consist of a six-membered metallacyclic structure in a boat conformation. Major conformers present the functionalized chain in the axial position, while in minor conformers it is located in the equatorial position.     

A new class of proton-conducting ionic plastic crystals based on organic cations and dihydrogen phosphate

Choline dihydrogen phosphate ([N_1.1.1.2OH]DHP) and 1-butyl-3-methylimidazolium dihydrogen phosphate ([C₄mim]DHP) were synthesized as a new class of proton-conducting ionic plastic crystals. Both [N_1.1.1.2OH]DHP and [C₄mim]DHP showed solid–solid phase transition(s) and showed a final entropy of fusion lower than 20 J K⁻¹ mol⁻¹ which is consistent with Timmerman’s criterion for molecular plastic crystals. The ionic conductivity of [N_1.1.1.2OH]DHP was in the range of 10⁻⁶ S cm⁻¹–10⁻³ S cm⁻¹ in the plastic crystalline phase. On the other hand, the ionic conductivity of [C₄mim]DHP showed about 10⁻⁵ S cm⁻¹ in the plastic crystalline phase. [N_1.1.1.2OH]DHP showed one order of magnitude higher ionic conductivity than [C₄mim]DHP in the temperature range where the plastic phase is stable.     

Synthesis and asymmetric catalytic application of chiral imidazolium–phosphines derived from (1R,2R)-trans-diaminocyclohexane

Reaction between a chiral imidazole–amine precursor derived from (1R,2R)-trans-diaminocyclohexane and P¹Cl (where P¹ = PPh₂, P(1,3,5-Me₃C₆H₃)₂, P(2,2′-O,O′-(1,1′-biphenyl), P((R)-(2,2′-O,O′-(1,1′-binaphthyl))) and P((S)-(2,2′-O,O′-(1,1′-binaphthyl)))) followed by RX (where R = ⁿPr, ⁱPr, CHPh₂, X = Br; R = ⁱPr, X = I), respectively, gives a selection of chiral imidazolium–phosphine compounds. Deprotonation of the imidazolium salt gives the corresponding NHC–P ligands that can be used in metal-mediated asymmetric catalytic applications. Catalytic reactions show that NHC–P ligands give a significantly greater rate of reaction for a palladium catalysed allylic substitution reaction in comparison to analogous di-NHC or NHC–imine ligands and that NHC–P hybrids are also effective for iridium catalysed transfer hydrogenation.     

Hemilability of 2-(1H-imidazol-2-yl)pyridine and 2-(oxazol-2-yl)pyridine ligands: Imidazole and oxazole ring Lewis basicity,Ni(II)/Pd(II) complex structures and spectra

Fourteen new organic molecules A1–A4, B1–B5, C1–C4 and D and a series of transition metal(II) complexes (Ni1–Ni9 and Pd1–Pd2b) were synthesized and studied in order to characterize the hemilability of 2-(1H-imidazol-2-yl)pyridine and 2-(oxazol-2-yl)pyridine ligands (A1–A4 = 2-R²-6-(4,5-diphenyl-1R¹-imidazol-2-yl)pyridines, R¹ = H or CH₃, R² = H or CH₃; B1–B5 = 1-R²-2-(pyridin-2-yl)-1R¹-phenanthro[9,10-d]imidazoles/oxazoles, R¹ = H or CH₃, R² = H or CH₃; C1–C4 = 2-(6-R²-pyridin-2-yl)-1H-imidazo/oxazo[4,5-f][1,10]phenanthrolines, R² = H or CH₃; D = 2-mesityl-1H-imidazo[4,5-f][1,10]phenanthroline). They were also used to study the substituent effects on the donor strengths as well as the coordination chemistries of the imidazole/oxazole fragments of the hemilabile ligands.All the observed protonation–deprotonation processes found within pH 1–14 media pertain to the imidazole or oxazole rings rather than the pyridyl Lewis bases. The donor characteristics of the imidazole/oxazole ring can be estimated by spectroscopic methods regardless of the presence of other strong N donor fragments. The oxazoles possessed notably lower donor strengths than the imidazoles. The electron-withdrawing influence and capacity to hinder the azole base donor strength of 4,5-azole substituents were found to be in the order phenanthrenyl (B series) > 4,5-diphenyl (A series) > phenanthrolinyl (C series). An X-ray structure of Ni5b gave evidence for solvent induced ligand reconstitution while the structure of Pd2b provided evidence for solvent induced metal–ligand bond disconnection.Interestingly, alkylation of 1H-imidazoles did not necessarily produce the anticipated push of electron density to the donor nitrogen. Furthermore, substituents on the 4,5-carbons of the azole ring were more important for tuning donor strength of the azole base. DFT calculations were employed to investigate the observed trends. It is believed that the information provided on substituent effects and trends in this family of ligands will be useful in the rational design and synthesis of desired azole-containing chelate ligands, tuning of donor properties and application of this family of ligands in inorganic architectural designs, template-directed coordination polymer preparations, mixed-ligand inorganic self-assemblies, etc.     

