16 research outputs found
Preparation of Neutral trans - Cis [Ru(O2CR)2P2(NN)], Cationic [Ru(O2CR)P2(NN)](O2CR) and Pincer [Ru(O2CR)(CNN)P2] (P = PPh3, P2= diphosphine) Carboxylate Complexes and their Application in the Catalytic Carbonyl Compounds Reduction
The diacetate complexes trans-[Ru(\u3ba1-OAc)2(PPh3)2(NN)] (NN = ethylenediamine (en) (1), 2-(aminomethyl)pyridine (ampy) (2), 2-(aminomethyl)pyrimidine (ampyrim) (3)) have been isolated in 76-88% yield by reaction of [Ru(\u3ba2-OAc)2(PPh3)2] with the corresponding nitrogen ligands. The ampy-type derivatives 2 and 3 undergo isomerization to the thermodynamically most stable cationic complexes [Ru(\u3ba1-OAc)(PPh3)2(NN)]OAc (2a and 3a) and cis-[Ru(\u3ba1-OAc)2(PPh3)2(NN)] (2b and 3b) in methanol at RT. The trans-[Ru(\u3ba1-OAc)2(P2)2] (P2 = dppm (4), dppe (5)) compounds have been synthesized from [Ru(\u3ba2-OAc)2(PPh3)2] by reaction with the suitable diphosphine in toluene at 95 \ub0C. The complex cis-[Ru(\u3ba1-OAc)2(dppm)(ampy)](6) has been obtained from [Ru(\u3ba2-OAc)2(PPh3)2] and dppm in toluene at reflux and reaction with ampy. The derivatives trans-[Ru(\u3ba1-OAc)2P2(NN)] (7-16; NN = en, ampy, ampyrim, 8-aminoquinoline; P2 = dppp, dppb, dppf, (R)-BINAP) can be easily synthesized from [Ru(\u3ba2-OAc)2(PPh3)2] with a diphosphine and treatment with the NN ligands at RT. Alternatively these compounds have been prepared from trans-[Ru(OAc)2(PPh3)2(NN)] by reaction with the diphosphine in MEK at 50 \ub0C. The use of (R)-BINAP affords trans-[Ru(\u3ba1-OAc)2((R)-BINAP)(NN)] (NN = ampy (11), ampyrim (15)) isolated as single stereoisomers. Treatment of the ampy-type complexes 8-15 with methanol at RT leads to isomerization to the cationic derivatives [Ru(\u3ba2-OAc)P2(NN)]OAc (8a-15a; NN = ampy, ampyrim; P2 = dppp, dppb, dppf, (R)-BINAP). Similarly to 2, the dipivalate trans-[Ru(\u3ba1-OPiv)2(PPh3)2(ampy)] (18) is prepared from [Ru(\u3ba2-OPiv)2(PPh3)2] (17) and ampy in CHCl3. The pincer acetate [Ru(\u3ba1-OAc)(CNNOMe)(PPh3)2] (19) has been synthesized from [Ru(\u3ba2-OAc)2(PPh3)2] and HCNNOMe ligand in 2-propanol with NEt3 at reflux. In addition, the dppb pincer complexes [Ru(\u3ba1-OAc)(CNN)(dppb)] (CNN = AMTP (20), AMBQPh (21)) have been obtained from [Ru(\u3ba2-OAc)2(PPh3)2], dppb, and HAMTP or HAMBQPh with NEt3, respectively. The acetate NN and pincer complexes are active in transfer hydrogenation with 2-propanol and hydrogenation with H2 of carbonyl compounds at S/C values of up to 10000 and with TOF values of up to 160000 h-1
Palladium Catalyzed Controllable Monoâ or DiâAllylic Substitution Reaction of Benzothiazolylacetate with Allylic Alcohols
Isolate-specific and broad-spectrum QTLs are involved in the control of clubroot in Brassica oleracea
56 ref.International audienc
La biodiversitĂ© des sols est-elle impactĂ©e par lâapport de cuivre ou son accumulation dans les sols vignes ? SynthĂšse des connaissances scientifiques
