Synthesis and characterization of ruthenium,rhenium and titanium formate,acetate and trifluoroacetate complexes. Correlation of IR spectral properties and bonding types

New formate (1–3; 4b, 6 and 7), acetate (8, 9) and trifluoroacetate (12, 13 and 15) complexes have been synthesized and characterized by elemental analysis and by IR and ¹H and ¹³C NMR spectroscopies. New data or new synthetic procedures are provided for several known complexes (4a, 5, 19, 11 and 14). X-ray structural data for cis-Ru(bpy)₂(CO)(OCHO)(PO₂F₂) (4b) clearly identify the η¹-bound formate ligand bound to an octahedral ruthenium center and the data for fac-Re(CO)₃(PPh₃(OCOMe) (9) show an η²-bound acetate ligand bound to an octahedral rhenium center. Infrared spectral data for four types of formate complexes, three bonding types of acetates and the two known types of trifluoroacetate ligands are discussed. Comparisons of the v_OCO bands for the carboxylate ligands in all of the complexes show that these bands are useful in identifying the bonding type of each carboxylate ligand.     

Synthesis and characterization of ruthenium and rhenium nucleosides

We report the synthesis and characterization of new ruthenium and rhenium nucleosides [Ru(tolyl-acac)2(IMPy)-T] (tolyl-acac=di(p-methylbenzonatemethane), IMPy=2'-iminomethylpyridine, T=thymidine) (5) and [Re(CO)3(IMPy)-T]Cl (9), respectively. Structural analysis of 9 shows that the incorporation of this metal complex causes minimal perturbation to the sugar backbone and the nucleobase. Eletrochemical (5, E1/2=0.265 V vs NHE; 9, E1/2=1.67 V vs NHE), absorption (5, lambdamax=600, 486 nm; 9, lambdamax=388 nm), and emission (9, lambdamax=770 nm, pi=17 ns) data indicate that 5 and 9 are suitable probes for DNA-mediated ground-state electron-transfer studies. The separation and characterization of diastereoisomers of 5 and bipyridyl-based ruthenium nucleoside [Ru(bpy)2(IMPy)-T]2+ (7) are reported.     

Preparation, characterization and structure of ruthenium phosphine complexes containing non-innocent ligands

Phosphine ruthenate complexes containing the non-innocent ligands 4-chloro-1,2-phenylenediamine (opda-Cl) and 3,3′,4,4′-tetraamminebiphenyl (diopda) were synthesized and characterized by means of X-ray diffraction, electrochemistry, ³¹P{¹H} NMR and electronic spectroscopies. Crystals of cis-[RuCl₂(dppb)(bqdi-Cl)] complex were isolated as a mixture of two conformational isomers due to different positions of the chlorine atoms of the o-phenylene ligand in relation to the P1 atom of the phosphine moiety.     

Preparation, characterization, and catalytic properties of ruthenium nitrosyl complexes with polypyrazolylmethane ligands

Ruthenium(II) nitrosyl complexes with polypyrazolylmethanes, [(Bpm)Ru(NO)Cl₃] [Bpm = bis(1-pyrazolyl)methane, 1], [(Bpm^∗)Ru(NO)Cl₃] [Bpm^∗ = bis(3,5-dimethyl-1-pyrazolyl)methane, 2], [(Tpm)Ru(NO)Cl₂][PF₆] [Tpm = tris(1-pyrazolyl)methane, 3], and [(Tpm^∗)Ru(NO)Cl₂][PF₆] [Tpm^∗ = tris(3,5-dimethyl-1-pyrazolyl)methane, 4], have been synthesized and characterized. The solid-state structures of [(Bpm^∗)Ru(NO)Cl₃] (2) and [(Tpm^∗)Ru(NO)Cl₂][PF₆] (4) were determined by single-crystal X-ray crystallographic analyses. These complexes have been tested as catalysts in the transfer hydrogenation of several ketones under mild conditions.     

