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A three starting material four component reaction is developed for the synthesis of α,β-unsaturated ketones and β-amino ketones. TMEDA is used a dual synthon to provide two carbons in the Selectfluor system.

A novel, green and efficient method is developed for the synthesis of methylene bridged bis(indolyl)methanes in good to excellent yields. The reaction employs methyl tert-butyl ether (MTBE) as the methylene source and selectfluor as an oxidizing agent. The scope and versatility of the methods have been successfully demonstrated with 48 examples. The metal-free transformation process is suitable for scale-up production. A selectfluor-promoted oxidative reaction mechanism is proposed based on the results of the experimental studies.

A synthesis of azepines by the expansion of pyridine rings promoted by iodine in air is reported. The scope of the method is demonstrated with 27 examples. Two iodinations are involved in the reaction, in which the second iodination leads to the opening of the six-membered ring.

A di-(2-pyridylmethyl)phenylamine ((PyCH2)2NPh) supported Cu(ii)/O2 catalytic system was explored with the synthesis of pyridylmethyl-based compounds of carboxylate (PyCOOH), amide (PyC(O)NHPh), and imine (PyCH[double bond, length as m-dash]NPh) from the oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine (PyCH2NHPh) and its derivatives, by means of controlling the addition of a base and/or water to the reaction system under a dioxygen atmosphere at room temperature. Experimental studies showed that the imine and amide species could be precursors in succession in the way to the final oxidation state of carboxylates. A cyclic catalytic mechanism was proposed including the base triggered C-H bond activation of the 2-pyridylmethyl group (PyCH2-) and the intermolecular Cu-OOH α-hydrogen atom abstraction from the coordinated imine substrate (PyCH[double bond, length as m-dash]NPh).

A dimeric tetranuclear carbonate-bridged Cu(II) complex [Cu4(DPA-iBu)4(μ2-CO3)2(MeOH)2]4 + 1 was prepared in-situ through oxidation of Cu(I) species by controlling the concentration of O2 in CO2. Lower concentration of O2 led to the formation of 1 after CO2 fixation but higher would give product as bis-μ2-hydroxo complex [Cu(DPA-iBu)(OH)]22 + 2, which was found to be an intermediate to generate trinuclear carbonated complex [Cu3(DPA-iBu)3(μ3-CO3)(MeCN)2(H2O)]4 + 3. The mechanism of this reaction was proposed and the nucleophilic attack of μ-peroxo Cu(II) species to CO2 molecules was suggested to be responsible for the generation of 1.

Four 2,5-pyridine dicarboxylate (pydc) metal (Mn, Mn/K, Zn, and Nd) coordination polymers with 2D and 3D architectures were synthesized, in which pydc ligand exhibits four new coordination modes to link up to seven metal atoms. Magnetic properties of the complexes are also discussed.

Solvothermal reaction of Mn(OAc)2 · 4H2O with 4,5-dicarboxyimidazole and phenanthroline resulted in a complex [Mn(phen)(Hdcbi)]n 1 in which Hdcbi as a μ2-bridge links two neighboring manganese(II) ions in chelating mode, forming one-dimensional zigzag chain framework. The fitting of magnetic data (J=−0.11 cm−1, zJ′=−0.06 cm−1, g=2.01) indicates weak antiferromagnetic coupling interactions between the Mn(II) sites.

Treatment of LZrCl2 (L - N, N'-ethylenebis(3,5-di-tert-butylsalicylideneiminato) (1), N, N'-o-phenylenebis(3,5-di-tert-butylsalicylideneiminato) (2)), which is an effective catalyst precursor for e ...

Two pyz complexes [Mn(pyz)(2)(H2O)(4)] (1) and [MnCl(pyz)(H2O)] (2) have been synthesized and structurally characterized. Complex 1 contains an eight-coordinate Mn(II) ion with square anti-prismati ...

