Optical activity of dimolybdenum complex induced by chiral,chelating diamine ligand; syntheses and structures of [Mo2(O2CCF3)2(S,S-dach)2(CH3CN)2][BF4]2 and [Mo2(O2CCF3)2(R,R-dach)2(CH3CN)2][BF4]2 (dach=1,2-diaminocyclohexane)

The first structurally characterized, quadruply bonded complexes containing chiral diamine ligands, [Mo₂(O₂CCF₃)₂(S,S-dach)₂(CH₃CN)₂][BF₄]₂ (1), and [Mo₂(O₂CCF₃)₂(R,R-dach)₂(CH₃CN)₂][BF₄]₂ (2); (dach=1,2-diaminocyclohexane) were prepared by reactions of [Mo₂(O₂CCF₃)₂(CH₃CN)₆][BF₄]₂ with S,S-dach and R,R-dach, respectively, in CH₃CN. Their UV–Vis and circular dichroism (CD) spectra have been recorded and their structures determined by X-ray crystallography. Crystals of complexes 1 and 2 conform to the space groups P2 with two independent half molecules in the asymmetric unit. The two molecules have a similar structure consisting of a Mo₂ unit bridged by two cis-trifluoroacetate ligands and chelated by two dach ligands. Two acetonitrile molecules are coordinated to the Mo centers along the MoMo bond. The absorption wavelength at 507 nm for both 1 and 2 can be assigned to δ_xy→δ_xy* transitions. The solution CD spectra of these two complexes show two prominent bands at 525 and 385 nm and form mirror images of each other. The solid CD spectra of complexes 1 and 2 show marked red-shift in the absorption energies as compared with those measured in solution. The one-electron static coupling mechanism was invoked to explain the CD spectra for these complexes and the second lowest energy bands were assigned to be δ_xy→δ_x²−y² transitions.     

Electrochemical behavior of S,S-bridged adducts of square planar metalladithiolene complexes [M(S2C2Ph2)2](M=Ni, Pd, and Pt)

The electrochemical behavior of the S,S^′-bridged adducts of square planar metalladithiolene complexes was investigated by using cyclic voltammetry and electrochemical spectroscopies (visible, near-IR, and ESR). The norbornene-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(C₇H₈)] (2a; C₇H₈=norbornene) formed by [Ni(S₂C₂Ph₂)₂] (1a) and quadricyclane (Q) was dissociated by an electrochemical reduction, and anion 1a⁻ and norbornadiene (NBD) were formed. Q was isomerized to NBD in the overall reaction. The o-xylyl-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(CH₂)₂(C₆H₄)] (3a; (CH₂)₂(C₆H₄)=o-xylyl) was also dissociated by an electrochemical reduction, and this reaction gave the o-xylyl radical (o-quinodimethane). The reduction of complex 3a in the presence of excess o-xylylene dibromide underwent the catalytic formation of o-quinodimethane. The butylene-bridged S,S^′-adduct [Ni(S₂C₂Ph₂)₂(CH₂)₄] (4a; (CH₂)₄=butylene) was stable on an electrochemical reduction. The lifetimes of reduced species of these adducts 2a-4a were influenced by the stability of the eliminated group (stability: NBD > o-xylyl radical (o-quinodimethane) > butylene radical). Therefore, the reduced species are stable in the sequence 4a⁻ > 3a⁻ > 2a⁻. Although the palladium complex [Pd(S₂C₂Ph₂)₂] (1b) was easier to reduce than the nickel complex 1a or the platinum complex [Pt(S₂C₂Ph₂)₂] (1c), their S,S^′-adducts were easier to reduce in the order of Ni adduct > Pd adduct > Pt adduct.     

The synthesis and reaction kinetics of some Co(IIl) and Cr(III) chloro complexes of 1,4,8-Triazaoctane (2,3-tri) and the isolation of chiral trans-dichloro [CoCl2(NH3)(2,3-tri)] ClO4