Synthesis, characterization and photophysics of alkyne bridged bimetallic rhenium(I) and ruthenium(II) complexes

Six new homobimetallic and heterobimetallic complexes of rhenium(I) and ruthenium(II) bridged by ethynylene spacer [(CO)₃(bpy)Re(BL)Re(bpy)(CO)₃]²⁺ [Cl(bpy)₂Ru(BL)Ru(bpy)₂Cl]²⁺ and [(CO)₃(bpy)Re(BL)Ru(bpy)₂Cl]²⁺ (bpy = 2,2′-bipyridine, BL = 1,2-bis(4-pyridyl)acetylene (bpa) and 1,4-bis(4-pyridyl)butadiyne (bpb) are synthesized and characterized. The electrochemical and photophysical properties of all the complexes show a weak interaction between two metal centers in heterobimetallic complexes. The excited state lifetime of the complexes is increased upon introduction of ethynylene spacer and the transient spectra show that this is due to delocalization of electron in the bridging ligand. Also, intramolecular energy transfer from *Re(I) to Ru(II) in Re–Ru heterobimetallic complexes occurs with a rate constant 4 × 10⁷ s⁻¹.     

Phosphinic complexes of rhenium and tungsten in reactions with stereoindicators

Stereoindicators (cis-4,4′-dimethoxystilbene (DMS) or cis-α,β-dinitrostilbene (DNS)) were used to investigate the donor/acceptor properties of the complexes trans-[ReCl(N₂)(dppe)₂] or trans-[W(CO)₄(dppe)]. The former induced cis/trans conversion of DMS, and the latter cis/trans conversion of DNS, both resulting from charge transfer (in the first case from DMS to the rhenium complex and, in the second case, from the tungsten cofnplex to DNS). The rhenium complex acts as an acceptor, and the tungsten complex as a donor in the framework of the stereoindicator approach.     

Synthesis,characterization and reactivity of some rhenium phosphite complexes

The preparation and characterization of some Re(III), Re(IV) and Re(V) chloro phosphite complexes are reported. Both Re(III) and Re(IV) complexes react with sodium borohydride, yielding the corresponding polyhydrides, ReH₅[P(OEt)₃]₃ and ReH₇[P(OEt)₃]₂. The thermal and photochemical reactivity of these complexes is described.     

Metathetical reactions of carbonylate anions with dichlororuthenium complexes: Preparation and characterization of ruthenium—molybdenum and ruthenium—manganese complexes

The possibility of making metal—metal bonded heterobimetallic species by metathesis of ruthenium dichlorides with anionic carbonylates is demonstrated by the isolation of MoRu(μ-Cl)(μ-CO)(CO)₂(PPh₃)₂(η-C₅H₅) (1) and MnRuCl(μ-CO)₂(CO)₃(μ-dppm)₂ (2), obtained by action of [Mo(CO)₃(η-C₅H₅]^? on RuCl₂(PPh₃)₃ and of Mn(CO)₅^? on RuCl₂(dppm)₂, respectively. In contrast, reaction of Mn(CO)₅^? with RuCl₂(PMe₃)₄ yielded an ionic species 3 containing the diruthenium cation Ru₂Cl₃(PMe₃)₆⁺. More interestingly, the action of Mn(CO)₅^? on RuCl₂(PPh₃)₃ resulted in the formation of the unexpected complex MnRu(μ-PPh₂)(CO)₆(PPh₃)₂ (4) in which the phosphido group PPh₂ bridges the two metals; this process is shown to involve a hydride intermediate, and elimination of a molecule of benzene, both identified in the reaction mixture.     

Preparation and structural characterization of tetracoordinated tungsten(II) diazadiene complexes

Reduction in situ of WCl₄(MeCN)₂ with zinc in the presence of diazadiene ligands 1b-f is reported and produces a series of diamagnetic complexes (DAD)WCl₂2b-f. All complexes were characterized by ¹H, ¹³C NMR and IR spectroscopic data. The crystal structures of complexes 2b and 2e were solved by X-ray diffraction methods.     

