01705nas 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-rutheniumii02343nas a2200193 4500008004100000245016200041210006900203260000800272300001600280490000700296520155600303100003301859700002501892700002401917700002001941700002501961700002001986856014302006 2013 eng d00aPNN-Ru pincer complexes based on phosphinated 2,2’-dipyridinemethane- and 2,2’-oxobispyridine. metal-ligand cooperation in cyclometallation and catalysis0 aPNNRu pincer complexes based on phosphinated 22 dipyridinemethan cMAY a2973–29820 v323 a

The synthesis of novel PNN ruthenium pincer complexes based on 2,2′-dipyridinemethane phosphine derivatives, as well as on 2,2′-oxobispyridine phosphine ligands, and their reactivity toward dearomatization and cyclometalation are described. The dearomatized compounds 7a,b undergo cyclometalation to yield complexes 8a,b. In order for cyclometalation to proceed, the coordination sphere around the Ru center has to rearrange, and this depends on the flexibility of the system, showing that the cyclometalation is qualitatively faster in the case of the dimethyl derivative 7a than in the case of the spyrocyclopentyl derivative 7b. The cyclometalation occurs diastereoselectively and leads to only one diastereomer of the cyclometalated compounds. In the case of the 2,2′-oxobispyridine complex 6c, the dearomatized complex was too unstable to be isolated; however it was possible to isolate and characterize a stable dicarbonyl-dearomatized ruthenium(II) complex, 9c, when the deprotonation was performed under a CO atmosphere. Dearomatization of 6a under CO also led to dicarbonyl-dearomatized ruthenium(II) complex 9a, which slowly rearranged into the dicarbonyl-aromatized ruthenium(0) complex 10a. These complexes were tested in catalytic alcohol–amine coupling, esterification of primary alcohols, and hydrogenation of secondary amides. Moderate activity was observed in hydrogenation of amides to alcohols and amines and low activity in the other transformations, owing mainly to the formation of stable cyclometalated compounds.

1 aBarrios-Francisco, Rigoberto1 aBalaraman, Ekambaram1 aDiskin-Posner, Yael1 aLeitus, Gregory1 aShimon, Linda, J. W.1 aMilstein, David uhttps://library.ncl.res.in/content/pnn-ru-pincer-complexes-based-phosphinated-22%E2%80%99-dipyridinemethane-and-22%E2%80%99-oxobispyridine01807nas a2200217 4500008004100000245016300041210006900204260000800273300001600281490000700297520098300304100001901287700001501306700001901321700002501340700002401365700002501389700002401414700002001438856013101458 2013 eng d00aStepwise metal-ligand cooperation via a reversible aromatization-deconjugation-sequence in ruthenium complexes with a tetradentate phenanthroline-based ligand0 aStepwise metalligand cooperation via a reversible aromatizationd cMAR a3407–34140 v193 a

The synthesis and reactivity of ruthenium complexes containing the tetradentate phenanthroline-based phosphine ligand 2,9-bis((di-tert-butylphosphino)methyl)-1,10-phenanthroline (PPhenP) is described. The hydrido chloro complex [RuHCl(PPhenP)] (2) undergoes facile dearomatization upon deprotonation of the benzylic position, to give [RuH(PPhenP-H)] (4). Addition of dihydrogen to 4 causes rearomatization of the phenanthroline moiety to trans-[Ru(H)2(PPhenP)] (5), followed by hydrogenation of an aromatic heterocycle in the ligand backbone, to give a new dearomatized and deconjugated complex [RuH(PPhenP*-H)] (6). These aromatization/deconjugation steps of the coordinated ligand were demonstrated to be reversible and operative in the dehydrogenation of primary alcohols without the need for a hydrogen acceptor. This aromatization/deconjugation sequence constitutes an unprecedented mode of a stepwise cooperation between the metal center and the coordinated ligand.

