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The discovery of new coordination compounds with anticancer properties is an active field of research due to the severe side effects of platinum-based compounds currently used in chemotherapy. In the search for new agents for the treatment of cancer, unsymmetrical N2O2-tetradentate ligand (H2L1 and H2L2) and their Ni(II) and Zn(II) asymmetric complexes (NiII-L1–2 and ZnII-L1–2) have been synthesized and fully characterized. 1H NMR studies revealed that the ligands and complexes were stable in mixtures of DMSO : D2O (9 : 1). Complementary UV-Vis studies confirmed that ZnII derivatives also exhibit high stability in mixtures DMSO : buffer (6 : 4) after 24 h. Single-crystal X-ray diffraction studies confirmed the molecular structures of H2L1, H2L2, NiII-L1, and NiII-L2. At the molecular level, complexes were completely planar without significant distortions of the square-planar geometry according to τ4 parameter. Furthermore, the crystalline structures revealed non-classical intermolecular interactions of the C–H⋯O and the Ni⋯Ni type. The ligands and complexes were screened against the human osteosarcoma (MG-63), human colon cancer (HCT-116), breast cancer (MDA-MB-231) cell lines, and non-cancerous cells (L929). H2L1 and H2L2 ligands not caused cytotoxic effects at a concentration of 100 μM, while NiII-L2, ZnII-L1, and ZnII-L2 complexes induce cytotoxic effects in all cell lines. NiII-L2 was a more active complex against MG-63 (3.9 ± 1.5) and HCT-116 (3.4 ± 1.7) cell lines with IC50 values in the low micromolar range. In addition, this compound was 10-, 5-, and 11-fold more potent than cisplatin in MG-63 (39 ± 1.8), HCT-116 (17.2), and MDA-MB-231 (131 ± 18), respectively. Three complexes exhibited great selectivity for tumoral cells with SI values ranging from 1.6 to 7.4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ruthenium complexes are active catalysts in hydrogen transfer to imine. • Hydrogen transfer to imine using ruthenium complexes containing nitrogen- phosphorus-nitrogen (NPN) ligands. • Synthesis and crystal structure of ruthenium complexes containing nitrogen-phosphorus-nitrogen ligands. This work reports the synthesis and characterization of ruthenium(II) complexes containing nitrogen-phosphorus-nitrogen (NPN) ligands, with L1 = N-(phenyl(pyridin-2-ylamino)phosphino)pyridin-2-amine and L2 = 4-methyl-N-((4-methylpyridin-2-ylamino)(phenyl)phosphino)pyridin-2-amine. The ruthenium complexes RuCl 2 PPh 3 (L1) (1) and RuCl 2 PPh 3 (L2) (2) show high activities in catalytic transfer hydrogenation of different substituted benzylideneanilines, with turnover frequencies up to 5882 h−1 and 5294 h−1, respectively. The RuCl(CO)PPh 3 (L1) (3) and RuCl(CO)PPh 3 (L2) (4) complexes were non-active in the reaction studied. Theoretical calculations conducted for complex 4 showed that the carbonyl group promotes σ-orbital interactions and backdonation phenomena from the metal centre to the π* orbitals in the CO ligand, presenting a strong orbital contribution. This supports the hypothesis that complexes 3 and 4 are less reactive species and therefore present poor or null catalytic performance in the reaction studied. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and spectroscopic and theoretical studies of new κ1-S monometallic Re-spy (1)/Re-thiopy (2) and κ1-N-bimetallic Re2-dps (3)/Re2-dpds (4) complexes substituted with 4-mercaptopyridine derivatives are reported. The obtainment of either monosulfide bridge-complex (3) or disulfide bridge-complex (4) depends on the reaction media. The structure of complex 3 was confirmed by monocrystal X-ray diffraction. Additionally it was possible to determine the presence of an intramolecular interconversion between 1 and 2 mediated by solvent molecules through the intermediate species 1-H+ using UV-Vis and NMR spectroscopy. Electronic spectra calculated by TD-DFT feature distinct MLCT transitions for 2 and show that the π-stacking interaction present in 1 is broken in the methanol/water mixture, leading to a structural distribution similar to 2. Cyclic voltammograms of all complexes display the characteristic reduction process for the rhenium center and the bipyridine ligand. Additionally, an irreversible process associated with the bridging ligand for 3 and 4 is observed. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of four copper(II) complexes with different terpyridyl ligands have been carried out, their crystal and molecular structures determined and their magnetic and luminescent properties analyzed. The ligands used in the coordination reactions were 4′-(3-methyl-2-thienyl)-4,2′:6′,4''-terpyridine ( 4-stpy ), -4′-(4-quinolinyl)-4,2′:6′,4''-terpyridine ( 4-qtpy ), 4′-(4-quinolinyl)-3,2′:6′,3''-terpyridine ( 3-qtpy, unreported so far) and 4′-(4-cyanophenyl)-4,2′:6′,4''-terpyridine ( 4-cntpy ); the reaction of these ligands with Cu(II)-hexafluoroacetylacetone ( Cu(hfacac) 2 ) gives rise to coordination polymers Cu(4-stpy)(hfacac) 2 ( I ), Cu(4-qtpy)(hfacac) 2 ( II ), Cu(3-qtpy)(hfacac) 2 ( III ) and Cu(4-cntpy)(hfacac) 2 ( IV ). The different location of the nitrogen atom of the outer ring is responsible for the different coordination modes. The emission spectra of dichloromethane solutions are consistent with dissociation of the complexes; the emission maxima simulate those of the free ligands. The emission of I , III and IV in the solid state is essentially quenched upon complexation with Cu(II), whereas for compound II an emission at 420 nm is observed. The interaction between copper centers has been related with the coplanarity of terpyridine rings. Complexes I–III exhibit a paramagnetic behavior, while compound IV , with the smallest torsion angle between pyridine moieties, shows an antiferromagnetic behavior described by a dimeric model, with J= −4.38 cm −1 , g =2.06 and ρ =0.07. [ABSTRACT FROM AUTHOR]