Synthesis and characterization of ruthenium heterocyclic-thiocarboxylate complexes

The cyclopentadienyl ruthenium complexes CpRuL₂SCO-het (Cp = η⁵-C₅H₅; L₂ = 2PPh₃ (1), dppe (2)) bearing heterocyclic thiocarboxylate ligands have been synthesized from the reaction of CpRuL₂SH with heterocyclic acid chlorides (ClCO-2-C₄H₃S (a); ClCO-2-C₄H₃O (b); ClCO-1-C₄H₈N (c)). Bubbling of CO gas through a THF solution of (1) produced the mixed carbonyl–phosphine complexes CpRu(PPh₃)(CO)SCO-het (3) with high yields. Complexes (1)-(3) were characterized by spectroscopic methods (i.r., ¹H-n.m.r., ³¹P-n.m.r.) and elemental analysis. The molecular structure of CpRu(PPh₃)₂SCO-2-C₄H₃S (1a) verifies that the thiocarboxylate ligands bind via the sulfur atom (Ru–S = 2.406(2) Å).     

Preparation, structure characterization, and oxidation activity of ruthenium complexes with tripodal ligands bearing noncovalent interaction sites

Ruthenium(II/III) complexes with tripodal tris(pyridylmethyl)amine ligands bearing one, two, or three pivalamide groups (MPPA, BPPA, TPPA: amide-series ligands) or neopentylamine ones (MNPA, BNPA, TNPA: amine-series ligands) at the 6-position of the pyridine ring have been synthesized and structurally characterized. The X-ray structure analyses of the single crystals of these complexes reveal that they complete an octahedral geometry with the tripodal ligand and some monodentate ligands. The amide-series ligands prefer to form a Ru(II) complex, while the amine-series ones give a Ru(III) complex. In the presence of PhIO oxidant, the catalytic activities for epoxidation of olefins, hydroxylation of alkane, and dehydrogenation of alcohol have been investigated using the six ruthenium complexes [Ru(II)(tppa)Cl(2)] (1), [Ru(III)(tnpa)Cl(2)]PF(6) (2), [Ru(II)(bppa)Cl]PF(6) (3), [Ru(III)(bnpa)Cl(2)]PF(6) (4), [Ru(II)(mppa)Cl]PF(6) (5), and [Ru(III)(mnpa)Cl(2)]PF(6) (6). Among them, the amide-series complexes, 1, 3, and 5, showed a higher epoxidation activity in comparison with the amine-series ones, 2, 4, and 6. On the other hand, the latter showed a higher reactivity for hydroxylation, allylic oxidation, and C=C bond cleavage reactions compared with the former. Such a complementary reactivity is interpreted by the character of the ruthenium-oxo species involving electronically equivalent formulas, Ru(V)=O and Ru(IV)-O.     

Synthesis,characterization, and properties of conjugated binuclear bis-terpyridyl ruthenium complexes

A series of binuclear bis-terpyridyl ruthenium complexes with different substituents were synthesized and characterized by physico-chemical and spectroscopic methods. The UV/Vis and fluorescence spectra indicated that the non-substituted binuclear bis(terpyridyl) ruthenium(II) complex has similar properties to those with electron-donating groups such as methyl and alkoxyl on the organic conjugated bridge units. Furthermore, similar oxidation–reduction potentials were observed according to their electrochemical properties in CH₂Cl₂ solution.     

Haloalkyl complexes of the transition metals : II. Some new chloromethyl and methoxymethyl complexes of manganese,rhenium and ruthenium

The reactions of Na[Mn(CO)₅] or Na[Mn(CO)₄(PPh₃)] with CH₂ClI yield the new chloromethyl complexes Mn(CO)₅CH₂Cl and Mn(CO)₄(PPh₃)CH₂Cl. Reaction of Na[Re(CO)₅] or Na[CpRu(CO)₂] with ClCH₂OMe yields Re(CO)₅CH₂Cl and CpRu(CO)₂CH₂Cl respectively, in addition to the corresponding methoxymethyl complexes (Cp = η⁵-C₅H₅). Reaction of CpRu(CO)₂CH₂OMe with HCl yields the corresponding chloromethyl complex.     

