Ruthenium(III) and iridium(III) complexes with nicotine

A new chloride-dimethylsulfoxide-ruthenium(III) complex with nicotine trans-[Ru^IIICl₄(DMSO)[H-(Nicotine)]] (1) and three related iridium(III) complexes; [H-(Nicotine)]trans-[Ir^IIICl₄(DMSO)₂] (2), trans-[Ir^IIICl₄(DMSO)[H-(Nicotine)]] (3) and mer-[Ir^IIICl₃(DMSO)(Nicotine)₂] (4) have been synthesized and characterized by spectroscopic techniques and by single crystal X-ray diffraction (1, 2, and 4). Protonated nicotine at pyrrolidine nitrogen is present in complexes 1 and 3 while two neutral nicotine ligands are observed in 4. In these three inner-sphere complexes coordination occurs through the pyridine nitrogen. Moreover, in the outer-sphere complex 2, an electrostatic interaction is observed between a cationic protonated nicotine at the pyrrolidine nitrogen and the anionic trans-[Ir^IIICl₄(DMSO)₂]^¯ complex.     

Synthesis and characterization of new paramagnetic tetraaryl derivatives of chromium and molybdenum

The low-temperature reaction of [CrCl₃(thf)₃] with LiC₆H₃Cl₂-2,6 yields the organochromium(III) compound [Li(thf)₄][Cr^III(C₆H₃Cl₂-2,6)₄] (1) in 48% yield. The homoleptic, anionic species [Cr^III(C₆H₃Cl₂-2,6)₄]⁻ is electrochemically related to the neutral one [Cr^IV(C₆H₃Cl₂-2,6)₄] (2) through a reversible one-electron exchange process (E_1/2 = 0.16 V, ΔE_p = 0.09 V, i_pa/i_pc = 1.18). Compound 2 was isolated in 74% yield by chemical oxidation of 1 with [N(C₆H₄Br-4)₃][SbCl₆]. Attempts to prepare the salt [NBu₄][Cr^III(C₆Cl₅)₄] (4) by direct arylation of [CrCl₃(thf)₃] with LiC₆Cl₅ in the presence of [NBu₄]Br gave the organochromium(II) salt [NBu₄]₂[Cr^II(C₆Cl₅)₄] (3) instead, as the result of a reduction process. The salt [NBu₄][Cr^III(C₆Cl₅)₄] (4) was cleanly prepared by comproportionation of 3 and [Cr^IV(C₆Cl₅)₄]. The reaction of [MoCl₄(dme)] with LiC₆Cl₅ in Et₂O solution proceeded with oxidation of the metal center to give the paramagnetic (S = 1/2), five-coordinate salt [Li(thf)₄][Mo^VO(C₆Cl₅)₄] (5). The crystal and molecular structures of 1 and 2 have been established by X-ray diffraction methods. The magnetic properties of 1 and 4 (S = 3/2) as well as those of 2 (S = 1) have been established by EPR spectroscopy as well as by ac and dc magnetization measurements.     

New bipyridyl/phenanthroline ruthenium(II) and ruthenium(III) complexes possessing acetate appended thioether. Evidence for oxidative linkage isomerization

