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.     

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.     

Reactivity of cationic methyl rhodium(III) complexes cis-[Rh(β-diket)(PPh3)2(CH3)(CH3CN)][BPh4] toward ligands of different character: pyridine, carbon monoxide, and triphenylphosphine

Cationic methyl complex of rhodium(III), cis-[Rh(Acac)(PPh₃)₂(CH₃)(Py)][BPh₄] (1) as a single isomer with Py in the trans to PPh₃ position, is formed upon the reaction of cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] with pyridine in methylene chloride solution.Complex 1 was characterized by elemental analysis and by ³¹P{¹H} and ¹H NMR spectra.Cationic pentacoordinate acetyl complexes, trans-[Rh(Acac)(PPh₃)₂(COCH₃)][BPh₄] (2) and trans-[Rh(BA)(PPh₃)₂(COCH₃)][BPh₄] (3), are prepared by action of carbon monoxide on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄], respectively, in methylene chloride solutions.Complexes 2 and 3 were characterized by elemental analysis and by IR, ³¹P{¹H}, ¹³C{¹H} and ¹H NMR. According to NMR data, 2 and 3 in solution are non-fluxional trigonal bipyramids with β-diketonate and acetyl ligands in the equatorial plane and axial phosphines.In solutions, 2 and 3 gradually isomerize into octahedral methyl carbonyl complexes trans-[Rh(Acac)(PPh₃)₂(CO)(CH₃)][BPh₄] (4) and trans-[Rh(BA)(PPh₃)₂(CO)(CH₃)][BPh₄] (5), respectively.Complexes 4 and 5 were characterized by IR, ³¹P{¹H}, ¹³C{¹H} and ¹H NMR, without isolation.Upon the action of PPh₃ on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] and cis-[Rh(BA)(PPh₃)₂(CH₃)(CH₃CN)] [BPh₄], reductive elimination of the methyl ligand as a phosphonium salt, [CH₃PPh₃][BPh₄], occurs to give square planar rhodium(I) complexes [Rh(Acac)(PPh₃)₂] and[Rh(BA)(PPh₃)₂], respectively. The reaction products were identified in the reaction mixtures by ³¹P{¹H} and ¹H NMR.     

Interaction of copper(II) and palladium(II) with linked 2,2′-dipyridylamine derivatives: Synthetic and structural studies

Interaction of copper(II) salts with 2,2′-dipyridylamine (1), N-cyclohexylmethyl-2,2′-dipyridylamine (2), di-2-pyridylaminomethylbenzene (3), 1,2-bis(di-2-pyridylaminomethyl)-benzene (4), 1,3-bis(di-2-pyridylaminomethyl)benzene (5), 1,4-bis(di-2-pyridylaminomethyl)benzene (6), 1,3,5-tris(di-2-pyridylaminomethyl)benzene (7) and 1,2,4,5-tetrakis(di-2-pyridylaminomethyl)benzene (8) has yielded the following complexes: [Cu(2)(μ-Cl)Cl]₂, [Cu(3)(μ-Cl)Cl]₂ · H₂O, [Cu₂(4)(NO₃)₄], [Cu₂(5)(NO₃)₄] · 2CH₃OH, [Cu₂(6)(CH₃OH)₂(NO₃)₄], [Cu₄(8)](NO₃)₄] · 4H₂O while complexation of palladium(II) with 1, 4, 5 and 6 gave [Pd(1)₂](PF₆)₂ · 2CH₃OH, [Pd₂(4)Cl₄], [Pd₂(4)(OAc)₄], [Pd₂(5)Cl₄], [Pd₂(6)Cl₄] and [Pd₂(6)(OAc)₄] · CH₂Cl₂, respectively. X-ray structures of [Cu(2)(μ-Cl)Cl]₂, [Cu(3)(μ-Cl)Cl]₂ · 2C₂H₅OH, [Cu₂(6)(CH₃OH)₂(NO₃)₄], [Pd(1)₂](PF₆)₂ · 2CH₃OH, [Pd₂(4)(OAc)₄] · 4H₂O and [Pd₂(6)(OAc)₄] · 2CH₂Cl₂ are reported. In part, the inherent flexibility of the respective ligands has resulted in the adoption of a diverse range of coordination geometries and lattice arrangements, with the structures of [Pd₂(4)(OAc)₄] · 4H₂O and [Pd₂(6)(OAc)₄] · 2CH₂Cl₂, incorporating the isomeric ligands 4 and 6, showing some common features. Liquid–liquid (H₂O/CHCl₃) extraction experiments involving copper(II) and 1–3, 5, 7and 8 show that the degree of extraction depends markedly on the number of dpa-subunits (and concomitant lipophilicity) of the ligand employed with the tetrakis-dpa derivative 8 acting as the most efficient extractant of the six ligand systems investigated.     