Mono- and di-manganese inclusion compounds 1 and 2 are reported. Two mono-manganese molecules Mn(bpy)2(NO3)2 (bpy=2,2′-bipyridine) and [Mn(bpy)2(NO3)(H2O)]·NO3 coexist in the mole ratio of 1:1 in the structure of 1, while two di-manganese molecules [Mn2O(bpy)2(phtha)2(H2O)2]·(NO3)2 (phtha=phthalate) and [Mn2O(bpy)2(phtha)2(NO3)(H2O)]·NO3 in the structure of 2. Refluxing Mn(NO3)2/bpy/phthalic acid reaction mixtures in CH3CN leads to the isolation of 1, further concentration of the reaction solution in raising temperature results in 2. The Mn1 and Mn2 units in the inclusion compounds 1 and 2 are similar to other reported Mn1 and Mn2 analogs, respectively. The Jahn–Teller distortion was observed to give rise to the elongation along the OterminalMnOcarboxyl axes for all the four Mn(III) sites in 2, leading to unexpected longer Mn(III)Oaqua than Mn(II)Oaqua in 1. Extensive hydrogen bonding interactions among H2O, NO3 − and COOH were observed in the two inclusion compounds. Cyclic voltammetry of 2 in DMF displays two quasi-reversible redox couples at +0.10/+0.22 and −0.43/−0.36 V assigned to the Mn(III)Mn(IV)/2Mn(III) and 2Mn(III)/Mn(III)Mn(II), respectively. Variable temperature magnetic susceptibilities of 1 and 2 were measured. The data were fit to a model including axial zero-field splitting term and a good fit was found with D=1.77 cm−1, g=1.98 and F=1.48×10−5 for 1. For 2, the least-squares fitting of the experimental data led to J=2.37 cm−1, g=2.02 and D=0.75 cm−1 with R=1.45×10−3.

The planar NNN-pincer complexes [M(II)(pyN(2)(Me2))(OH)](1-) (M(II) = Ni, Cu) fix CO(2) in η(1)-OCO(2)H complexes; results for the copper system are described. Mn(II), Fe(II), Co(II), and Zn(II) behave differently, forming [M(II)(pyN(2)(Me2))(2)](2-) with N(4)O(2) coordination. Incorporation of the Ni(II) pincer into binucleating macrocycle 2 containing a triamino M(II) locus connected by two 1,3-biphenylene groups affords proximal Ni(II) and M(II) sites for investigation of the synthesis, structure, and reactivity of Ni-X-M bridge units. This ligand structure is taken as a reference for variations in M(II) atoms and binding sites and bridges X = OH(-) and CN(-) to produce additional members of the macrocyclic family with improved properties. Macrocycle 2 with a 22-membered ring is shown to bind M(II) = Mn, Fe, and Cu with hydroxo bridges. Introduction of the 4-Bu(i)O group (macrocycle 3) improves the solubility of neutral complexes such as those with Ni(II)-OH-Cu(II) and Ni(II)-CN-Fe(II) bridges. Syntheses of macrocycle 5 with a 7-Me-[12]aneSN(3) and macrocycle 6 with a 1,8-Me(2)-[14]aneN(4) M(II) binding site are described together with hydoxo-bridged Ni/Cu and cyano-bridged Ni/Fe complexes. This work was motivated by the presence of a Ni···(HO)-Fe bridge grouping in a reactive state of carbon monoxide dehydrogenase. Attempted decrease in Ni-(OH)-M distances (3.70-3.87 Å) to smaller values observed in the enzyme by use of macrocycle 4 having 1,2-biphenylene connectors led to a mononuclear octahedral Ni(II) complex. Bridge structural units are summarized, and the structures of 14 macrocyclic complexes including 8 with bridges are described.