The acetate bearing dithioether, sodium di(2-carboxymethylsufanyl)maleonitrile, L¹ upon reaction with [Ru^II(bpy)₂Cl₂]·2H₂O, [Ru^II(phen)₂Cl₂]·2H₂O, [Ru^III(bpy)₂Cl₂]⁺ or [Ru^III(phen)₂Cl₂]⁺ in methanol formed complexes of the type [(bpy)₂Ru{S₂(CH₂COO)₂C₂(CN)₂}], (1), [(phen)₂Ru{S₂(CH₂COO)₂C₂(CN)₂}], (2), [(bpy)₂Ru{(OOCCH₂)₂S₂C₂(CN)₂}]⁺, (5) and [(phen)₂Ru{(OOCCH₂)₂S₂C₂(CN)₂}]⁺, (6) respectively. Four other Ru(III) complexes with di(benzylsulfanyl)maleonitrile, L², [(bpy)₂Ru{S₂(PhCH₂)C₂(CN)₂}]³⁺, (7) and [(phen)₂Ru{S₂(PhCH₂)₂C₂(CN)₂}]³⁺, (8), and with acetate, [(bpy)₂Ru(OOCCH₃)₂]⁺, (9) and [(phen)₂Ru(OOCCH₃)₂]⁺, (10) were also synthesized. In the cyclic voltammetry, complexes (1) and (2) exhibited quasireversible oxidation waves at 1.01 and 1.02 V vs. Ag/AgCl over GC electrode in DMF, while the corresponding Ru(III) L¹ complexes (5) and (6) exhibit reversible oxidation at E_1/2 0.59 and 0.58 V, respectively, under identical conditions. This is unlike the voltammetric behavior of the Ru(II) and Ru(III) L² complexes, wherein the complex pairs (3), (7) and (4), (8) exhibited identical voltammograms with single reversible one electron waves at E_1/2 0.98 and 0.92 V, respectively under identical conditions. The voltammograms of Ru(II)-L² complexes (3) and (4) also became irreversible in presence of nearly four molar equivalent of sodium acetate. Hence, the irreversible redox behavior of complexes (1) and (2) has been interpreted in terms of rapid linkage isomerization, i.e. shift in κ²-S,S′ to κ²-O,O′ coordination, following the Ru(II)/Ru(III) electrode process. The electronic spectra of Ru(III)-L¹ complexes (5) and (6) resemble closely with that of (9) and (10) instead of Ru(III)-L² complexes (7) and (8), further supports proposed linkage isomerization. The cationic complexes were obtained as [PF₆]⁻ salts and all compounds were characterized using analytical and spectral (IR, ¹H NMR, UV-vis and mass) data.     

Further studies of tetrakis(N,N′-dialkylbenzamidinato)diruthenium(III) chloro and alkynyl compounds: molecular engineering of metallayne monomers

Three diruthenium(III) compounds Ru₂(L)₄Cl₂, where L is mMeODMBA (N,N′-dimethyl-3-methoxybenzamidinate, 1a), DiMeODMBA (N,N′-dimethyl-3,5-dimethoxy benzamidinate, 1b), or DEBA (N,N′-diethylbenzamidinate, 1c), were prepared from the reactions between Ru₂(OAc)₄Cl and respective HL under reflux conditions. Metathesis reactions between 1 and LiC₂Y resulted in bis-alkynyl derivatives Ru₂(L)₄(C₂Y)₂ [Y=Ph (2), SiMe₃ (3), SiⁱPr₃ (4) and C₂SiMe₃ (5)]. The parent compounds 1 are paramagnetic (S=1), while bis-alkynyl derivatives 2-5 are diamagnetic and display well-solved ¹H- and ¹³C-NMR spectra. Molecular structures of compounds 1b, 1c, 2c, 3c and 4b were established through single crystal X-ray diffraction studies, which revealed RuRu bond lengths of ca. 2.32 Å for parent compounds 1 and 2.45 Å for bis-alkynyl derivatives. Cyclic voltammograms of all compounds feature three one-electron couples: an oxidation and two reductions, while the reversibility of observed couples depends on the nature of axial ligands.     

Half-sandwich η-benzene Ru(II) complexes of phenolate-based pyridylalkylamine/alkylamine ligands: Synthesis, structure, and stabilization of one-electron oxidized species

