Alkyl- und arylkomplexe des iridiums und rhodiums : VIII. Ungewöhnlich hoher trans-einfluss des carbonylliganden. Molekülstrukturen von cis- und trans-Ir(2,4,6-Me3C6H2)(CO)(PPh3)2

The molecular structures of cis- and trans-Ir(2,4,6-Me₃C₆H₂)(CO)(PPh₃)₂ have been determined by X-ray diffraction methods. Crystals of cis-Ir-(2,4,6-Me₃C₆H₂)(CO)(PPh₃)₂ (A) are monoclinic (P2₁/c) with a 1311.0(3), b 1888.5(6), c 1589.7(5) pm, β 101.85(2)°, and Z = 4. The trans complex B likewise crystallizes in the monoclinic space group P2₁/c with four molecules per unit cell, the lattice parameters being a 981.2(4), b 1214.7(7), c 3579.8(17) pm, and β 102.29(3)°. Based on 2971 and 2883 intensity data, the structures have been refined by full-matrix least squares to R values of 0.051 and 0.059 for A and B, respectively. The molecular geometries may be described as square planar. In the case of the cis-isomer the coordination shows some degree of tetrahedral distortion as a result of steric crowding. IrP distances in B are 231.3(5) and 231.9(5) pm, while in A IrP trans to mesityl is 232.4(3) pm, but trans to CO 237.0(3) pm. The carbonyl ligand thus seems to exert an even stronger trans-influence on IrP than the aryl group. This effect is discussed in terms of dπdπ participation in the metal—phosphine linkage. A very close contact of 244 pm is observed between the central metal and one of the ortho-methyl hydrogens in A which may contribute to kinetic stabilization of the thermodynamically unfavoured cis-isomer.     

Metallorganische verbindungen des iridiums und rhodiums: XXV. Darstellung,spektroskopie und strukturanalyse einiger (2-6-η-1-oxocyclohexadienyl)rhodium(I)-komplexe des typs (η-2,6-t-bu2-4-MeC6H2)RhL2

The interaction of 2,6-t-Bu₂-4-MeC₆H₂OLi with several chlororhodium(I) complexes gave the compounds (2,6-t-Bu₂-4-MeC₆H₂O)RhL₂ (2 L = CO, PPh₃ (I); 2 PPh₃ (II); 2 C₂H₄ (III); cyclo-C₈H₁₂ (IV)) containing the phenoxide ion as an η⁵-bonded oxocyclohexadienyl ligand. I-IV have been characterized by IR and NMR spectroscopy, as well as by two X-ray structure determinations of the CO/PPh₃ and cyclo-C₈H₁₂ substituted half-sandwich derivatives I and IV.     

Alkyl- und aryl-komplexe des iridiums und rhodiums: X. Chelatphosphin-stabilisierte rhodiumorganyle Rh(R)[PhP(CH2CH2CH2PPh2)2]: synthese,NMR-spektroskopischer cis,trans-einfluss und molekülstruktur von Rh(2-MeC6H4)[PhP(CH2CH2CH2PPh2)2]

The organorhodium(I) complexes Rh(R)[PhP(CH₂CH₂CH₂PPh₂)₂] (R  CH₂CMe₃, CH₂SiMe₃; 2-MeC₆H₄, 4-MeC₆H₄, 2,4-Me₂C₆H₃, 2,4,6-Me₃C₆H₂; C₂Ph) have been prepared and characterized by ³¹P and ¹H NMR spectroscopy and an X-ray structure determination of the tolyl derivative Rh(2-MeC₆H₄)-[PhP(CH₂CH₂CH₂PPh₂)₂].For these compounds, the relative ³¹P coordination shifts Δ(PPh₂) > Δ(PPh) distinctly reflect the electron-releasing properties of the organoligands σ-bonded trans to PPh. As expected, coupling between the ¹⁰³Rh nucleus and phenylphosphino P atoms is weak and varies only little as the strong trans influence groups R are changed. In contrast to this insensitivity of ¹J(Rh-PPh) to R, Rh-P coupling within the Ph₂P-Rh-PPh₂ moieties shows considerable dependence upon the nature of the C-donor producing the cis influence series sp³-C <sp²-C < sp-C.The ortho-tolyl complex crystallizes from toluene as 1/1 solvate Rh(2-MeC₆H₄)[PhP(CH₂CH₂CH₂PPh₂)₂] · C₇H₈. Crystals are orthorhombic, space group Pbc2₁, with a 1017.9(7), b 1974.3(14), c 2177.6(11) pm, and Z = 4. The structure has been refined to R = 0.079 for 2249 unique data with F₀ > 3σ(F₀). Metal-phosphorus distances are 225.7(5) and 229.6(6) pm for Rh-PPh₂ and 227.3(6) pm for Rh-PPh.     