Lithium diphenylphosphide unexpectedly provokes the ring-opening of tetrahydrofuran (THF) and by reaction with 3,6-dichloropyridazine leads to the formation of the ligand 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine (P…N), which was isolated. The reaction of this ligand with the (Re(CO)3(THF)Br)2 dimer yields the novel complex [Br(CO)3Re(μ-3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine)2Re(CO)3Br] (BrRe(P…N)(N…P)ReBr), which was crystallized in the form of a chloroform solvate, (C46H40Br2Cl2N4O8P2Re2)·(CHCl3). The monoclinic crystal (P21/n) displays a bimetallic cage structure with a symmetry inversion centre in the middle of the rhenium to rhenium line. The molecule shows two oxidation signals occurring at +1.50 V and +1.76 V which were assigned to the ReI/ReII and ReII/ReIII metal-centered couples, respectively, while signals observed at −1.38 V and −1.68 V were assigned to ligand centered reductions. Experimental and DFT/TDDFT results indicate that the UV-Vis absorption maximum of BrRe(P…N)(N…P)ReBr occurring near 380 nm displays a metal to ligand charge transfer (MLCT) character, which is consistent with CV results. Upon excitation at this wavelength, a weak emission (Φem ＜ 1 × 10−3) is observed around 580 nm (in dichloromethane) which decays with two distinct lifetimes τ1 and τ2 of 24 and 4.7 ns, respectively. The prevalence of non-radiative deactivation pathways is consistent with efficient internal conversion induced by the high conformational flexibility of the P…N ligand's long carbon chain. Measurements in a frozen solvent at 77 K, where vibrational deactivation is hindered, show intense emission associated with the 3MLCT state. These results demonstrate that BrRe(P…N)(N…P)ReBr preserves the dual emitting nature previously reported for the mononuclear complex RePNBr, with emission associated with UGRAPHIC DISPLAY="INLINE" ID="UGT1" SRC="UGT1"/ and UGRAPHIC DISPLAY="INLINE" ID="UGT2" SRC="UGT2"/ states. [ABSTRACT FROM AUTHOR]