Four half-sandwich ruthenium(II) complexes [(η⁶-C₆H₆)Ru(L¹-O)][PF₆] (1), [(η⁶-C₆H₆)Ru(L²-O)][PF₆] (2), [(η⁶-C₆H₆)Ru(L³-O)][PF₆] (3), [(η⁶-C₆H₆)Ru(L⁴-O)][PF₆] (4a), and [(η⁶-C₆H₆)Ru(L⁴-O)][BPh₄] (4b) [L¹-OH, 4-nitro-6-{[(2′-(pyridin-2-yl)ethyl)methylamino]methyl}-phenol; L²-OH, 2,4-di-tert-butyl-6-{[(2′-(pyridin-2-yl)ethyl)methylamino]methyl}-phenol; L³-OH, 2,4-di-tert-butyl-6-{[2′-((pyridin-2-yl)benzylamino)methyl}-phenol; L⁴-OH, 2,4-di-tert-butyl-6-{[(2′-imethylaminoethyl)methylamino]methyl}-phenol (L⁴-OH)], supported by a systematically varied series of tridentate phenolate-based pyridylalkylamine and alkylamine ligands are reported. The molecular structures of 1-3, 4a, and 4b have been elucidated in solution using ¹H NMR spectroscopy and of 1, 3, and 4b in the solid state by X-ray crystallography. Notably, due to coordination by the ligands the Ru center assumes a chiral center and in turn the central amine nitrogen also becomes chiral. The ¹H NMR spectra exhibit only one set of signals, suggesting that the reaction is completely diastereoselective [1: S_Ru,S_N/R_Ru,R_N; 2: R_Ru,R_N/S_Ru,S_N; 3: S_Ru,R_N/R_Ru,S_N; 4b: S_Ru,R_N/R_Ru,S_N]. The crystal packing in 1 and 3 is stabilized by C-H^…O interactions, in 4b no meaningful secondary interactions are observed. From the standpoint of generating phenoxyl radical, as investigated by cyclic voltammetry (CV), complex 1 is redox-inactive in MeCN solution. However, 2, 3, and 4a generate a one-electron oxidized phenoxyl radical coordinated species [2]²⁺, [3]²⁺, and [4a]²⁺, respectively. The radical species are characterized by CV, UV-Vis, and EPR spectroscopy. The stability of the radical species has been determined by measuring the decay constant (UV-Vis spectroscopy).     

Synthesis, characterisation and catalytic activities of manganese(III) complexes of pyridoxal-based ONNO donor tetradenatate ligands

Reaction of Mn^II(CH₃COO)₂ with dibasic tetradentate ligands, N,N′-ethylenebis(pyridoxylideneiminato) (H₂pydx-en, I), N,N′-propylenebis(pyridoxylideneiminato) (H₂pydx-1,3-pn, II) and 1-methyl-N,N′-ethylenebis(pyridoxylideneiminato) (H₂pydx-1,2-pn, III) followed by aerial oxidation in the presence of LiCl gives complexes [Mn^III(pydx-en)Cl(H₂O)] (1) [Mn^III(pydx-1,3-pn)Cl(CH₃OH)] (2) and [Mn^III(pydx-1,2-pn)Cl(H₂O)] (3), respectively. Crystal and molecular structures of [Mn(pydx-en)Cl(H₂O)] (1) and [Mn(pydx-1,3-pn)Cl(CH₃OH)] (2) confirm their octahedral geometry and the coordination of ligands through ONNO(2-) form. Reaction of manganese(II)-exchanged zeolite-Y with these ligands in refluxing methanol followed by aerial oxidation in the presence of NaCl leads to the formation of the corresponding zeolite-Y encapsulated complexes, abbreviated herein as [Mn^III(pydx-en)]-Y (4), [Mn^III(pydx-1,3-pn)]-Y (5) and [Mn^III(pydx-1,2-pn)]-Y (6). These encapsulated complexes are used as catalysts for the oxidation, by H₂O₂, of methyl phenyl sulfide, styrene and benzoin efficiently. Oxidation of methyl phenyl sulfide under the optimized reaction conditions gave ca. 86% conversion with two major products methyl phenyl sulfoxide and methyl phenyl sulfone in the ca. 70% and 30% selectivity, respectively. Oxidation of styrene catalyzed by these complexes gave at least five products namely styrene oxide, benzaldehyde, benzoic acid, 1-phenylethane-1,2-diol and phenylacetaldehyde with a maximum of 76.9% conversion of styrene by 4, 76.3% by 5 and 76.0% by 6 under optimized conditions. The selectivity of the obtained products followed the order: benzaldehyde > benzoic acid > styrene oxide > phenylacetaldehyde > 1-phenylethane-1,2-diol. Similarly, ca. 93% conversion of benzoin was obtained by these catalysts, where the selectivity of the products followed the order benzil > benzoic acid > benzaldehyde-dimethylacetal. Tests for the recyclability and heterogeneity of the reactions have also been carried. Neat complexes are equally active. However, the recycle ability of encapsulated complexes makes them better over neat ones.     

