Preparation and reactivity of osmium(II) hydride complexes with phosphites and polypyridyls

Chloro-complexes [OsCl(N-N)P₃]BPh₄ (1, 2) [N-N=2,2^′-bipyridine (bpy) and 1,10-phenanthroline (phen); P=P(OEt)₃ and PPh(OEt)₂] were prepared by allowing OsCl₄(N-N) to react with zinc dust in the presence of phosphites. Treatment of the chloro-complexes 1, 2 with NaBH₄ yielded, in the case of bpy, the hydride [OsH(bpy)P₃]BPh₄ (4) derivatives. Mono-phosphite [OsCl(bpy)₂P]BPh₄ (3) complexes were also prepared by reacting the [OsCl₂(bpy)₂]Cl compound with zinc dust in the presence of phosphite. Protonation reaction of the hydride [OsH(bpy)P₃]⁺ (4) cations with Brønsted acid was studied and led to thermally unstable (above 0 °C) dihydrogen [Os(η²-H₂)(bpy)P₃]²⁺ (4*) derivatives. The presence of the H₂ ligand is supported by variable-temperature NMR spectra and T_1min measurements. Carbonyl [Os(CO)(bpy){P(OEt)₃}₃](BPh₄)₂ (5), nitrile [Os(CH₃CN)(bpy){P(OEt)₃}₃](BPh₄)₂ (6), and hydrazine [Os(bpy)(NH₂NH₂){P(OEt)₃}₃](BPh₄)₂ (7) complexes were prepared by substituting the H₂ ligand in the η²-H₂ (4*) derivatives. Aryldiazene complex [Os(C₆H₅NNH)(bpy){P(OEt)₃}₃](BPh₄)₂ (8) was also obtained by allowing the hydride [OsH(bpy)P₃]BPh₄ to react with phenyldiazonium cation.     

Synthesis and property of BrCCH- and BrCCBr-coordinated tetrairon clusters

The reaction of (η⁵-C₅H₄Me)₄Fe₄(HCCH)₂ (1) with 1 equiv. of N-bromosuccinimide (NBS) gives the one-electron oxidized form in 83% yield. Further treatment of [1]⁺ with NBS results in the stepwise bromination of four acetylenic protons to give [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(HCCBr)]⁺ ([2]⁺), [(η⁵-C₅H₄Me)₄Fe₄(HCCBr)₂]⁺ ([3a]⁺), [(η⁵-C₅H₄Me)₄Fe₄(HCCBr)(BrCCBr)]⁺ ([4]⁺), and [(η⁵-C₅H₄Me)₄Fe₄(BrCCBr)₂]⁺ ([5]⁺) in moderate yields, with the isomer of [3a]⁺, [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(BrCCBr)]⁺ ([3b]⁺), formed as a minor product. These compounds are characterized by analytical and spectroscopic techniques, and the molecular structures of [2](PF₆), [4](TFPB), and [5](TFPB) are established by X-ray diffraction analysis [TFPB = tetrakis{bis(3,5-trifluoromethyl)phenyl}borate]. The compounds are confirmed to retain the butterfly core of four iron atoms as in [1](TFPB). The bromoacetylene part in [2]⁺ exhibits high reactivity toward various nucleophiles: Cluster[2]⁺ is moisture-sensitive and is converted to a mixture of [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(μ₃-CH)(μ₃-CO)]⁺ ([6]⁺) and [1]⁺. Reactions of [2]⁺ with ZnR₂ (R = Me, Et) give [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(HCC-R)]⁺ in good yields (R = Me ([9]⁺, 88%), Et ([10]⁺, 91%)). Accordingly, treatment of [2]⁺ with HC CMgBr and LiS^pTol leads to the introduction of the ethynyl and thiolate groups to give [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(HCC-CCH)]⁺ ([11]⁺, 95%) and [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(HCC-S^pTol)]⁺ ([12]⁺, 78%), respectively. Substitution of the bromo group in [2]⁺ with pyridine affords [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(HCC-Py)]²⁺ ([13]²⁺) in 90% yield. The reaction with 4,4′-bipyridyl (bpy) requires the severer conditions (70 °C, 2 days), probably due to the relative low basicity of bpy, giving [(η⁵-C₅H₄Me)₄Fe₄(HCCH)(HCC-bpy)]²⁺ ([14]²⁺) in 54% yield. The substitution reaction with 4,4′-bipyridyl is strongly accelerated by treatment with silver salt to give [14]²⁺ in 90% yield. The products derived from [2]⁺ and nucleophiles are unequivocally determined by elemental, spectroscopic, and X-ray diffraction analyses.     

