PMe2 Ph Research Articles

Synthesis and Characterization of a Rhenanaphthalene Isomer.

Exploration of organometallic metallacycles has led to the development of various polycyclic compouds with fascinating structures, which could be used as functional materials. In this work, a new rhenanaphthalene isomer was isolated from the reaction of ReH5(PMe2Ph)3 with o-ethynylphenyl alkyne in the presence of excess HCl. Its structure was then identified using the single-crystal X-ray diffraction and NMR spectroscopy. DFT studies suggest that its formation involves two protonation reactions and two migration reactions. This new rhenanaphthalene isomer enriches the family of metallacycles.

Synthesis, Characterization and Electronic Structure of Dirhenadehyro[12]annulene Complexes.

Treatment of the SiMe3 -protected dichloro-rhenium carbyne complexes Re{≡CCH=C(R)C≡CSiMe3 }Cl2 (PMe2 Ph)3 (R = CMe3 , 1-adamantyl) with CsF in methanol directly afforded the 12-membered metallacycles {ReCl(PMe2 Ph)3 }2 {≡CCH=C(R)C≡C-}2 . The electronic structure of the metallacycle was investigated by density functional calculations. The UV-vis spectrum of the metallacycle shows a red-shifted band compared to that of the starting dichlorocarbyne complex. Treatment of {ReCl(PMe2 Ph)3 }2 {≡CCH=C(CMe3 )C≡C-}2 with HCl produced the dichloro-rhenium carbyne complex Re{≡CCH=C(CMe3 )C≡CH}Cl2 (PMe2 Ph)3 , which is consistent with the electronic structure of the 12-membered metallacycles.

Molybdenum Imido, Tungsten Imido and Tungsten Oxo Alkylidene N-Heterocyclic Carbene Olefin Metathesis Catalysts.

This article outlines the fundamental concept to molybdenum imido, tungsten imido and tungsten oxo alkylidene N-heterocyclic carbene (NHC) catalysts for olefin metathesis. Starting from Mo(NR)(CHCMe2 R')(OTf)2 ⋅DME (R=alkyl, aryl; R'=CH3 , Ph; OTf=CF3 SO3 ; DME=1,2-dimethoxyethane), W(NR)(CHCMe2 Ph)X2 (X=pyrrolide, OR'', SiPh3 ) and W(O)Cl2 (CHCMe2 Ph)(PMe2 Ph)2 , respectively, the neutral, pentacoordinated 16-valence electron (VE) complexes became accessible. These serve as precursors for the corresponding cationic, tetracoordinated 14-VE catalysts. This class of olefin metathesis catalysts based on group 6 metal alkylidene NHCs is characterized by a broad structural variability, high activity, high productivity and, in tailored systems, high functional group tolerance even vs. protic groups including alcohols and carboxylic acids. Also, high regio- and stereoselectivity is achieved, both in ring-opening metathesis polymerization (ROMP) and in the cyclopolymerization of α,ω-diynes. Fundamentals concerning the influence of the imido/oxo ligand, the different NHCs and the anionic ligands on catalyst performance and stability as well as reaction pathways are summarized. Also, the concepts for catalyst immobilization, whether via the NHC or by substitution of an alkoxide, are presented. Finally, special features such as the use of betaine-type anionic ligands (alkoxides and sulfonates), which offer access to ionic catalysts for use biphasic reaction setups, are briefly outlined.

Synthesis and Characterization of Dirhenadehydro[12]annulenes.

The 12-membered-ring metallacycles [mer-Re{≡CCH=C(R)C≡C-}Cl(PMe2 Ph)3 )]2 (R=CMe3 , 1-adamantyl), which are organometallic analogues of antiaromatic octadehydro[12]annulene, are prepared by heating the methyl carbyne complexes mer-Re{≡CCH=C(R)C≡CH}(CH3 )Cl(PMe2 Ph)3 . An intermolecular σ-bond metathesis between the Re-CH3 bond and the acetylenic C-H bond is proposed for their formation.

Double Jahn-Teller Distortion in AuGe Complexes Leading to a Dual Blue-Orange Emission.