The reaction of 2,3-tri with CrCl₃·6H₂O₁, dehydrated in boiling DMF, results in the formation of mer-CrCl₃(2,3-tri) and anation of hydrolysed solutions of mer-MCl₃(2,3,-tri) (M=Co, Cr) with 6 M HCl containing HClO₄, forms trans-dichloro- mer-[MCl₂(2,3-tri)(OH₂)]ClO₄·H₂O (M=Cr, Co; I, II). trans-Dinitro-mer-[Co(NO₂)₂(NH₃)(2,3-tri)] ClO₄ crystallises from the reaction between mer-Co(NO₂)₃(2,3-tri) and aqueous 7 M ammonia, on addition of NaClO₄·H₂O, and trans-dichloro-mer-[CoCl₂(NH₃)(2,3-tri)]ClO₄ (III) can be isolated by treatment of the dinitro with 12 M HCl. Reaction of mer-CoCl₃(2,3-tri) with C₂O₄₂⁻, followed by addition of aqueous NH₃ and NaClO₄·H₂O results in the isolation of racemic mer-[Co(ox)(NH₃)(2,3-tri)]ClO₄· H₂O. This complex was resolved into its enantiomeric forms and treatment of these with SOCl₂/MeOH/ HClO₄ gave the chiral forms of trans-dichloro-mer- [CoCl₂(NH₃)(2,3-tri)]ClO₄ (R or S at the see-NH center). The rates of loss of the first chloro ligand from these dichloro complexes have been measured spectrophotometrically in 0.1 M HNO₃ over a 15 K temperature range to give the following kinetic parameters; (I) k_H(298)=7.25 × 10⁻⁵ s⁻¹, E_a=78.5 kJ mol⁻¹, δS₂₉₈^#=₋69 J K⁻¹ mol⁻¹; (II) k_H(298)=4.00 × 10⁻³ s⁻¹, E_a=89.9, δS₂₉₈^#= +87.5; (III) k_H(298)=3.09 × 10⁻⁴ s⁻¹, E_a=103, δS₂₉₈^#=+27. Treatment of the dichloro cations with Hg²⁺/HNO₃ results in the generation of mer- M(2,3-tri)(OH₂)₃³⁺ (M=Cr, Co; IV, V) and trans- diaqua-mer-Co(NH₃)(2,3-tri)(OH₂)₂³⁺ (VI). The Co(III) cations isomerise to the fac configuration with (V) K_isom(298) μ=1.0 M)=2.97 × 10⁻⁵ s⁻¹, E_a=115, δS₂₉₈^#=+46. (VI) K_isom(298) (μ=1.0 M)=4.13 × 10⁻⁵ s⁻¹, E_a=113, δS₂₉₈^#=+52.     

The structure of a dinuclear silver(I) complex: Ag2[S2C2(CN)2] [P(C6H5)3]4

The crystal structure of the dimeric Ag maleonitriledithiolate complex, Ag₂[S₂C₂(CN)₂] [P(C₆- H₅)₃]₄ (1), has been performed. Complex 1 crystallizes in the space group P2₁/c with a = 12.2898(77), b = 23.8325(91), c = 23.1790(118) Å, β = 101.315(43)° and Z = 4. Refinement using 3253 reflections with F_o²>3σ(F_o²) yielded R = 0.0662, R_w= 0.0669. The most interesting aspect of the structure is the strong bridging interaction of the chelating maleonitriledithiolate ligand with the second Ag center, where a Ag-S distance of 2.478 Å is observed. The residual bonding capability of the sulfur atoms in the chelating anion [Ag(S₂C₂(CN)₂)(PPh₃)₂]⁻ for [Ag(PPh₃)₂]⁺ is demonstrated.     

A dithiocarbamate-stabilized copper(I) cube

The disproportionation reaction between the copper(II) complexes, Cu(ClO₄)₂ · 6H₂O and [Cu(S₂CNR₂)₂] is a well-established route to copper(III) complexes [Cu(S₂CNR₂)₂][ClO₄] but to date the nature of the copper(I) species generated has remained a mystery. We now show that with [Cu(S₂CNPr₂)₂] this is the copper(I) cluster, [Cu₈(μ²,μ²-S₂CNPr₂)₆][ClO₄]₂, which contains a cubic array of copper atoms, each face cube being capped by a dithiocarbamate ligand such that the sulfur atoms define an icosahedron and the backbone carbons an octahedron around the cube centroid. A crystal structure of [Cu₄(μ²,η¹-S₂CNBu₂)₄] is also presented for comparison.     