Synthesis and characterization of rhenium carbonyltrifluoroacetate complexes with phosphites,phosphonites and phosphinites

The rhenium(I) complexes [Re(O₂CCF₃)(CO)₃(L)] (1) and [Re(O₂CCF₃)(CO)₂LL′] (L = Ph₂POCH₂CH₂OPPh₂; L′ = PPh_n(OR)_3−n; R = Me, Et; n = 0–2) (2a–f) have been synthesised by the reaction of the parent bromo derivatives with AgO₂CCF₃. These compounds have been characterized by microanalysis, IR, NMR, mass spectrometry and, in the cases of 1 and 2a, by X-ray diffraction. The metal is in a distorted octahedral environment with the trifluoroacetate ligand acting in a monodentate manner.     

Synthesis,characterization, and antitumor activity of mononuclear and dinuclear ruthenium complexes

Abstract

Dinuclear ruthenium complexes [Ru₂(bpy)₄BL](ClO₄)₂ (Ru-1), where bpy = 2,2′-bipyridine and BL = 2,2′-((1E,1′E)-((E)-diazene-1,2-diyl-bis(2,1-phenylene))-bis(azanylylidene))bis(methanylylidene))diphenol (a bidentate bridging ligand), and mononuclear ruthenium complexes [Ru(bpy)₂L](ClO₄) (Ru-2), where L = (E)-2-((phenylimino)methyl)phenol, were synthesized and characterized by elemental analysis and electrospray ionization mass spectrometry. Their photophysical and electrochemical properties were also studied. The cytotoxicity of the two complexes in vitro was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The results indicated that Ru-1 and Ru-2 exhibited significant dose-dependent cytotoxicity to human breast cancer (MCF-7), gastric cancer (SGC-7901), cervical cancer (Hela), and lung cancer (A549) tumor cell lines. Ru-1 showed excellent antitumor effects in a cellular study (IC₅₀ values of 3.61 μM for MCF-7 human breast cancer cells in vitro). However, Ru-2 exhibited the highest cytotoxicity to Hela cells; the IC₅₀ value is 3.71 μM. The results reveal that Ru-1 and Ru-2 have obvious selectivity and might be a potential anticancer agent that could improve the efficacy of common anticancer therapies.     

Synthesis, characterization, and electrochemistry of biorelevant photosensitive low-potential orthometalated ruthenium complexes

Redox potentials of photosensitive cyclometalated RuII derivatives of 2-phenylpyridine or 2-(4-tolyl)pyridine are controllably decreased by up to 0.8 V within several minutes. This is achieved by irradiation of the ruthena(II)cycles cis-[Ru(o-X-2-py)(LL)(MeCN)2]PF6 (2, X = C6H4 (a) or 4-MeC6H3 (b), LL = 1,10-phenanthroline or 2,2'-bipyridine). The cis geometry of the MeCN ligands has been confirmed by the X-ray structural studies. The sigma-bound sp2 carbon of the metalated ring is trans to LL nitrogen. Complexes 2 are made from [Ru(o-X-2-py)(MeCN)4]PF6 (1) and LL. This "trivial" ligand substitution is unusual because 1a reacts readily with phen in MeCN as solvent to give cis-[Ru(o-C6H4-2-py)(phen)(MeCN)2]PF6 (2c) in a 83% yield, but bpy does not afford the bpy-containing 2 under the same conditions. cis-[Ru(o-C6H4-2-py)(bpy)(MeCN)2]PF6 (2e) has been prepared in CH2Cl2 (74%). Studies of complexes 2c,e by cyclic voltammetry in MeOH in the dark reveal RuII/III quasy-reversible redox features at 573 and 578 mV (vs Ag/AgCl), respectively. A minute irradiation 2c and 2e converts them into new species with redox potentials of -230 and 270 mV, respectively. An exceptional potential drop for 2c is accounted for in terms of a photosubstitution of both MeCN ligands by methanol. ESR, 1H NMR, and UV-vis data indicate that the primary product of photolysis of 2c is an octahedral monomeric low-spin (S = 1/2) RuIII species, presumably cis-[RuIII(o-C6H4-2-py)(phen)(MeOH)2]2+. The primary photoproduct of bpy complex 2e is cis-[RuII(o-C6H4-2-py)(bpy)(MeCN)(MeOH)]+, and this accounts for a lower decrease in the redox potential. Irradiation of 2c in the presence of added chloride affords [(phen)(o-C6H4-2-py)ClRuIIIORuIVCl(o-C6H4-2-py)(phen)]PF6, a first mu-oxo-bridged mixed valent dimer with a cyclometalated unit. The structure of the dimer has been established by X-ray crystallography.     

