04566nas a2200193 4500008004100000245020100041210006900242260000800311300001400319490000700333520377300340100001904113700002504132700002504157700001704182700002004199700001904219856013404238 2010 eng d00aStructural diversity in manganese, iron and cobalt complexes of the ditopic 1,2- bis(2,2’-bipyridyl-6-yl)ethyne ligand and observation of epoxidation and catalase activity of manganese compounds0 aStructural diversity in manganese iron and cobalt complexes of t cJUN a7266-72750 v393 a

A ditopic 1,2-bis(2,2′-bipyridyl-6-yl)ethyne ligand, L, has been synthesized for the first time by consecutive Suzuki and Sonogashira coupling reactions either in a one- or two-step synthesis. Coordination of L with some first-row transition metals, Fe, Mn and Co showed a very rich structural diversity that can be obtained with this ligand. Reaction of L with MnII(OAc)2 yielded a dimanganese(II) complex, [Mn2L(μ-OAc)3]PF6, (1) where the two somewhat inequivalent trigonal-bipyramidal Mn atoms separated by 3.381 Å are bridged by L and three acetate moieties. A similar reaction of L with MnIII(OAc)3 yielded a very different dimanganese complex [Mn2L′(OH)(OAc)2(DMF)2]PF6·DMF (2) where L′ is a E-1,2-bis(2,2′-bipyridyl-6-yl)ethene fragment that was formed in situ. The L′ ligand bridges between the two Mn centers, despite its trans configuration, which leads to a very strained ethene bridging moiety. The Mn atoms are also bridged by two acetate ligands and a hydroxy group that bridges between the Mn atoms and the ethene fragment; DMF completes the octahedral coordination around each Mn atom which are separated by 3.351 Å. A comproportionation reaction of L with MnII(OAc)2 and n-Bu4NMnO4 yielded a tetramanganese compound, [Mn4(μ3-O)2(OAc)4(H2O)2L2](PF6)2·2CH3CN (3). Compound 3 has a dimer of dimers structure of the tetranuclear Mn core that consists of binuclear [Mn2O(OAc)2L]+ fragment and a PF6 anion. BVS calculations indicate that 3 is a mixed-valent 2MnII plus 2MnIII compound where two [MnII2O(OAc)2L]+ fragments are held together by MnIII–O inter-fragment linkers which have a distorted octahedral geometry. The Mn atoms in the [Mn2O(OAc)2L]+ fragments have a capped square-pyramid configuration where an aqua ligand is capped on one of the faces. Although the aqua ligand is well within a bonding distance to a carbon atom of the proximal ethyne bridge, there does not appear to be an oxygen–carbon bond formation, rather the ligand is constrained in this position, as deduced by the observation that the bond lengths and angles of the ligand are essentially the same as those for the free ligand, L. Reaction of L with perchlorate or triflate salts of Fe(II), Mn(II) and Co(II) in dry acetonitrile yielded binuclear triple helicate structures (2[thin space (1/6-em)]:[thin space (1/6-em)]3 metal to L ratios) [Fe2L3](CF3SO3)4·CH3CN (4), [Mn2L3](ClO4)4·1.7CH3CN·1.65EtOEt (5) and [Co2L3](ClO4)4·2CH3CN·2EtOEt (6) where each M(II) center with a slightly distorted octahedral geometry is bridged by three of the ditopic ligands. The M–M distances varied; 5.961 Å (Mn), 6.233 Å (Co) 6.331 Å (Fe). Reaction of L with Co(ClO4)2·6H2O in wet acetonitrile yielded a dicobalto(III) compound, [Co2L′3(O)2](ClO4)2·H2O (7), with two types of L′ fragments; one bridging between the two Co centers and two non-bridging ligands, each bonded to a Co atom via one bipyridyl group where the other is non-bonding. The octahedral coordination sphere around each Co atom is completed by the formation of a cobalt–carbon bond from the two carbon atoms of the ethene moiety of the bridging ligand and by a hydroxy moiety that is also bonded to the ethene group of the non-bridging ligand. Reaction of L with Co(ClO4)2·6H2O in dry acetonitrile in the presence of Et3N yielded the tetracobalto(II) complex {[Co2L4(OH)4](ClO4)4}2 (8) with a unique twisted square configuration of cobalt ions with Co–Co distances of 3.938 to 4.131 Å. In addition to the L bridging ligand the Co atoms are linked by hydroxy moieties. Some preliminary catalytic studies showed that the Mn compounds 1 and 2 were active (high yield within 3 min) for alkene epoxidation with peracetic acid and hydrogen peroxide dismutation (catalase activity).