New ferrocenylmethylphosphines - Preparation, characterisation and coordination chemistry of PH(CH2Fc)2, P(CH2Fc)3 [Fc = Fe(η-C5H5)(η-C5H4)] and their derivatives

The new ferrocenylmethylphosphines PH(CH₂Fc)₂ (1) [Fc = Fe(η⁵-C₅H₅)(η⁵-C₅H₄)] and P(CH₂Fc)₃ (2) and the phosphonium salt [P(CH₂Fc)₃(CH₂OH)]I (3) were synthesised from P(CH₂OH)₃ and [FcCH₂NMe₃]I. [P(CH₂Fc)(CH₂OH)₃]Cl (4) was obtained from P(CH₂Fc)(CH₂OH)₂, CH₂O and HCl. The new phosphines and phosphonium salts were fully characterised by NMR and IR spectroscopy and MS. [Mo(CO)₆] reacts with 1 to give [Mo(CO)₅{PH(CH₂Fc)₂}] (5) in high yield, but attempts to employ 2 as a ligand failed. The reaction of [P(CH₂Fc)₃(CH₂OH)]I (3) and [PH(CH₂Fc)₃]I (obtained in situ from 3 and Na₂S₂O₅) with [WI₂(CO)₃(NCMe)₂] gave the complex salts [P(CH₂Fc)₃(CH₂OH)][WI₃(CO)₄] (6) and [PH(CH₂Fc)₃][WI₃(CO)₄] (7), respectively. [P(CH₂Fc)₄]I (8) was synthesized from PH₂CH₂Fc and [FcCH₂NMe₃]I. Crystal structures were obtained for 1, 3-8.     

Nickel(II) and zinc(II) complexes of N-substituted di(2-picolyl)amine derivatives: Synthetic and structural studies

The interaction of di(2-picolyl)amine (1) and its secondary N-substituted derivatives, N-(4-pyridylmethyl)-di(2-picolyl)amine (2), N-(4-carboxymethyl-benzyl)-di(2-picolyl)amine (3), N-(4-carboxybenzyl)-di(2-picolyl)amine (4), N-(1-naphthylmethyl)-di(2-picolyl)amine (5), N-(9-anthracenylmethyl)-di(2-picolyl)amine (6), 1,4-bis[di(2-picolyl)aminomethyl]benzene (7), 1,3-bis[di(2-picolyl)aminomethyl]benzene (8) and 2,4,6-tris[di(2-picolyl)amino]triazine (9) with Ni(II) and/or Zn(II) nitrate has resulted in the isolation of [Ni(1)(NO₃)₂], [Ni(2)(NO₃)₂], [Ni(3)(NO₃)₂], [Ni(4)(NO₃)₂]·CH₃CN, [Ni(5)(NO₃)₂], [Ni(6)(NO₃)₂], [Ni₂(7)(NO₃)₄], [Ni₂(8)(NO₃)₄], [Ni₃(9)(NO₃)₆]·3H₂O, [Zn(3)(NO₃)₂]·0.5CH₃OH, [Zn(5)(NO₃)₂], [Zn(6)(NO₃)₂], [Zn(8)(NO₃)₂] and [Zn₂(9)(NO₃)₄]·0.5H₂O. X-ray structures of [Ni(4)(NO₃)₂]·CH₃CN, [Ni(6)(NO₃)₂] and [Zn(5)(NO₃)₂] have been obtained. Both nickel complexes exhibit related distorted octahedral coordination geometries in which 4 and 6 are tridentate and bound meridionally via their respective N₃-donor sets, with the remaining coordination positions in each complex occupied by a monodentate and a bidentate nitrato ligand. For [Ni(4)(NO₃)₂]·CH₃CN, intramolecular hydrogen bond interactions are present between the carboxylic OH group on one complex and the oxygen of a monodentate nitrate on an adjacent complex such that the complexes are linked in chains which are in turn crosslinked by intermolecular offset π-π stacking between pyridyl rings in adjacent chains. In the case of [Ni(6)(NO₃)₂], two weak CH?O hydrogen bonds are present between the axial methylene hydrogen atoms on one complex and the oxygen of a monodentate nitrate ligand on a second unit such that four hydrogen bonds link pairs of complexes; in addition, an extensive series of π-π stacking interactions link individual complex units throughout the crystal lattice. The X-ray structure of [Zn(5)(NO₃)₂] shows that the metal centre once again has a distorted six-coordinated geometry, with the N₃-donor set of N-(1-naphthylmethyl)-di(2-picolyl)amine (5) coordinating in a meridional fashion and the remaining coordination positions occupied by a monodentate and a bidentate nitrato ligand. The crystal lattice is stabilized by weak intermolecular interactions between oxygens on the bound nitrato ligands and aromatic CH hydrogens on adjacent complexes; intermolecular π-π stacking between aromatic rings is also present.     