The tetrahedral AuI complexes [Au(GeCl3 )L3 ] (L=PMe3 (1), PMe2 Ph (2), PMePh2 (3), PPh3 (4)) were synthesized by in situ treatment of the [Au(GeCl3 )(tht)] complex with three equivalents of the corresponding tertiary phosphine. The crystal structures of complexes 1 and 3 have been determined through X-ray diffraction studies and show [GeCl3 ]- fragments bonded to the corresponding [Au(PR3 )3 ]+ units through covalent bonds, leading to a tetrahedral coordination environment for gold. Complexes 3 and 4 show dual phosphorescence in the solid state at 77 K and, in the case of complex 4, an interesting room-temperature mechanochromism effect is observed. Correlated MP2, SCS-MP2, SCS-CC2, and ONIOM MP2/UFF calculations suggest the existence of two largely distorted and thermally connected triplet excited states (T1 and T2 ) for a model system of complex 4. The AuP3 + moiety can be distorted in two different planes leading to the two triplet excited states T1 and T2 , leaving the GeCl3 - unit almost unaltered. The emissions of these phosphorescent AuI GeII complexes is mainly ascribed to a metal (gold)-centered (3 MC) transition with some contribution from the [GeCl3 ]- fragments.

Synthesis of well-defined bicapped octahedral iron clusters [((tren) L)2 Fe8 (PMe2 Ph)2 ](n) (n=0, -1).

The synthesis of polynuclear clusters with control over size and cluster geometry remains an unsolved challenge. Herein, we report the synthesis and characterization of open-shell octairon clusters supported by two heptaamine ligands [o-H2 NC6 H4 NH(CH2 )2 ]3 N ((tren) LH9 ). The crystal structure of the all-ferrous species ([(tren) L)2 Fe8 (PMe2 Ph)2 ] (1) displays a bicapped octahedral geometry with FeFe distances ranging from 2.4071(6) to 2.8236(5) Å, where the ligand amine units are formally in amine, amide, and imide oxidation states. Several redox states of the octairon cluster are accessible, as ascertained using cyclic voltammetry. The one-electron-reduced clusters [M](+) [((tren) L)2 Fe8 (PMe2 Ph)2 ](-) (M=Bu4 N (2 a); (15-crown-5)Na(thf) (2 b)) were isolated and characterized. Variable-temperature magnetic susceptibility data indicates that the exchange coupling within the [Fe8 ] core is antiferromagnetic which is attenuated upon reduction to the mixed valent anion.

Terminal and Bridging Parent Amido 1,5‐Cyclooctadiene Complexes of Rhodium and Iridium

The ready availability of rare parent amido d(8) complexes of the type [{M(μ-NH2)(cod)}2] (M=Rh (1), Ir (2); cod=1,5-cyclooctadiene) through the direct use of gaseous ammonia has allowed the study of their reactivity. Both complexes 1 and 2 exchanged the di-olefines by carbon monoxide to give the dinuclear tetracarbonyl derivatives [{M(μ-NH2)(CO)2}2 ] (M=Rh or Ir). The diiridium(I) complex 2 reacted with chloroalkanes such as CH2Cl2 or CHCl3, giving the diiridium(II) products [(Cl)(cod)Ir(μ-NH2)2Ir(cod)(R)] (R=CH2Cl or CHCl2) as a result of a two-center oxidative addition and concomitant metal-metal bond formation. However, reaction with ClCH2CH2Cl afforded the symmetrical adduct [{Ir(μ-NH2)(Cl)(cod)}2] upon release of ethylene. We found that the rhodium complex 1 exchanged the di-olefines stepwise upon addition of selected phosphanes (PPh3, PMePh2, PMe2Ph) without splitting of the amido bridges, allowing the detection of mixed COD/phosphane dinuclear complexes [(cod)Rh(μ-NH2)2Rh(PR3)2], and finally the isolation of the respective tetraphosphanes [{Rh(μ-NH2)(PR3)2}2]. On the other hand, the iridium complex 2 reacted with PMe2 Ph by splitting the amido bridges and leading to the very rare terminal amido complex [Ir(cod)(NH2)(PMePh2)2]. This compound was found to be very reactive towards traces of water, giving the more stable terminal hydroxo complex [Ir(cod)(OH)(PMePh2)2]. The heterocyclic carbene IPr (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) also split the amido bridges in complexes 1 and 2, allowing in the case of iridium to characterize in situ the terminal amido complex [Ir(cod)(IPr)(NH2)]. However, when rhodium was involved, the known hydroxo complex [Rh(cod)(IPr)(OH)] was isolated as final product. On the other hand, we tested complexes 1 and 2 as catalysts in the transfer hydrogenation of acetophenone with iPrOH without the use of any base or in the presence of Cs2CO3, finding that the iridium complex 2 is more active than the rhodium analogue 1.