A dinuclear cobalt(ii), [Co2(κ4-O,O′,N,N′-L)2(μ-O,O′-HCOO)](ClO4)·(C2H5)2O (1) and a linear mixed valence trinuclear manganese, [Mn3(κ4-O,O′,N,N′-L)2(μ-CH3O)2(μ-O,O′-CH3COO)2]·2(C2H5)2O (2) complexes with the ligand N-(2-pyridyl-methyl)-N,N-bis-[2′-hydroxy-5′-methyl-benzyl]-amine (H2L) are reported. For both complexes the ligand is present in the deprotonated form. The coordination sphere of the cobalt centres can be described as slightly distorted octahedral with two bridging O-phenoxo, one N-pyridine, one N-amine, one terminal O-phenoxo and one bridging O-formate donor atoms. Interestingly, the bridging formate resulted from the aerial oxidation of methanol. The manganese complex (2) has a linear mixed valence MnIII–MnII–MnIII, with the MnII and MnIII centres bridged by alkoxo, carboxylate and phenoxo groups. Cyclic voltammetry studies show both metal and ligand centred redox processes consistent with the structure of the complexes. Complex (2) has an S = 3/2 ground state; magnetic susceptibility measurements indicate a weak antiferromagnetic interaction. The best fit of the magnetic susceptibility data as a function of temperature was obtained using a conventional trinuclear linear model [H = −2J(S1S2 + S1S3)] with J = −0.79 cm−1 and g = 1.99. [ABSTRACT FROM AUTHOR]

In the present work, the synthesis and structural characterization of two new polyoxovanadoborate (BVO) frameworks, based on the [V12B18O60H6]10−polyanion, are reported, K(H3O)(enH2)4[V12B18O60H6]·9.60H2O (1) and Li8(NH4)2[V12B18O60H6]·8.02H2O (2). Both compounds are obtained in a mixed valence ratio of 10VIV/2VV. Framework1is characterized by potassium ions coordinated by the BVO cluster and ethylenediammonium and hydronium ions as charge-compensating agents. In framework2, the BVO clusters are coordinating lithium ions and the charge is compensated by ammonium ions. Using the SHAPE 2.1 program, it was possible to calculate the best geometry for the existing lithium and potassium ions. For2, the lithium ions are five-coordinate, best described by a square pyramid (SPY-5), while the coordination sphere around the potassium ions in1are six-coordinate. For1, the coordination sphere of the existing potassium ions in the framework can be described as trigonal prism (TPR-6). Calculations were also done for a previously reported cluster [Na10[(H2O)V12B18O60H6]·18H2O] (3), in which the sodium ions are six-coordinate but in two different geometries, these being octahedral and TPR-6. The influence of the interactions of the alkali ions with the [V12B18O60H6]10−polyanion, on the vanadate and borate absorption bands observed in the infrared spectra, is discussed. [ABSTRACT FROM PUBLISHER]

In the structure of the title compound, {[Cu2(C10H2O8)(H2O)6]·4H2O} n, the benzene-1,2,4,5-tetracarboxylate ligand, (btec)4−, is located on a crystallographic inversion centre in a μ4-coordination mode. The coordination environment of each pentacoordinated CuII centre is square pyramidal (SBP), formed by three water molecules and two carboxylate O atoms from two different (btec)4− ligands. The completely deprotonated (btec)4− ligand coordinates in a monodentate mode to four CuII atoms. The alternation of (btec)4− ligands and SBP CuII centres leads to the formation of a planar two-dimensional covalent network of parallelograms, parallel to the ab plane. Hydrogen bonds between a basal water molecule and an apical one from an adjacent [Cu(btec)0.5(H2O)3] unit exist in the intralayer space. Hydrogen bonds are also present between the two-dimensional network and the water molecules filling the channels in the structure. [ABSTRACT FROM AUTHOR]