The planar complexes [Ni(II)(pyN(2)(R2))(OH)](-), containing a terminal hydroxo group, are readily prepared from N,N'-(2,6-C(6)H(3)R(2))-2,6-pyridinedicarboxamidate(2-) tridentate pincer ligands (R(4)N)(OH), and Ni(OTf)(2). These complexes react cleanly and completely with carbon dioxide in DMF solution in a process of CO(2) fixation with formation of the bicarbonate product complexes [Ni(II)(pyN(2)(R2))(HCO(3))](-) having η(1)-OCO(2)H ligation. Fixation reactions follow second-order kinetics (rate = k(2)'[Ni(II)-OH][CO(2)]) with negative activation entropies (-17 to -28 eu). Reactions were monitored by growth and decay of metal-to-ligand charge-transfer (MLCT) bands at 350-450 nm. The rate order R = MemacroEtPr(i)Bu(i)Ph at 298 K (macro = macrocylic pincer ligand) reflects increasing steric hindrance at the reactive site. The inherent highly reactive nature of these complexes follows from k(2)' ≈ 10(6) M(-1) s(-1) for the R = Me system that is attenuated by only 100-fold in the R = Ph complex. A reaction mechanism is proposed based on computation of the enthalpic reaction profile for the R = Pr(i) system by DFT methods. The R = Et, Pr(i), and Bu(i) systems display biphasic kinetics in which the initial fast process is followed by a slower first order process currently of uncertain origin.

Pyridine-2,6-dimethanethiolate and pyridine-2,6-dithiocarboxylate form sparingly soluble Ni(II) pincer complexes formulated as [Ni(pdmt)](2) and [Ni(pdtc)](2), respectively, with two Ni-(mu(2)-S)-Ni bridges. In acetonitrile reaction systems, the latter undergoes the facile bridge cleavage reactions [Ni(pdtc)](2) + 2L(0,-) --> 2[Ni(pdtc)L](0,-) with an extensive set of nucleophiles to afford planar mononuclear products with L(-) = halide, CN, Me(3)SiO(-), RS(-) and L(0) = Et(3)P and a N-heterocyclic carbene. [Ni(pdmt)](2) is considerably less reactive toward bridge disruption. Cleavage products support several reactions of interest leading to other mononuclear species and to di- and trinuclear complexes. [Ni(pdtc)(OSiMe(3))](1-) deprotonates acetonitrile and acetone to form [Ni(pdtc)(CH(2)R)](1-) (R = CN, COMe). Reaction of [Ni(pdtc)SEt](1-) with Fe(II) yields the thiolate-bridged dimer {[Ni(pdtc)](2)(SEt)}(1-). Refluxing an acetonitrile solution of [Ni(pdtc)SH](1-) in air results in formation of trinuclear [Ni(pdtc)](3)S](2-) containing the rare unsupported Ni(3)(mu(3)-S) bridge core. Reaction of [Ni(pdtc)CN](1-) with [Fe(Me(6)tren)(OTf)](1+) forms the complex [Ni(pdtc)CNFe(Me(6)tren)](1+), the only example of a single Ni-C[triple bond]N-Fe bridge within a molecule. Structures of the various types of reaction products are presented. This work demonstrates the potential utility of bridge cleavage of polynuclear Ni(II) thiolates, an extensive family of compounds, to produce mononuclear products.