NMR, IR and DFT studies of phenylplatinum complexes with O-monodentate coordinated silsesquioxanate and auxiliary phosphine ligands

The molecular structure and spectroscopic properties of a series of phenylplatinum complexes containing silsesquioxanate and phosphine ligands with general formula trans-[Pt{O 10Si 7(R) 7(OH) 2}(Ph)(L) 2] ( 1: R = cyclo-C 5H 9, L = PEt 3; 2: R = iso-C 4H 9, L = PEt 3; 3: R = CH 3, L = PEt 3; 4: R = cyclo-C 5H 9, L = PMe 3; 5: R = cyclo-C 5H 9, L = PMe 2Ph; 6: R = cyclo-C 5H 9, L = PPh 2Me; 7: R = cyclo-C 5H 9, L = PPh 3) have been investigated by DFT/OPW91/6-31G(d) calculations, 1H, 13C, 29Si and 31P NMR and IR spectroscopy. DFT molecular modeling based on available X-ray and NMR data for complexes 1 and 2 allowed deriving structure-NMR spectra correlations. It was found that the alkyl substituents (R) attached to Si atoms, cyclo-C 5H 9, iso-C 4H 9 and CH 3, slightly influence the geometry and multinuclear NMR parameters of the complexes in the series studied. The molecular structures of the Pt(II) complexes with R = cyclo-C 5H 9 ( 4– 7) were predicted by DFT calculations of their simplified models with R = CH 3 ( 4′ −7′). The geometry optimizations of 4′ −7′ showed square-planar configuration of Pt(II) center bonded to two trans phosphine ligands, a phenyl group and an O-monocoordinated silsesquioxanate. The structures 4′ −6′ are stabilized by two intramolecular hydrogen bonds similar to 1 and 2. A fast conformer exchange process A↔B and switching of H-bonds in solution of 1– 6 were suggested based on (i) the calculated conformer energies and small barrier of the process, and (ii) the observed single 1H NMR signal at low magnetic field. The stability of the Pt(II) complexes depends on the nature of the phosphine ligands and decreases in the order PMe 2Ph > PMe 3 > PPh 2Me > PEt 3 > PPh 3. The PPh 3 ligands attached to Pt(II) in 7 cause the largest geometry changes and a new set of weaker hydrogen bonds. The comparison of the calculated NMR and IR parameters with the experimental spectroscopic data reveals good coincidence and thus confirmed the suggested molecular structures.

Synthesis and spectroscopy of cis-configured mononuclear palladium(II) and platinum(II) complexes of chalcogeno o-carboranes and structures of [Pt(SCb oPh) 2(dppm)], [Pt(SeCb oPh) 2(dppm)], [Pt(SCb oS)(PMe 2Ph) 2] and [Pt(SCb oS)(PMePh 2) 2

The reactions of [MCl 2(P ∩P)] and [MCl 2(PR 3) 2)] with 1-mercapto-2-phenyl- o-carborane/NaSeCb oPh and 1,2-dimercapto- o-carborane yield mononuclear complexes of composition, [M(SCb oPh) 2(P ∩P)], [M(SeCb oPh) 2(P ∩P)] (M = Pd or Pt; P ∩P = dppm (bis(diphenylphosphino)methane), dppe (1,2-bis(diphenylphosphino)ethane) or dppp (1,3-bis(diphenylphosphino)propane)) and [M(SCb oS)(PR 3) 2] (2PR 3 = dppm, dppe, 2PEt 3, 2PMe 2Ph, 2PMePh 2 or 2PPh 3). These complexes have been characterized by elemental analysis and NMR ( 1H, 31P, 77Se and 195Pt) spectroscopy. The 1J(Pt–P) values and 195Pt NMR chemical shifts are influenced by the nature of phosphine as well as thiolate ligand. Molecular structures of [Pt(SCb oPh) 2(dppm)], [Pt(SeCb oPh) 2(dppm)], [Pt(SCb oS)(PMe 2Ph) 2] and [Pt(SCb oS)(PMePh 2) 2] have been established by single crystal X-ray structural analyses. The platinum atom in all these complexes acquires a distorted square planar configuration defined by two cis-bound phosphine ligands and two chalcogenolate groups. The carborane rings are mutually anti in [Pt(SCb oPh) 2(dppm)] and [Pt(SeCb oPh) 2(dppm)].