Hydrocarbon (π- and σ-) complexes of nickel,palladium and platinum: Synthesis,reactivity and applications

With the exception of metallocenes, transition metal complexes with hydrocarbon ligands only are rare. However, complexes of this type containing Group 10 metals are known and have been shown to be quite stable. These complexes are versatile precursors for many organometallic compounds. In addition, such compounds can play an important role in many reactions including C–H or C–C activation reactions and have useful applications in the thermal and photochemical production of metal films by chemical vapour deposition (CVD). The present review summarizes the synthesis, properties and chemistry of hydrocarbon complexes of Group 10 metals of the type L_nM or L_nMR₁R₂ (where L_n = σ- or π-hydrocarbon ligands; M = Ni, Pd and Pt; R₁, R₂ = σ-hydrocarbon ligands) without the involvement of any hetero donor ligands such as N, P, O and S in the metal coordination spheres.     

Oxidative addition of MeI to cationic Rh(I) carbonyl complexes with pyridyl bis(carbene) ligands

A series of cationic Rh(I) carbonyl complexes of the form [Rh(CO)(L)]PF₆ (where L = 2,6-bis (alkylimidazol-2-ylidene)-pyridine; alkyl = Me (1a), Et (1b), CH₂Ph (1c)) have been prepared by the reactions of [Rh(CO)₂(OAc)]₂ with diimidazolium pyridine salts in the presence of NEt₃. The ν(CO) values for 1 are ca. 1982 cm⁻¹, indicating that the N-heterocyclic carbene ligands impart high electron density on the Rh(I) centres, despite the overall cationic charge. Each of the Rh(I) complexes reacts with MeI to form two isomeric Rh(III) methyl species, and a third unidentified species. Kinetic measurements on the MeI oxidative addition reactions give second-order rate constants (MeCN, 25 °C) of 0.0927, 0.0633 and 0.0277 M⁻¹ s⁻¹ for 1a, 1b and 1c, respectively. Comparison of these data with those for related Rh(I) carbonyl complexes shows that 1 have remarkably high nucleophilicity for cationic species.     

Phosphino-(α-sulfinylalkyl)phosphonium ylide complexes (Rh,Pd) with a configurationally stable asymmetric ylidic carbon

The synthesis and structure of Rh(I) and Pd(II) complexes of chiral P,C-chelating phosphino-(α-sulfinylalkyl)phosphonium ylide ligands with a trisubstituted asymmetric ylidic center P⁺–C1R(S1(O)p-Tol)–M (R = alkyl group) have been investigated, and compared to those of the analogous disubstituted ylide complexes (R = H). Reaction of the ethyl onium ylide of o-bis(diphenylphosphino)benzene with (?)-menthyl-(S)-p-tolylsulfinate afforded the corresponding racemic erythro phosphino-(α-sulfinylethyl)phosphonium in 90% de (R = Me). The racemization process is interpreted by a Berry-like pseudorotation mechanism driven by the steric repulsion between the α-methyl substituent and the bulky menthyloxy S-substituent or sulfur lone pair in the intermediate ylide-sulfinyl adduct. The ylide of phosphino-(α-sulfinylethyl)phosphonium reacts with [Rh(cod)₂][PF₆] and PdCl₂(MeCN)₂ to afford the corresponding P,C1-chelated threo-Rh(I) and erythro-Pd(II) mononuclear complexes in 70% yield and total diastereoselectivity. These respective complexes act as efficient catalytic precursors for the hydrogenation of (Z)-α-acetamidocinnamic acid and allylic substitution of 3-acetoxy-1,3-diphenyl-1-propene with sodium dimethyl malonate. The bonding features of the erythro-Pd(II) complex exhibiting a sulfinyl O?Pd interaction are studied theoretically at the DFT level using ELF and MESP analyses. The η²-P,C haptomeric form of the ylide ligand is estimated to compete at 19% with the η¹-C haptomeric form dominating at 81%.     

