Chlorido Ligands Research Articles

Synthesis and Structural Characterisation of cis‐ and trans‐[(hppH)2PtCl2], [(hppH)3­PtCl]+Cl– and Some New Salts of the [hppH2]+ Cation (hppH = 1,3,4,6,7,8‐Hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine): The Importance of Hydrogen Bonding

AbstractThe reaction between the guanidine derivative hppH (hppH = 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine) and K2PtCl4 in H2O affords the salt [hppH2]2[PtCl4], which reacts further with Li(hpp) in thf to give cis‐[(hppH)2PtCl2]. The corresponding trans isomer is obtained from the reaction between [(dmso)2PtCl2] and hppH. hppH easily replaces another chlorido ligand to give [(hppH)3PtCl]+Cl–. [hppH2]Cl is formed as a hygroscopic side‐product in the synthesis of [(hppH)2PtCl2] and takes up 1 equiv. of H2O to give [hppH2]Cl·H2O. We report the crystal structures of cis‐ and trans‐[(hppH)2PtCl2], [(hppH)3PtCl]+Cl– and some salts of the [hppH2]+ cation, namely [hppH2]2[PtCl4] and the Pt‐free salts [hppH2][BPh4], [hppH2]Cl and [hppH2]Cl·H2O, which have an increasing degree of directed intermolecular hydrogen contacts. The crystal structure of [hppH2]Cl·H2O features helical chains of Cl–·H2O connected via [hppH2]+ cations. The effects of hydrogen bonding on the structures of these compounds in the solid state are discussed. Finally, quantum chemical calculations provide further insight into the structures and properties of some of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Acetato complexes of molybdenum(V): A novel tetranuclear core based on the metal–metal bonded {Mo 2O 4} 2+ units

A series of acetato complexes of molybdenum(V), based on the singly metal–metal bonded {Mo 2O 4} 2+ structural fragment, has been prepared. A dinuclear (PyH) 3[Mo 2O 4Cl 4(OOCCH 3)] · CH 3CN ( 1) (PyH + = pyridinium cation, C 5H 5NH +) was obtained upon the reaction of (PyH) 5[MoOCl 4(H 2O)] 3Cl 2 with the equimolar solution of pyridine and acetic acid in acetonitrile at ambient conditions. The acetato ligand in 1 is coordinated to a pair of molybdenum atoms in a syn– syn bidentate bridging manner. (PyH) n [MoOBr 4] n afforded in an analogous synthetic procedure a tetranuclear cluster, [Mo 4O 8(OOCCH 3) 3(OH)Py 4] · 1/2CH 3CN · 1/2H 2O ( 3), with a novel core which may be envisioned as the acetate- and hydroxide-assisted assembly of {Mo 2O 4} 2+ building blocks. Its structure is presented in terms of known tetranuclear clusters which are also composed of two {Mo 2O 4} 2+ units. The acetato ligands in 3 adopted apart from bidentate bridging binding modes also a monodentate one. Partial substitution of chlorido ligands in (PyH) 3[Mo 2O 4Cl 4(OOCCH 3)] · CH 3CN ( 1) with pyridine resulted in a neutral [Mo 2O 4Cl(OOCCH 3)Py 3] · Pr i OH · Py ( 2) which retained the original acetate coordination. The title compounds were fully characterized by X-ray diffraction studies and infrared vibrational spectroscopy.

Dichlorido(9-methyladenine-κN7)(η5-pentamethylcyclopentadienyl)iridium(III) dichloromethane solvate

In the title complex, [Ir(C10H15)Cl2(C6H7N5)]·CH2Cl2 or [Ir(η5-C5Me5)Cl2(9-MeAde-κN 7)]·CH2Cl2 (9-MeAde = 9-methyl­adenine), the coordination geometry of the IrIII atom approximates to a three-legged piano stool. The 9-methyl­adenine ligand is coordinated in a monodentate fashion to the Ir centre through its N-7 atom. The crystal structure contains centrosymmetric pairs of mol­ecules, inter­acting through two N—H⋯N hydrogen bonds. An intra­molecular N—H⋯Cl hydrogen bond is formed between the H atom of an NH2 group and a chlorido ligand. Further short intra- and inter­molecular C—H⋯Cl contacts are observed.

