Intermediates of copper(I)-catalyzed C-S cross coupling of thiophenol with aryl halide by in situ ESI-MS study

Complexes [Cu(SPh)(2)](-), [Cu(SPh)I](-) and K[Cu(SPh)(2)(Ph)](+) were observed by in situ electrospray ionization mass spectrometry (ESI-MS) analysis of the copper(i)-catalyzed C-S coupling reaction under catalytic reaction conditions indicating that they are intermediates in the reaction. A catalytic cycle was proposed based on these observations.     

Mechanistic studies of copper(I)-catalyzed allylic amination

The reactions of nitrosobenzene and N,N'-diethyl-4-nitrosoaniline with [Cu(CH3CN)4]PF6 provide novel Cu(I) complexes, [Cu(PhNO)3]PF6 (1) and [Cu(Et2NPhNO)3]PF6 (2); in 2 the copper atom is N-coordinated to the nitrosoarenes in a distorted trigonal planar geometry. Complex 1 is strongly implicated as a reactive intermediate in the Cu(I)-catalyzed allylic amination of olefins based on (i) its isolation from the catalytic reaction, (ii) its stoichiometric regioselective allylic amination of alpha-methyl styrene (AMS), (iii) the non-involvement of free PhNO in its amination of AMS, and (iv) its function as a catalyst for the amination of alkenes from phenylhydroxylamine. The reaction between AMS and 1 (80 degrees C, dioxane) is first order in both alkene and 1. Relative rate studies of the reaction of 1 with para substituted AMS derivatives gives a Hammett rho value of -0.035. Alkene adducts isolated from the reaction of 1 with styrene and alpha-methylstyrene are formulated as [(PhNO)3Cu(eta(2)-alkene)]PF6 (7,8) on the basis of spectroscopic characterization and thermolysis. PM3 and DFT MO calculations support the role of [(alkene)Cu(RNO)3]+ and (eta(1)- or eta(3)-allyl)Cu(RNO)2(RNHOH)+ complexes as probable catalytic intermediates and address the origin of the distinctive reaction regioselectivity. A mechanistic scheme is proposed which is consistent with the accumulated experimental and computational results.     

Structural comparison of copper(I) and copper(II) complexes with tris(2-pyridylmethyl)amine ligand

Copper(I) complexes with the tris(2-pyridylmethyl)amine (TPMA) ligand were synthesized and characterized to examine the effect of counteranions (Br(-), ClO(4)(-), and BPh(4)(-)), as well as auxiliary ligands (CH(3)CN, 4,4'-dipyridyl, and PPh(3)) on the molecular structures in both solid state and solution. Partial dissociation of one of the pyridyl arms in TPMA was not observed when small auxiliary ligands such as CH(3)CN or Br(-) were coordinated to copper(I), but was found to occur with larger ones such as PPh(3) or 4,4'-dipyridyl. All complexes were found to adopt a distorted tetrahedral geometry, with the exception of [Cu(I)(TPMA)][BPh(4)], which was found to be trigonal pyramidal because of stabilization via a long cuprophilic interaction with a bond length of 2.8323(12) ?. Copper(II) complexes with the general formula [Cu(II)(TPMA)X][Y] (X = Cl(-), Br(-) and Y = ClO(4)(-), BPh(4)(-)) were also synthesized to examine the effect of different counterions on the geometry of [Cu(II)(TPMA)X](+) cation, and were found to be isostructural with previously reported [Cu(II)(TPMA)X][X] (X = Cl(-) or Br(-)) complexes.     

Reaction behaviour of dinuclear copper(I) complexes with m-xylyl-based ligands towards dioxygen

Intramolecular ligand hydroxylation was observed during the reactions of dioxygen with the dicopper(I) complexes of the ligands L(1)(L(1)=alpha,alpha'-bis[(2-pyridylethyl)amino]-m-xylene) and L(3)(L(3)=alpha, alpha'-bis[N-(2-pyridylethyl)-N-(2-pyridylmethyl)amino]-m-xylene). The dinuclear copper(I) complex [Cu(2)L(3)](ClO(4))(2) and the dicopper(II) complex [Cu(2)(L(1)-O)(OH)(ClO(4))]ClO(4) were characterized by single-crystal X-ray structure analysis. Furthermore, phenolate-bridged complexes were synthesized with the ligand L(2)-OH (structurally characterized [Cu(2)(L(2)-O)Cl(3)] with L(2)=alpha, alpha'-bis[N-methyl-N-(2-pyridylethyl)amino]-m-xylene; synthesized from the reaction between [Cu(2)(L(2)-O)(OH)](ClO(4))(2) and Cl(-)) and Me-L(3)-OH: [Cu(2)(Me-L(3)-O)(mu-X)](ClO(4))(2)xnH(2)O (Me-L(3)-OH = 2,6-bis[N-(2-pyridylethyl)-N-(2-pyridylmethyl)amino]-4-methylphenol and X = C(3)H(3)N(2)(-)(prz), MeCO(2)(-) and N(3)(-)). The magnetochemical characteristics of compounds were determined by temperature-dependent magnetic studies, revealing their antiferromagnetic behaviour [-2J(in cm(-1)) values: -92, -86 and -88; -374].     