Preparation and protonation reactions of aryl complexes of manganese and rhenium

Aryl M(κ¹-Ar)(CO)_nP_5−n [M = Mn, Re; Ar = C₆H₅, 4-CH₃C₆H₄; n = 2, 3; P = P(OEt)₃, PPh(OEt)₂, PPh₂OEt] and Re(κ¹-C₆H₅)(CO)₃[Ph₂PO(CH₂)₃OPPh₂] complexes were prepared by allowing hydrides MH(CO)_nP_5−n to react first with triflic acid and then with the appropriate aryl lithium (LiAr) compounds. The complexes were characterized spectroscopically (IR and ¹H, ³¹P, ¹³C NMR) and by the X-ray crystal structure determination of Re(κ¹-C₆H₅)(CO)₃[Ph₂PO(CH₂)₃OPPh₂] derivative. Protonation reaction of the aryl complexes with HBF₄ · Et₂O lead to free hydrocarbons Ar-H and the unsaturated [M(CO)_nP_5−n]⁺ cations, separated as solids in the case of [Re(CO)₃P₂]BF₄ derivatives.     

Half-sandwich ruthenium complexes with Schiff base ligands bearing a hydroxyl group: Preparation,characterization and catalytic activities

Three half-sandwich ruthenium(II) complexes with hydroxyl group functionalized Schiff-base ligands [Ru(p-cymene)LCl] ( 2a-2c ) have been synthesized and characterized. All ruthenium complexes were fully characterized by ¹H and ¹³C NMR spectra, mass spectrometry and infrared spectrometry. The molecular structure of ruthenium complex 2c was confirmed by single-crystal X-ray diffraction methods. Furthermore, these half-sandwich ruthenium complexes were found to exhibit high catalytic activity for nitro compounds reduction using NaBH₄ reducing agent in the presence of cetyltrimethylammonium bromide (CTAB) in water at room temperature.     

Preparation and characterization of oxoperoxo tungsten(VI) complexes with morpholinomethyl urea and related ligands

The monooxodiperoxo complexes of tungsten(VI) of the type [WO(O₂)₂ L-L] (where L-L = morpholinomethyl urea, morpholinomethyl thiourea, piperidinomethyl urea, piperidinomethyl thiourea, pyrrolidinomethyl urea, and pyrrolidinomethy thiourea) have been synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility, and conductivity measurements, in addition to TGA/DTA. The energy-minimized structures of these complexes have been obtained by molecular modeling using Hyperchem release 7.52. The text was submitted by the authors in English.     

Ruthenium titanocene and ruthenium titanium half-sandwich bimetallic complexes in catalytic cyclopropanation

The reaction of the phosphine functionalised titanium half-sandwich complexes 7, 9 and 10 with the binuclear complex [(p-cymene)RuCl₂]₂ allowed the access to three new early-late bimetallic complexes (p-cymene)[(μ-η⁵:η¹-C₅H₄(CH₂)_nPR₂)TiX₃]RuCl₂ (11-13). The structure of 11 (n = 0, X = Cl) has been confirmed by X-ray diffraction. The ruthenium titanium half-sandwich bimetallic complexes so formed and the ruthenium titanocene analogues 4-6 catalyse the addition of ethyl diazoacetate to styrene with high selectivity toward cyclopropanation versus metathesis contrary to the monometallic complexes (p-cymene)RuCl₂PR₃.