Encapsulating ruthenium and osmium with tris(2-aminoethyl)amine based tripodal ligands

The reaction of a series of tripodal ligands, H₃L^1,2 and L^3-6, with [M(PPh₃)₂Cl₂] (M = Ru, Os) affords a family of coordination cage compounds of the type [M^IIIL^1,2] (1-4) or [M^IIL^3-6](BPh₄)₂ (5-12). The Schiff base ligands (H₃L¹, L³, L⁵) have been synthesized by condensation of tris(2-aminoethyl)amine with salicylaldehyde, pyridine-2-aldehyde and 1-methyl-2-imidazolecarboxaldehyde. These ligands were further reduced and subsequently methylated to form the new ligands (H₃L², L⁴, L⁶). Single crystal X-ray diffraction studies of 1 and 2 show that the tripodal ligand wraps around the metal center as a hexadentate ligand to form a cage. All the synthesized compounds have been thoroughly characterized by ESI-MS, FT-IR, UV-Vis and NMR spectroscopic methods. To the best of our knowledge, this is the first ever report of osmium complexes with tris(2-aminoethyl)amine based tripodal ligands. DFT calculations were performed to obtain geometry optimized structures of all the other complexes (3-12).     

Ferrocenylpyrazole—A versatile building block for hydrogen-bonded organometallic supramolecular assemblies

The crystal architectures of 5-ferrocenylpyrazole (1) and its metal complexes were investigated. Compound 1 can form non-solvated and chloroform-solvated crystals. In both cases, 1 forms a zigzag one-dimensional architecture via NH?N hydrogen bonds. The hydrogen bond exhibits a twofold disorder, which was shown to be static by solid-state ¹³C NMR. In the solvated crystal, the chloroform is released at 415 K, associated with melting of the crystal. The reaction of 1 with metal salts provided metal-centered ferrocenyl clusters [Zn(NO₃)₂(1)₄] (4), [Co(NO₃)₂(1)₄] (5), [CoCl₂(1)₄] (6), [Zn(NCS)₂(1)₂] (7), cis-[Pt(NH₃)₂(1)₂](PF₆)₂ (8), and trans-[Pt(NH₃)₂(1)₄](PF₆)₂ (9). In all of these complexes, 1 acts as a monodentate ligand. In 4, 5, and 7, the multinuclear units are joined via hydrogen bonds to form supramolecular chains. Two polymorphs were found for the crystals of 4. Both are composed of the same hydrogen-bonded chains, but their arrangements are different. 5-Ferrocenyl-1-tritylpyrazole (2) and 4-ferrocenyl-1-methylpyrazole (3) were also crystallographically characterized.     

Structure,biological and electrochemical studies of transition metal complexes from N,S,N′ donor ligand 8-(2-pyridinylmethylthio)quinoline

The semirigid tridentate 8-(2-pyridinylmethylthio)quinoline ligand (Q1) is shown to form the structurally characterized transition metal complexes [Cu(Q1)Cl₂] (1), [Co(Q1)(NO₃)₂] (2), [Cd(Q1)(NO₃)₂] (3), [Cd(Q1)I₂] (4). [Cu(Q1)₂](BF₄)₂·(H₂O)₂ (5), [Cu(Q1)₂](ClO₄)₂·(CH₃COCH₃)₂ (6), [Zn(Q1)₂](ClO₄)₂(H₂O)₂ (7), [Cd₂(Q1)₂Br₄] (8), [Ag₂(Q1)₂(ClO₄)₂] (9), and [Ag₂(Q1)₂(NO₃)₂] (10). Four types of structures have been observed: ML-type in complexes 1–4, in which the anions Cl⁻, NO₃⁻ or I⁻ also participate in the coordination; ML₂⁻ type in complexes 5–7 without direct coordination of the anions BF₄⁻ or ClO₄⁻ and with more (Cu²⁺) or less (Zn²⁺) distorted bis-fac coordinated Q1; M₂L₂-type in complex 8, in which two Br⁻ ions act as bridges between two metal ions; and M₂(μ-L)₂-type in complexes 9 and 10, in which the ligand bridges two anion binding and Ag–Ag bonded ions. Depending on electron configuration and size, different coordination patterns are observed with the bonds from the metal ions to N_pyridyl longer or shorter than those to N_quinoline. Typically Q1 acts as a facially coordinating tridentate chelate ligand except for the compounds 9 and 10 with low-coordinate silver(I). Except for 6 and 8, the complexes exhibit distinct constraining effects against both G(+) and G(-) bacteria. Complexes 1, 3, 4, 5, 7 have considerable antifungal activities and complexes 1, 5, 7, and 10 show selective effects to restrain certain botanic bacteria. Electrochemical studies show quasi-reversible reduction behavior for the copper(II) complexes 1, 5 and 6.     