High thermodynamic stability and extraordinary kinetic inertness of copper(II) complexes with 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid): example of a rare isomerism between kinetically inert penta- and hexacoordinated copper(II) complexes

In an aqueous solution at room temperature, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid) (H(4)L(1)) and Cu(I) (I) form a pentacoordinated (pc) complex, pc-[Cu(L(1))](2-), exhibiting conformation I of the cyclam ring. At high temperature, the complex isomerises to a hexacoordinated isomer, trans-O,O-[Cu(L(1))](2-), with a trans-III conformation of the cyclam ring. In pc-[Cu(L(1))](2-), four ring nitrogen atoms and one phosphonate oxygen atom are arranged around Cu(I) (I) in a structure that is half-way between a trigonal bipyramid and a tetragonal pyramid, with one phosphonic acid group uncoordinated. In the trans-O,O-[Cu(L(1))](2-) isomer, the nitrogen atoms form a plane and the phosphonic acid groups are in a mutually trans configuration. A structurally very similar ligand, 4-methyl-1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid) (H(4)L(2)), forms an analogous pentacoordinated complex, pc-[Cu(L(2))](2-), at room temperature. However, the complex does not isomerise to the octahedral complex analogous to trans-O,O-[Cu(L(1))](2-). Because of the high thermodynamic stability of pc-[Cu(L(1))](2-), (logbeta=25.40(4), 25 degrees C, I=0.1 mol dm(-3) KNO(3)) and the formation of protonated species, Cu(I) (I) is fully complexed in acidic solution (-log [H(+)] approximately 3). Acid-assisted decomplexation of both of the isomers of [Cu(H(2)L(1))] takes place only after protonation of both uncoordinated oxygen atoms of each phosphonate moiety and at least one nitrogen atom of the cycle. The exceptional kinetic inertness of both isomers is illustrated by their half-lives tau(1/2)=19.7 min for pc-[Cu(H(2)L(1))] and tau(1/2) about seven months for trans-O,O-[Cu(H(2)L(1))] for decomplexation in 5 M HClO(4) at 25 degrees C. The mechanism of formation of pc-[Cu(L(1))](2-) is similar to those observed for other macrocyclic complexes.     

Synthesis and reactivity of copper(I) complexes containing a bis(imidazolin-2-imine) pincer ligand

The new pincer ligand 2,6-bis[(1,3-di-tert-butylimidazolin-2-imino)methyl]pyridine (TL(tBu)) has been prepared in high yield from 2,6-bis(hydroxymethyl)pyridine (1) and 1,3-di-tert-butylimidazolin-2-imine (3). Reaction of TL(tBu) with [Cu(MeCN)4]PF6 affords the highly reactive copper(I) complex [(TL(tBu))Cu]PF6, [5]PF6, which forms the stable copper(I) isocyanide complexes [6a]PF6 (nu(CN) = 2179 cm(-1)) and [6b]PF6 (nu(CN) = 2140 cm(-1)) upon addition of tert-butyl or 2,6-dimethylphenyl isocyanide, respectively. For the cations 6a and 6b, DFT calculations reveal ground-state electronic structures of the type [(TL(tBu)-kappaN(1):kappaN(2))Cu(CNR)] with tricoordinate geometries around the copper atoms. Exposure of [5]PF6 to the air readily leads to trapping of atmospheric CO2 to form the square-planar complex [(TL(tBu))Cu(HCO3-kappaO)]PF6, [7]PF6, with the bicarbonate ligand adopting a rarely observed monodentate coordination mode. In chlorinated solvents such as dichloromethane or chloroform, [5]PF(6) rapidly abstracts chloride by reductive dechlorination of the solvent to yield [(TL(tBu))CuCl]PF6, [8]PF6 quantitatively. Reaction of TL(tBu) with copper(I) bromide or chloride affords complexes 9a and 9b, respectively, for which X-ray diffraction analysis, low-temperature NMR experiments and DFT calculations reveal the presence of a kappa(2)-coordinated ligand of the type [(TL(tBu)-kappaN(1):kappaN(2))CuX]. In solution, complex 9b undergoes slow disproportionation forming the mixed-valence copper(II)/copper(I) system [(TL(tBu))CuCl][CuCl2], [8]CuCl2 with a linear dichlorocuprate(I) counterion.     