The mononuclear macrocyclic complexes [Au(I)([9]aneS2O)2]BF4 x MeCN 1a, [Au(II)([9]aneS2O)2](BF4)2 x 2 MeCN 2a, and [Au(III)([9]aneS2O)2](ClO4)6(H5O2)(H3O)2 3 ([9]aneS2O = 1-oxa-4,7-dithiacyclononane) have been prepared and structurally characterized by single crystal X-ray crystallography. The oxidation of [Au([9]aneS2O)2](+) to [Au([9]aneS2O)2](2+) involves a significant reorganization of the co-ordination sphere from a distorted tetrahedral geometry in [Au([9]aneS2O)2](+) [Au-S 2.3363(12), 2.3877(12), 2.6630(11), 2.7597(13) A] to a distorted square-planar co-ordination geometry in [Au([9]aneS2O)2](2+). The O-donors in [Au([9]aneS2O)2](2+) occupy the axial positions about the Au(II) center [Au...O = 2.718(2) A] with the S-donors occupying the equatorial plane [Au-S 2.428(8) and 2.484(8) A]. [Au([9]aneS2O)2](3+) shows a co-ordination sphere similar to that of [Au([9]aneS2O)2](2+) but with significantly shorter axial Au...O interactions [2.688(2) A] and equatorial Au-S bond lengths [2.340(4) and 2.355(6) A]. The cyclic voltammogram of 1 in MeCN (0.2 M NBu4PF6, 253 K) at a scan rate of 100 mV s(-1) shows an oxidation process at E(p)(a) = +0.74 V and a reduction process at E(p)(c) = +0.41 V versus Fc(+)/Fc assigned to the two-electron Au(III/I) couple and a second reduction process at E(p)(c) = +0.19 V assigned to the Au(I/0) couple. This electrochemical assignment is confirmed by coulometric and UV-vis spectroelectrochemical measurements. Multifrequency EPR studies of the mononuclear Au(II) complex [Au([9]aneS2O)2](2+) in a fluid solution at X-band and as frozen solutions at L-, S-, X-, K-, and Q-band reveal g(iso) = 2.0182 and A(iso) = -44 x 10(-4) cm(-1); g(xx) = 2.010, g(yy) = 2.006, g(zz) = 2.037; A(xx) = -47 x 10(-4) cm(-1), A(yy) = -47 x 10(-4) cm(-1), A(zz) = -47 x 10(-4) cm(-1); P(xx) = -18 x 10(-4) cm(-1), P(yy) = -10 x 10(-4) cm(-1), and P(zz) = 28 x 10(-4) cm(-1). DFT calculations predict a singly occupied molecular orbital (SOMO) with 27.2% Au 5d(xy) character, consistent with the upper limit derived from the uncertainties in the (197)Au hyperfine parameters. Comparison with [Au([9]aneS3)2](2+) reveals that the nuclear quadrupole parameters, P(ii) (i = x, y, z) are very sensitive to the nature of the Au(II) co-ordination sphere in these macrocyclic complexes. The observed geometries and bond lengths for the cations [Au([9]aneS2O)2](+/2+/3+) reflect the preferred stereochemistries of d(10), d(9), and d(8) metal ions, respectively, with the higher oxidation state centers being generated at higher anodic potentials compared to the related complexes [Au([9]aneS3)2](+/2+/3+).

A reaction system consisting of terephthalic acid, NaOH, inorganic Mn(II) or Mn(III) salt, and salicylidene alkylimine resulted in dinuclear manganese complexes (salpn)(2)Mn(2)(mu-phth)(CH(3)OH)(2) (1, salpn = N,N'-1,3-propylene-bis(salicylideneiminato); phth = terephthalate dianion), (salen)(2)Mn(2)(mu-phth)(CH(3)OH)(2) (2, salen = N,N'-ethylene-bis(salicylideneiminato)), (salen)(2)Mn(2)(mu-phth)(CH(3)OH)(H(2)O) (3), and (salen)(2)Mn(2)(mu-phth) (4), while the absence of NaOH in the reaction led to a mononuclear Mn complex (salph)Mn(CH(3)OH)(NO(3)) (5, salph = N,N'-1,2-phenylene-bis(salicylideneiminato)). In addition, a trinuclear mixed metal complex H[Mn(2)Na(salpn)(2)(mu-OAc)(2)(H(2)O)(2)](OAc)(2) (6) was obtained from the reaction system by using maleic acid instead of terephthalic acid. Five-coordinate Mn ions were found in 4 giving rise to an intermolecular interaction and constructing a one-dimensional linear structure. Antiferromagnetic exchange interactions were observed for 1-3, and a total ferromagnetic exchange of 4 was considered to stem from intermolecular magnetic coupling. (1)H NMR signals of phenolate ring and alkylene (or phenylene) backbone of the diamine are similar to those reported in the literature, and the phth protons are at -2.3 to -10.1 ppm. Studies on structure, bond valence sum analysis, and magnetic properties indicate the oxidation states of the Mn ions in 6 to be +3, which are also indicated by ESR spectra in dual mode. Ferromagnetic exchange interaction between the Mn(III) sites was observed with J = 1.74 cm(-1). A quasireversible redox pair at -0.29V/-0.12V has been assigned to the redox of Mn(2)(III)/Mn(III)Mn(II), implying the intactness of the complex backbone in solution.