A structural and magnetic characterization of a trinuclear chiral Mn(ll) formate three-dimensional framework exhibiting a triangular arrangement is presented. Compound Na[sub3][Mn[sub3](HCOO)[sub9]] was obtained by solvothermal synthesis and crystallizes in the chiral cubic space group P2[sub1]3 and is well described by a Δ conformation. The structure displays triangular Mn[sub3] building blocks, in which the metal centers are bonded byformate ligands in a syn-anti mode (Mn-Mn 5.697(1) Å). The coordination sphere of manganese(ll) is completed by six oxygen atoms from six formate ligands, resulting in an octahedral geometry. Magnetic susceptibility measurements showed antiferromagnetic interactions at high temperature and a strongly field dependent magnetic behavior below 40 K. At fields higher than 1 .0 kOe only the antiferromagnetic interactions can be observed. At applied fields lower than 1.0 kOe magnetic susceptibility becomes irreversible with maxima observed at 22 and 34 K. These maxima suggest a weak ferromagnetic behavior because of spin canting, allowed by the presence of the noncentrosymmetric syn-anti HCOO bridges linking the Mn sites. This non-collinear antiferromagnetism and irreversible behavior can be due to the existence of a high degree of frustration in this unique lattice composed of linked triangular arrangements of interacting magnetic centers. [ABSTRACT FROM AUTHOR]

Examines the solvothermal reaction of carboxylate ligands with trifluoroacetic acid and acetic anhydride. Measurement on cyclic voltammetry; Synthesis of high metal content compounds; Synthesis on the structure of rhenium trifluoroacetate.

Abstract: This article describes the partial hydrolysis of the multidentate ligand 2,4,6-tris(pyrazol-1-yl)-1,3,5-triazine in the presence of copper(II), to give the anionic ligand 2,4-dione-1,3,5-(1H)-triazin-1-amido, which was isolated as the cupric complex catena-[CuL(H2O)Cl] n , where L is the amido ligand. No other hydrolysis products were isolated or identified. The complex defines a zigzag 1D covalent chain, along the b cell axis, through apical copper–oxygen bonds (Cu–N–C–O···Cu bridges). [Copyright &y& Elsevier]

Four mononuclear complexes [Cu(HL¹)CI]PF6·CH3OH (1), [Cu(HSL¹)Cj]PF6-O.75H2O (2), [Cu(HL2)CUPF6.CH3- OH (3), [Cu(HSL2)O]PF6- 1 .5CH3OH (4), and Iwo polynudear complexes [Cu2(SL2)2](PF6)2-2CH3OH (5) and (Cu[Cu(SL2)(Cl))2)(PF6)2 (6) (HL1: 2-[(bis(2-pytidylmethyl)-amino)methyl]-4-methylphenol; HSL¹: 2-[(bis(2-pyridyf- methy[)amino) methylf4-methyl-6-(meth4-thio)phenoI; HL2: 2-((2-pyitddmethy)(2'-pytidyteth4)-aminomethl)]4methyl- phenol; HSL2: 2.[(2-py dmethyl)(2'-pyrtdytethyl)amino-methyl]-4-methyl-6-(methytthio)phenol were obtained and characterized. The crystal structures of the mononuclear complexes 1-4 show the copper centers in a square-base pyramidal environment with the phepolic oxygen coordhiated at the axial position. Dinuclear complex 5 has two copper centers with different geometry and bridged by phenoxo oxygens; one of the copper atoms is square pyramidal while the other can be described with a highly distorted octahedral geometry with a long Cu-S distance (2.867 Å). Density functional theory calculations were used to obtain the reported structure oF6, since single crystals suitable for X-ray diffraction were not isolated. Magnetic studies done for 5 and 6 show an antiferromagnetic behavior for 5 (J = -134 cm-1) and a ferromagnetic behavior for 6 (J = +11.9 cm-1). Redox potentials for the mononuclear complexes were measured by cyclic vohammetty the values show the effectof the chelating ring size (-213 my and -142 mV for Cu-HL¹ and Cu-HL2, respectively) and the presence of the thiomethyl substituent (-213 my and -184 mV for Cu-HL¹ and Cu-HSL¹, respectively). [ABSTRACT FROM AUTHOR]