Synthesis and molecular structure of [Re2(μ:η-C24H18N4)(CO)6] containing the rtct-tetrakis(2-pyridyl)cyclobutandiyl ligand, derived from the reaction of [Re2(CO)8(MeCN)2] and 1,2-bis(2-pyridyl)ethene

The reaction of the labile compound [Re₂(CO)₈(CH₃CN)₂] with trans-1,2-bis(2-pyridyl)ethene (C₁₂H₁₀N₂) at room temperature in tetrahydrofuran affords the compounds [Re₂(μ:η³-C₁₂H₁₀N₂)(CO)₈] (1) and the oxidative addition product [Re₂(μ-H)(μ:η³-C₁₂H₉N₂)(CO)₇] (2). When the reaction is carried out at temperatures of refluxing tetrahydrofuran, besides compounds 1 and 2, the oxidative addition product [Re₂(μ-H)(μ:η⁴-C₁₂H₉N₂)(CO)₆] (3), the insertion product [Re₂(μ:η⁴-C₁₂H₁₀N₂)(CO)₈] (4) and [Re₂(μ:η⁶-C₂₄H₁₈N₄)(CO)₆] (5) are obtained. Compound 5 contains the organic ligand rtct-tetrakis(2-pyridyl)cyclobutandiyl which is derived from a [2 + 2] cycloaddition of 1,2-bis(2-pyridyl)ethene mediated by its coordination to the bimetallic framework. The molecular structures of 1, 2, 4 and 5 were confirmed by X-ray crystallographic studies.     

NH-functionalized tungsten complexes of 2-(dimethylphosphino)imidazole

Ligand substitution in W(CO)₄(NO)(ClAlCl₃) with 2-(dimethylphosphino)imidazole (dmpi) bearing an acidic NH functionality afforded W(Cl)(CO)(NO)(bdmpi)(dmpi) (1) (bdmpi = 1,2-bis(dimethyl-phosphino)imidazole), while the reaction of dmpi with W(Cl)(NO)(P(OMe)₃)₄ led to the isolation of W(Cl)(NO)(dmpi)₄ (2) together with W(Cl)(NO)(bdmpi)(dmpi)₂ (3). Attempts to replace the chloride by a hydride ligand in 1-3 applying various hydride reagents did not lead to stable products. The soluble compound W(Cl)(NO)(dmpe)(dmpi)₂ (5) was prepared by an alternative route from W(Cl)(NO)[P(OMe)₃)]₄ via the intermediacy of W(Cl)(NO)(P(OMe)₃)₂(dmpe) (4). The protection of the NH function in 5 was approached applying BuLi and subsequently Me₃SiCl to afford [W(Cl)(NO)(dmpe)(tmsdmpi)₂] (tmsdmpi = 1-trimethylsilyl-2-dimethylphosphino-imidazole) (6) which could not be isolated in pure form. The reaction of 5 with NaHBEt₃ led to the formation of a deprotonated and nitrogen-coordinated salt Na[W(NO)(dmpe)(dmpi)(tebdmpi)] (7) (tebdmpi = 2-dimethylphosphino-3-triethylboro-imidazole). Compound 7 crystallized from CH₃CN to establish a one-dimensional chain structure in the solid state. The structures of compounds 1-5 and 7 were studied by single-crystal X-ray diffraction.     