The use of X-ray photoelectron spectroscopy to assign formal oxidation states in complexes of tungsten (vi), (v) and (iv)

X-ray photoelectron spectra of {[WCl 4(NPh)] 2}, WCl 4(O) and the η 2-acetylene complex {[WCl 4(η 2-PhC 2Ph)] 2}show W 4f 7/2 binding energies (35.8, 37.0 and 35.1 eV, respectively) which are consistent with a formal oxidation state of W(vi). [WCl 2(NPh)(NCMe 3)(bipy)] and [WCl 2(O)(CHC{CH 3} 3)(PMe 3) 2] (binding energies 34.2 and 34.1 eV) are also W(vi). The imido complexes [WCl 3(NPh)(PMe 3) 2], {WCl 3[NC 6H 3( Pr 2 i )-2,6](PMe 3) 2}, {WCl 3[NC 6H 3( Pr 2 i )-2,6](dmbipy)} and the η 2-acetylene complexes [WCl 3(η 2-PhC 2Ph)(PMe 3) 2] and [WCl 3(η 2-PhC 2Ph)(PMe 2Ph) 2] have binding energies in the range 33.6–34.2 eV consistent with tungsten (v). Imido complexes [WCl 2(NPh)(PMe 3) 3],[BPh 4][WCl(NPh)(MeCN)(PMe 3) 2], [WCl 2(NPh)(L)(PMe 3) 3] (L = Me 2CCH 2, PhC 2Ph), {WCl 2[NC 6H 3(Pr i) 2-2,6](PhC 2H)(PMe 3) 2], {WCl 2[NC 6H 3(Pr i) 2-2,6](PhC 2Ph)(dmbipy)] and [WCl 2(NCMe 3)(PhC 2Ph)(bipy)] have binding energies in the range 32.5–34.0 eV consistent with W(iv). The η 2-nitrile complex [WCl 2(η 2-NCC 6H 4Me-4)(PMe 3) 3] (binding energy 32.9 eV) is also W(iv). The range of binding energies for the complexes [WCl 4(P) 2] (P = PMe 3, PMe 2Ph and PEt 3) and [WCl 4(PMe 3) 3] which are more obviously W(iv) is 33.5–34.4 eV. The η 2-acetylene complexes [WCl 2(η 2-PhC 2Ph)(L)(PMe 3) 2] (L = PMe 3, CH 2CH 2 and CO) and [WCl 2(η 2-PhC 2Ph)(CO)(PMe 2Ph) 2] have binding energies (range 32.7–33.8 eV) consistent with W(iv). The range of W 4f 7/2 binding energies for these complexes confirms that the electron withdrawing properties of ligands are more important in determining core electron level energies than structural considerations.

Carbon–carbon and carbon–chlorine bond formation on reaction of iodine(III) reagents with the bis(alkynyl)palladium(II) motif, and structural chemistry of trans-Pd(C [tbnd]C- o-Tol) 2(PMe 2Ph) 2] and trans-[PdCl(C [tbnd]C- o-Tol)(PMe 2Ph) 2

Trans-di( ortho-tolylethynyl)bis(dimethylphenylphosphine)palladium(II) reacts above −20 °C with the iodonium reagent IPhCl 2 to give predominantly o-Tol–C C–Cl, above 15 °C with IPh 2(OTf) (OTf = triflate) to give o-Tol–C C–Ph and ( o-Tol–C C) 2 in ca. 3:1 ratio, and above 10 °C with IPh(C CR)(OTf) (R = Bu t, SiMe 3) to give predominantly o-Tol–C C–C C–R and ( o-Tol–C C) 2. 31P NMR spectra provide evidence for detection of intermediates. The complexes trans-[Pd(C C- o-Tol) 2(PMe 2Ph) 2] and trans-[PdCl(C C- o-Tol)(PMe 2Ph) 2] are obtained on reaction of trans-[PdCl 2(PMe 2Ph) 2] with Li(C C- o-Tol) and o-Tol-C CH/Et 3N, respectively, and have been characterised by X-ray crystallography.