Two new ligands, 2-[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenol (HL) and 2-[(bis(2-pyridylmethyl)amino)methyl]-4-methyl-6-(methylthio)phenol (HSL), were synthesized and were used to prepare the trinuclear copper(II) complex {-[CuSL(Cl)]2Cu}(PF6)2·H2O (1) and the corresponding binuclear complexes [Cu2(SL)2](PF6)2 (2) and [Cu2L2](PF6)2 (3). The crystal structure of 1 shows two different coordination environments: two square base pyramidal centers (Cu1 and Cu1a, related by a C2 axes), acting as ligands of a distorted square planar copper center (Cu2) by means of the sulfur atom of the SCH3 substituent and the bridging phenoxo oxygen atom of the ligand (Cu2-S = 2.294 A). Compounds 2 and 3 show two equivalent distorted square base pyramidal copper(II) centers, bridged in an axial-equatorial fashion by two phenoxo groups, thus defining an asymmetric Cu2O2 core. A long copper-sulfur distance measured in 2 (2.9261 (18) Å) suggests a weak bonding interaction. This interaction induces a torsion angle between the methylthio group and the phenoxo plane resulting in a dihedral angle of 41 .4(5)°. A still larger distortion is observed in 1 with a dihedral angle of 74.0(6)°. OFT calculations for 1 gave a ferromagnetic exchange between first neighbors interaction, the calculated J value for this interaction being +11.7 cm-1. In addition, an antiferromagnetic exchange for 1 was obtained for the second neighbor interaction with a J value of -0.05 cm-1. The Bleaney-Bowers equation was used to fit the experimental magnetic susceptibility data for 2 and 3; the best fit was obtained with J values of +3.4 and -16.7 cm-1, respectively. DFT calculations for 2 and 3 confirm the nature and the values of the J constants obtained by the fit of the experimental data. ESR and magnetic studies on the reported compounds show a weak exchange interaction between the copper(II) centers. The low values obtained for the coupling constants can be explained in terms of a poor overlap between the magnetic orbitals, due to the axial-equatorial phenoxo bridging mode observed in these complexes. [ABSTRACT FROM AUTHOR]

The bis-pyridine tridentate ligands (6-R-2-pyridylmethyl)-(2-pyridylmethyl) benzylamine (RDPMA, where R = CH3, CF3), (6-R-2-pyridylmethyl)-(2-pyridylethyl) benzylamine (RPMPEA, where R = CH3, CF3), and the bidentate ligand di-benzyl-(6-methyl-2-pyridylmethyl)amine (BiBzMePMA) have been synthesized and their copper(I) complexes oxidized in a methanol solution to afford self-assembled bis-μ-methoxo-binuclear copper(II) complexes (1, 2, 4, 6) or hydroxo-binuclear copper(II) complexes (3). Oxidation of the nonsubstituted DPMA (R = H) in dichloromethane gives a chloride-bridged complex (5). The crystal structures for [Cu(MeDPMA)(MeO)]2(ClO4)2 (1), [Cu(RPMPEA)-(MEO)]2(ClO4)2 (for 2, R= Me, and for 4, R = CF3), [Cu(BiBzMePMA)(MeO)]2(ClO4)2 (6), [Cu(FDPMA)(OH)]2-(ClO4)2 (3), and [Cu(DPMA)(Cl)]2(ClO4)2 (5) have been determined, and their variable-temperature magnetic susceptibility has been measured in the temperature range of 10–300 K. The copper coordination geometries are best described as square pyramidal, except for 6, which is square planar, because of the lack of one pyridine ring in the bidentate ligand. In 1–4 and 6, the basal plane is formed by two pyridine N atoms and two O atoms from the bridging methoxo or hydroxo groups, whereas in 5, the bridging Cl atoms occupy axial-equatorial sites. Magnetic susceptibility measurements show that the Cu atoms are strongly coupled antiferromagnetically in the bis-methoxo complexes 1, 2, 4, and 6, with -2J > 600 cm-1, whereas for the hydroxo complex 3, -2J = 195 cm-1 and the chloride-bridged complex 5 shows a weak ferromagnetic coupling, with 2J = 21 cm-1 (2J is an indicator of the magnetic interaction between the Cu centers). [ABSTRACT FROM AUTHOR]