Synthesis and crystal structure of Ru-supported tungstoantimonate [Sb2W20Ru2(H2O)2(dmso)6O68]

The first Ru^III-supported tungstoantimonate [Ru^II(bpy)₃]₂[Sb₂W₂₀Ru^III₂(H₂O)₂(dmso)₆O₆₈]·3dmso (bpy=bi-pyridine) (1a) has been successfully isolated as [Ru(bpy)₃]²⁺ (Rubpy) salt by routine synthetic reaction in mixed solutions with dmso and water. Single-crystal X-ray analysis was carried out on 1a, which crystallizes in the triclinic system space group P-1 with a=16.804 (6), b=16.988 (6), c=17.666 (6) Å, α=107.397 (13)°, β=106.883 (13)°, γ=103.616 (12)°. V=4309 (3) Å³, Z=1 with R1=0.0773. The compound 1a reveals the following features: (1) Rubpy is firstly used as an alternative ruthenium-source for the synthesis of Ru-substituted heteropolytungstate; (2) the structure of 1a consists of four Ru^III-O-S(CH₃)₂ and two W-O-S(CH₃)₂ bonds resulting in an assembly with C₂ symmetry; (3) the Ru^III ions are linked to two dmso groups via two Ru^III-O-S(CH₃)₂ bonds, which represents the other dmso-coordination mode to Ru^III in POM chemistry. The cyclic voltammetry studies of 1a in dmso/H₂SO₄ (3/1 v/v) at pH 2.5 medium using the glassy carbon electrode as a working electrode show the respective electrochemical behaviors of the W-centers and the Ru-centers within 1a, which could be separated clearly. In addition, the compound 1a exhibits photoluminescence arising from π*−t_2g ligand-to-metal transition of Rubpy.     

Synthesis, X-ray crystal structure and cytotoxicity of a new tetranuclear ruthenium arene complex

The tetranuclear ruthenium arene compound [(cym)₄Ru₄(2)Cl₆]Cl₂ (3) (cym = η⁶-p-cymene, 2 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane) was prepared and characterised by one- and two-dimensional NMR techniques. Its cytotoxicity against four different cell lines was determined and, with an approximate IC₅₀ of >100 μM 3 can be regarded as non-toxic. Its partition coefficient in n-octanol/water (log D_7.4) was also determined. The structures of complex 3 as well as of the related compound [(cym)₂Ru₂(4)Cl₂]Cl₂ (5) (4 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane dioxide) were determined by single crystal structure analysis. Upon oxidation in protic solvents, ligand 2 shows P-C bond cleavage reactions to yield P,P′-bis(N-methylimidazol-2-yl)ethylene diphosphinic acid (6).     

Diruthenium(I,I) saccharinate complexes: Synthesis, molecular structure, and evaluation as catalysts for carbenoid reactions of diazoacetates

The dinuclear ruthenium complexes [Ru₂(μ-sac)₂(CO)₆] (1), [Ru₂(μ-sac)₂(CH₃CN)₂(CO)₄] (3), [Ru₂(μ-sac)₂(CO)₅(PPh₃)] (4) and [Ru₂(μ-sac)₂(CO)₄(PPh₃)₂] (5) as well as the tetranuclear ruthenium complex [Ru₂(μ-sac)₂(CO)₅]₂ (2) (sac = saccharinate, C₇H₄NO₃S⁻) were synthesized starting from Ru₃(CO)₁₂ and saccharin. X-ray crystal structure analysis of 1, 3A × p-xylene, 4 × CH₂Cl₂ and 5 × 3CH₂Cl₂ showed that the core is bridged through the amidate moieties of the two saccharinate ligands, with a head-tail arrangement in complexes 1, 3A and 5, and a head-head arrangement in 4. For complex 3, an equilibrium mixture of the head-head regioisomer 3A and a second species 3b exists in solution. Complexes 1 and 2 are suitable catalysts for the cyclopropanation of nucleophilic alkenes (styrene, cyclohexene and 2-methyl-2-butene) with methyl diazoacetate.     

