New catalysts for the chemoselective reduction of α,β-unsaturated ketones: Synthesis, spectral, structural and DFT characterizations of mixed ruthenium(II) complexes containing 2-ethene-1,3-bis(diphenylphosphino)propane and diamine ligands

Design, Synthesis, Characterization of Novel Ruthenium(II) Catalysts: Highly Efficient and Selective Hydrogenation of Cinnamaldehyde to (E)-3-Phenylprop-2-en-1-ol

“…The 31 P{ 1 H} signals in the 31 P-NMR spectrum of complex 1 show a splitting of the 31 P{ 1 H} signals; this is due to the asymmetric nature of diamine in N 1 -(3-(trimethoxysilyl)propyl)ethane-1,2-diamine co-ligand without a C2 axis which will lead to AX resonance patterns for complex 1 , as shown in Figure 1. The phosphorous chemical shifts and the 31 P- 31 P coupling constants ( Jpp = 35.8 Hz) suggested that the phosphine ligand was positioned trans to the diamine, with trans -dichloro atoms, to form the kinetically favored trans -Cl 2 Ru(II) isomer [7,8,9,10].…”

“…Figure 4 shows the electronic absorption of the desired complex. On the basis of its intensity and position, the lowest energy transitions at 200–350 nm has been tentatively assigned to intra-ligand π-π* / n-π* transitions [7,8,9,10]. Similarly, the lowest energy transition in the visible region at 484 nm has been tentatively assigned to metal-to-ligand charge transfer transition (MLCT) [10,11,12,13,14,15,16,17,18,19,20,21,22].…”

“…Ruthenium(II) complexes chelated with mixed diphosphine/diamine ligands have received much attention because of their potential application in the field of homogeneous catalysis [1,2,3,4,5,6,7,8,9]. In 1995, Noyori discovered that complexes derived from the parent [RuCl 2 (diphosphine) 2 (diamine) 2 ] can be utilized as homogeneous catalysts for the hydrogenation of α,β-unsaturated ketones [2,3,4].…”

“…In this aspect, hydrogenations of C=C and C=O functionalities have found important applications in organic and fine chemicals synthesis [14,15,16,17,18,19,20,21,22,23,24,25,26]. The catalytic reactivity and selectivity of these complexes are due to their well-designed structural, electronic, and stereochemical features [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32]. A high turnover frequency (TOF) can be obtained by designing suitable molecular catalysts and reaction conditions.…”

“…In previous work, we have examined the catalytic activity of mixed-ligand ruthenium(II) complexes obtained from diamine and diphosphine ligands as homogenous catalysts for the hydrogenation of unsaturated carbonyl compounds [8,9,10,11,12,13,14,15,16,17,18,19,20]. Some of these catalysts were supported on polysiloxane and examined as interphase catalysts [22,23,24,25,26,27,28].…”