The reaction of [ P,N -{(C 6 H 5 ) 2 (C 5 H 4 N)P}Re(CO) 3 Br] ( RePNBr ) with silver triflate leads to the complex [ P,N -{(C 6 H 5 ) 2 (C 5 H 4 N)P}Re(CO) 3 ( O -CF 3 SO 3 )] ( RePNTfO ) with moderate yield. This new P,N -Re I triflate compound contains the anion directly coordinated to the metal, completing an octahedral environment. RePNTfO displays in dichloromethane (DCM) solution an irreversible oxidation about +1.35 V and three irreversible reduction processes at −1.38 V, −2.03 V and −2.30 V. Oxidation has been attributed to the Re I /Re II couple, while the reduction corresponds to PN -ligand processes, which is consistent with those computed by means of DFT. The absorption spectrum of RePNTfO in DCM displays a maximum at 295 nm ( ε = 7.1 × 10 3 M −1 cm −1 ) and a shoulder around 350 nm ( ε = 1.8 × 10 3 M −1 cm −1 ), which have been assigned to intraligand (π → π ∗ ) and metal to ligand charge transfer (MLCT, dπ → π ∗ ) transitions with the help of DFT/TDDFT. Excitation of RePNTfO in DCM at 350 nm leads to an emission spectrum centered at 535 nm. The analysis of the variation of the absorption and emission spectra in coordinating solvents compared to non-coordinating DCM, DFT/TDDFT calculations modeling and ELF analysis suggests for coordinating solvents that triflate ligand is replaced in the coordination sphere of Re I in solution. Kinetics of the exchange of triflate by bromide measured in DCM at different temperatures allowed to estimate the Eyring parameters: Δ H ≠ , Δ S ≠ and Δ G ≠ , 50.8 kJ mol −1 , −109.6 J K −1 mol −1 and 83.5 kJ mol −1 respectively. The high negative entropy is indicative of a compact transition state, compatible with an associative mechanism, I a , for the exchange. [ABSTRACT FROM AUTHOR]

[(pypyr)Re(CO) 3 Br] has a moderate emission quantum yields while [(pypyr-anthra)Re(CO) 3 Br] and [Br(CO) 3 Re(pypyr-anthra-pypyr)Re(CO) 3 Br] are very weak ones but these two last molecules showed a remarkably high yield for molecular oxygen sensitization. [Display omitted] The ligand 2-(1H -pyrazol-1-yl)pyrazine (pypyr) was prepared by reaction of 2-bromopyrazine with N -lithium pyrazolate with 92.5% yield, while the anthracenyl derivatives 2-(anthracen-9-yl)-5-(1 H -pyrazol-1-yl)pyrazine (pypyr-anthra) and 9,10-bis(5-(1 H -pyrazol-1-yl)pyrazin-2-yl)anthracene (pypyr-anthra-pypyr) were prepared by reaction of the 9-anthraceneboronic or bis-boronic acid pinacol ester with 2-bromo-5-(1 H -pyrazol-1-yl)pyrazine with medium yields (49.6 and 31.5 % respectively). The respective ReI(CO) 3 Br complexes: [(pypyr)Re(CO) 3 Br] , [(pypyr-anthra)Re(CO) 3 Br] and [Br(CO) 3 Re(pypyr-anthra-pypyr)Re(CO) 3 Br] were prepared in high yields (94, 84 and 78 % respectively) by reaction with bromotricarbonyl(tetrahydrofuran)rhenium(I) dimer. DFT modelling suggests the anthracenyl moiety is not coplanar with the pyrazolyl-pyrazine fragment, defining a dihedral angle of 65° and 67° for [(pypyr-anthra)Re(CO) 3 Br] and [Br(CO) 3 Re(pypyr-anthra-pypyr)Re(CO) 3 Br] respectively. Each one of the three rhenium(I) molecules shows a quasi-reversible reduction wave around − 1.10 V, assigned by comparison with the uncoordinated ligand, the pypyr fragment, while additional reductions waves related to this core or the anthryl arms are present. UV–Vis spectra show absorption bands and/or shoulders around 400–450 nm for the series of compounds in solution. The respective extinction coefficients (∼4 × 103 M−1cm−1), the sensitivity to solvent polarity and DFT modelling suggest they corresponds to MLCT Re dπ → π (pyr) * transitions. Despite their high emissivity, the uncoordinated ligands completely lose their emission upon coordinated to ReI(CO) 3 Br. The rhenium(I) complexes emit around 650 nm upon excitation, although [(pypyr)Re(CO) 3 Br] is a moderate emissive molecule, while [(pypyr-anthra)Re(CO) 3 Br] and [Br(CO) 3 Re(pypyr-anthra-pypyr)Re(CO) 3 Br] are very weak ones. In contrast these two last molecules showed a remarkably high yield as singlet oxygen sensitizers. [ABSTRACT FROM AUTHOR]