Alkyl- und Arylkomplexe des Iridiums und Rhodiums. XIX. Reaktion von Carbonsäuren mit ausgewählten Organoverbindungen von Ir(I) und Rh(I): Bildung von Arylhydrido-, Carboxylatohydrido- und Carboxylato-Derivaten

Alkyl and Aryl Complexes of Iridium and Rhodium. XIX. Reaction of Carboxylic Acids with Selected Organo Compounds of Ir(I) and Rh(I): Formation of Arylhydrido, Carboxylatohydrido, and Carboxylato Derivatives cis-Arylhydridoiridium(III) complexes IrH(Ar)(O₂CR)(CO)(PPh₃)₂ (R = Me: Ar = C₆H₅, 4-MeC₆H₄; R = Et: Ar = 4-MeC₆H₄, 2,4-Me₂C₆H₃) could be prepared by oxidative addition of carboxylic acids to aryliridium(I) compounds Ir(Ar)(CO)(PPh₃)₂. Reaction of aliphatic carboxylic acids with alkyliridium(I) derivatives Ir(Alk)(CO)(PPh₃)₂ and Ir(Alk)[PhP(CH₂CH₂CH₂PPh₂)₂] (Alk = CH₂CMe₃, CH₂SiMe₃) lead to dicarboxylatoiridium(III) hydrides IrH(O₂CR)₂(CO)(PPh₃)₂ (R = Me, Et, i-Pr) and IrH(O₂CR)₂[PhP(CH₂CH₂CH₂PPh₂)₂] (R = Me, Et). Ir(4-MeC₆H₄CO₂)(CO)(PPh₃)₂ was obtained from Ir(CH₂SiMe₃)(CO)(PPh₃)₂ and 4-MeC₆H₄CO₂H. Interaction of organorhodium complexes Rh(R′)(CO)(PPh₃)₂ (R′ = CH₂SiMe₃, 4-MeC₆H₄) and Rh(R′)[PhP(CH₂CH₂CH₂PPh₂)₂] (R′ = CH₂CMe₃, 4-MeC₆H₄) with aliphatic and aromatic carboxylic acids yielded carboxylatorhodium(I) compounds Rh(O₂CR)(CO)(PPh₃)₂ (R = Me, t-Bu, 4-MeC₆H₄) and Rh(O₂CR)[PhP(CH₂CH₂CH₂PPh₂)₂] (R = Me, 4-MeC₆H₄).     

Alkylidentriphenylphosphoran-komplexe von kupfer(I)- und silber(I)-chlorid : II. 1/1-komplexe

Stable 1/1 complexes have been obtained from the ylides methylene, ethylidene and isobutylidene triphenylphosphorane with CuCl, and from (C₆H₅)₃-P=CH₂ and AgCl. In these organometallic compounds of copper and silver the ylides are attached to the metal through the carbanionic donor atom. A cubane-type structure is proposed for the oligomers of the general formula [(C₆H₅)₃-PCHR·MCl]_n, (M = Cu, Ag; R = H, CH₃, CH(CH₃)     

Halbsandwichkomplexe mit stickstoffliganden: II. Cyclopentadienyl-diazadien-kobalt(I)-komplexe