Aqueous solution chemistry of alkyltin(IV) compounds for speciation studies in biological fluids and natural waters

Organotin(IV) cations behave as Lewis acids of different strength depending on the charge, according to the following acidity scale: RSn³⁺ > R₂Sn²⁺ > R₃Sn⁺. For this reason they can react with Lewis bases containing –O, –N, –S donor groups to form complex species of different stability. Complex formation of organotin(IV) moieties with a great number of inorganic and organic ligands in aqueous solution is reviewed here in the light of their environmental and biological impact. To this end, complex species formation was considered in different ionic media and at different ionic strengths, with reference to the composition of natural waters and biological fluids. In particular, the interaction of alkyltin(IV) compounds with the following ligands was taken into account: hydroxo, chloride, sulfate, fluoride, carbonate and phosphate; carboxylates, amines, amino-carboxylates, nucleotides, saccharides, S-containing ligands and antibiotics. Moreover, the interaction of organotin(IV) cations with synthetic (polyacrylate) and natural occurring (fulvic and alginic acids) polyelectrolytes was also considered. The strength of interaction is reported in terms of stability constants of complex species formed and of other thermodynamic parameters, such as formation enthalpy. The stability trend of the complexes is alkyltin(IV)-S > alkyltin(IV)-N > alkyltin(IV)-O-donor ligands. On the basis of data in the literature, empirical relationships are provided to predict the stability of alkyltin(IV) species with some classes of ligands. The complexation models proposed by the different authors for the species formation of mono-, di- and tri-alkyltin(IV) in the presence of various ligands were considered in the light of defining the speciation picture of this class of compounds in aquatic systems.     

Synthesis and catalytic properties of cationic palladium(II) and rhodium(I) complexes bearing diphosphinidinecyclobutene ligands

Cationic palladium(II) and rhodium(I) complexes bearing 1,2-diaryl-3,4-bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobutene ligands (DPCB–Y) were prepared and their structures and catalytic activity were examined (aryl = phenyl (DPCB), 4-methoxyphenyl (DPCB–OMe), 4-(trifluoromethyl)phenyl (DPCB–CF₃)). The palladium complexes [Pd(MeCN)₂(DPCB–Y)]X₂ (X = OTf, BF₄, BAr₄ (Ar = 3,5-bis(trifluoromethyl)phenyl)) were prepared by the reactions of DPCB–Y with [Pd(MeCN)₄]X₂, which were generated from Pd(OAc)₂ and HX in MeCN. On the other hand, the rhodium complexes [Rh(MeCN)₂(DPCB–Y)]OTf were prepared by the treatment of [Rh(μ-Cl)(cyclooctene)₂]₂ with DPCB–Y in CH₂Cl₂, followed by treatment with AgOTf in the presence of MeCN. The cationic complexes catalyzed conjugate addition of benzyl carbamate to α,β-unsaturated ketones.     

Synthesis and reactions of heterodinuclear organopalladium–cobalt complexes acting as copolymerization catalyst for aziridine and carbon monoxide

A series of heterodinuclear acylpalladium–cobalt complexes having a bidentate nitrogen ligand, L₂(RCO)Pd–Co(CO)₄ (L₂ = bpy, R = Me (5), Ph (6); L₂ = tmeda, R = Me (7), Ph (8); L₂ = phen, R = Me (9), Ph (10)) are prepared by metathetical reactions of PdRIL₂ with Na⁺[Co(CO)₄]⁻ followed by treatment with CO. These complexes are characterized by NMR and IR spectroscopies and elemental analyses, and the molecular structures of 6, 8, and 9 are determined by X-ray structure analysis. Geometry at Pd is essentially square planar and the Co atom is considered to have d¹⁰ tetrahedral structure, where cobalt(-I) anion coordinates to palladium(II) cation. Heterodinuclear organopalladium–cobalt complexes are shown to catalyze copolymerization of aziridines and CO under mild conditions. Reaction of (dppe)MePd–Co(CO)₄ (1) with aziridine gives a cationic (aziridine)palladium(II) complex with [Co(CO)₄]⁻ anion, [PdMe(aziridine)(dppe)]⁺[Co(CO)₄]⁻ (13).     

Complex formation between manganese(II), cobalt(II), nickel(II), copper(II) and a series of new ligands derived from N,N′-O-phenylenebis(salicylideneimine)

A series of new ligands derived from N,N′-O-phenylenebis(salicylideneimine) have been synthesized and characterized by spectrometric methods. Their protonation constants and the stability constants of their complexes with Mn²⁺, Co²⁺, Ni²⁺ et Cu²⁺ have been determined by potentiometric methods in a water–ethanol (90:10 v/v) mixture at a 0.2 mol l⁻¹ ionic strength (NaCl) and at 25.0 ± 0.1 °C. The Sirko program was used to determine the protonation constants as well as the binding constants of both species [M(HL)]⁺ and [ML]. The stability order obtained is in agreement with Irving–Williams series.     