μ-Coordination chemistry of NO ligands: Adducts of trans-Mo(dmpe)2(H)(NO) with lithium salts

Four adducts were formed by the reaction of trans-Mo(dmpe)₂(H)(NO) (1) (dmpe = bis(dimethylphosphino)ethane) and a respective lithium reagent to afford, [Mo(dmpe)₂(H)(NO)LiHBEt₃]₂ (2), [Mo(dmpe)₂(H)(NO)LiN(SiMe₃)₂]₂ (3), [Mo(dmpe)₂(H)(NO)]₃(LiBH₄)₂ (4), and {[Mo(dmpe)₂(H)(NO)]₂[LiBH₄]₅}_n (5). Structures 2-5 were characterized by crystal X-ray diffraction analyses. Structures 2 and 3 revealed to be dimers of the 1:1 adduct of 1 and the lithium salt. The two nitrosyl oxygen atoms in 2 are μ₂-bridged connecting two separate LiHB(C₂H₅)₃ moieties, whereas in 3 these oxygen atoms exhibit a terminal coordination mode binding to two lithium ions of the dimeric [LiN(SiMe₃)₂]₂ unit. Structure 4 shows a discrete structure formed by two separate mononuclear LiBH₄ units being bridged by the nitrosyl oxygen atoms of three Mo(dmpe)₂(H)(NO) moieties. Structure 5 displays a complicated chain structure with differently coordinated lithium centers, various types of bridging BH₄ and bridging nitrosyl groups.     

Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pr2C6H3)

The compounds [MoCl(NAr)₂R] (R=CH₂CMe₂Ph (1) or CH₂CMe₃(2); Ar=2,6-Prⁱ₂C₆H₃) have been prepared from [MoCl₂(NAr)₂(dme)] (dme=1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether. Similarly, the mixed-imido complex [MoCl₂(NAr)(NBu^t)(dme)] affords [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)] (3). Chloride substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)₂(CH₂CMe₂Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)₂(CH₂CMe₂Ph)] (5) (Ind=Indenyl), [Mo(OBu^t)(NAr)₂(CH₂CMe ₂Ph)] (6), [MoMe(NAr)₂(CH₂CMe₂Ph)] (7), [MoMe(PMe₃)(NAr)₂(CH₂CMe ₂Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂CMe₂P h)](9). In the latter case, a by-product {[Mo(NAr)₂(CH₂CMe₂Ph) ]₂(μ-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for which the evidence is unclear) there are α-agostic interactions present.     

Synthesis of new heterometallic complexes by tin-sulfur bond cleavage of pySSnPh3 (pySH = pyridine-2-thiol) at triruthenium and triosmium centres

The ruthenium-tin complex, [Ru₂(CO)₄(SnPh₃)₂(μ-pyS)₂] (1), the main product of the oxidative-addition of pySSnPh₃ to Ru₃(CO)₁₂ in refluxing benzene, is [Ru(CO)₂(pyS)(SnPh₃)] synthon. It reacts with PPh₃ to give [Ru(CO)₂(SnPh₃)(PPh₃)(κ²-pyS)] (2) and further with Ru₃(CO)₁₂ or [Os₃(CO)₁₀(NCMe)₂] to afford the butterfly clusters [MRu₃(CO)₁₂(SnPh₃)(μ₃-pyS)] (3, M=Ru; 4, M=Os). Direct addition of pySSnPh₃ to [Os₃(CO)₁₀(NCMe)₂] at 70 °C gives [Os₃(CO)₉(SnPh₃)(μ₃-pyS)] (5) as the only bimetallic compound, while with unsaturated [Os₃(CO)₈{μ₃-PPh₂CH₂P(Ph)C₆H₄}(μ-H)] the previously reported [Os₃(CO)₈(μ-pyS)(μ-H)(μ-dppm)] (6) and the new bimetallic cluster [Os₃(CO)₇(SnPh₃){μ-Ph₂PCH₂P(Ph)C₆H₄}(μ-pyS)[(μ-H)] (7) are formed at 110 °C. Compounds 1, 2, 4, 5 and 7 have been characterized by X-ray diffraction studies.     