Catena-Poly[bis-(sulfamethoxazolium) [[trichloridocadmate(II)]-μ-chlorido] monohydrate

In the title compound, {(C10H12N3O3S)2[CdCl4]·H2O}n, the CdII atom is five-coordinate with a distorted trigonal–bipyramidal geometry formed by chloride ions. The Cd atom and two of the Cl atoms lie on a mirror plane. The cation is protonated on the amino group N atom; it is not coordinated to cadmium, but is hydrogen bonded to the chlorido ligands. Each water mol­ecule bridges two chlorido ligands, generating ring motifs along the –Cd—Cl—Cd– chains. The isoxazole unit and the amide groups are linked through a pair of N—H⋯N hydrogen bonds. The crystal structure is stabilized by N—H⋯O, O—H⋯Cl, C—H⋯N, N—H⋯Cl and C—H⋯O hydrogen bonds.

N,N′-Bis(2,6-dimethylphenyl)pentane-2,4-diiminato-κ2 N,N′]trichlorido(tetrahydrofuran-κO)zirconium

The nacnac (pentane-2,4-diiminato) ligand in the title compound, [Zr(C21H25N2)Cl3(C4H8O)], displays a κ2-coordination to the Zr center. Three chlorido ligands and a coordinated tetrahydrofuran (THF) molecule complete the octahedral environment of the metal. Despite the C 2 symmetry observed in the 1H NMR spectrum, the THF molecule is found trans to one of the N atoms of the nacnac ligand. The asymmetric unit contains two molecules. In one THF ligand one C atom and four H atoms are disordered over two sites in the ratio ca 0.58:0.42.

Synthesis and Characterization of Mononuclear Ruthenium(III) Pyridylamine Complexes and Mechanistic Insights into Their Catalytic Alkane Functionalization with m‐Chloroperbenzoic Acid

A series of mononuclear RuIII complexes [RuCl2(L)]+, where L is tris(2-pyridylmethyl)amine (TPA) or one of four TPA derivatives as tetradentate ligand, were prepared and characterized by spectroscopic methods, X-ray crystallography, and electrochemical measurements. The geometry of a RuIII complex having a non-threefold-symmetric TPA ligand bearing one dimethylnicotinamide moiety was determined to show that the nicotine moiety resides trans to a pyridine group, but not to the chlorido ligand. The substituents of the TPA ligands were shown to regulate the redox potential of the ruthenium center, as indicated by a linear Hammett plot in the range of 200 mV for RuIII/RuIV couples with a relatively large rho value (+0.150). These complexes act as effective catalysts for alkane functionalization in acetonitrile with m-chloroperbenzoic acid (mCPBA) as terminal oxidant at room temperature. They exhibited fairly good reactivity for oxidation of cyclohexane (C--H bond energy 94 kcal mol(-1)), and the reactivity can be altered significantly by the electronic effects of substituents on TPA ligands in terms of initial rates and turnover numbers. Catalytic oxygenation of cyclohexane by a RuIII complex with 16O-mCPBA in the presence of H2 18O gave 18O-labeled cyclohexanol with 100% inclusion of the 18O atom from the water molecule. Resonance Raman spectra under catalytic conditions without the substrate indicate formation of a RuIV==O intermediate with lower bonding energy. Kinetic isotope effects (KIEs) in the oxidation of cyclohexane suggest that hydrogen abstraction is the rate-determining step and the KIE values depend on the substituents of the TPA ligands. Thus, the reaction mechanism of catalytic cyclohexane oxygenation depends on the electronic effects of the ligands.