1-Selenolato-2-phenyl- o-carborane complexes of palladium(II) and platinum(II): Synthesis, spectroscopy and structures

The reactions of PhCb oSeNa (Cb o = o-C 2B 10H 10), prepared by reductive cleavage of Se–Se bond in (PhCb oSe) 2 by NaBH 4 in methanol, with Na 2PdCl 4, MCl 2(PR 3) 2 and [M 2Cl 2(μ-Cl) 2(PR 3) 2] afforded a variety of complexes, viz., [Pd(SeCb oPh)Cl] ( 1), [M(SeCb oPh) 2(PR 3) 2], [M 2Cl 2(μ-SeCb oPh)(μ-Cl)(PR 3) 2] (M = Pd, Pt) and [Pd 2Cl(SeCb 0Ph)(μ-Cl)(μ-SeCb oPh)(PEt 3) 2] ( 7) have been isolated. These complexes were characterized by elemental analyses and NMR ( 1H, 31P, 77Se, 195Pt) spectroscopy. The structures of [Pd(SeCb oPh) 2(PEt 3) 2] ( 2), [Pt(SeCb oPh) 2(PMe 2Ph) 2] ( 3), [Pd 2Cl 2(μ-SeCb oPh)(μ-Cl)(PMe 2Ph) 2] ( 5) and [Pd 2Cl(SeCb oPh)(μ-Cl)(μ-SeCb oPh)(PEt 3) 2] ( 7) were established by X-ray crystallography. The latter represents the first example of asymmetric coordination of selenolate ligands in binuclear bis chalcogenolate complexes of palladium and platinum. Thermolysis of [Pd(SeCb oPh) 2(PEt 3) 2] ( 2) in HDA (hexadecylamine) at 330 °C gave nano-crystals of Pd 17Se 15.

Reactivity of the bis(silyl) palladium(II) complex toward organic isothiocyanates

The bis(silyl) palladium(II) complex [Pd(SiHPh 2) 2(dmpe)] (dmpe = 1,2-bis(dimethylphosphino)ethane) reacted with organic isothiocyanates R–NCS (R = Ph, i Pr, allyl) to give a dithiocarbonimidato [Pd(S 2C N–Ph)(dmpe)] ( 1), a diphenylsilanedithiolato [Pd(S 2SiPh 2)(dmpe)] ( 2), or a π-allyl [( η 3-allyl)Pd](NCS) ( 3) palladium complex, depending on the isothiocyanate type and reaction conditions. In addition, various dithiocarbonimidato Pd(II) complexes were also obtained from trans-[PdEt 2L 2] (L = PMe 3, PMe 2Ph) ( 4– 6) or [Pd(styrene)L 2] and organic isothiocyanates.

Differences in the η 1-ligating properties of 2,4,6-tritertiarybutyl-phosphabenzene, [formula omitted] and 2,4,6-tritertiarybutyl-1,3,5-triphosphabenzene, [formula omitted

Several η 1-complexes of 2,4,6-tritertiarybutylphosphabenzene, PC 5 H 2 Bu 3 t , have been synthesised and structurally characterised including trans-[PtCl 2(PEt 3)(η 1- PC 5 Bu 3 t )], cis-[PdCl(C 10H 6CHMe(NMe 2)(η 1- PC 5 H 2 Bu 3 t )] and [AuCl(η 1- PC 5 H 2 Bu 3 t )]. NMR spectroscopic evidence is presented for the partial isomerisation in solution of the 2,4,6-tritertiarybutyl-1,3,5-triphosphabenzene complexes trans-[PtCl 2(PR 3)(η 1- P 3 C 3 Bu 3 t )], (PR 3 = PMe 3 and PMe 2Ph), to the corresponding cis-isomers.

Synthesis, spectroscopy and structures of palladium(II) and platinum(II) complexes containing mercapto- o-carborane

The reactions of [M 2Cl 2(μ-Cl) 2(PMe 2Ph) 2] with mercapto- o-carboranes in the presence of pyridine afforded mono-nuclear complexes of composition, [MCl(SCb°R)(py)(PMe 2Ph)] (M = Pd or Pt; Cb° = o-C 2B 10H 10; R = H or Ph). The treatment of [PdCl 2(PEt 3) 2] with PhCb°SH yielded trans-[Pd(SCb°Ph) 2(PEt 3) 2] ( 4) which when left in solution in the presence of pyridine gave another substitution product, [Pd(SCb°Ph) 2(py)(PEt 3)] ( 5). The structures of [PdCl(SCb°Ph)(py)(PMe 2Ph)] ( 1), [Pd(SCb°Ph) 2(PEt 3) 2] ( 4) and [Pd(SCb oPh) 2(py)(PEt 3)] ( 5) were established unambiguously by X-ray crystallography. The palladium atom in these complexes adopts a distorted square-planar configuration with neutral donor atoms occupying the trans positions. Thermolysis of [PdCl(SCb°)(py)(PMe 2Ph)] ( 2) in TOPO (trioctylphosphine oxide) at 200 °C gave nanocrystals of TOPO capped Pd 4S which were characterized by XRD pattern and SEM.