Metallo-Carbosiloxan-Dendrimere mit Titanocendichlorid-Endgruppen

The synthesis of titanocenedichloride end-grafted carbosiloxane dendrimers of the 1^st and 2^nd generation is reported. To find the optimal reaction conditions, Me₂ClSiH (1) was reacted with (η⁵-C₅H₄SiMe₂CHCH₂)(η⁵-C₅H₅)TiCl₂ (2). The best result could be obtained with the Karstedt catalyst, whereby exclusively the β-isomer ((η⁵-C₅H₄SiMe₂CH₂CH₂SiMe₂Cl)(η⁵-C₅H₅)TiCl₂, 3) is formed. Under similar conditions Me₃SiOCH(Me)(CH₂)₄SiMe₂H (4) reacts with 2 to give (η⁵-C₅H₄SiMe₂CH₂CH₂SiMe₂(CH₂)₄CH-(Me)OSiMe₃)(η⁵-C₅H₅)TiCl₂ (5). When using MeSi(OCH(Me)(CH₂)₄SiMe₂H)₃ (6), Si(OCH(Me)(CH₂)₄SiMe₂H)₄ (8) and MeSi[O(CH₂)₃SiMe(OCH(Me)(CH₂)₄SiMe₂H)₂]₃ (10) instead of 1 and 4, the respective metallo dendrimers MeSi[OCH(Me)(CH₂)₄-SiMe₂CH₂CH₂SiMe₂(η⁵-C₅H₄)(η⁵-C₅H₅)TiCl₂]₃ (7), Si[OCH(Me)(CH₂)₄SiMe₂CH₂CH₂SiMe₂(η⁵-C₅H₄)(η⁵-C₅H₅)TiCl₂]₄ (9) and MeSi{O(CH₂)₃SiMe[OCH(Me)(CH₂)₄SiMe₂CH₂CH₂SiMe₂(η⁵- C₅H₄)(η⁵-C₅H₅)TiCl₂]₂}₃ (11) can be isolated.Compounds 3, 5, 7, 9 and 11 were characterised by elemental analysis as well as IR and NMR spectroscopy (¹H, ¹³C{¹H}, ²⁹Si{¹H}).     

Copper(II) complexes with neutral bis(pyrazolyl)methane ligands: The influence of steric hindrance on their structures and properties

By using the neutral bidentate nitrogen-containing ligands; bis(3,5-dimethyl-1-pyrazolyl)methane (L0″), bis(3,5-diisopropyl-1-pyrazolyl)methane (L1″), bis(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)methane (L3″), and bis(3,5-ditertiary-butyl-1-pyrazolyl)methane (L4″), the copper(II) nitrato complexes [Cu(L0″)₂(NO₃)]NO₃ (1NO₃), [Cu(L0″)(NO₃)₂] (2), [Cu(L1″)(NO₃)₂] (3), [Cu(L3″)(NO₃)₂] (4), and [Cu(L4″)(NO₃)₂] (5), chloro complexes [Cu(L0″)₂Cl]₂(CuCl₄) (6CuCl₄), [Cu(L0″)₂Cl]₂(Cu₂Cl₆) (6Cu₂Cl₆), [Cu(L1″)Cl₂] (7), and [Cu(L3″)Cl₂] (8), nitrito complexes [Cu(L0″)(ONO)₂] (9) and [Cu(L1″)(ONO)₂] (10), and the complexes with perchlorate ions [Cu(L0″)₂(CH₃OH)](ClO₄)₂ (11ClO₄) and [Cu(L1″)₂(H₂O)](ClO₄)₂ (12ClO₄) were systematically synthesized and fully characterized by X-ray crystallography and by IR, far-IR, UV–Vis absorption, and ESR spectroscopy. In comparison with the obtained complexes with four bis(pyrazolyl)methanes having different bulkiness at pyrazolyl rings, the second coordination sphere effects on the ligands are discussed in detail. Moreover, the structures and physicochemical properties of these obtained complexes are compared with those of the related complexes with the neutral tridentate tris(pyrazolyl)methane ligand.     