Coordination chemistry of the cyclo-(P(5)tBu(4))(-) ion: monomeric and oligomeric copper(I), silver(I) and gold(I) complexes

[Na{cyclo-(P(5)tBu(4))}] (1) reacts with [CuCl(PCyp(3))(2)] (Cyp=cyclo-C(5)H(9)) and [CuCl(PPh(3))(3)] (1:1) to give the corresponding copper(I) complexes with a tetra-tert-butylcyclopentaphosphanide ligand, [Cu{cyclo- (P(5)tBu(4))}(PCyp(3))(2)] (2) and [Cu{cyclo-(P(5)tBu(4))}(PPh(3))(2)] (3). The CuCl adduct of 2, [Cu(2)(mu-Cl){cyclo-(P(5)tBu(4))}(PCyp(3))(2)] (4), was obtained from the reaction of 1 with [CuCl(PCyp(3))(2)] (1:2). Compounds 2 and 3 rearrange, even at -27 degrees C, to give [Cu(4){cyclo- (P(4)tBu(3))PtBu}(4)] (5), in which ring contraction of the [cyclo-(P(5)tBu(4))](-) anion has occurred. The reaction of 1 with [AgCl(PCyp(3))](4) or [AgCl(PPh(3))(2)] (1:1) leads to the formation of [Ag(4){cyclo-(P(4)tBu(3))PtBu}(4)] (6). Intermediates, which are most probably mononuclear, "[Ag{cyclo-(P(5)tBu(4))}(PR(3))(2)]" (R=Cyp, Ph) could be detected in the reaction mixtures, but not isolated. Finally, the reaction of 1 with [AuCl(PCyp(3))] (1:1) yielded [Au{cyclo-(P(5)tBu(4))}(PCyp(3))] (7), whereas an inseparable mixture of [Au(3){cyclo-(P(5)tBu(4))}(3)] (8) and [Au(4){cyclo-(P(4)tBu(3))PtBu}(4)] (9) was obtained from the analogous reaction with [AuCl(PPh(3))]. Complexes 3-7 were characterised by (31)P NMR spectroscopy, and X-ray crystal structures were determined for 3-9.     

Catecholase activity of a series of dicopper(II) complexes with variable Cu-OH(phenol) moieties

The catecholase activity of a series of dicopper(II) complexes containing different numbers of phenol groups coordinated to the metal centers was studied to identify functional as well as structural models for the type III copper enzymes tyrosinase and catechol oxidase. The syntheses and characterization of complexes [Cu(2)(H(2)bbppnol)(mu-OAc)(H(2)O)(2)]Cl(2).2H(2)O (1) and [Cu(2)(Hbtppnol)(mu-OAc)](ClO(4))(2) (2) were previously reported by us (Inorg. Chim. Acta 1998, 281, 111-115; Inorg. Chem. Commun. 1999, 2, 334-337), and complex [Cu(2)(P1-O(-))(OAc(-))](ClO(4))(2) (3) was previously reported by Karlin et al. (J. Am. Chem. Soc. 1997, 119, 2156-2162). The catalytic activity of the complexes 1-3 on the oxidation of 3,5-di-tert-butylcatechol was determined spectrophotometrically by monitoring the increase of the 3,5-di-tert-butyl-o-benzoquinone characteristic absorption band at about 400 nm over time in methanol saturated with O(2)/aqueous buffer pH 8 solutions at 25 degrees C. The complexes were able to oxidize 3,5-di-tert-butylcatechol to the corresponding o-quinone with distinct catalytic activity. A kinetic treatment of the data based on the Michaelis-Mentèn approach was applied. The [Cu(2)(H(2)bbppnol)(mu-OAc)(H(2)O)(2)]Cl(2) small middle dot2H(2)O complex showed the highest catalytic activity of the three complexes as a result of a high turnover rate (k(cat) = 28 h(-1)) combined with a moderate substrate-catalyst binding constant (K(ass) = 1.3 x 10(3) M(-1)). A mechanism for the oxidation reaction is proposed, and reactivity differences, k(cat)/K(M) of the complexes, were found to be dependent on (DeltaE)(1,2), the difference in the driving force for the reduction reactions Cu(II)(2)/Cu(II)Cu(I) and Cu(II)Cu(I)/Cu(I)(2).     