Cyclopentadienyl- and pentamethylcyclopentadienyl-cobalt(I) complexes, [(C₅H₅)Co(dad)] (II) and [(C₅Me₅)Co(dad)] (IV) (dad = 1,4-diaza-1,3-diene, RN=CR′CR′=NR), can be prepared via substitution and reduction reactions. These complexes, which are thermally stable but extremely sensitive to oxidation, show a pseudo-C_2ν symmetry in their room temperature NMR spectra; at 205 K different conformers can be detected in the NMR spectrum of IIf (dad If: R = i-C₃H₇, R′ = CH₃), indicating steric hindrance, which prevents, in spite of low ionization energies (IE₁ for IIa 6.17 eV), typical “base reactions” of the metal, e.g. addition of methyl iodide. The unusually small half-width of the main transition in the electronic spectra, characteristic of complexes II, is better described as a complex π →- π^★ transition than as a CT transition. Together with NMR and electron spectroscopic data the electrochemical behaviour and photoelectron spectroscopic results for IIa and other electron-rich dad complexes are included in the discussion and the comparison with tetraazadiene analogues.     

Basische Carbonate des Dysprosiums: Dy2O2(CO3) und Dy(OH)(CO3)

Basic Carbonates of Dysprosium: Dy₂O₂(CO₃) and Dy(OH)(CO₃) Single crystals of the basic carbonates Dy₂O₂(CO₃) and Dy(OH)(CO₃) are obtained via hydrothermal synthesis from a mixture of DyCl₃ · 6 H₂O and K₂CO₃ and Cs₂CO₃, respectively, as well as CO₂ and H₂O in a steel autoclave at 480 and 400 °C, respectively. The crystal structures are isotypic with those of II‐Nd₂O₂(CO₃) and B–Nd(OH)(CO₃), respectively; Dy₂O₂(CO₃): hexagonal, P6₃/mmc, Z = 2; a = 386.9(2), c = 1516.3(3) pm; Dy(OH) · (CO₃): hexagonal, P‐6, Z = 18; a = 1201.0(1), c = 971.8(9) pm.     

Metallorganische verbindungen des iridiums und rhodiums: XXVI. CH-metallierung und hydridbildung im system Ir2Cl2(C8H14)4/PR3(PR3 = P(CH2CMe3)3, t-BuP(CH2CMe3)2, t-Bu2PCH2CMe3; i-Pr3P

Treatment of Ir₂Cl₂(C₈H₁₄)₄ with the phosphines t-Bu_3?nP(CH₂CMe₃)_n (n = 3,2,1) in hot toluene followed by crystallization of the products from C₇H₈/ EtOH mixtures gave the cyclometallated hydrides (C₈H₁₄)₂Ir-μ-Cl₂$\text{IrH[CH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$(CH₂CMe₃)₂][P(CH₂ (I) [t-BuP(CH₂CMe₃)₂]₂H₂Ir-μ-Cl₂$\text{IrH[CH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$Bu^t(CH₂CMe₃)][t-BuP(CH₂CMe₃)₂] (II), and [(t-Bu₂$\text{PCH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{)HI}$rCl]₂ (III). The dihydrides IrH₂Cl[t-BuP(CH₂CMe₃)₂]₂ (IIa) and IrH₂Cl(t-Bu₂PCH₂CMe₃)₂ (IIIa) were also isolated; these species were, however, more conveniently obtained by bubbling hydrogen through the solution of Ir₂Cl₂ (C₈H₁₄)₄ and the respective phosphine in toluene. i-Pr₃ reacted with the olefiniridium(I) precursor in C₇H₈/EtOH to yield the carbonyl complexes (i-Pr₃P)₂H₂Ir-μ-Cl₂Ir(CO)(PPrⁱ₃)₂ (IV) and IrCl(CO)(PPⁱ₃)₂ (IVa), no cyclometallated product being detected. The stereochemistries of the complexes were deduced from IR, ¹H, ³¹P, and ¹³C NMR data. The crystal structures of IIIa and IVa were also determined.     