The spectroscopic, electrochemical and photophysical properties of the new complex [ P,N -{(C 6 H 5 ) 2 (C 5 H 4 N)NHP}Re(CO) 3 Br] ( RePNN ) are reported. The UV–Vis spectrum in dichloromethane (DCM) shows an absorption maximum centered at 300 nm and a shoulder at 350 nm. These absorption bands have been characterized, having a π py → π ∗ py and a MLCT character. Excitation at the first wavelength (higher energy) leads to an emission band centered at 365 nm. Cyclic voltammetry shows a fully irreversible oxidation wave around +1.45 V, assigned to Re I /Re II couple, whereas two irreversible reduction signals centered at −0.75 and −1.20 V are assigned to ligand reduction processes. The photophysical results show that emission from the RePNN complex comes exclusively from the ligand. The MLCT excited state shows to be non-emissive by coupling to vibrational modes leading to non-radiative decay path to ground state. The luminescent decay fits to a bi-exponential function. DFT calculations suggest that intra-ligand π py → π ∗ py and π py → π ∗ ph excited states may account for the existence of these two decay lifetimes. The additional –NH– fragment present in the 2-(diphenylphosphinoamino)pyridine ligand compared to 2-pyridylphosphine, makes it more flexible and in consequence, enhances the non-radiative decay rate constant from the 3 MLCT to the ground state in the RePNN complex compared to those of 2-pyridylphosphine, [ P,N -{(C 6 H 5 ) 2 (C 5 H 4 N)PRe(CO) 3 Br] ( RePN ). [ABSTRACT FROM AUTHOR]

• The synthesized Ru(II) complexes reported high conversions in imines hydrogen using the hydrogen transfer reaction as hydrogen source. • The synthesized Ru(II) complexes achieved high conversions in hydrogen transfer reaction to acetophenone. • The electronic, structural, and steric properties of the ligands influence catalytic performance of the synthesized complexes. This work describes the synthesis and characterization of Ru(II) compounds with general formula cis-Cl- cis-P cis-N- RuCl 2 (PN) 2 (where PN represents a heterobidentate PN-donor chelated ligand) and their application as catalysts in the reduction of acetophenone and imines hydrogenation via hydrogen transfer reaction using 2-propanol as the hydrogen source. Single crystal diffraction analysis for all synthesized ruthenium complexes shows non-regular octahedral coordination around the metal. All the synthesized Ru(II) complexes achieved high conversions and turnover frequencies in hydrogen transfer reaction to acetophenone (830 h−1) and imine hydrogenation (760 h−1 for N-benzylideneaniline). The complex (dichloro bis-(8-(diphenylphosphino)quinoline)ruthenium(II)) (RuL2) achieved high conversion in imine hydrogenation, while the complex(dichloro bis-(N-(diphenylphosphino)pyridin-2-amine)ruthenium(II)) (RuL3) showed high conversion in acetophenone reduction. It was found that the electronic, structural, and steric properties of the ligands could influence catalytic performance. [Display omitted] [ABSTRACT FROM AUTHOR]