Magnetic circular dichroism studies on monomeric and dimeric iron—sulfur complexes

Magnetic Circular dichroism (MCD) spectra were obtained for bis(o-xylyl-dithiolato)ferrate(III) ([Fe(S₂-o-xylyl)₂]⁻) and bis[o-xylyl-dithiolato-μ₂-sulfidoferrate(III)] ([Fe₂S^*₂(S₂-o-xylyl)₂]²⁻) ions. The MCD magnitude of the dimeric [Fe₂S^*₂(S₂-o-xylyl)₂]²⁻ ion was found to be only one half of that for the monomeric [Fe(S₂-o-xylyl)₂]⁻ ion. The difference in MCD magnitudes was attributed to the change in the thermal populations of ground state sublevels derived from the magnetic exchange interaction.     

Synthesis,EPR, electrochemistry and EXAFS studies of ruthenium(III) complexes with a symmetrical tetradentate N2O2 Schiff base

A series of new hexa-coordinated ruthenium(III) complexes of the type [RuX(Nap-o-phd)(EPh₃)] (where, H₂-Nap-o-phd = N,N′-bis(2-hydroxy-1-naphthaldehyde) o-phenylene diamine; X = Cl or Br; E = P or As) have been prepared by reacting [RuX₃(EPh₃)₃] and [RuBr₃(PPh₃)₂(MeOH)] (where X = Cl or Br; E = P or As) with tetradentate Schiff base ligand (H₂-Nap-o-phd) in 1:1 molar ratio. The complexes have been characterized by elemental analyses, infra red, electronic, electron paramagnetic resonance spectroscopy and cyclic voltammetry. The coordination geometry and structure of the complexes have been investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy and an octahedral structure has been proposed.     

Copper-thioarylazoimidazole complexes: Structures, photochromism and redox interconversion between Cu(II) ↔ Cu(I) and correlation with DFT calculation

Reaction of Cu(ClO₄)₂·6H₂O, SRaaiNR′ (1-alkyl-2-[(o-thioalkyl)phenylazo]imidazole) and NH₄SCN (1:1:2 mol ratio) affords distorted square pyramidal, [Cu^II(SRaaiNR′)(SCN)₂] (3) compound while identical reaction with [Cu(MeCN)₄](ClO₄) yields -SCN- bridged coordination polymer, [Cu^I(SRaaiNR′)(SCN)]_n (4). These two redox states [Cu^II and Cu^I] are interconvertible; reduction of [Cu^II(SRaaiNR′)(SCN)₂] by ascorbic acid yields [Cu^I(SRaaiNR′)(SCN)]_n while the oxidation of [Cu^I(SRaaiNR′)(SCN)]_n by H₂O₂ in presence of excess NH₄SCN affords [Cu^II(SRaaiNR′)(SCN)₂]. They are structurally confirmed by single crystal X-ray diffraction study. Cyclic voltammogram of the complexes show Cu(II)/Cu(I) redox couple at ∼0.4 V and azo reductions at negative to SCE. UV light irradiation in MeCN solution of [Cu^I(SRaaiNR′)(SCN)]_n (4) show trans-to-cis isomerisation of coordinated azoimidazole. The reverse transformation, cis-to-trans, is very slow with visible light irradiation while the process is thermally accessible. Quantum yields (?_t→c) of trans-to-cis isomerisation are calculated and free ligands show higher ? than their Cu(I) complexes. The activation energy (E_a) of cis-to-trans isomerisation is calculated by controlled temperature experiment. Copper(II) complexes, 3, do not show photochromism. DFT and TDDFT calculation of representative complexes have been used to determine the composition and energy of molecular levels and results have been used to explain the solution spectra, photochromism and redox properties of the complexes.     

Chromium(III) complexes with 1,5,9-triazanonane (3,3-tri) - CrX3(3,3-tri)n+ and CrCl(diamine)(3,3-tri)2+