Pyridine- and pyrimidine-2-thiolate complexes of ruthenium

A series of mononuclear ruthenium complexes containing pyridine- and pyrimidine-2-thiolato ligands was prepared and characterized. The new compounds of general formula CpRu(PPh₃)(κ²S,N-SR) (1) (SR = pyridine-2-thiolate (a), pyrimidine-2-thiolate (b)) were prepared directly by reacting the thiolato anions (RS⁻) with CpRu(PPh₃)₂Cl. Complexes 1 readily react with NOBF₄ or CO in THF at room temperature to give [CpRu(PPh₃)(NO)(κ¹S-HSR)][BF₄]₂ (2) and CpRu(PPh₃)(CO)(κ¹S-SR) (3), respectively. The one-pot reaction of CpRu(PPh₃)₂Cl, thiolato anions and bis(diphenylphosphino)ethane (dppe) gave CpRu(dppe)(κ¹S-SR) [dppe: Ph₂PCH₂CH₂PPh₂ (4)]. The complex salts, [CpRu(PPh₃)₂(κ¹S-HSR)]BPh₄ (5) are prepared by mixing CpRu(PPh₃)₂Cl, HSR and NaBPh₄ at room temperature. The structures of CpRu(PPh₃)(κ²S,N-Spy) (1a), [CpRu(PPh₃)(NO)(κ¹S-HSpy)][BF₄]₂ (2a) and CpRu(PPh₃)(CO)(κ¹S-Spy) (3a), (py = C₅H₄N) have been determined.     

Synthesis of homo- and heteronuclear ruthenium-gold clusters with diphosphine and thiolato bridged ligands. Single crystal molecular structure of [Ru3(CO)10(μ-AuPPh3)(μ-SC5H4N)] and [Ru3(CO)8(μ-H)(μ-SC5H4N)(μ-dppe)]

The reaction between [Ru₃(CO)₁₀(NCMe)₂] and [AuClPPh₃] gave compound [Ru₃(CO)₁₀(μ-Cl)(μ-AuPPh₃)] (1) in quantitative yield under very mild conditions. The reaction of 1 with 4-mercaptopyridine (4-pyS) using ultrasonic reaction conditions gave the heteronuclear compound [Ru₃(CO)₁₀(μ-AuPPh₃)(μ-SC₅H₄N)] (2) in moderate yield. There was no spectroscopic evidence that indicates the formation of the hydride isolobal analog in this reaction. The homonuclear cluster [Ru₃(CO)₈(μ-H)(μ-SC₅H₄N)(μ-dppe)] (3) was prepared by a selective reaction employing the ruthenium-diphosphine derivative [Ru₃(CO)₁₀(μ-dppe)] (dppe = 1,2-bis(diphenylphosphine)ethane) with 4-pyS in THF solution. The isolobal analog to compound 3, compound [Ru₃(CO)₈(μ-AuPPh₃)(μ-SC₅H₄N)(μ-dppe)] (4) was synthesized by the reaction between compound 2 and dppe in refluxing dichloromethane. Compounds 1-4 were characterized in solution by spectroscopic methods and the molecular structure of compounds 2 and 3 in the solid state was obtained by single crystal X-ray diffraction studies.     

Synthesis and structure of dipalladium complexes containing cyclooctatetraene and bicyclooctatrienyl ligands

The reaction of a substitutionally labile dipalladium(I) complex [Pd₂(CH₃CN)₆][BF₄]₂ (1) with 1,3,5,7-cyclooctatetraene (COT) in acetonitrile afforded [Pd₂(μ-η³:η³-C₈H₈)(CH₃CN)₄][BF₄]₂ (2). The reaction of 2 with COT in acetonitrile yielded [Pd₂(μ-η³:η³-C₁₆H₁₆)(CH₃CN)₄][BF₄]₂ (4), where COT is dimerized via C-C bond formation. Complexes 2 and 4 were structurally characterized by X-ray diffraction analyses. In dichloromethane, COT isomerized to styrene at room temperature in the presence of catalytic amount of 1, 2, or 4.     