Lanthanide complexes of the monovacant Dawson polyoxotungstate [α2-As2W17O61] with 1D chain: Synthesis, structures, and photoluminescence properties

Six new lanthanide complexes, (H₃O)[Ln₃(H₂O)₁₇(α₂-As₂W₁₇O₆₁)]·nH₂O ((1) Ln=Ce^III and n≈13; (2) Ln=Pr^III and n≈9; (3) Ln=Nd^III and n≈14; (4) Ln=Sm^III and n≈8; (5) Ln=Eu^III and n≈4; (6) Ln=Gd^III and n≈7), have been isolated by conventional solution method and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. All the complexes are isomorphic and crystallize in the triclinic space group P-1. These complexes are 1D chain-like structures constructed by lanthanide cations and monovacant Dawson-type [α₂-As₂W₁₇O₆₁]¹⁰⁻ polyoxoanions. The striking feature of the structures is that there are three kinds of coordination environments for lanthanide cations, which are responsible for the formation of polymeric structures. Photoluminescence measurements reveal that 4 and 5 exhibit orange and red fluorescent emission at room temperature, respectively.     

Controlling the electronic density of the [Ru2(DPhF)3(O2CR)] core to obtain one-dimensional compounds

The substitution of the acetate ligand in [Ru₂Cl(DPhF)₃(O₂CMe)] (DPhF⁻ = N,N′-diphenylformamidinate) by the pentafluorobenzoate group gives the complex [Ru₂Cl(DPhF)₃(O₂CC₆F₅)(OH₂)] (1), and the reaction of 1 with AgSO₃CF₃ leads to the compound [Ru₂(DPhF)₃(O₂CC₆F₅)(OH₂)₂]SO₃CF₃ (2). The low donor character of the pentafluorobenzoate ligand compared to the acetate group decreases the electron density of the Ru₂⁵⁺ unit which permits ligands to bond at both axial positions of the diruthenium moiety. The use of the [Au(CN)₂]⁻ group yields the new complex {[Ru₂(DPhF)₃(O₂CC₆F₅)][Au(CN)₂]} (3). Complexes 1–3 are characterized by elemental analysis, ¹⁹F{¹H} NMR, IR and electronic spectroscopy, mass spectrometry and variable-temperature magnetic measurements. The crystal structure of 2·H₂O is also reported. The magnetic properties of complex 1 is in accordance with the ground-state configuration σ²π⁴δ²(π*δ*)³. In contrast, the slope of representation of the magnetic moment towards temperature in complex 2 indicates a gradual transition from essentially high spin (S = 3/2) to low spin (S = 1/2) configuration.     

Synthesis and crystal structure characterization of iron(II), cobalt(II) and nickel(II) complexes with 1,3-bis(2-pyridylmethylthio)propane

Three new mononuclear complexes of nitrogen–sulfur donor sets, formulated as [Fe^II(L)Cl₂] (1), [Co^II(L)Cl₂] (2) and [Ni^II(L)Cl₂] (3) where L = 1,3-bis(2-pyridylmethylthio)propane, were synthesized and isolated in their pure form. All the complexes were characterized by physicochemical and spectroscopic methods. The solid state structures of complexes 1 and 3 have been established by single crystal X-ray crystallography. The structural analysis evidences isomorphous crystals with the metal ion in a distorted octahedral geometry that comprises NSSN ligand donors with trans located pyridine rings and chlorides in cis positions. In dimethylformamide solution, the complexes were found to exhibit Fe^II/Fe^III, Co^II/Co^III and Ni^II/Ni^III quasi-reversible redox couples in cyclic voltammograms with E_1/2 values (versus Ag/AgCl at 298 K) of +0.295, +0.795 and +0.745 V for 1, 2 and 3, respectively.     