The reaction of CrCl₃ · 6H₂O (dehydrated in DMSO) with 1,5,9-triazanonane (3,3-tri) gives mer- CrCl₃(3,3-tri), the configuration being established by isomorphism with the corresponding Co(III) complex. This non-electrolyte is hydrolyzed in aqueous acidic solution and mer-[CrCl₂(3,3-tri)- (OH₂)]ClO₄ can be isolated by anation with HCl in the presence of HClO₄. Reaction of mer-CrCl₃- (3,3-tri) in DMF with diamines produces complexes of the type [CrCl(diamine)(3,3-tri)] Cl₂ [diamine= 1,2-diaminoethane (en), 1.2-diaminopropane (pn), 1,3-diaminopropane (tn), 2,2-dimethyl-1,3-diaminopropane (Me₂tn) and cyclohexanediamine (chxn, cis plus trans mixture; two isomers A and B)] and these have been characterized as the ZnCl₄²⁻ salts. The configuration of the triamine ligand in these complexes has been established as mer-(H↓)- by a single crystal X-ray analysis of [CrCl(en)(3,3-tri)]- ZnCl₄, monoclinic, P2₁, a=7.932, b= 14.711, c= 8.312 Å, β=104.6° and Z=2, refined to a conventional R factor of 0.034. The kinetics of the Hg²⁺- assisted chloride release from [CrCl(diamine)(3,3- tri)]ZnCl₄ salts were measured spectrophotometrically (μ=1.0 M HClO₄ or HNO₃) over 15 K temperature ranges to give, in order, 10⁴k_Hg (298.2 K) (M⁻¹ s⁻¹), E_a(kJ mol⁻¹), ΔS^# (J K⁻¹ mol⁻¹): en- (HClO₄): 5.95, 78.1, -53; pn(HClO₄); 5.24, 81.2; -44; tn(HClO₄): 26.7, 85.6, -15; Me₂tn(HClO₄): 21.8, 78.6, -40; A-chxn(HNO₃): 7.60, 81.0,-41; B-chxn(HNO₃): 18.3, 56.8, -115. A ‘non-replaced ligand effect’ on the rate is observed for the first time in this series of homologous Cr(III) complexes. The kinetics of the thermal aquation (k_H, 0.1 M HClO₄) were measured titrimetrically for CrCl(diamine) (3,3-tri)²⁺ to give the following kinetic parameters: diamine=en: 10⁷ k_H (298.2)=5.34 s⁻¹, E_a=99.2 kJ mol⁻¹, ΔS^#=-40 J K⁻¹ mol^-1; diamine =tn: 10⁷ k_H (298.2)=5.04 s⁻¹, E_a= 82.8, ΔS^#= -96.     

Complexes of N-thiophosphorylthioureas RNHC(S)NHP(S)(OiPr)2 (HL) (R = pyridin-2-yl, pyridin-3-yl, 6-amino-pyridin-2-yl) with copper(I): Crystal structures of Cu(PPh3)nL (n = 1, 2)

Reaction of the potassium salts of N-thiophosphorylated thioureas of common formula RNHC(S)NHP(S)(OiPr)₂ [R = pyridin-2-yl (HL^a), pyridin-3-yl (HL^b), 6-amino-pyridin-2-yl (HL^c)] with Cu(PPh₃)₃I in aqueous EtOH/CH₂Cl₂ leads to mononuclear [Cu(PPh₃)₂L^a,b-S,S′] (1, 2) and [Cu(PPh₃)L^c-S,S′] (3) complexes. Using copper(I) iodide instead of Cu(PPh₃)₃I, polynuclear complexes [Cu_n(L-S,S′)_n] (4-6) were obtained. The structures of these compounds were investigated by IR, ¹H, ³¹P{¹H} NMR spectroscopy, ES-MS and elemental analyses. The crystal structures of Cu(PPh₃)₂L^b (2) and Cu(PPh₃)L^c (3) were determined by single-crystal X-ray diffraction.     

The rate of reduction of cis-, cis-, trans-[PtIV(NH2Pri)2Cl2(OH)2], CHIP,the anti-cancer drug by ascorbic acid

cis,cis,trans-[Pt^IV(NH₃)₂Cl₂(OH)₂] reacts reversibly with ascorbic acid to give dehydroascorbic acid and mainly cis-[Pt^II(NH₂Prⁱ)₂Cl₂]. The parameters for the forward reaction are: k_f = 0.584 M⁻ s⁻ at 37.0 °C, ΔH^≠_f = 108.6 −+ 6.4 kJ mol⁻¹ andΔS^≠_f = 101 −+ 22 J K⁻¹ mol⁻¹.     