Isomerism in tetrahedral rhenium cluster complexes [Re 4Q 4(PMe 2Ph) 4X 8]·nCH 2Cl 2 (Q = Se, X = Br; Q = Te, X = Cl, Br)

Three new tetrahedral rhenium cluster compounds [Re 4Se 4(PMe 2Ph) 4Br 8]·1.5CH 2Cl 2 ( 1), [Re 4Te 4(PMe 2Ph) 4Br 8]·CH 2Cl 2 ( 2), and [Re 4Te 4(PMe 2Ph) 4Cl 8]·CH 2Cl 2 ( 3) have been synthesized by the reaction of the corresponding precursor chalcohalide complexes [Re 4Q 4(TeX 2) 4X 8] (X = Br, Q = Se (for 1), Te (for 2); X = Cl, Q = Te (for 3)) with dimethylphenylphosphine in CH 2Cl 2. All compounds have been characterized by X-ray single-crystal diffraction and elemental analyses, IR and 31P NMR spectroscopy. 31P NMR spectroscopy indicates the formation of isomers in solution, confirmed by single-crystal X-ray analysis.

Influence of Ligand Electronic Effects on the Structure of Monovalent Cobalt Complexes

The syntheses, spectroscopic properties, and structures of the monovalent cobalt complexes, [PhTt (tBu)]Co(L), 1-L {PhTt (tBu) = phenyltris[( tert-butylthio)methyl]borate; L = PPh 3, PMe 3, PEt 3, PMe 2Ph, PMePh 2, P(OPh) 3, CNBu (t)}, are described. Complexes 1-L are prepared via the sodium amalgam reduction of [PhTt (tBu)]CoCl in the presence of L. The complexes display magnetic moments and paramagnetically shifted (1)H NMR spectra consistent with triplet, S = 1, ground states. The molecular geometries, determined by X-ray diffraction methods, reveal that some of the complexes display structures in which the L donor is moved off of the inherent 3-fold axis. In the most extreme cases (e.g., 1-P(OPh) 3 or 1-CNBu ( t )), the geometries can be described as cis-divacant octahedra. The origin of the geometric distortions is a consequence of the electronic characteristics of L as first deduced by Detrich et al. for [Tp (Np)]Co(L) ( J. Am. Chem. Soc. 1996, 118, 1703). The results establish a linear correlation between the magnitude of the structural distortion and the electronic parameter of the phosphine donor.

4-Thiolatobenzoate-Bridged Gold/Zirconium Complex and Its Mononuclear Precursors

The selective synthesis of a Au (I) complex of 4-mercaptobenzoic acid, namely, [Au(SC 6H 4-4-COOH)(PMe 2Ph)] ( 1), is reported. It shows interesting photoluminescence (PL) properties, for example, high PL quantum yield, multicomponent emission, and an unusually large PL lifetime. This complex was further applied as a metalloligand for the synthesis of [Cp* 2Zr{kappa (1) O-OOCC 6H 4-4-SAu(PMe 2Ph)}{kappa (2) O,O'-OOCC 6H 4-4-SAu(PMe 2Ph)}] ( 3), one of the rare Au (I)/Zr (IV) complexes. For the first time the exchange between the two ligands, which are bound in mono- and bidentate fashion, respectively, could be observed with the help of variable-temperature NMR spectroscopy. For the corresponding monometallic zirconocene complex [Cp* 2Zr(kappa (1) O-O 2CC 6H 4-4-SH)(kappa (2) O,O'-O 2CC 6H 4-4-SH)] ( 2) the activation parameters of this exchange could be determined by line shape analysis.