National audiencePendant 150 ans, le sulfate de cuivre a Ă©tĂ© utilisĂ© de façon intensive comme fongicide pour lutter contre les maladies de la vigne. De ce fait, le cuivre sâest fortement accumulĂ© dans les solsviticoles, atteignant des concentrations potentiellement nocives pour les organismes des sols.Bien que les doses de cuivre appliquĂ©es aujourdâhui soient 10 fois plus faibles quâil y a 50 ans,son utilisation dans le contexte de la transition agroĂ©cologique est encore soumise Ă dĂ©bat caril est un des rares pesticides autorisĂ©s en agriculture biologique. Dans ce travail, nous avonsconduit une mĂ©ta-analyse de la littĂ©rature acadĂ©mique internationale pour objectiver lâimpactdu cuivre sur la qualitĂ© biologique des sols quand il est appliquĂ© aux doses agricoles actuelles,mais Ă©galement lâimpact de son accumulation dans les sols. Parmi les 300 articles passĂ©s enrevue, seulement 19 rĂ©pondaient Ă la question de façon pertinente.Les rĂ©sultats montrent que lâactivitĂ© microbienne dĂ©croĂźt de 30% Ă lâapplication dâune dosesupĂ©rieures Ă 400 kgCu/ha/an. Lâabondance des nĂ©matodes reste inchangĂ©e pour des doses decuivre jusquâĂ 3 200 kg/ha/an. La reproduction des collemboles et des enchytrĂ©es diminue de50 % aprĂšs application de 400 et 1895 kgCu/ha/an respectivement. La biomasse lombricienneest rĂ©duite de 15 % aprĂšs application de 200 kgCu/ha/an. Dâautre part, dans des sols avec desteneurs en cuivre supĂ©rieures Ă 200 kgCu/ha, la respiration microbienne est rĂ©duite de 50 %.Aucun effet des teneurs en cuivre du sol nâest observĂ© sur les collemboles. Globalement, bienquâune toxicitĂ© du cuivre soit observĂ©e sur la biodiversitĂ© du sol, la littĂ©rature montre quâelleconcerne des doses au moins 50 fois supĂ©rieures Ă la dose de 4 kgCu/ha/an actuellement auto risĂ©e par la Commission EuropĂ©enne en viticulture. Par consĂ©quent, appliquer du cuivre Ă 4 kgCu/ha/an ne devrait pas substantiellement modifier la qualitĂ© et les fonctions biologique du so
Preparation of monocarbonyl ruthenium complexes bearing bidentate nitrogen and phosphine ligands and their catalytic activity in carbonyl compound reduction
Monocarbonyl complexes [RuCl2(CO)(PR3)(NN)] (R = Cy, NN = en 1, ampy 2; R = iPr; NN = en 3) have
been prepared in a one pot reaction from [RuCl2(CO)(dmf)(PPh3)2], PR3 and the NN ligand in CH2Cl2.
Treatment of [Ru(OAc)2(CO)(PPh3)2] with NN ligands in methanol gives the cationic derivatives [Ru(OAc)
(CO)(PPh3)(NN)]OAc (NN = en 4, ampy 5) in which one acetate acts as a bidentate ligand, whereas the
other is not coordinated. Diphosphine complexes [RuCl2(CO)(PP)(PPh3)] (PP = dppb 6, dppf 7, (R)-BINAP 8,
(R,Sp)-Josiphos 9 and (R,R)-Skewphos 10) have been obtained starting from [RuCl2(CO)(dmf)(PPh3)2]
and the PP ligand in CHCl3 or toluene at reflux. The reaction of [Ru(OAc)2(CO)(PPh3)2] with PP in CH2Cl2
or toluene affords the fluxional acetate derivatives [Ru(OAc)2(CO)(PP)] (PP = dppb 11, dppf 12, (R)-BINAP
13, and (R,R)-Skewphos 14). The cationic diphosphine complexes [RuCl(CO)(PP)(en)]Cl (PP = dppb 15,
dppf 16) are prepared from [RuCl2(CO)(dmf)(PPh3)2], PP and en in CH2Cl2 or, alternatively, from
[RuCl2(CO)2]n or the 6, 7 derivatives. Similarly, [Ru(OAc)(CO)(PP)(NN)]OAc (PP = dppb, NN = en 17, ampy
18; PP = dppf, NN = en 19, ampy 20) are isolated starting from [Ru(OAc)2(CO)(PPh3)2], PP and NN ligands
or from 11, 12. The derivatives [Ru(OAc)2(CO)(PP)] show a fluxional behavior in solution as the result of the
flexible coordination of acetate ligands. These complexes are found to be active in the transfer hydrogenation
and hydrogenation of ketones and aldehydes, including furfural derivatives, at an S/C up to
10 000 and a TOF up to 18 000 h 121