Reactivity of the triruthenium ortho-metalated cluster [Ru3(CO)9{μ3-η,κ,κ-PhP(C6H4)CH2PPh}] with tri(2-thienyl)phosphine and tri(2-furyl)phosphine: Formation of 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine complexes via phosphorus-carbon bond formation

Reaction of [Ru₃(CO)₉{μ₃-η¹,κ¹,κ²-PhP(C₆H₄)CH₂PPh}] (1) with tri(2-thienyl)phosphine (PTh₃) in refluxing THF afforded [Ru₃(CO)₉(PTh₃)(μ-dpbm)] (3) {dpbm = PhP(C₆H₄)(CH₂)PPh} and [Ru₃(CO)₆(μ-CO)₂{μ-κ¹,η¹-PTh₂(C₄H₂S)}{μ₃-κ¹,κ²-Ph₂PCH₂PPh}] (5) in 18% and 12% yields, respectively, while a similar reaction with tri(2-furyl)phosphine (PFu₃) gave [Ru₃(CO)₉(PFu₃)(μ-dpbm)] (4) and [Ru₃(CO)₇(μ-η¹,η²-C₄H₃O)(μ-PFu₂){μ₃-η¹,κ¹,κ²-PhP(C₆H₄)CH₂PPh}] (6) in 24% and 27% yields, respectively. Compounds 2 and 4 are phosphine adducts of 1 in which the diphosphine ligand is transformed into 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine (dpbm) via phosphorus-carbon bond formation. Cluster 5 results from metalation of a thienyl ring, the cleaved proton being transferred to the diphosphine. Carbon-phosphorus bond cleavage of a PFu₃ ligand is observed in 6 to afford a phosphido-bridge and a furyl fragment, the latter bridging in a σ,π-vinyl fashion. The molecular structures of 3, 5 and 6 have been determined by X-ray diffraction studies.     

Novel carbonyl complexes of ruthenium with α-substituted oxime derivatives of terpenes

The reactions of Ru₃(CO)₁₂ with 1R,4S,6S-4-dimethylamino-4,7,7-trimethylbicyclo[4.1.0]heptane-3-one oxime (dimethylaminocaraneoxime) (I), 1R,4S,6S-4-methylamino-4,7,7-trimethylbicyclo[4.1.0]heptane-3-one oxime (methylaminocarane oxime) (II), and 1R,2R,5R-2-benzylthio-2,6,6-trimethylbicyclo[3.1.1]heptane-3-one oxime (benzylthiopinaneoxime) (III) were studied. The binuclear complex Ru₂(CO)₄{μ-η³(O,N,X)-L}₂ was formed as the main product in every reaction, when Ru₃(CO)₁₂ was heated with terpenoid to 80°C. In the above complex, two terpene ligands are coordinated in the form of ‘head-to tail’ bridge by the oxime groups at a binuclear metal fragment Ru-Ru. The heteroatom of the second functional group of every bridging ligand (nitrogen of amino group in I and II, sulfur of the thio group in III) is additionally coordinated to the ruthenium atom to give the chelate five-membered ring. Also the reactions of terpenoids I, II, III with Ru₃(CO)₁₂ were performed at room temperature using Me₃NO. In this case, as in the thermal reactions, the main product was the binuclear complex. However, in the reactions of Ru₃(CO)₁₂ with I and II, the trinuclear clusters were isolated that readily transformed to binuclear complexes in a solution. The complexes synthesized can exist as two diasteromers due to their chiral metal core. However, in all the cases, only one diastereomer was isolated, which indicates stereospecific nature of the above reactions. The compounds obtained were characterized by IR, ¹H-, ¹³C{¹H}-, COSY, and HXCOBI-NMR spectroscopy, the specific optical rotation angles were measured. For the binuclear complexes with ligands I, III and for trinuclear cluster with ligand II, single crystals were obtained and studied by X-ray diffraction.     