Alkoxo, chlorido, and methyl derivatives of oxidomolybdenum(VI) complexes with tetradentate [O 3N]-type ligands

Dioxomolybdenum(VI) complex [MoO 2(Heg) 2] (H 2eg = 1,2-ethanediol) reacts with phenolic ligand precursors tris(2-hydroxy-3,5-dimethylbenzyl)amine (H 3L Me) and tris(2-hydroxy-3,5-di- tert-butylbenzyl)amine (H 3L tBu ) to form oxomolybdenum(VI) complexes of type [MoO(L R) (Heg)]. The Heg ligand can be replaced by other alcohols (i.e. 2-aminoethanol, 2-amino-2-methylpropan-1-ol, 2-(dimethylamino)ethanol or allyl alcohol) in the reaction at refluxing toluene or at neat alcohol. Treatment of [MoO(L R)(Heg)] with Me 3SiCl yields corresponding chlorido complexes [MoO(L R)Cl]. These are also formed in the reaction of H 3L R with [MoO 2Cl 2(dmf) 2]. The reaction of [MoO(L R)Cl] with MeMgI yields air-stable monomethyl derivatives [MoO(L R)(Me)]. X-ray analyses of [MoO(L tBu )X] (X = Heg, 2-methyl-2-aminopropanolate anion or Cl) reveal that the ligand L R has a tetradentate coordination through three oxygen donors and one nitrogen donor, which is located trans to the terminal oxo group. The sixth coordination site is occupied by an oxygen donor, a chlorido ligand or a methyl group.

1,3-Bis(α-aminoisopropyl)benzene, meta-C 6H 4(CMe 2NH 2) 2: An N, N-bridging and N, C, N-cyclometalating ligand

Saponification of the bis(carbamic acid ester) 1,3-C 6H 4(CMe 2NHCO 2Me) 2 ( 1), made by the addition of methanol to commercial 1,3-C 6H 4(CMe 2NCO) 2, yielded the meta-phenylene-based bis(tertiary carbinamine) 1,3-C 6H 4(CMe 2NH 2) 2 ( 2). Dinuclear [{(η 4-1,5-C 8H 12)RhCl} 2{μ-1,3-C 6H 4(CMe 2NH 2) 2}] ( 3) resulted from the action of 2 on [{(η 4-1,5-C 8H 12)Rh(μ-Cl)} 2] in toluene. Combination of 2 with PdCl 2 or K 2[PdCl 4] gave the dipalladium macrocycle trans, trans-[{μ-1,3-C 6H 4(CMe 2NH 2) 2} 2(PdCl 2) 2] ( 4) along with cyclometalated [{2,6-C 6H 3(CMe 2NH 2) 2-κ N,κ C 1,κ N′}PdCl] ( 5). Substitution of PEt 3 for the labile chlorido ligand of 5 afforded [{2,6-C 6H 3(CMe 2NH 2) 2-κ N,κ C 1, κ N′}Pd(PEt 3)]Cl ( 6). The crystal structures of the following compounds were determined: bis(carbamic acid ester) 1, ligand 2 as its bis(trifluoroacetate) salt [1,3-C 6H 4(CMe 2NH 3) 2](O 2CCF 3) 2, 2 · ( HAc f) 2, complexes 3 and 6, as well as 1,3-C 6H 4(CMe 2OH) 2 (the diol analogue of 2).

(4-Aminobenzoato-κ2O,O′)chlorido(di-2-pyridylamine-κ2N,N′)copper(II) monohydrate

In the title compound, [Cu(C7H6NO2)Cl(C10H9N3)]·H2O, the Cu atom has a distorted square-pyramidal geometry defined by one N,N-bidentate 2,2′-bipyridylamine (C10H9N3) mol­ecule, one O,O-bidentate p-amino­benzene­carboxyl­ate (C7H6NO2−) anion and one apical chlorido ligand. The Cu atom deviates from the mean plane of the basal atoms towards the Cl atom by 0.2591 (1) A. The component species are connected to each other by N—H⋯Cl, O—H⋯Cl, N—H⋯O and O—H⋯O hydrogen bonds.