Komplexchemie polyfunktioneller liganden : XXXVII. Darstellungsmethoden für hydrido-kobalt(I)-komplexe des 1,1,1-tris(diphenylphosphinomethyl)äthans

[Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] (R  C₆H₅) reacts with NaBH₄, depending on the reaction conditions, to give CoH(CO)₂(R₂PCH₂)₂C(CH₃)CH₂PR₂ · BH₃ and CoH(CO)(R₂PCH₂)₃CCH₃. The hydride CoH(CO)(R₂PCH₂)₃CCH₃ is also formed by the reaction of [Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] with LiOH, NaOH and NaNH₂. The reaction with LiOH primarily gives (acetone)₃-LiCo(CO)(R₂PCH₂)₃CCH₃, which is also formed by reduction of [Co(CO)₂(R₂PCH₂)₂C(CH₃)CH₂PR₂]₂ with lithium in THF/acetone solution. In liquid ammonia [Co(CO)₂(R₂PCH₂)₃CCH₃][Co(CO)₄] at 20°C yields Co(CONH₂)(CO)(R₂PCH₂)₃CCH₃. This compound reacts in the same solvent at 60°C to yield the hydride CoH(CO)(R₂PCH₂)₃CCH₃. CH₃I and HClO₄ react with CoH(CO)(R₂PCH₂)₃CCH₃ yielding CoI(R₂PCH₂)₃CCH₃ and the unstable [Co(H)₂(CO)(R₂PCH₂)₃CCH₃]ClO₄, respectively. The deutero complex CoD(CO)(R₂PCH₂)₃CCH₃ was also synthesized. The new compounds were characterized, as much as possible, by their IR, ¹H NMR and ³¹P NMR data.     

Beiträge zur Komplexchemie der Phosphine und Phosphinoxide. XXI. Komplexchemisches Verhalten des Methylen-(diphenylphosphins) und des Lithium-bis(diphenylphosphino)-methanids

Preparation and properties are described of the complexes resulting by reaction of methylene-bis(diphenylphosphine) (MDP) and lithium-bis(diphenylphosphino)-methanide with π-allyl-pallladium chloride. (π-C₃H₅PdCl)₂ gives with MDP 1:1 and 1:2 complexes, whereas a 1:3 complex is not obtained. LiCH(PPh₂)₂ reacts with PdCl₂ and (π-C₃H₅PdCl)₂ to form [(PPh₂)₂ CHPdCl]₂ and [π-C₃H₅PdCH(PPh₂)₂]₂, respectively. These compounds are dimeric by associating via phosphine bridges. The latter are cleaved on heating with one mole of MDP. The compounds were characterized by IR and UV/VIS absorption spectra, conductivity and tested for catalytic properties.     

Arylkomplexe des typs trans-[Ir(Ar)(CO)(PPh3)2]

The preparation and properties as well as some reactions of a series of arylcarbonylbis(triphenylphosphine)iridium(I) complexes [Ir(Ar)(CO)(PPh₃)₂] (Ar = C₆H₅, C₆F₅, 2-C₆H₄CH₃, 3-C₆H₄CH₃, 4-C₆H₄CH₃, 2-C₆H₄OCH₃, 2,6-C₆H₃-(OCH₃)₂, 4-C₆H₄N(CH₃)₂, 3-C₆H₄Cl, 4-C₆H₄Cl, 4-C₆H₄Cl, 3-C₆H₄CF₃, 4-C₆H₄CF₃) are described, and the most important IR data as well as the ³¹P NMR parameters of these, without exception trans-planar, compounds are given.

Some of the complexes react with molecular oxygen to form well defined dioxygen adducts [Ir(Ar)(O₂)(CO)(PPh₃)₂] (Ar = C₆H₅, 3-C₆H₄CH₃, 4-C₆H₄CH₃). Complexes with ortho-substituted aryl ligands are not oxygenated. This effect is referred to as a steric shielding of the metal center by the corresponding ortho-substituents. With SO₂ the similar irreversible addition compound [Ir(4-C₆H₄CH₃)-(SO₂)(CO)(PPh₃)₂] is obtained. Sulfur dioxide insertion into the Ir---C bond cannot be observed.

The first step of the reaction between [Ir(4-C₆H₄CH₃)(CO)(PPh₃)₂] and hydrogen chloride involves an oxidative addition of HCl to give [Ir(H)(Cl)(4-C₆-H₄CH₃)(CO)(PPh₃)₂]. Ir---C bond cleavage by reductive elimination of toluene from the primary adduct does not occur except at elevated temperature.     