Structural diversity of indium complexes containing a tetradentate (OSSO)-type bis(phenolate) ligand

Indium bis(phenolato) complexes [{In(CH₃)₂(THF)}₂(L)] (L = 1,4-dithiabutanediylbis(4,6-di-tert-butylphenolato) (etbbp), 2) and [In(cytp)(CH₃)]₂ (L = (1,2-cyclohexanediyldithio)-2,2′-diphenolato (rac-cytp), 3) were prepared from [In(CH₃)₃] and the tetradentate 1,2-dithiaalkanediyl-bridged bis(phenol) LH₂. The nature of the ligand bridging two indium centers was shown by X-ray diffraction studies of the complex [{In(CH₃)₂(THF)}₂(etbbp)] (2) that was synthesized from complex [In(etbbp)(CH₃)(THF)_n] (1) by reaction with a second equivalent of [In(CH₃)₃]. A related ligand without bulky substituents on the aromatic rings leads to the dimeric compound [In(cytp)(CH₃)]₂ (3) with distorted octahedral configuration in the solid state. It was converted into the cation [In(cytp)]⁺ by methyl abstraction with [B(C₆F₅)₃].     

Thermal properties and reactions towards nucleophiles of an iron complex displaying an acetyl and a pyruvoyl ligands

Thermal evolution at 4 °C of the structurally characterized cis(CO)₄Fe[C(O)C(O)CH₃][C(O)CH₃] (1(2)) gives rise to the cis(CO)₄Fe[C(O)CH₃]₂ (1(3)) which, probably owing to synthetic problems, has never been described in the literature. By reaction with anionic nucleophiles (Nu⁻), 1(2) affords anionic trifunctionalized metallalactones {(CO)₃Fe[C(O)CH₃][C(O)C(CH₃)(Nu)OC⁷(O);(Fe-C⁷)]}⁻ (3) formed by addition of the nucleophile reagent on the β carbon of the pyruvoyl moiety followed by the cyclization of this ligand on a terminal carbonyl of the complex. Anions 3 are characterized by ¹H and ¹³C NMR and by X-ray diffraction for the complex with Nu = C(H)(CO₂C₂H₅)₂. Complexes 3 are also prepared by reaction of CH₃Li with the neutral metallalactones (CO)₄Fe[C(O)C(CH₃)(Nu)OC⁷(O);Fe-⁷C] (2). The results of this study shed light on the reaction of cyclization of a pyruvoyl ligand as they clearly show that the presence of a second ligand (for example CO₂R) with a labile OR group is not required to perform the formation of the metallalactone ring and then that the observed reaction has no connection with organic chain-ring transformations.     

Reactivity of [Os3(CO)10(NCMe)2] and [Os3(CO)10(μ-Cl)(μ-AuPPh3)] with 4-mercaptopyridine: X-ray structure of [Os3(CO)10(μ-H)(μ-SC5H4N)] and [Os3(CO)10(μ-AuPPh3)(μ-SC5H4N)]

The compound [Os₃(CO)₁₀(μ-Cl)(μ-AuPPh₃)] (2) was prepared from the reaction between [Os₃(CO)₁₀(NCMe)₂] (1) and [AuClPPh₃] under mild conditions. The reaction of 2 with 4-mercaptopyridine (4-pyS) ligand yielded compounds [Os₃(CO)₁₀(μ-H)(μ-SC₅H₄N)] (4), formed by isolobal replacement of the fragment [AuPPh₃]⁺ by H⁺ and [Os₃(CO)₁₀(μ-AuPPh₃)(μ-SC₅H₄N)] (5). [Os₃(CO)₁₀(μ-H)(μ-SC₅H₄N)] (4) was also obtained by substitution of two acetonitrile ligands in the activated cluster 1 by 4-pyS, at room temperature in dichloromethane. Compounds 2-5 were characterized spectroscopically and the molecular structures of 4 and 5 in the solid state were obtained by single crystal X-ray diffraction studies.