Aiding Factors in the Formation of Azaplatinacyclobutane Rings – X‐ray and Crystal Structure of [Pt{CH(Ph)CH2NEt2‐κC,κN}(N,N,N′,N′‐tetramethylethylenediamine)]+ and of Its Open‐Chain Precursor

AbstractThe addition products 2 of a secondary amine to a coordinated olefin, in the cationic complexes [PtCl(η2‐CH2=CHR)(tmeda)]+ (tmeda = N,N,N′,N′‐tetramethylethylenediamine; R = Me, 1a; Ph, 1b, H, 1c), undergo in basic medium an intramolecular nucleophilic substitution with elimination of the chlorido ligand and formation of an azaplatinacyclobutane ring 3. The ring‐closing process occurs notwithstanding the absence of a labilizing ligand trans to the leaving chlorido ligand and of bulky substituents on the amino–ethanide chain. If the addition product 2 is a mixture of Markovnikov and anti‐Markovnikov isomers, the ring‐closing reaction is faster for the anti‐Markovnikov form, and this leads to an increase of the relative amount of the anti‐Markovnikov isomer in the cyclized species 3. The difference in the rate of formation of the azaplatinacyclobutane ring between the two isomers has been interpreted on the basis of a more favorable stereochemistry in the case of the anti‐Markovnikov form. The X‐ray crystal structures of [Pt{CH(Ph)CH2NEt2‐κC,κN}(tmeda)]+ (3bn) and of its open‐chain precursor, [PtCl{CH(Ph)CH2NHEt2}(tmeda)]+ (2bn) fully support this hypothesis.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Tripyrrinatocadmium Complexes: Enforcing Supramolecular Aggregation by a Large Ion

AbstractA newly developed method for the preparation of free base tripyrrin ligands HTrpy by cyanide‐promoted demetalation of nickel chelates TrpyNiNCO was used in order to explore the chemistry of cadmium tripyrrins TrpyCdX with a variety of anionic co‐ligands X. The introduction of the large CdII ion into the tripyrrin N3 coordination site was accomplished by the use of cadmium acetate as the metal precursor. Ligand exchange experiments using sodium salts of different anions disclose a marked tendency for pentacoordination, which is achieved either by the formation of chelates or of 1D coordination polymers that form as a consequence of the size of the central metal. The attempted introduction of chlorido, iodido, or cyanato ligands thus leads mainly to decomposed material, while the use of 1,1,1‐trifluoracetylacetonate, salicylate, and acetate ligands results in stable, pentacoordinate and monomeric complexes with the external ligand bound as a four‐ or six‐membered O,O‐chelate ring. With the pseudohalogenido ligands thiocyanate, selenocyanate, and azide as well as with the weakly coordinating trifluoroacetate 1D coordination polymers with a variety of chain structures were obtained and investigated by X‐ray diffraction studies. Interestingly TrpyCdN3 is present in the crystal as a coordinatively and hydrogen‐bonded methanol adduct with a dimeric repeating subunit. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthetic and X-ray Structural and Reactivity Studies of Cp*RuIVComplexes Containing Bidentate Dithiocarbonate, Xanthate, Carbonate, and Phosphinate Ligands (Cp* = η5-C5Me5)

The reaction of [Cp*RuCl2]2 (1; Cp* = eta5-C5Me5) with tetraalkyldithiuram disulfides (R2NC(S)SS(S)CNR2, R = Me, Et), isopropylxanthic disulfide ([iPrOC(S)S]2), and bis(thiophosphoryl) disulfide ([(iPrO)2P(S)S]2) led to the isolation of dark-red crystalline solids of Cp*RuIVCl2(eta2-dithiolate) complexes [dithiolate = S2CNR2, DTCR (2a, R = Me; 2b, R = Et), S2COiPr (3), and S2P(iPrO)2 (4)]. Dichlorido substitution in 2 and 3 with DTCEt and S2COiPr anions yielded RuIV derivatives containing bis(DTC) and mixed DTC-dithiocarbonate ligands. These are the first organoruthenium complexes of such ligands. The reaction of monophosphines with 2a resulted in monochlorido substitution, whereas the analogous reaction with 3 resulted in displacement of both chlorido ligands and reduction of the metal center to RuII. Reduction at Ru was also observed in the reaction of 2a with [CpCr(CO)3]2. Of these complexes, only 2 and 3 are air-stable in the solid state for an extended period. All of the complexes have been spectrally characterized, and selected compounds are also crystallographically characterized.