Electrical conductivity and luminescence in coordination polymers based on copper(I)-halides and sulfur-pyrimidine ligands

The solvothermal reactions between pyrimidinedisulfide (pym(2)S(2)) and CuI or CuBr(2) in CH(2)Cl(2):CH(3)CN lead to the formation of [Cu(11)I(7)(pymS)(4)](n) (pymSH = pyrimidine-2(1H)-thione) (1) and the dimer [Cu(II)(μ-Br)(Br)L](2) (L = 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde) (2). In the later reaction, there is an in situ S-S, S-C(sp(2)), and C(sp(2))-N multiple bond cleavage of the pyrimidinedisulfide resulting in the formation of 2-(pyrimidin-2-ylamino)-1,3-thiazole-4-carbaldehyde. Interestingly, similar reactions carried out just with a change in the solvent (H(2)O:CH(3)CN instead of CH(2)Cl(2):CH(3)CN) give rise to the formation of coordination polymers with rather different architectures. Thus, the reaction between pym(2)S(2) and CuI leads to the formation of [Cu(3)I(pymS)(2)](n) (3) and [CuI(pym(2)S(3))] (pym(2)S(3) = pyrimidiltrisulfide) (4), while [Cu(3)Br(pymS)(2)](n) (5) is isolated in the reaction with CuBr(2). Finally, the solvothermal reactions between CuI and pyrimidine-2-thione (pymSH) in CH(2)Cl(2):CH(3)CN at different ratios, 1:1 or 2:1, give the polymers [Cu(2)I(2)(pymSH)(2)](n) (6) and [Cu(2)I(2)(pymSH)](n) (7), respectively. The structure of the new compounds has been determined by X-ray diffraction. The studies of the physical properties of the novel coordination polymers reveal that compounds 3 and 5 present excellent electrical conductivity values at room temperature, while compounds 1, 3, and 5-7 show luminescent strong red emission at room temperature.     

Linear and cyclic tetranuclear copper(I) complexes containing anions of N,N'-bis(pyrimidine-2-yl)formamidine

The reaction of Kpmf (pmf = anion of N,N[prime or minute]-bis(pyrimidyl-2-yl)formamidine, Hpmf) with CuSCN afforded the complexes K[Cu4(pmF)3(SCN)2], 1, and Cu(4)(pmf)4, 2. Reaction of 1 with [(n-Bu)4N]PF6 in THF gave the complex [(n-Bu)4N][Cu4(pmf)3(SCN)2], 3. Their structures were characterized by X-ray crystallography. Complexes 1 and 3 are the first linear tetranuclear complexes containing only Cu(I) atoms, while complex 2 is cyclic. The four Cu(I) atoms of complexes 1 and 3 are helically bridged by three tetradentate pmf- ligands. The [Cu4(pmf)3(SCN)2]- anions of 1 show weak interactions with adjacent [K(THF)5]+ cations through the sulfur atoms, forming infinite chains which are subjected to a series of intermolecular pi-pi interactions. In complex 2, the pmf- ligands are coordinated to the copper atoms in bidentate fashion through the two central amine nitrogen atoms, leaving the pyrimidine nitrogen atoms uncoordinated. Unexpected fluxional behaviors were observed for complexes 1 and 3 in solution. By the DNMR analysis, the free energy of activation (DeltaGc(not equal)) for the exchange is 12.8 kcal mol(-1) at 278 K (T(c)), and the rate constant of exchange (K(c)) is 470 s(-1) for 1. The DeltaGc(not equal) and Kc are 12.6 kcal mol(-1) at 273 K and 433 s(-1), respectively, for 3.     

Brightly phosphorescent trinuclear copper(I) complexes of pyrazolates: substituent effects on the supramolecular structure and photophysics