Solvent-dependent formation of two different Cd(II) complexes with p-BrC6H4C(S)NHP(O)(OiPr)2 (HL). Crystallographic modification of Cd(HL)2L2

Reaction of the potassium salt of N-(diisopropoxyphosphoryl)-p-bromothiobenzamide p-BrC₆H₄C(S)NHP(O)(OiPr)₂ (HL) with Cd(II) cations in freshly dried and distilled EtOH leads exclusively to the complex [Cd(p-BrC₆H₄C(S)NH₂-S)(L-O,S)₂] ([Cd(L^I)L₂]), while the same reaction in H₂O leads to the complex [Cd(HL-O)₂(L-O,S)₂] ([Cd(HL)₂L₂]). The corresponding reactions with Zn(II) always lead to the complex [Zn(L-O,S)₂] ([ZnL₂]) regardless of the solvent. The crystal structure of [Cd(HL)₂L₂]^.2/3H₂O reveals to be a polymorph to the previously reported anhydrous [Cd(HL)₂L₂].     

Effect of chain length on the formation of intramolecular and intermolecular products: Reaction of diols with cyclotriphosphazene

The reactions of cyclotriphosphazene, N₃P₃Cl₆ (1), in a 1:1.2 stoichiometry with the sodium derivative of seven diols [ethane- (2a), 1,3-propane- (2b), 1,4-butane- (2c), 1,5-pentane- (2d), 1,6-hexane- (2e), 1,8-octane- (2f) and 1,10-decane- (2g) diol] in THF solution at room temperature have been used to investigate the effect of chain length on the formation of reaction products. Although no new products were found for the reaction of 1 with diols 2a-c compared to those in the literature using other bases and solution conditions, the reactions of 1 with the diols 2d-g gave six different types of products, whose structures have been characterized by elemental analysis, mass spectrometry, ¹H and ³¹P NMR spectroscopy; ansa compounds N₃P₃Cl₄[O(CH₂)_nO], (5d-5g); single-bridged compounds N₃P₃Cl₅[O(CH₂)_nO]N₃P₃Cl₅(6d-6f); double-bridged compounds N₃P₃Cl₄[O(CH₂)_nO]₂N₃P₃Cl₄ (7d-7g, syn and anti) and triple-bridged compounds, N₃P₃Cl₃[O(CH₂)_nO]₃N₃P₃Cl₃ (8d-f). Where suitable single crystals were obtained, X-ray crystallographic studies confirmed the structures of two ansa compounds (5d and 5f), one single-bridged compound (6e), and five double-bridged compounds (meso-anti for 7d, 7e, 7f and meso-syn for 7d and 7f). ³¹P NMR measurements of the reaction mixtures were used to quantify the formation of products for the reactions 1 with all the diols, 2a-g; it is found that, with increasing chain length of the diol, there is a decrease in the products formed by intramolecular reactions (spiro and ansa derivatives) and a concomitant increase in the amounts of products formed by intermolecular reactions (single-, double- and triple-bridged derivatives) of cyclophosphazene.     

Chalcogen-capped ruthenium carbonyl clusters derived from diphosphazane mono- and dichalcogenides of the type X2P(E)N(R)PX2 and X2P(E)N(R)P(E)X2 (E = S or Se)