Synthesis and reactivity of hydride and dihydrogen complexes of ruthenium with tris(pyrazolyl)borate and phosphite ligands

Chloro phosphite complexes RuClTpL(PPh₃) (1a, 1b) [L = P(OEt)₃, PPh(OEt)₂] and RuClTp[P(OEt)₃]₂ (1c) [Tp = hydridotris(pyrazolyl)borate] were prepared by allowing RuClTp(PPh₃)₂ to react with an excess of phosphite. Treatment of the chloro complexes 1 with NaBH₄ in ethanol yielded the hydride RuHTpL(PPh₃) (2a, 2b) and RuHTp[P(OEt)₃]₂ (2c) derivatives. Protonation reaction of 2 with Brønsted acids was studied and led to thermally unstable (above 10 °C) dihydrogen [Ru(η²- H₂)TpL(PPh₃)]⁺ (3a, 3b) and [Ru(η²-H₂)Tp{P(OEt)₃}₂]⁺ (3c) complexes. The presence of the η²-H₂ ligand is indicated by short T_1 min values and J_HD measurements of the partially deuterated derivatives. Aquo [RuTp(H₂O)L(PPh₃)]BPh₄ (4), carbonyl [RuTp(CO)L(PPh₃)]BPh₄ (5), and nitrile [RuTp(CH₃CN)L(PPh₃)]BPh₄ (6) derivatives [L = P(OEt)₃] were prepared by substituting H₂ in the η²-H₂ derivatives 3. Vinylidene [RuTp{CC(H)R}L(PPh₃)]BPh₄ (7, 8) (R = Ph, ^tBu) and allenylidene [RuTp(CCCR1R2)L(PPh₃)]BPh₄ (9-11) complexes (R1 = R2 = Ph, R1 = Ph R2 = Me) were also prepared by allowing dihydrogen complexes 3 to react with the appropriate HCCR and HCCC(OH)R1R2 alkynes. Deprotonation of vinylidene complexes 7, 8 with NEt₃ was studied and led to acetylide Ru(CCR)TpL(PPh₃) (12, 13) derivatives. The trichlorostannyl Ru(SnCl₃)TpL(PPh₃) (14) compound was also prepared by allowing the chloro complex RuClTpL(PPh₃) to react with SnCl₂ · 2H₂O in CH₂Cl₂.     

Organometallic Gold（Ⅲ） Derivatives with Anionic Oxygen Ligands-mononuclear Hydroxo,Alkoxo, and Acetato Complexes： Synthesis and Spectral Study

A variety of gold（Ⅲ） adducts having a-ligated oxygen-donor ligands have been prepared from [Au（ppy）Cl2]（ppy.phenylpyridine）（1） either by partial or total replacement of the chloride ions. The new species comprise hydroxo-[Au（ppy）（OH）Cl]（2）, and [Au（ppy）（OH）2]（3）, oxo-[Au2（ppy）2（μ-O）2]（4）, acetate-[Au（ppy）（O2CMe2）] （5）, and alkoxo complexes-[Au（ppy）（OR）Cl]（6, 7） and [Au（ppy）（OR）2]（8--10）（R=Me, 6 and 8; Et, 7 and 9; Pr, 10）. The dihydroxo and the oxo complexes can be interconverted by refluxing the former in anhydrous THF and the latter in water. The hydroxides 2 and 3 and the acetato complex 5 undergo σ-ligand metathesis in ROH solution（R=Me, Et or Pr） to give the corresponding alkoxides.     