1 aLanger, Robert1 aFuchs, Ido1 aVogt, Matthias1 aBalaraman, Ekambaram1 aDiskin-Posner, Yael1 aShimon, Linda, J. W.1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/stepwise-metal-ligand-cooperation-reversible-aromatization-deconjugation-sequence-ruthenium02868nas a2200241 4500008004100000245012800041210006900169260000800238300001600246490000700262520200600269100001702275700001902292700001902311700002802330700002502358700002402383700002002407700002502427700002402452700002002476856013002496 2013 eng d00aSynthesis, structures, and dearomatization by deprotonation of iron complexes featuring bipyridine-based PNN pincer ligands0 aSynthesis structures and dearomatization by deprotonation of iro cJUL a9636–96490 v523 a

The synthesis and characterization of new iron pincer complexes bearing bipyridine-based PNN ligands is reported. Three phosphine-substituted pincer ligands, namely, the known tBu-PNN (6-((di-tert-butylphosphino)methyl)-2,2′-bipyridine) and the two new iPr-PNN (6-((di-iso-propylphosphino)methyl)-2,2′-bipyridine) and Ph-PNN (6-((diphenylphosphino)methyl)-2,2′-bipyridine) ligands were synthesized and studied in ligation reactions with iron(II) chloride and bromide. These reactions lead to the formation of two types of complexes: mono-chelated neutral complexes of the type [(R-PNN)Fe(X)2] and bis-chelated dicationic complexes of the type [(R-PNN)2Fe]2+. The complexes [(R-PNN)Fe(X)2] (1: R = tBu, X = Cl, 2: R = tBu, X = Br, 3: R = iPr, X = Cl, and 4: R = iPr, X = Br) are readily prepared from reactions of FeX2 with the free R-PNN ligand in a 1:1 ratio. Magnetic susceptibility measurements show that these complexes have a high-spin ground state (S = 2) at room temperature. Employing a 2-fold or higher excess of iPr-PNN, diamagnetic hexacoordinated dicationic complexes of the type [(iPr-PNN)2Fe](X)2 (5: X = Cl, and 6: X = Br) are formed. The reactions of Ph-PNN with FeX2 in a 1:1 ratio lead to similar complexes of the type [(Ph-PNN)2Fe](FeX4) (7: X = Cl, and 8: X = Br). Single crystal X-ray studies of 1, 2, 4, 6, and 8 do not indicate electron transfer from the FeII centers to the neutral bipyridine unit based on the determined bond lengths. Density functional theory (DFT) calculations were performed to compare the relative energies of the mono- and bis-chelated complexes. The doubly deprotonated complexes [(R-PNN*)2Fe] (9: R = iPr, and 10: R = Ph) were synthesized by reactions of the dicationic complexes 6 and 8 with KOtBu. The dearomatized nature of the central pyridine of the pincer ligand was established by X-ray diffraction analysis of single crystals of 10. Reactivity studies show that 9 and 10 have a slightly different behavior in protonation reactions.

1 aZell, Thomas1 aLanger, Robert1 aIron, Mark, A.1 aKonstantinovski, Leonid1 aShimon, Linda, J. W.1 aDiskin-Posner, Yael1 aLeitus, Gregory1 aBalaraman, Ekambaram1 aBen-David, Yehoshoa1 aMilstein, David uhttps://library.ncl.res.in/content/synthesis-structures-and-dearomatization-deprotonation-iron-complexes-featuring-bipyridine01285nas a2200241 4500008004100000022001400041245010700055210006900162260005700231300001200288490000800300520042200308653001200730653001200742653002500754653002200779653002000801100002500821700002200846700002400868700002000892856013100912 2015 eng d a1011-372X00aDirect synthesis of secondary amines from alcohols and ammonia catalyzed by a ruthenium pincer complex0 aDirect synthesis of secondary amines from alcohols and ammonia c a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcJAN a139-1440 v1453 a

Efficient and selective direct synthesis of secondary amines from primary alcohols and ammonia with liberation of water has been achieved, with high turnover numbers and with no generation of waste. In case of benzylic alcohols, imines rather than amines are obtained. This atom economical, environmentally benign reaction is homogenously catalyzed by a well-defined bipyridine based Ru(II)-PNN pincer complex.

10aAlcohol10aAmmonia10aHomogenous catalysis10aRu-pincer complex10aSecondary amine1 aBalaraman, Ekambaram1 aSrimani, Dipankar1 aDiskin-Posner, Yael1 aMilstein, David uhttps://library.ncl.res.in/content/direct-synthesis-secondary-amines-alcohols-and-ammonia-catalyzed-ruthenium-pincer-complex-0