Synthetic details, solid-state structures, and photophysical properties of a group of trimeric copper(I) complexes containing pyrazolate ligands are described. The reaction of copper(I) oxide and the fluorinated pyrazoles [3-(CF(3))Pz]H, [3-(CF(3)),5-(Me)Pz]H, and [3-(CF(3)),5-(Ph)Pz]H leads to the corresponding trinuclear copper(I) pyrazolates, {[3-(CF(3))Pz]Cu}(3), {[3-(CF(3)),5-(Me)Pz]Cu}(3), and {[3-(CF(3)),5-(Ph)Pz]Cu}(3), respectively, in high yield. The {[3,5-(i-Pr)(2)Pz]Cu}(3) compound was obtained by a reaction between [Cu(CH(3)CN)(4)][BF(4)], [3,5-(i-Pr)(2)Pz]H, and NEt(3). These compounds as well as {[3,5-(Me)(2)Pz]Cu}(3) and {[3,5-(CF(3))(2)Pz]Cu}(3) adopt trimeric structures with nine-membered Cu(3)N(6) metallacycles. There are varying degrees and types of intertrimer Cu...Cu interactions. These contacts give rise to zigzag chains in the fluorinated complexes, {[3-(CF(3))Pz]Cu}(3), {[3-(CF(3)),5-(Me)Pz]Cu}(3), {[3-(CF(3)),5-(Ph)Pz]Cu}(3), and {[3,5-(CF(3))(2)Pz]Cu}(3), whereas the nonfluorinated complexes, {[3,5-(Me)(2)Pz]Cu}(3) and {[3,5-(i-Pr)(2)Pz]Cu}(3) form dimers of trimers. Out of all the compounds examined in this study, {[3-(CF(3)),5-(Ph)Pz]Cu}(3) has the longest (3.848 Angstroms) and {[3,5-(Me)(2)Pz]Cu}(3) has the shortest (2.946 Angstroms) next-neighbor intertrimer Cu...Cu distance. The Cu...Cu separations within the trimer units do not vary significantly (typically 3.20-3.26 Angstroms). All of these trinuclear copper(I) pyrazolates show bright luminescence upon exposure to UV radiation. The luminescence bands are hugely red-shifted from the corresponding lowest-energy excitations, rather broad, and unstructured even at low temperatures, suggesting metal-centered emissions owing to intertrimer Cu...Cu interactions that are strengthened in the phosphorescent state. The {[3-(CF(3)),5-(Ph)Pz]Cu}(3) compound exhibits an additional highly structured phosphorescence with a vibronic structure corresponding to the pyrazolyl (Pz) ring. The luminescence properties of solids and solutions of the trimeric compounds in this study show fascinating trends with dramatic sensitivities to temperature, solvent, concentration, and excitation wavelengths.     

Tripodal bis(imidazole) thioether copper(I) complexes: mimics of the Cu(M) site of copper hydroxylase enzymes

Tripodal bis(imidazole) thioether ligands, (N-methyl-4,5-diphenyl-2-imidazolyl)2C(OR)C(CH3)2SR' (BIT(OR,SR'); R = H, CH3; R' = CH3, C(CH3)3, C(C6H5)3), have been prepared, offering the same N2S donor atom set as the CuM binding site of the hydroxylase enzymes, dopamine beta hydroxylase and peptidylglycine hydroxylating monooxygenase. Isolable copper(I) complexes of the type [(BIT(OR,SMe))Cu(CO)]PF6 (3a and 3b) are produced in reactions of the respective tripodal ligands 1a (R = H) and 1b (R = Me) with [Cu(CH3CN)4]PF6 in CH2Cl2 under CO (1 atm); the pyramidal structure of 3a has been determined crystallographically. The infrared (IR) nu(CO)'s of 3a and 3b (L = CO) are comparable to those of the Cu(M)-carbonylated enzymes, indicating similar electronic character at the copper centers. The reaction of [(BIT(OH,SMe))Cu(CH3CN)]PF6 (2a) with dioxygen produces [(BIT(O,SOMe))2Cu2(DMF)2](PF6)2 (4), whose X-ray structure revealed the presence of bridging BIT-alkoxo ligands and terminal -SOMe groups. In contrast, oxygenation of 2b (R = Me) affords crystallographically defined [(BIT(OMe,SMe))2Cu2(mu-OH)2](OTf)2 (5), in which the copper centers are oxygenated without accompanying sulfur oxidation. Complex 5 in DMF is transformed into five-coordinate, mononuclear [CuII(BIT(OMe,SMe))(DMF)2](PF6)2 (6). The sterically hindered BIT(OR,SR') ligands 9 and 10 (R' = t-Bu; R = H, Me) and 11 and 12 (R' = CPh3; R = H, Me) were also prepared and examined for copper coordination/oxygenation. Oxygenation of copper(I) complex 13b derived from the BIT(OMe,SBu-t) ligand is slow, relative to 2b, producing a mixture of (BIT(OMe,SBu-t))2Cu2(mu-OH)2-type complexes 14b and 15b in which the -SBu-t group is uncoordinated; one of these complexes (15b) has been ortho-oxygenated on a neighboring aryl group according to the X-ray analysis and characterization of the free ligand. Oxygenation of the copper(I) complex derived from BIT(OMe,SCPh3) ligand 12 produces a novel dinuclear disulfide complex, [(BIT(OMe,S)2Cu2(mu-OH)2](PF6)2 (17), which is structurally characterized. Reactivity studies under anaerobic conditions in the presence of t-BuNC indicate that 17 is the result of copper(I)-induced detritylation followed by oxygenation of a highly reactive copper(I)-thiolate complex.     