Polyhedral metallathiaborane chemistry: Synthesis and characterisation of metallathiaboranes based on the twelve-vertex icosahedral closo-{MSB 10H 10} unit, where M is Rh or Ir

The reaction of [ nido-7-SB 10H 12] with [RhCl(PPh 3) 3] in the presence of N, N, N′ N′-tetramethylnaphthalene-1,8-diamine (tmnd) in CH 2Cl 2 gives twelve-vertex [2,2-(PPh 3) 2-2-H- closo-2,1-RhSB 10H 10] ( 1) and eleven-vertex [8,8-(PPh 3) 2- nido-8,7-RhSB 9H 10] ( 2), as major products, plus the dimeric species [{(PPh 3)- closo-RhSB 10H 10} 2] ( 3) as a minor product. Reaction of 1 with PMe 2Ph in CH 2Cl 2 results in phosphine exchange and hydride substitution, affording the chloro analogue of 1, [2,2-(PMe 2Ph) 2-2-Cl- closo-2,1-RhSB 10H 10] ( 4). By contrast, reaction between [IrCl(PPh 3) 3] and [ nido-7-SB 10H 12] in CH 2Cl 2 with tmnd affords only one product, twelve-vertex [2,2-(PPh 3) 2-2-H- closo-2,1-IrSB 10H 10] ( 5). [RhCl 2(η 5-C 5Me 5)] 2 with [ nido-7-SB 10H 12] under the same conditions gives twelve-vertex [2-(η 5-C 5Me 5)- closo-2,1-RhSB 10H 10] ( 6). All the compounds are characterised by NMR spectroscopy, and by mass spectrometry, and the molecular structure of [2,2-(PMe 2Ph) 2-2-Cl- closo-2,1-RhSB 10H 10] ( 4) was established by single-crystal X-ray diffraction analysis. This last rhodathiaborane 4 is fluxional in solution through a process that involves a reversible partial rotation of the {RhCl(PMe 2Ph) 2} unit above the {SB 4} pentagonal face of the {SB 10H 10} fragment.

Synthesis, characterization, and thermodynamic studies of cobalt Schiff base complexes with amines

The [ N, N′-bis(Salicyliden)-2,3-diaminopyridine]tributylphosphinecobalt(III) perchlorate monohydrate, [Co(Salpyr)(PBu 3)]ClO 4 · H 2O, was synthesized and characterized. For the new five coordinate complex and some others, such as [ N, N′-bis(Salicyliden)-1,2-phenylenediamine]tributylphosphinecobalt(III) perchlorate monohydrate, [Co(Saloph)(PBu 3)]ClO 4 · H 2O, [ N, N′-bis(4-methylSalicyliden)-1,2-phenylenediamine]tributylphosphine cobalt(III) perchlorate monohydrate, [Co(4-MeSaloph)(PBu 3)]ClO 4 · H 2O, [ N, N′-bis(4-nitroSalicyliden)-1,2-phenylenediamine]tributylphosphinecobalt(III) perchlorate monohydrate, [Co(4-NO 2Saloph)(PBu 3)]ClO 4 · H 2O, and [ N, N′-bis(Salicyliden)-1,2-phenylenediamine]dimethylphenylphosphinecobalt(III) perchlorate monohydrate, [Co(Saloph)(PMe 2Ph)]ClO 4 · H 2O, the formation constants and the thermodynamic parameters of the interaction of Co(III) Schiff bases with amines were measured spectrophotometrically. Furthermore, the formation constant of these 1:1 adducts in 96% ethanol solvent and in constants ionic strength ( I = 0.1 M NaClO 4) and at different temperatures were determined using the Ketelaar equation. Also the adduct formation of [Co(Saloph)(PBu 3)]ClO 4 · H 2O, with Imidazol, 2-MeImidazol, 4-MeImidazol, 2-EtImidazol, and BzImidazol in 96% ethanol was studied. The formation constants and the thermodynamic parameters for [Co(Salpyr)(PBu 3)]ClO 4 · H 2O as an acceptor with some aliphatic amines, such as n-butylamine, sec-butylamine, tert-butylamine, benzylamine, and diethylamine as donors were determined in DMA. The comparison of formation constants and the thermodynamic parameters show that the trend of formation constants of pentacoordinate cobalt(III) Schiff base complexes toward a given donor at lower temperature of the range used (283 and 293) K is as follows: 4 -MeSaloph > Saloph > 4 - NO 2 Saloph > Salpyr. Also the following binding trend of the donors toward a given cobalt(III) Schiff base complex is in sequence: Im > 4-MeIm > 2-MeIm > 2-EtIm > BzIm and for aliphatic amines is as follows: Benzylamine > sec-butylamine ∼ n-butylamine > tert-butylamine > diethylamine. The formation constants for a given donor change according to the following trend for phosphine axial ligands: PBu 3 < PMe 2Ph.