Reactions of Ru₃(CO)₁₂ with diphosphazane monoselenides Ph₂PN(R)P(Se)Ph₂ [R = (S)-∗CHMePh (L⁴), R = CHMe₂ (L⁵)] yield mainly the selenium bicapped tetraruthenium clusters [Ru₄(μ₄-Se)₂(μ-CO)(CO)₈{μ-P,P-Ph₂PN(R)PPh₂}] (1, 3). The selenium monocapped triruthenium cluster [Ru₃(μ₃-Se)(μ_sb-CO)(CO)₇{κ²-P,P-Ph₂PN((S)-∗CHMePh)PPh₂}] (2) is obtained only in the case of L⁴. An analogous reaction of the diphosphazane monosulfide (PhO)₂PN(Me)P(S)(OPh)₂ (L⁶) that bears a strong π-acceptor phosphorus shows a different reactivity pattern to yield the triruthenium clusters, [Ru₃(μ₃-S)(μ₃-CO)(CO)₇{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (9) (single sulfur transfer product) and [Ru₃(μ₃-S)₂(CO)₅{κ²-P,P-(PhO)₂PN(Me)P(OPh)₂}{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (10) (double sulfur transfer product). The reactions of diphosphazane dichalcogenides with Ru₃(CO)₁₂ yield the chalcogen bicapped tetraruthenium clusters [Ru₄(μ₄-E)₂(μ-CO)(CO)₈{μ-P,P-Ph₂PN(R)PPh₂}] [R = (S)-∗CHMePh, E = S (6); R = CHMe₂, E = S (7); R = CHMe₂, E = Se (3)]. Such a tetraruthenium cluster [Ru₄(μ₄-S)₂(μ- CO)(CO)₈{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (11) is also obtained in small quantities during crystallization of cluster 9. The dynamic behavior of cluster 10 in solution is probed by NMR studies. The structural data for clusters 7, 9, 10 and 11 are compared and discussed.     

Aminobis(phenolate)s of imidomolybdenum(VI) and -tungsten(VI)

The reactions of trans-[MoO(ONO^Me)Cl₂] 1 (ONO^Me = methylamino-N,N-bis(2-methylene-4,6-dimethylphenolate) dianion) and trans-[MoO(ONO^tBu)Cl₂] 2 (ONO^tBu = methylamino-N,N-bis(2-methylene-4-methyl-6-tert-butylphenolate) dianion) with PhNCO afforded new imido molybdenum complexes trans-[Mo(NPh)(ONO^Me)Cl₂] 3 and trans-[Mo(NPh)(ONO^tBu)Cl₂] 4, respectively. As analogous oxotungsten starting materials did not show similar reactivity, corresponding imido tungsten complexes were prepared by the reaction between [W(NPh)Cl₄] with aminobis(phenol)s. These reactions yielded cis- and trans-isomers of dichloro complexes [W(NPh)(ONO^Me)Cl₂] 5 and [W(NPh)(ONO^tBu)Cl₂] 6, respectively. The molecular structures of 4, cis-6 and trans-6 were verified by X-ray crystallography. Organosubstituted imido tungsten(VI) complex cis-[W(NPh)(ONO^tBu)Me₂] 7 was prepared by the transmetallation reaction of 6 (either cis or trans isomer) with methyl magnesium iodide.     

The influence of substituents (R) at the C carbon on bonding properties of thiosemicarbazones {RC(H)N-NH–C(S)–NH2} in palladium(II) complexes

Reactions of the trans-PdCl₂(PPh₃)₂ precursor with furan-2-carbaldehyde thiosemicarbazone (Hftsc) and thiophene-2-carbaldehyde thiosemicarbazone (Httsc), in 1:1 molar ratios in the presence of Et₃N base, removed one Cl and one PPh₃ group from the Pd^II center, and yielded the complexes [Pd(η²-N³,S-ftsc)(PPh₃)Cl] (1) and [Pd(η²-N³,S-ttsc)(PPh₃)Cl] (2), respectively. However, when a 1:2 molar ratio (M:L) was used, both Cl and PPh₃ ligands were removed, yielding the complexes trans-[Pd(η²-N³,S-ftsc)₂] (3) and trans-[Pd(η²-N³,S-ttsc)₂] (4). Complexes 1–4 have been characterized with the help of analytical data, spectroscopic techniques (IR, ¹H and ³¹P NMR) and single crystal X-ray crystallography. The thiosemicarbazone ligands behave as uninegative N³,S-chelating ligands in complexes 1–4. In contrast, pyrrole-2-carbaldehyde thiosemicarbazone (H₂ptsc) and salicylaldehyde thiosemicarbazone (H₂stsc) invariably formed the complexes [Pd(η³-N⁴,N³,S-ptsc)(PPh₃)] (5) and [Pd(η³–O, N³,S-stsc)(PPh₃)] (6), respectively, and the ligands acted as binegative tridentate donors (N⁴, N³, S, 5; O, N³, S, 6).