Effects of N-heteroaromatic ligands on highly luminescent mononuclear copper(I)–halide complexes

A series of mononuclear Cu(I)–halide complexes, [CuX(PPh₃)₂(L)] (X = Cl⁻, Br⁻, I⁻; PPh₃ = triphenylphosphine; L = pyridine (py), isoquinoline (iq), 1,6-naphthyridine (nap)), were synthesized. The emission color of [CuX(PPh₃)₂(L)] varies from blue to red by changing the L ligands and the halide ions, and all the complexes exhibit high emission quantum yields (0.16–0.99) in the crystals. The emission studies revealed that the emissive states of [CuX(PPh₃)₂(L)] differ depending on the L ligand. Complexes [CuX(PPh₃)₂(py)] and [CuX(PPh₃)₂(nap)] mainly emit from the singlet metal-to-ligand charge transfer mixed with the halide-to-ligand charge transfer (¹(M + X)LCT) state at room temperature. In contrast, emissions from [CuX(PPh₃)₂(iq)] at room temperature originate from both ³(M + X)LCT and ³ππ* states. These results indicate that N-heteroaromatic ligands play an important role in the emission properties of mononuclear Cu(I)–halide complexes.     

Synthesis,characterization, thermal,electrochemical, and DFT studies of mononuclear cyclopalladated complexes containing bidentate phosphine ligands and their biological evaluation as antioxidant and antibacterial agents

The non-symmetric phosphorus ylides and their Pd(II) complexes have been synthesized as potential antioxidant and antibacterial compounds and their structures were elucidated using a variety of physicochemical techniques. The reaction of 1 equiv non-symmetric phosphorus ylides, Ph₂PCH₂PPh₂C(H)C(O)PhX (X = Br (Y¹), Cl (Y²), NO₂ (Y³), OCH₃ (Y⁴)) with [Pd(dppe)Cl₂] (M¹), followed by treatment with 2 equiv AgOTf led to monomeric chelate complexes, [(dppe)Pd(Ph₂PCH₂PPh₂C(H)C(O)PhX)] (OSO₂CF₃)₂ (X = Br (C¹), Cl (C²), NO₂ (C³), OCH₃ (C⁴)), which contain a five-membered P,P chelate ring in one side and a five-membered P,C chelate ring in the other side. Palladium ion complexes were synthesized and investigated by cyclic voltammetry, FT-IR, UV–visible, multinuclear (¹H, ³¹P and ¹⁹F) NMR, thermal analysis and ESI-mass spectroscopic studies. Some complexes and ligands have been studied by powder XRD and single crystal X-ray diffraction techniques. FT-IR and ³¹P NMR studies revealed that the ylides Y are coordinated to the metal ions via the terminal phosphorus (P_c) of the ylides and methene group (CH). The proposed coordination geometry around the Pd atom in these complexes is defined as slightly distorted square planar by UV-Visible and DFT studies. Thermal stability of all complexes was also shown by TG/DTG methods. Furthermore, the electrochemical behavior of the complexes was investigated by cyclic voltammetry. The results indicate that all complexes are successfully synthesized from the initial ligands. All complexes were analyzed for their antioxidant properties by DPPH free radical scavenging assay. In addition, the antibacterial effects of the hexane-solved complexes were investigated by disc diffusion method against four Gram positive and negative bacteria. All complexes represented antibacterial activity against bacteria tested especially on Gram positive ones. A theoretical study on the structure, ¹H and ³¹P NMR chemical shifts and the interaction energy between the Pd²⁺ ion and ligands dppe and ylide Y is also reported.     

Novel nano-structured Pd+yttrium doped ZrO2 cathodes for intermediate temperature solid oxide fuel cells

Novel nano-structured Pd+yttrium doped ZrO₂ (YSZ) electrodes have been developed as cathodes of intermediate temperature solid oxide fuel cells (IT-SOFCs). Nano-sized Pd particles were introduced into the rigid and porous YSZ structure by PdCl₂ solution impregnation. The results show that Pd nanoparticles (20–80 nm) were uniformly distributed in the porous YSZ structure; and such nano-structured composite cathodes were highly active for the O₂ reduction reaction, with polarization resistances (R_E) of 0.11 and 0.22 Ω cm² at 750 and 700 °C and activation energy of 105 kJ mol⁻¹ that is significantly lower than those for the conventional perovskite-based cathodes (130–201 kJ mol⁻¹).     