Cationic methyl complexes of rhodium(III): synthesis, structure, and some reactions

Cationic methyl complex of rhodium(III), trans-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1) is prepared by interaction of trans-[Rh(Acac)(PPh₃)₂(CH₃)I] with AgBPh₄ in acetonitrile. Cationic methyl complexes of rhodium(III), cis-[Rh(Acac)(PPh₃)₂ (CH₃)(CH₃CN)][BPh₄] (2) and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (3) (Acac, BA are acetylacetonate and benzoylacetonate, respectively), are obtained by CH₃I oxidative addition to rhodium(I) complexes [Rh(Acac)(PPh₃)₂] and [Rh(BA)(PPh₃)₂] in acetonitrile in the presence of NaBPh₄. Complexes 2 and 3 react readily with NH₃ at room temperature to form cis-[Rh(Acac)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (4) and cis-[Rh(BA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (5), respectively. Complexes 1-5 were characterized by elemental analysis, ¹H and ³¹P{¹H} NMR spectra. Complexes 1, 2, 3 and 4 were characterized by X-ray diffraction analysis. Complexes 2 and 3 in solutions (CH₂Cl₂, CHCl₃) are presented as mixtures of cis-(PPh₃)₂ isomers involved into a fluxional process. Complex 2 on heating in acetonitrile is converted into trans-isomer 1. In parallel with that isomerization, reductive elimination of methyl group with formation of [CH₃PPh₃][BPh₄] takes place. Replacement of CH₃CN in complexes 1 and 2 by anion I⁻ yields in both cases the neutral complex trans-[Rh(Acac)(PPh₃)₂(CH₃)I]. Strong trans influence of CH₃ ligand manifests itself in the elongation (in solid) and labilization (in solution) of rhodium-acetonitrile nitrogen bond.     

Syntheses, spectroscopic and structural characterizations and metal ion binding properties of Schiff bases derived from 4′-aminobenzo-15-crown-5

A series of benzyloxybenzaldehyde derivatives (1-4) were synthesized by the reactions of 4-(bromomethyl)benzonitrile with 4-hydroxy-3-methoxybenzaldehyde (vanillin), 2-hydroxy-3-methoxybenzaldehyde (o-vanillin), 2-hydroxy-4-methoxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde. Condensation reactions among the new benzyloxybenzaldehyde derivatives (1-4) with 4′-aminobenzo-15-crown-5 yielded the new Schiff base compounds (5-8). Sodium complexes (5a-8a) and potassium complexes (5b-8b) were prepared with NaClO₄ and KI, respectively. All of these synthesized compounds were characterized on the basis of FT-IR, ¹H and ¹³C NMR, mass spectrometry and elemental analyses data. The solid state structures of compounds 8 and 5a were determined by X-ray crystallography. The extraction abilities of compounds 5-8 were also evaluated in CH₂Cl₂ by using several main group and transition metal picrates, such as Na⁺, K⁺, Pb²⁺, Cr³⁺, Ni²⁺, Cu²⁺ and Zn²⁺.     

Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies

Reactions of 0.5 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ (arene = η⁶-C₆H₆, η⁶-p-ⁱPrC₆H₄Me) and [(Cp∗)M(μ-Cl)Cl]₂ (M = Rh, Ir; Cp∗ = η⁵-C₅Me₅) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η⁶-C₆H₆)Ru(L)Cl]⁺ (L = L1, 1; L2, 2; L3, 3), [(η⁶-p-ⁱPrC₆H₄Me)Ru(L)Cl]⁺ (L = L1, 4; L2, 5; L3, 6), [(Cp∗)Rh(L)Cl]⁺ (L = L1, 7; L2, 8; L3, 9) and [(Cp∗)Ir(L)Cl]⁺ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η⁶-arene)Ru(μ-Cl)Cl]₂ and [(Cp∗)M(μ-Cl)Cl]₂ give rise to the dicationic dinuclear complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (L = L1, 13; L2, 14; L3, 15), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (L = L1, 16; L2, 17; L3, 18), [{(Cp∗)RhCl}₂(L)]²⁺ (L = L1, 19; L2, 20; L3, 21) and [{(Cp∗)IrCl}₂(L)]²⁺ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF₆, [6]PF₆, [7]PF₆ and [18](PF₆)₂ have been established by single crystal X-ray structure analysis.     