Synthesis and characterization of vanadium(V)-phosphinimide complexes

Synthetic routes to vanadium(V)-phosphinimide derivatives are addressed. Initial synthetic efforts afforded the known compound formulated as VCl(2)(NPPh(3))(3) which was crystallographically determined to be the salt [VCl(NPPh(3))(3)]Cl (1). Reactions of the vanadium-imide precursors VCl(3)(NAr) (Ar = Ph, C(6)H(3)-2,6-iPr(2)) with R(3)PNSiMe(3) (R = Ph, iPr, tBu) afforded VCl(2)(NPh)(NPPh(3)) (4), VCl(2)(NPh)(NPiPr(3)) (5), VCl(2)(NPh)(NPtBu(3)) (6), VCl(2)(NC(6)H(3)-2,6-iPr(2))(NPPh(3)) (7), VCl(2)(NC(6)H(3)-2,6-iPr(2))(NPiPr(3)) (8), and VCl(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (9) in yields ranging from 72% to 84%. Subsequent alkylation or arylation reactions resulted in VMe(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (10), VPh(2)(NPh)(NPtBu(3)) (11), VPh(2)(NC(6)H(3)-2,6-iPr(2))(NPiPr(3)) (12), and VPh(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (13) while substitution reactions with Li[N(SiMe(3))(2)] and Li[SBn] gave VCl(N(SiMe(3))(2))(NPh)(NPtBu(3)) (14) and V(SBn)(2)(NC(6)H(3)-2,6-iPr(2))(NPtBu(3)) (15) in yields ranging from 40% to 49% yield. Polarization of the N-P phosphinimide bond and V-N multiple bond character are evidenced by crystallographic data.     

Photoluminescent copper(I) complexes with amido-triazolato ligands

A series of heteroleptic copper(I) complexes incorporating amido-triazole and diphosphine ligands, [Cu(I)(N-phenyl-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (1), [Cu(I)(N-(4-methylphenyl)-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (2), [Cu(I)(N-(4-methoxyphenyl)-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (3), [Cu(I)(N-(4-chlorophenyl)-2-(1-phenyl-1H-1,2,3-triazol-4-yl)aniline)(dppb)] (4), [Cu(I)(2,6-dimethyl-N-[2-(1-phenyl-1H-1,2,3-triazol-4-yl)phenyl]aniline)(dppb)] (5), [Cu(I)(2,6-dimethyl-N-[2-(1-benzyl-1H-1,2,3-triazol-4-yl)phenyl]aniline)(dppb)] (6), (dppb = 1,2-bis(diphenylphosphino)benzene), have been prepared. The complexes adopt a distorted tetrahedral geometry in the solid state with the amido-triazole ligand forming a six-member ring with the Cu(I) ion. The complexes exhibit long-lived photoluminescence with colors ranging from yellow to red-orange in the solid state, in frozen glass at 77 K, and in fluid solution with modest quantum yields of up to 0.022. Electrochemically, complexes 1-4 show irreversible oxidation waves while 5 and 6 are characterized by quasi-reversible oxidations as determined by cyclic voltammetry. For 1-4, the emission energy and oxidation potential are found to vary linearly with the Hammett parameter σ(p) of the substituent in the para position of the amido ligand, while in 5 and 6, large differences in emission are observed because of the nature of N3 substitution in the triazole ring. Density functional theory calculations have been performed on the singlet ground states (S(o)) of all complexes at the BP86/6-31G(d) level to assist in assignment of the excited states. On the basis of both experimental and computational results, we have assigned the excited states as intraligand + metal-to-ligand charge transfer (3)(ILCT+MLCT) or ligand-to-ligand charge transfer mixed with MLCT (3)(MLCT +LLCT) in these complexes.     

Triamidotriazacyclononane complexes of group 3 metals. Synthesis and crystal structures