Thermodynamic studies on complexation of divalent transition metal ions with some zwitterionic buffers for biochemical and physiological research

The interaction between the zwitterionic buffers (3-[N-bis(2-hydroxyethyl)amino]-2-hydroxy propane sulfonic acid, N-(2-actamido)-2-aminoethane sulfonic acid, and 3-[(1,1-dimethyl-2-hydroxyethyl)amino]-2-hydroxy propane sulfonic acid) with some divalent transition metal ions (Cu^II, Ni^II, Co^II, Zn^II, and Mn^II) were studied at different temperatures (298.15 to 328.15) K at ionic strength I = 0.1 mol · dm⁻³ NaNO₃ and in the presence of 10%, 30%, and 50% (w/w) dioxene by using potentiometry. The thermodynamic stability constants were calculated as well as the free energy change for the 1:1 binary complexation. The protonation constants of the zwitterionic buffers were also determined potentiometrically under the above conditions.     

New tripodal N-heterocyclic carbene chelators for small molecule activation

In an effort to develop new tripodal N-heterocyclic carbene (NHC) ligands for small molecule activation, two new classes of tripodal NHC ligands TIME^R and TIMEN^R have been synthesized. The carbon-anchored tris(carbene) ligand system TIME^R (R = Me, t-Bu) forms bi- or polynuclear metal complexes. While the methyl derivative exclusively forms trinuclear 3:2 complexes [(TIME^Me)₂M₃]³⁺ with group 11 metal ions, the tert-butyl derivative yields a dinuclear 2:2 complex [(TIME^t-Bu)₂Cu₂]²⁺ with copper(I). The latter complex shows both “normal” and “abnormal” carbene binding modes and accordingly, is best formulated as a bis(carbene)alkenyl complex. The nitrogen-anchored tris(carbene) ligands TIMEN^R (R = alkyl, aryl) bind to a variety of first-row transition metal ions in 1:1 stoichiometry, affording monomeric complexes with a protected reactivity cavity at the coordinated metal center. Complexes of TIMEN^R with Cu(I)/(II), Ni(0)/(I), and Co(I)/(II)/(III) have been synthesized. The cobalt(I) complexes with the aryl-substituted TIMEN^R (R = mesityl, xylyl) ligands show great potential for small molecule activation. These complexes activate for instance dioxygen to form cobalt(III) peroxo complexes that, upon reaction with electrophilic organic substrates, transfer an oxygen atom. The cobalt(I) complexes are also precursors for terminal cobalt(III) imido complexes. These imido complexes were found to undergo unprecedented intra-molecular imido insertion reactions to form cobalt(II) imine species. The molecular and electronic structures of some representative metal NHC complexes as well as the nature of the metal–carbene bond of these metal NHC complexes was elucidated by X-ray and DFT computational methods and are discussed briefly. In contrast to the common assumption that NHCs are pure σ-donors, our studies revealed non-negligible and even significant π-backbonding in electron-rich metal NHC complexes.     

Pulse radiolysis studies of the reactions of bromine atoms and dimethyl sulfoxide–bromine atom complexes with alcohols

Dimethylsulfoxide (DMSO)–Br complexes were generated by pulse radiolysis of DMSO/bromomethane mixtures and the formation mechanism and spectral characteristics of the formed complexes were investigated in detail. The rate constant for the reaction of bromine atoms with DMSO and the extinction coefficient of the complex were obtained to be 4.6×10⁹ M⁻¹ s⁻¹ and 6300 M⁻¹ cm⁻¹ at the absorption maximum of 430 nm. Rate constants for the reaction of bromine atoms with a series of alcohols were determined in CBrCl₃ solutions applying a competitive kinetic method using the DMSO–Br complex as the reference system. The obtained rate constants were ∼10⁸ M⁻¹ s⁻¹, one or two orders larger than those reported for highly polar solvents. Rate constants of DMSO–Br complexes with alcohols were determined to be ∼ 10⁷ M⁻¹ s⁻¹. A comparison of the reactivities of Br atoms and DMSO–Br complexes with those of chlorine atoms and chlorine atom complexes which are ascribed to hydrogen abstracting reactants strongly indicates that hydrogen abstraction from alcohols is not the rate determining step in the case of Br atoms and DMSO–Br complexes.