Cyanide bridged tetranuclear complex with a novel terthiophene based ligand

A new terthiophene based ligand (L = 3-(2-pryridyl)-5-(2,2′:5′,2″-terthien-3′-yl) pyrazole was synthesized. The reaction of Ni(BF₄)₂·6H₂O, L and nBu₄N[Fe(CN)₃tp^∗] (tp^∗ = tris(3,5-dimethylpyrazol-1-yl)borohyrdide) with NaBPh₄ in MeOH/acetone yielded a cyanide bridged tetranuclear complex [Fe₂Ni₂(CN)₆(tp^∗)₂(L)₄](BPh₄)₂ (1). The electrochemical properties of both 1 and L were investigated, and magnetic susceptibility measurements of 1 were conducted, revealing that ferromagnetic interactions were operative within the tetranuclear core.     

Mono and dinuclear complexes of half-sandwich platinum group metals (Ru, Rh and Ir) bearing a flexible pyridyl-thiazole multidentate donor ligand

The mononuclear cationic complexes [(η⁶-C₆H₆)RuCl(L)]⁺ (1), [(η⁶-p-ⁱPrC₆H₄Me)RuCl(L)]⁺ (2), [(η⁵-C₅H₅)Ru(PPh₃)(L)]⁺ (3), [(η⁵-C₅Me₅)Ru(PPh₃)(L)]⁺ (4), [(η⁵-C₅Me₅)RhCl(L)]⁺ (5), [(η⁵-C₅Me₅)IrCl(L)]⁺ (6) as well as the dinuclear dicationic complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (7), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (8), [{(η⁵-C₅H₅)Ru(PPh₃)}2(L)]²⁺ (9), [{(η⁵-C₅Me₅)Ru(PPh₃)}₂(L)]²⁺ (10), [{(η⁵-C₅Me₅)RhCl}₂(L)]²⁺ (11) and [{(η⁵-C₅Me₅)IrCl}₂(L)]²⁺ (12) have been synthesized from 4,4′-bis(2-pyridyl-4-thiazole) (L) and the corresponding complexes [(η⁶-C₆H₆)Ru(μ-Cl)Cl]₂, [(η⁶-p-ⁱPrC₆H₄Me)Ru(μ-Cl)Cl]₂, [(η⁵-C₅H₅)Ru(PPh₃)₂Cl)], [(η⁵-C₅Me₅)Ru(PPh₃)₂Cl], [(η⁵-C₅Me₅)Rh(μ-Cl)Cl]₂ and [(η⁵-C₅Me₅)Ir(μ-Cl)Cl]₂, respectively. All complexes were isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV-vis spectroscopy. The X-ray crystal structure analyses of [3]PF₆, [5]PF₆, [8](PF₆)₂ and [12](PF₆)₂ reveal a typical piano-stool geometry around the metal centers with a five-membered metallo-cycle in which 4,4′-bis(2-pyridyl-4-thiazole) acts as a N,N′-chelating ligand.     

New structural motifs of silver and gold complexes of pyridine-functionalized benzimidazolylidene ligands

Reaction of 1,3-bis(picolyl)benzimidazolium chloride ([HL1]Cl) with Ag₂O yields mononuclear complex [Ag(L1)Cl] (2), further reaction of 2 with Au(Et₂S)Cl afforded [Au(L1)Cl] (3). Treatment of 2 with AgBF₄ gave the trinuclear silver cluster [Ag₃(L1)₃](BF₄)₃ (4), whereas the digold complex [Au₂(L1)₂](BF₄)₂ (5) can be easily obtained from the carbene transfer reaction of 4 with Au(Et₂S)Cl. A one-dimensional coordination polymer {[Ag(L2)](BF₄) · CH₃CN}_n (8) was isolated from the reaction of [Ag(L2)Cl] (7, L2 = 1-benzyl-3-picolylbenzimidazolylidene) with additional Ag⁺ in good yield. The dinuclear [Ag₂(L3)₂](PF₆)₂ (12, L3 = 1,4-di(N-benzylbenzimidazolylidene)but-2-yne) is a 18-membered macrocycle. All these complexes have been structurally characterized. Complex 2 shows a dimeric structure because of intermolecular Ag?Cl interactions. Complex 4 consists of a triangular Ag₃ ring with very short Ag-Ag contacts 2.777(1) Å, the Au-Au distance in 5 is 3.206(2) Å showing very weak Au-Au interaction and the macrocyclic cations in 12 are aligned one above another to form channels filled with hexafluorophosphate anions. The complexes 2-5, 8, and 12 are intensely luminescent upon irradiation of uv light, and their emission properties are briefly described.     