Reaction of yttrium and lanthanide trichlorides (Ln = La, Eu, Yb) with 1 equiv of the trisodium salt of 1,4,7-tris(dimethylsilylaniline)-1,4,7-triazacyclononane (Na(3)[(SiMe(2)NPh)(3)-tacn](THF)(2)) gives good yields of the compounds [M[(SiMe(2)NPh)(3)-tacn]] (M = Y (1), Eu (3), Yb (4)) and [La[(SiMe(2)NPh)(3)-tacn](THF)] (2). Reduction of 3 with Na/Hg followed by recrystallization in the presence of diglyme yielded crystals of [Eu[(SiMe(2)NPh)(3)-tacn]][Na(diglyme)(2)] (5). Synthesis of the uranium(III) complex [U[(SiMe(2)NPh)(3)-tacn]] (6) is achieved by reaction of 1 equiv of Na(3)[(SiMe(2)NPh)(3)-tacn](THF)(2) with uranium triiodide. The U(IV) complexes, [U[(SiMe(2)NPh)(3)-tacn]X] (X = Cl (7); I (8)), were prepared via oxidation of 6 with benzyl chloride or I(2), but salt metathesis from UCl(4) provided a higher yield route for 7. The solid-state structures of 1-7 were determined by single-crystal X-ray diffraction. The ligand [(SiMe(2)NPh)(3)-tacn] generates a trigonal prismatic coordination environment for the metal center in the neutral complexes 1, 3, 4, and 6 and the ionic 5. In 2 the six nitrogen atoms of the ligand are in a trigonal prismatic configuration with the oxygen atom of the THF capping one of the triangular faces of the trigonal prism. In 7 the coordination geometry around the uranium atom is best described as bicapped trigonal bipyramidal.     

Synthesis, characterisation and theoretical studies of amidinato-indium(I) and thallium(I) complexes: isomers of neutral group 13 metal(I) carbene analogues

The synthesis and characterisation of the monomeric amidinato-indium(I) and thallium(I) complexes, [M(Piso)].PisoH, M = In or Tl, Piso- = [ArNC(Bu(t))NAr]-, Ar = C6H3Pr(i)2-2,6, are reported. These complexes, in which the metal centre is chelated by the amidinate ligand in an N,eta3-arene-fashion, can be considered as isomers of four-membered group 13 metal(I) carbene analogues. Theoretical studies have compared the relative energies of both isomeric forms of a model complex, [In{PhNC(H)NPh}].     

Carbon-halogen bond activation mechanism by copper(I) complexes of (2-pyridyl)alkylamine ligands

The reaction of p-substituted benzyl halides ((Y)BnX; X = Cl, Br, and I; Y = p-substituent, OMe, t-Bu, Me, H, F, Cl, and NO(2)) and copper(I) complexes supported by a series of (2-pyridyl)alkylamine ligands has been investigated to shed light on the mechanism of copper(I) complex mediated carbon-halogen bond activation, including ligand effects on the redox reactivity of copper(I) complexes which are relevant to the chemistry. For both the tridentate ligand (Phe)L(Pym2) [N,N-bis(2-pyridylmethyl)-2-phenylethylamine] and tetradentate ligand TMPA [tris(2-pyridylmethyl)amine] complexes, the C-C coupling reaction of benzyl halides proceeded smoothly to give corresponding 1,2-diphenylethane derivatives and copper(II)-halide complex products. Kinetic analysis revealed that the reaction obeys second-order kinetics both on the copper complex and the substrate; rate = k[Cu](2)[(Y)BnX](2). A reaction mechanism involving a dinuclear copper(III)-halide organometallic intermediate is proposed, on the basis of the kinetic results, including observed electronic effects of p-substituents (Hammett plot) and the rate dependence on the BDE (bond dissociation energy) of the C-X bond, as well as the ligand effects.     

Copper complexes of mono- and ditopic [(methylthio)methyl]borates: missing links and linked systems en route to copper enzyme models

TMEDA-free (TMEDA: tetramethylethylenediamine) LiCH(2)SMe is a suitable reagent for the selective introduction of (methylthio)methyl groups into PhBBr(2) and its p-silylated derivative Me(3)Si--C(6)H(4)--BBr(2). The resulting compounds, R*--C(6)H(4)--B(Br)(CH(2)SMe) (R*=H: 2; R*=SiMe(3): 7) and PhB(CH(2)SMe)(2) (3), form cyclic dimers through B--S adduct bonds in solution and in the solid state. Compounds 2 and 3 have successfully been used for preparing the (N(2)S) scorpionate [PhBpz(2)(CH(2)SMe)](-) ([5](-)) (pz: pyrazol-1-yl) and the (NS(2)) scorpionate [PhBpz(CH(2)SMe)(2)](-), respectively. Compound 7 proved to be an excellent building block for the heteroditopic poly(pyrazol-1-yl)borate p-[pz(3)B--C(6)H(4)--Bpz(2)(CH(2)SMe)](2-) ([10](2-)) that mimics the two ligation sites of the copper enzymes peptidylglycine alpha-hydroxylating monooxygenase and dopamine beta-monooxygenase. Treatment of the monotopic tripod [5](-) with CuCl and CuBr(2) results in the formation of complexes K[Cu(5)(2)] and [Cu(5)(2)]. An X-ray crystallography study of K[Cu(5)(2)] revealed a tetrahedral (N(2)S(2)) coordination environment for the Cu(I) ion, whereas the Cu(II) ion of [Cu(5)(2)] possesses a square-pyramidal (N(4)S) ligand sphere (S-atom in the axial position). The remarkable redox properties of K[Cu(5)(2)] and [Cu(5)(2)] have been assessed by cyclic voltammetry and quantum chemical calculations. The reaction of K[Cu(5)(2)] with dry air leads to the Cu(II) species [Cu(5)(2)] and to a tetranuclear Cu(II) complex featuring [PhB(O)pz(2)](2-) ligands. Addition of CuCl to K(2)[10] gives the complex K(3)[Cu(10)(2)] containing two ligand molecules per Cu(I) center. The Cu(I) ion binds to both heteroscorpionate moieties and thereby establishes a coordination environment similar to that of the Cu(I) ion in K[Cu(5)(2)].     