Homogeneous green catalysts for olefin oxidation by mono oxovanadium(V) complexes of hydrazone Schiff base ligands

Three mono oxovanadium(V) complexes of tridentate Schiff base ligands [VO(OMe)L¹] (1), [VO(OMe)L²] (2) and [VO(OMe)L³] (3) obtained by monocondensation of 3-hydroxy-2-naphthohydrazide and aromatic o-hydroxyaldehydes have been synthesized (H₂L¹ = (E)-3-hydroxy-N′-(2-hydroxy-3-methoxybenzylidene)-2-naphthohydrazide, H₂L² = (E)-3-hydroxy-N′-(2-hydroxybenzylidene)-2-naphthohydrazide and H₂L³ = (E)-N′-(5-bromo-2-hydroxybenzylidene)-3-hydroxy-2-naphthohydrazide). The complexes were characterized by spectroscopic methods in the solid state (IR) and in solution (UV-Vis, ¹H NMR). Single crystal X-ray analyses were performed with 1 and 2. The catalytic potential of these complexes has been tested for the oxidation of cyclooctene using H₂O₂ as the terminal oxidant. The effects of various parameters including the molar ratio of oxidant to substrate, the temperature, and the solvent have been studied. The catalyst 2 showed the most powerful catalytic activity in oxidation of various terminal, cyclic and phenyl substituted olefins. Excellent conversions have been obtained for the oxidation of cyclic and bicyclic olefins.     

Synthesis,structures and urease inhibitory activity of cobalt(III) complexes with Schiff bases

A series of new cobalt(III) complexes were prepared. They are [CoL¹(py)₃]·NO₃ (1), [CoL²(bipy)(N₃)]·CH₃OH (2), [CoL³(HL³)(N₃)]·NO₃ (3), and [CoL⁴(MeOH)(N₃)] (4), where L¹, L², L³ and L⁴ are the deprotonated form of N′-(2-hydroxy-5-methoxybenzylidene)-3-methylbenzohydrazide, N′-(2-hydroxybenzylidene)-3-hydroxylbenzohydrazide, 2-[(2-dimethylaminoethylimino)methyl]-4-methylphenol, and N,N′-bis(5-methylsalicylidene)-o-phenylenediamine, respectively, py is pyridine, and bipy is 2,2′-bipyridine. The complexes were characterized by infrared and UV–Vis spectra, and single crystal X-ray diffraction. The Co atoms in the complexes are in octahedral coordination. Complexes 1 and 4 show effective urease inhibitory activities, with IC₅₀ values of 4.27 and 0.35 μmol L⁻¹, respectively. Complex 2 has medium activity against urease, with IC₅₀ value of 68.7 μmol L⁻¹. While complex 3 has no activity against urease. Molecular docking study of the complexes with Helicobacter pylori urease was performed.     

Ruthenium-modified proteins. Reactions of cis-[ Ru(NH3)4(OH2)2]2+ and cis-[ Ru(en)2(OH2)2]2+ with azurin,myoglobin and cytochrome c

Reactions of cis-[Ru(en)₂(OH₂)₂]²⁺ (or cis-[Ru (NH₃)₄(OH₂)₂]²⁺) with Pseudomonas aeruginosa azurin (Az), horse heart myoglobin (Mb^h), and horse heart cytochrome c (cyt c) give Ru-labelled proteins. The ruthenium binding sites in the singly modified derivatives are His-83 (Az), His-81 (Mb^h), and His-33 (cyt c). Spectroscopic and electrochemical measurements indicate that the structures of the proteins are not perturbed by the surface-bound ruthenium complexes. The E°_f values of the Ru(III)/(II) couple in these Ru-modified proteins fall between −0.07 and −0.13 V vs. NHE.     

Unusual ligand design: A platinum(II) mediated [2+2] photocycloaddition followed by a nickel(II) induced methoxyactivation