1 aMadhu, Vedichi1 aEkambaram, Balaraman1 aShimon, Linda, J. W.1 aDiskin, Yael1 aLeitus, Gregory1 aNeumann, Ronny uhttps://library.ncl.res.in/content/structural-diversity-manganese-iron-and-cobalt-complexes-ditopic-12-bis22%E2%80%99-bipyridyl-601705nas a2200193 4500008004100000245019700041210006900238260000800307300001800315490000700333520090500340100002401245700001901269700002501288700002501313700002401338700001901362856013001381 2011 eng d00aPhotocatalytic splitting of CS2 to a carbon-sulfur polymer and S8 catalyzed by a bimetallic ruthenium(II) compound with a tertiary amine binding site - towards photocatalytic splitting of CO2?0 aPhotocatalytic splitting of CS2 to a carbonsulfur polymer and S8 cOCT a11273–112750 v503 a

The catalytic photocleavage of CS2 to S8 and a (CxSy)n polymer with visible light using a dinuclear ruthenium(II) compound with a bipyridine units for photoactivity and a vicinal tertiary amine binding site for CS2 activation was studied. The catalyst was characterized by X-ray diffraction, 1H NMR, and 13C NMR, ESI-MS and elemental analysis. CS2 photocleavage was significant (240 turnovers, 20 h) to yield isolable S8 and a (CxSy)n polymer. A mononuclear catalyst or one without an amine binding site showed significantly less activity. XPS of the (CxSy)n polymer showed a carbon/sulfur ratio ∼1.5–1.6 indicating that in part both C–S bonds of CS2 had been cleaved. Catalyst was also included within the polymer. The absence of peaks in the 1H NMR verified the (CxSy)n nature of the polymer, while 13C NMR and IR indicated that the polymer had multiple types of C–S and C–C bonds.

1 aLivanov, Konstantin1 aMadhu, Vedichi1 aBalaraman, Ekambaram1 aShimon, Linda, J. W.1 aDiskin-Posner, Yael1 aNeumann, Ronny uhttps://library.ncl.res.in/content/photocatalytic-splitting-cs2-carbon-sulfur-polymer-and-s8-catalyzed-bimetallic-rutheniumii01048nas a2200193 4500008004100000022001400041245013800055210006900193260000800262300001400270490000600284520032000290100002000610700002700630700002200657700001900679700002500698856013100723 2018 eng d a2044-475300aDirect access to N-alkylated amines and imines via acceptorless dehydrogenative coupling catalyzed by a cobalt(ii)-NNN pincer complex0 aDirect access to Nalkylated amines and imines via acceptorless d cJUL a3469-34730 v83 a

A simple, phosphine-free Co(ii)-NNN pincer complex catalyzed direct N-alkylation of anilines with alcohols via hydrogen auto-transfer (HA) and selective acceptorless dehydrogenative coupling (ADC) of benzylamines with alcohols affording imines with the liberation of molecular hydrogen and water is reported.

1 aMidya, Siba, P.1 aPitchaimani, Jayaraman1 aLandge, Vinod, G.1 aMadhu, Vedichi1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/direct-access-n-alkylated-amines-and-imines-acceptorless-dehydrogenative-coupling-catalyzed01486nas a2200193 4500008004100000245011800041210006900159260000800228300001400236490000700250520076300257100002001020700002001040700002701060700003001087700001901117700002501136856013101161 2018 eng d00a Ni-catalyzed alpha-alkylation of unactivated amides and esters with alcohols by hydrogen auto-transfer strategy 0 aNicatalyzed alphaalkylation of unactivated amides and esters wit cNOV a3911-39160 v113 aA transition-metal-catalyzed borrowing hydrogen/hydrogen auto-transfer strategy allows the utilization of feedstock alcohols as an alkylating partner, which avoids the formation of stoichiometric salt waste and enables a direct and benign approach for the construction of C-N and C-C bonds. In this study, a nickel-catalyzed alpha-alkylation of unactivated amides and ester (tert-butyl acetate) is carried out by using primary alcohols under mild conditions. This C-C bond-forming reaction is catalyzed by a new, molecularly defined nickel(II) NNN-pincer complex (0.1-1 mol %) and proceeds through hydrogen auto-transfer, thereby releasing water as the sole byproduct. In addition, N-alkylation of cyclic amides under Ni-catalytic conditions is demonstrated.1 aMidya, Siba, P.1 aRana, Jagannath1 aPitchaimani, Jayaraman1 aNandakumar, Avanashiappan1 aMadhu, Vedichi1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/ni-catalyzed-alpha-alkylation-unactivated-amides-and-esters-alcohols-hydrogen-auto-transfer01174nas a2200205 4500008004100000022001400041245010200055210006900157260000800226300001200234490000600246520045100252100002200703700002700725700002000752700002600772700001900798700002500817856012600842 2018 eng d a2044-475300aPhosphine-free cobalt pincer complex catalyzed Z-selective semi-hydrogenation of unbiased alkynes0 aPhosphinefree cobalt pincer complex catalyzed Zselective semihyd cJAN a428-4330 v83 a

Herein, we report a novel, molecularly defined NNN-type cobalt pincer complex catalyzed transfer semi-hydrogenation of unbiased alkynes to Z-selective alkenes. This unified process is highly stereo-and chemo-selective and exhibits a broad scope as well as wide functional group tolerance. Ammonia-borane (AB), a bench-stable substrate with high gravimetric hydrogen capacity, was used as a safe and practical transfer hydrogenating source.

1 aLandge, Vinod, G.1 aPitchaimani, Jayaraman1 aMidya, Siba, P.1 aSubaramanian, Murugan1 aMadhu, Vedichi1 aBalaraman, Ekambaram uhttps://library.ncl.res.in/content/phosphine-free-cobalt-pincer-complex-catalyzed-z-selective-semi-hydrogenation-unbiased