π‐Conjugated α,ω‐Diphenylpolyene Complexes of RuClCp* Fragment(s) inη4‐s‐cis Conformation

Abstractπ‐Conjugated polyene complexes of the general formula (RuClCp*)n(polyene) [2: n = 1, polyene = 1,4‐diphenylbuta‐1,3‐diene; 3: n = 1, polyene = 1,6‐diphenylhexa‐1,3,5‐triene; 4: n = 2, polyene = 1,8‐diphenylocta‐1,3,5,7‐tetraene; 5: n = 2, polyene = 1,10‐diphenyldeca‐1,3,5,7,9‐pentaene; 6: n = 3, polyene = 1,12‐diphenyldodeca‐1,3,5,7,9,11‐hexaene], in which each ruthenium(II) atom has Cp* (Cp* = η5‐C5Me5) and chlorido ligands, were prepared by treating [Ru(μ3‐Cl)Cp*]4 (1) with the corresponding α,ω‐diphenylpolyenes. All diene units of the complexes were fully metalated by the coordination of “RuClCp*” fragments in an η4‐s‐cis conformation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The Assembly of Dinuclear Alkoxido‐Bridged CuII Halide Complexes of Pyridine Alcohols To Form Tetranuclear and Polynuclear Compounds: Synthesis, Structure, and Magnetic Properties

AbstractReaction of CuX2 (X = Cl, Br) with pyridine alcohol ligands [2‐(hydroxymethyl)pyridine = Hhmp, 2‐(hydroxyethyl)pyridine = Hhep and 2‐(hydroxypropyl)pyridine = Hhpp] affords a series of new CuII alkoxide complexes with a similar Cu2O2 structural motif: a dinuclear complex, [Cu2(hpp)2Br2] (1), two tetranuclear compounds, [Cu4(hpp)4Br4] (2) and [Cu4(hpp)4Cl4] (3), and polynuclear chains, [Cu2(hep)2Cl2]n (4) and [Cu2(Hhmp)2Cl4]n (5). The dinuclear complex 1 represents the basic building unit of the four other materials. In this family of compounds, the pyridine alcohol type ligands (Hhmp, Hhep, or Hhpp) provide the two alkoxido functions that bridge the CuII centers. The tetranuclear analogues exhibit an unusual structure of the defect dicubane‐like type with two missing vertices. The one‐dimensional polymers 4 and 5 are composed of Cu2O2 dinuclear units interlinked through bridging chlorido ligands to form infinite chains. The analysis of the magnetic susceptibility measurements indicates the presence of strong antiferromagnetic coupling between the S = 1/2 CuII metal ions through the bis(alkoxido) bridge. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Formation and Structural Characterization of [RuCl2(CO)2(SPh2)2], [RuCl2(CO)3(OH2)], and [Ru(OH2)6][RuCl3(CO)3]2 · 2H2O

While the room temperature reaction of [RuCl2(CO)3]2 and Ph2S in tetrahydrofuran in air affords [RuCl2(CO)2(SPh2)2] (1) in moderate yield, that in dichloromethane results in the formation of a mixture of [RuCl2(CO)3(H2O)] (2) and [Ru(H2O)6][RuCl3(CO)3]2·2H2O (3). Very small amounts of 1 are produced only upon prolonged reflux of the reagents. All compounds were characterized by X-ray crystallography. 1 crystallizes as discrete octahedral cis(CO), cis(Cl), trans(Ph2S) complexes, which are joined into stacks by weak H···Cl hydrogen bonds. 2 is also composed of discrete octahedral complexes. Four hydrogen bonds involving aqua and chlorido ligands link two complexes into a dimer. The structure of 3 consists of octahedral hexaaquaruthenium cations and two tricarbonyltrichloridoruthenate anions. The water of crystallization is involved in hydrogen bonding between the cations and anions resulting in the formation of a continuous three-dimensional network.