The novel dimer of the composition [Pt₂Cl₄(μ-(κP¹:κP²-o-MeO-trans-dppen))₂] (1) (o-MeO-trans-dppen = 1,2-(bis(o-methoxyphenyl)phosphanyl)ethylene) has been prepared and characterized by a single crystal X-ray structure analysis, NMR spectroscopy, mass spectrometry and elemental analysis. This latter compound undergoes a [2+2] photocycloaddition reaction yielding the tetraphosphane all-trans-1,2,3,4-tetrakis(di(o-methoxyphenyl)phosphanyl)cyclobutane (o-MeO-dppcb). The X-ray structure of the dimeric Ni(II) complex that contains the latter ligand, of the formula [Ni₂Cl₄(μ-(κP¹:κP²:κP³:κP⁴-o-MeO-dppcb))] (2) reveals that the apical coordination sites of both square pyramidal Ni(II) coordination spheres are occupied by methoxy-oxygen atoms of the ligand. As a consequence, this dimeric Ni(II) complex 2 is prone to a thermally induced regio- and diastereoselective metal-assisted methoxy-group cleavage. The stepwise formed new mono- and bis-phenolate complexes [Ni₂Cl₃(μ-(κO¹,κP¹:κP²:κP³:κP⁴-o-MeO-O-dppcb))] (3) and [Ni₂Cl₂(μ-(κO¹,κP¹:κP²:κO²,κP³:κP⁴-o-MeO-O,O′-dppcb))] (4), respectively, contain the novel chiral tetraphosphane ligands all-trans-1,2,3-tris((di-o-methoxyphenyl)phosphano)-4-((o-methoxy-phenyl)(o-phenolate)phosphano)cyclobutane (o-MeO-O-dppcb) and all-trans-1,2-bis((di-o-methoxyphenyl)phosphano)-3,4-bis((o-methoxyphenyl)(o-phenolate)phosphano)cyclobutane (o-MeO-O,O′-dppcb). Compounds 3 and 4 have been synthesized independently and are also fully characterized by both single crystal X-ray structure analyses, NMR spectroscopy, mass spectrometry and elemental analyses. The conversion of 2 into 3 and then further into 4 has been followed by a variable-temperature ³¹P{¹H} NMR experiment with compound 2 in DMF-d⁷, revealing that the cleavage of the second methoxy group is kinetically disfavoured. This is in agreement with the X-ray structure analysis of 3, indicating the lack of any methoxy-oxygen atom coordination that could easily induce a further methoxy-group cleavage. o-MeO-O-dppcb and o-MeO-O,O′-dppcb are rare P-stereogenic tetraphosphine ligands and contribute to the synthetic field of new κ³-P,P,O-coordinating phosphanylphenolate ligands that are believed to be important for the SHOP process (SHOP, Shell Higher Olefin Process).     

Reactivity of phenyldi(2-thienyl)phosphine towards group 7 metal carbonyls: Carbon-phosphorus bond activation

Addition of phenyldi(2-thienyl)phosphine (PPhTh₂) to [Re₂(CO)_10−n(NCMe)_n] (n = 1, 2) affords the substitution products [Re₂(CO)_10−n(PhPTh₂)_n] (1, 2) together with small amounts of fac-[ClRe(CO)₃(PPhTh₂)₂] (3) (n = 2). Reaction of [Re₂(CO)₁₀] with PPhTh₂ in refluxing xylene affords a mixture which includes 2, [Re₂(CO)₇(PPhTh₂)(μ-PPhTh)(μ-H)] (4), [Re₂(CO)₇(PPhTh₂)(μ-PPhTh)(μ-η¹,κ¹(S)-C₄H₃S)] (5) and mer-[HRe(CO)₃(PPhTh₂)₂] (6). Phosphido-bridged 4 and 5 are formed by the carbon-phosphorus bond cleavage of the coordinated PPhTh₂ ligand, the cleaved thienyl group being retained in the latter. Reaction of [Mn₂(CO)₁₀] with PPhTh₂ in refluxing toluene affords [Mn₂(CO)₉(PPhTh₂)] (7) and the carbon-phosphorus bond cleavage products [Mn₂(CO)₆(μ-PPhTh)(μ-η¹,η⁵-C₄H₃S)] (8) and [Mn₂(CO)₅(PPhTh₂)(μ-PPhTh)(μ-η¹,η⁵-C₄H₃S)] (9). Both 8 and 9 contain a bridging thienyl ligand which is bonded to one manganese atom in a η⁵-fashion.     

Copper(I)-organophosphine complexes of bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand

Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR₃ (PR₃ = P(C₆H₅)₃; P(C₆H₅)₂(4-C₆H₄COOH); P(C₆H₅)₂(2-C₆H₄COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH₂OH)₃, tris(hydroxymethyl)phosphine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS₂]. Mono-nuclear complexes of the type [LCS₂]Cu[PR₃] have been obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹³C and ³¹P) NMR spectral data; in these complexes the ligand behaves as a κ³-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex [LCS₂]Cu[P(CH₂OH)₃]₂, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure of [LCS₂]Cu[P(C₆H₅)₃] has been determined. The [LCS₂]Cu[P(C₆H₅)₃] complex has a pseudo tetrahedral copper site where the bis(3,5-dimethylpyrazolyl)dithioacetate ligand acts as a κ³-N,N,S donor.     