Quantitative evaluation of d-pi interaction in copper(I) complexes and control of copper(I)-dioxygen reactivity

Crystal structures of the copper(I) complexes 1(X), 2, and 3 of a series of tridentate ligands L1(X), L2, and L3, respectively (L1(X): p-substituted derivatives of N,N-bis[2-(2-pyridyl)ethyl]-2-phenylethylamine; X=H, Me, OMe, Cl, NO(2); L2: N,N-bis[2-(2-pyridyl)ethyl]-2-methyl-2-phenylethylamine; L3: N,N-bis[2-(2-pyridyl)ethyl]-2,2-diphenylethylamine) were solved to demonstrate that all the copper(I) complexes involve an eta(2) copper-arene interaction with the phenyl ring of the ligand sidearm. The Cu(I) ion in each complex has a distorted tetrahedral geometry consisting of the three nitrogen atoms (one tertiary amine nitrogen atom and two pyridine nitrogen atoms) and C(1)-C(2) of the phenyl ring of ligand sidearm, whereby the Cu-C distances of the copper-arene interaction significantly depend on the para substituents. The existence of the copper-arene interaction in a nonpolar organic solvent (CH(2)Cl(2)) was demonstrated by the observation of an intense MLCT band around 290 nm, and the magnitude of the interaction was evaluated by detailed analysis of the (1)H and (13)C NMR spectra and the redox potentials E(1/2) of the copper ion, as well as by means of the ligand-exchange reaction between the phenyl ring and CH(3)CN as an external ligand. The thermodynamic parameters DeltaH(o) and DeltaS(o) for the ligand-exchange reaction with CH(3)CN afforded a quantitative measure for the energy difference of the copper-arene interaction in the series of copper(I) complexes. Density functional studies indicated that the copper(I)-arene interaction mainly consists of the interaction between the d(z(2) ) orbital of Cu(I) and a pi orbital of the phenyl ring. The copper(I) complexes 1(X) reacted with O(2) at -80 degrees C in CH(2)Cl(2) to give the corresponding (micro-eta(2):eta(2)-peroxo)dicopper(II) complexes 4, the formation rates k(obs) of which were significantly retarded by stronger d-pi interaction, while complexes 2 and 3, which exhibit the strongest d-pi interaction showed significantly lower reactivity toward O(2) under the same experimental conditions. Thus, the d-pi interaction has been demonstrated for the first time to affect the copper(I)-dioxygen reactivity, and represents a new aspect of ligand effects in copper(I)-dioxygen chemistry.     

Reaction of copper(II) with ferrocene and 1,1'-dimethylferrocene in aqueous acetonitrile: the copper(II/I) self-exchange rate

The kinetics of the reactions of copper(II) with ferrocene (Fc) and 1,1'-dimethylferrocene (Dmfc) have been studied at 25 degrees C in aqueous acetonitrile (AN) containing 50-97.5 vol % AN. With increasing % AN, the rate constant increases along with the driving-force for the reaction. The results are analyzed in terms of Marcus theory to estimate the Cu(II/I) electron self-exchange rate constant (k11) for the system. Over the solvent range studied, the calculated k11)changes from 1.1 x 10(-9) to 17 x 10(-9) M(-1) s(-1), with an average value of 5 x 10(-9). In addition, the structures of the trifluoromethanesulfonate salts of [Cu(AN)4]+, [Cu(OH2)2(AN)2]2+, and [Cu(AN)4]2+ are reported. It is found that the Cu-NCCH3 bond-length difference between the Cu(I) and Cu(II) oxidation states is only approximately 0.02 A.