om1c00059_si_001.pdf (13.52 MB)
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
journal contribution
posted on 2021-04-14, 12:33 authored by Salvatore Baldino, Steven Giboulot, Denise Lovison, Hans Günter Nedden, Alexander Pöthig, Antonio Zanotti-Gerosa, Daniele Zuccaccia, Maurizio Ballico, Walter BarattaThe diacetate complexes trans-[Ru(κ1-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(κ2-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(κ1-OAc)(PPh3)2(NN)]OAc (2a and 3a) and cis-[Ru(κ1-OAc)2(PPh3)2(NN)] (2b and 3b) in methanol
at RT. The trans-[Ru(κ1-OAc)2(P2)2] (P2 = dppm (4), dppe (5)) compounds have been synthesized
from [Ru(κ2-OAc)2(PPh3)2] by reaction with the suitable diphosphine in toluene at
95 °C. The complex cis-[Ru(κ1-OAc)2(dppm)(ampy)](6) has been obtained
from [Ru(κ2-OAc)2(PPh3)2] and dppm in toluene at reflux and reaction with ampy. The
derivatives trans-[Ru(κ1-OAc)2P2(NN)] (7–16;
NN = en, ampy, ampyrim, 8-aminoquinoline; P2 = dppp, dppb,
dppf, (R)-BINAP) can be easily synthesized from [Ru(κ2-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 °C. The use of (R)-BINAP affords trans-[Ru(κ1-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(κ2-OAc)P2(NN)]OAc (8a–15a; NN = ampy, ampyrim; P2 = dppp, dppb, dppf, (R)-BINAP). Similarly to 2, the dipivalate trans-[Ru(κ1-OPiv)2(PPh3)2(ampy)] (18) is prepared from [Ru(κ2-OPiv)2(PPh3)2] (17) and ampy in CHCl3. The pincer acetate [Ru(κ1-OAc)(CNNOMe)(PPh3)2] (19) has been synthesized from [Ru(κ2-OAc)2(PPh3)2] and HCNNOMe ligand
in 2-propanol with NEt3 at reflux. In addition, the dppb
pincer complexes [Ru(κ1-OAc)(CNN)(dppb)] (CNN = AMTP
(20), AMBQPh (21)) have been
obtained from [Ru(κ2-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.