A new hexanuclear rhenium cluster complex with six terminal acetate ligands: Synthesis, structure, and properties of K4[Re6S8(CH3COO)6]·8H2O

A room-temperature reaction between [Re₆S₈(OH)₆]⁴⁻ and acetic acid in an aqueous solution resulted in the substitution of all terminal hydroxo groups by acetate ligands, affording a new hexanuclear anionic rhenium cluster complex [Re₆S₈(CH₃COO)₆]⁴⁻. The complex was isolated as a potassium salt with the composition of K₄[Re₆S₈(CH₃COO)₆]·8H₂O (1) and characterized by X-ray single-crystal diffraction and elemental analyses, IR, ¹H NMR, UV-Vis, and luminescence spectroscopies.     

Homogeneous CO hydrogenation and transfer hydrogenation catalyzed by ruthenium(II) complexes containing optically active Ph2PCH(Ph)CH(Me)NH2 and 1,2-C5H8(PPh2)2 ligands

Combination of (1S,2S)-cyclopentanediylbis(diphenylphosphine) with [Ru(η⁴-C₈H₁₂){η³-(CH₂)₂CMe}₂] afforded the chelate complex [Ru{η³-(CH₂)₂CMe}₂{(1S,2S)-C₅H₈(PPh₂)₂}] (1), which gave (OC-6-13)-[RuCl₂{(1S,2S)-C₅H₈(PPh₂)₂}{(1S,2S)-Ph₂PCH(Ph)CH(Me)NH₂}] (2) upon reaction with methanolic HCl in acetone, followed by the addition of the β-aminophosphine in DMF. The (P ∩ N)₂-chelated complexes (OC-6-13)-[RuCl₂{(1S,2S)-Ph₂PCH(Ph)CH(Me)NH₂}₂] (3) and (OC-6-13)-[RuCl₂{(1R,2S)-Ph₂PCH(Ph)CH(Me)NH₂}₂] (4) resulted from RuCl₃ · 3H₂O and the P,N ligands under reducing conditions. The crystal structures of 3 and 4 were determined by single-crystal X-ray diffraction. Following activation by KOBu-t in isopropanol, compounds 2–4 catalyzed the enantioselective transfer hydrogenation of acetophenone with i-PrOH as the hydrogen source as well as the direct hydrogenation of the ketone by H₂ in low to moderate e.e. (up to 67%).     

Spectroscopic and reactivity comparison of pentacyanonitrosylruthenate(2-) with pentacyanonitrosylferrate(2-), nitroprusside

Lithium penta(cyano-¹³C)nitrosylruthenate (2-), Li₂[Ru(¹³CN)₅NO], in which the anion is the ruthenium analogue of the nitroprusside ion, has been synthesized at 90% isotopic enrichment, and characterized spectroscopically. Despite the very high level of ¹³C enrichment, no two-bond coupling ²J(¹³C_ax-Ru¹³C_eq) was detected in the high-frequency ¹³C NMR spectrum of Li₂[Ru(¹³CN)₅NO], nor was any such coupling observed in Li₄[Ru(¹³CN)₅(¹⁵NO₂)] although both two-bond couplings to ¹⁵N, ²J(¹³C_ax-Ru¹⁵NO₂) and ²J(¹³C_eqRu¹⁵N) were observed. Li₂[Ru(¹³CN)₅(¹⁴NO)] reacted with excess of Li[¹⁵NO₂] to yield Li₄[Ru(¹³CN)₅(¹⁵NO₂)] only: no Li₂[Ru(¹³CN)₅(¹⁵NO)] was observed. Li₄[Ru(¹³CN)₅(¹⁴NO₂)] however showed no exchange with Li[¹⁵NO₂]. While [Ru(CN)₅NO]²⁻ reacted with both OH⁻ and SH⁻ in reactions similar to those of [Fe(CN)₅NO]²⁻, no reactions were detected between [Ru(CN)₅NO]²⁻ and piperidine, [CH(CN)₂]⁻, [CH(COCH₃)₂]⁻, MeS⁻, or [S₂O₄]²⁻, all of which are known to react readily with [Fe(CN)₅NO]²⁻