C 4H 3SSeCH 2CH 2OC 6H 5: synthesis, characterization and reaction with palladium(II) and nickel(II)

ThSeCH 2CH 2OPh (Th=2-thienyl, C 4H 3S-; Ph=phenyl) ( 2) has been prepared by the reaction of BrCH 2CH 2OPh ( 1) and ThSeLi. The compound was characterized by 13C{ 1H}- and 77Se-NMR spectroscopy and X-ray crystallography. 2 is monoclinic, space group P2 1/ c, a=10.865(2), b=5.152(1), c=41.996(8) Å, β=92.20(3)°. All bond lengths and angles are quite normal as exemplified by the respective SeC(alkyl) and SeC(aryl) bonds of 1.957(6)–1.966(6) and 1.901(7)–1.905(7) Å. The lattice is composed of discrete molecules that are joined together by weak hydrogen bonds into a three-dimensional network. Upon treating ThSeCH 2CH 2OPh with [PdCl 2(NCPh) 2] and [NiCl 2(PPh 3) 2] in benzene, a dinuclear palladium complex [Pd 2Cl 2(μ-Cl)(μ-SeTh)(PPh 3) 2] ( 3) and a mononuclear complex [PdCl 2(PPh 3) 2] ( 4) were formed together with a precipitation of NiCl 2. The X-ray quality crystals were recrystallized in CH 2Cl 2. 3·2.5CH 2Cl 2 is monoclinic, space group C2/ c, a=32.907(7), b=14.545(3), c=22.433(5) Å, β=114.37(3)° and contains a novel asymmetrical arrangement of one bridging chlorido and thienylselenolato ligand. Both palladium atoms show an square-planar coordination. The terminal PdCl bond lengths are 2.388(1) and 2.346(1) Å with slightly longer distances of 2.418(1) and 2.450(1) Å involving the bridging chlorido ligand. The PdSe distances are 2.4092(9) and 2.4376(7) Å.

Mono(pentamethylcyclopentadienyl)tantalum Complexes Containing a Structurally Versatile Enediamido(2−) Ligand

Treatment of Cp*TaCl4 with 1 equiv of Li2(R2-dad) in THF afforded Cp*Ta(R2-dad)Cl2 (R = iPr (1), tBu (2)). The chlorido ligands of 1 and 2 reacted smoothly with 2 equiv of LiC⋮CtBu, MeMgI and LiStBu, resulting in Cp*Ta(R2-dad)(C⋮CtBu)2 (R = iPr (3), tBu (4)), Cp*Ta(R2-dad)Me2 (R = iPr (5), tBu (6)), and Cp*Ta(tBu2-dad)(StBu)2 (7), respectively. The X-ray analyses of 1, 3, 4, 5, and 7 have been carried out. In the structures of 1, 3, 4, and 5, the R2-dad ligand is bound to the metal center with a σ2(N,N‘), π(C,C‘)-coordination mode, which opts for a supine conformation with respect to the Cp* group for 1 and 3, while an alternative prone conformation is adopted for 4 and 5. In contrast, the tBu2-dad ligand of 7 assumes an intriguing η2(N,C) coordination geometry. Treatment of 7 in toluene at 80 °C was found to induce C−S bond cleavage of the thiolates generating Cp*Ta(tBu2-dad)(S) (8), in which the dad ligand resumes a σ2, π-coordination geometry with a prone conformation.

Tetraphenylborate derivatives of titanium(III)

Three new titanium(III) compounds which incorporate solvent molecules have been prepared by replacing the chlorido ligand of cp2TiCl by the non-coordinating group BPh4-. The new compounds are formulated as [cp2Ti(H2O)3]2[BPh4]2, [cp2Ti(N≡CCH3)2]BPh4, and [cp2Ti(py)2]BPh4. The methyl cyanide and pyridine complexes are monomeric and show the normal paramagnetic behaviour of isolated titanium(III) compounds, but the aquo derivative is dimeric with magnetic interaction between titanium atoms.