Synthesis and metal ion complexation of spin labeled 18-crown-6 ethers containing an acridone or an acridine fluorophore unit

Double (spin and fluorescence) labeled pyrroline derivatives of crown ethers containing an acridone or an acridine fluorophore unit (1 and 2) and their diamagnetic analogues (3 and 4) were synthesized. Their fluorescent behavior as well as their complexation properties toward selected metal ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Zn²⁺) were examined.     

Complexing properties of two benzocrown-ether moieties arranged at a cyclobutane ring system

Biscrown ethers 2a-c and 3a-c arranged at a cyclobutane ring were prepared by intermolecular [2+2] photocycloaddition of vinylated benzocrown ethers. The complexing behavior of 2a-c toward alkali metal cations was evaluated by ESI-MS analysis, liquid-liquid extraction, and the comparison of complexing stability constant. An intramolecular sandwich-type 1:1 (host/guest) complexation was observed by ESI-MS analysis in the competitive system where 2a-Na⁺, 2b-K⁺, and 2c-Cs⁺ were formed selectively. In the liquid-liquid extraction, however, 2a hardly extracted any cation, while both 2b and 2c efficiently extracted larger cations such as K⁺, Rb⁺, and Cs⁺. It was found that the complexing stability constant of 2a-Na⁺ is lower than that of benzo-15-crown-5-Na⁺ though extraordinarily high values were obtained for 2b-K⁺ and 2c-Cs⁺ complexes compared with those of 18-crown-6-K⁺ and dibenzo-24-crown-8-Cs⁺ complexes, respectively. Hence, the excellent complexing ability was achieved by using the cyclobutane ring, which strongly preorganized two benzocrown-ether moieties for the larger alkali metal cations.     

Syntheses and characterization of mono and dinuclear complexes of platinum group metals bearing benzene-linked bis(pyrazolyl)methane ligands

Reaction of the benzene-linked bis(pyrazolyl)methane ligands, 1,4-bis{bis(pyrazolyl)-methyl}benzene (L1) and 1,4-bis{bis(3-methylpyrazolyl)methyl}benzene (L2), with pentamethylcyclopentadienyl rhodium and iridium complexes [(η⁵-C₅Me₅)M(μ-Cl)Cl]₂ (M = Rh and Ir) in the presence of NH₄PF₆ results under stoichiometric control in both, mono and dinuclear complexes, [(η⁵-C₅Me₅)RhCl(L)]⁺ {L = L1 (1); L2 (2)}, [(η⁵-C₅Me₅)IrCl(L)]⁺ {L = L1 (3); L2 (4)} and [{(η⁵-C₅Me₅)RhCl}₂(μ-L)]²⁺ {L = L1 (5); L2 (6)}, [{(η⁵-C₅Me₅)IrCl}₂(μ-L)]²⁺ {L = L1 (7); L2 (8)}. In contrast, reaction of arene ruthenium complexes [(η⁶­arene)Ru(μ-Cl)Cl]₂ (arene = C₆H₆, p-ⁱPrC₆H₄Me and C₆Me₆) with the same ligands (L1 or L2) gives only the dinuclear complexes [{(η⁶-C₆H₆)RuCl}₂(μ-L)]²⁺ {L = L1 (9); L2 (10)}, [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(μ-L)]²⁺ {L = L1 (11); L2 (12)} and [{(η⁶-C₆Me₆)RuCl}₂(μ-L)]²⁺ {L = L1 (13); L2 (14)}. All complexes were isolated as their hexafluorophosphate salts. The single-crystal X-ray crystal structure analyses of [7](PF₆)₂, [9](PF₆)₂ and [11](PF₆)₂ reveal a typical piano-stool geometry around the metal centers with six-membered metallo-cycle in which the 1,4-bis{bis(pyrazolyl)-methyl}benzene acts as a bis-bidentate chelating ligand.     

Trifluoroacetylacetonate rhodium(III) methyl complexes, cis-[Rh(TFA)(PPh3)2(CH3)(L)][BPh4] and cis-[Rh(TFA)(PPh3)2(CH3)(I)] (L = CH3CN, NH3, pyridine), in comparison with their acetylacetonate analogs

The oxidative addition of CH₃I to planar rhodium(I) complex [Rh(TFA)(PPh₃)₂] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1), or neutral, cis-[Rh(TFA)(PPh₃)₂(CH₃)(I)] (4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH₃ and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (2) and cis-[Rh(TFA)(PPh₃)₂(CH₃)(Py)][BPh₄] (3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh₃)₂(CH₃)(I)] (5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] in acetone at −15 °C. Complexes 1-5 were characterized by elemental analysis, ³¹P{¹H}, ¹H and ¹⁹F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1-5 and related complexes are discussed from the viewpoint of their isomerism.     

Synthesis and reactivity of [(η-[32](1,3)Cyclophane)Mn(CO)3][BF4]

The manganese cyclophane complex, [(η⁶-[3₂](1,3)cyclophane)Mn(CO)₃][BF₄] 2, was prepared by the reaction of [[3₂](1,3)cyclophane] 1 with Mn(CO)₅FBF₃. Reaction of 2 with NaBH₃CN yielded the cyclohexadienyl manganese complex [(η⁵-6H-[3₂](1,3)cyclophane)Mn(CO)₃] 3. Interestingly, treatment of 3 with Mn(CO)₅FBF₃ gave the bis-manganese complex (η⁶,η⁵-6H-[3₂](1,3)cyclophane)[Mn(CO)₃]₂[BF₄] 4. When NaBH₃CN was treated with 4, [(η⁵,η⁵-6H,6^′H-[3₂](1,3)cyclophane)Mn(CO)₃] 5 was isolated as yellow crystals. The structure of compounds 2 and 3 were determined by single-crystal X-ray crystallography.     

Crystal structure, spectroscopy and magnetism of trinuclear nickel(II), cobalt(II) complexes and their solid solution

Four new complexes [Ni₃(μ-L)₆(H₂O)₆](NO₃)₆·6H₂O (1), [Co₃(μ-L)₆(H₂O)₆](NO₃)₆·6H₂O (2), [Ni₃(μ-L)₆(H₂O)₄(CH₃OH)₂](NO₃)₆·4H₂O (3), [Co₃(μ-L)₆(H₂O)₄(CH₃OH)₂](NO₃)₆·4H₂O (4) (L = 4-amino-3,5-dimethanyl-1,2,4-triazole) were synthesized and structurally characterized by X-ray single-crystal diffraction. The structural analyses show that complex 1 and 2 are isomorphous; complex 3 and 4 are isomorphous. Four complexes all consist of the linear trinuclear cations ([M₃(μ-L)₆(H₂O)₆]⁶⁺ (M = Ni,Co) for 1 and 2; [M₃(μ-L)₆(H₂O)₄(CH₃OH)₂]⁶⁺ (M = Ni,Co) for 3 and 4), NO₃⁻ anions and crystallized water molecules. In the trinuclear cations, the central M(II) ions and two terminal M(II) ions are bridged by three triazole ligands. Other eleven solid solution compounds which are isomorphous with complex 3 and 4 were obtained by using different ratio of Ni(II) and Co(II) ions as reactants and ICP result indicates that ligand L has higher selectivity of Ni(II) ions than that of Co(II) ions. The magnetic analysis was carried out by using the isotropic spin Hamiltonian ? = −2J(?₁?₂ + ?₂?₃) (for complexes 1 and 3) and simultaneously considering the temperature dependent g factor (for complexes 2 and 4). Both the UV-Vis spectra and the magnetic properties of the solid solutions can be altered systematically by adjusting the Co(II)/Ni(II) ratio.