Synthesis and Reactivity of Iridium(I) Fluorido Complexes: Oxidative Addition of SF4 at trans-[Ir(F)(CO)(PEt3)2]

The facile access to the Vaska type fluorido complexes trans-[Ir(F)(CO)(PR₃)₂] [ 6 : R = Et, 7 : R = Ph, 8 : R = iPr, 9 : R = Cy, 10 : R = tBu] was achieved by halide exchange at trans-[Ir(Cl)(CO)(PR₃)₂] ( 1 – 5 ) with Me₄NF. Furthermore, the reaction of complex 6 with SF₄ gave cis,trans-[Ir(F)₂(SF₃)(CO)(PEt₃)₂] ( 11 ), whereas 8 – 10 did not react. Reactivity studies revealed that 11 can selectively be manipulated at the sulfur atom by hydrolysis or fluoride abstraction to give cis,trans-[Ir(F)₂(SOF)(CO)(PEt₃)₂] ( 12 ) and cis,trans-[Ir(F)₂(SF₂)(CO)(PEt₃)₂][AsF₆] ( 13 ), respectively.     

Element-Element-Bindungen. I. Synthese und Struktur des Tetra(tert-butyl)tetrarsetans und des Tetra(tert-butyl)tetrastibetans

Element-Element Bonds. I. Syntheses and Structure of Tetra(tert-butyl)tetrarsetane and of Tetra(tert-butyl)tetrastibetane Dilithium (tert-butyl)arsenide reacts with (tert-butyl)dichloroarsine to give tetra-(tert-butyl)tetrarsetane 1 ; homologous tetra(tert-butyl)tetrastibetane 2 is formed by reduction of (tert-butyl)dichlorostibane with magnesium. The isotypic compounds 1/2 crystallize in the monoclinic space group P2₁/c with Z = 4. The dimensions of the unit cells determined at ?45 ± 5°C are: a = 957.4(8)/1 000.2(3); b = 1 399.1(14)/1 423.9(4); c = 1 697.4(9)/1 749.8(7) pm; β = 96.02(6)/96.77(3)°. As shown by low temperature X-ray structure determinations (3 531/3 232 symmetry independent reflections; R_g = 4.0/4.6%) the four membered rings E₄ (E = As or Sb) are folded; in all-trans configuration the bulky organic substituents occupy pseudo-equatorial positions. Characteristic averaged bond distances and angles are: E? E 244/282; E? C 202/221 pm; ? E? E? E 86/85° ? E? E? C 101/99°. The dihedral angels of the bisphenoides built up by the atoms of the rings are found to be 139/133°.     

Isocyanidkomplexe : II. Pentacarbonylisocyanboranchrom(0)-komplexe

The reaction of K[(CO)₅CrCN] (I) with haloboranes R₂BX yields the isocyanoborane complexes (CO)₅CrCNBR₂ with R = Et (II), R = OMe (III) and R = NMe₂ (IV). II and III react with pyridine forming the corresponding adducts. Complex IV can also be formed by treatment of (CO)₅Cr(THF) with the cyanoborane NCB(NMe₂)₂. (CO)₅CrCNBCl(OMe) · NMe₃ (VII), prepared from I and Cl₂BOMe · NMe₃, yields {(CO)₅CrCN}₂BOMe · NMe₃ (VIII) when treated with excess I. The compounds are characterized by IR, NMR and mass spectra.     

Transient mixed-valence character of Re(I)(4)(CO)(12)(4,4'-bpy)(4)Cl(4)

This study addresses, in detail, the orbital nature and the extent of metal-metal communication in the lowest emitting triplet state of Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) (where 4,4'-bpy = 4,4'-bipyridine) as well as the symmetry of the lowest (3)MLCT manifold in comparison to that of the ground state. All spectral evidence points to (1). a (3)MLCT excited manifold localized between a single Re(I) corner and an adjacent bridging ligand, (2). a transient mixed-valence state that is completely localized between a single transiently oxidized Re center and the adjacent metals, and (3). a second-order charge transfer from a localized transiently reduced bridging ligand to the adjacent Re(I) center to which it is attached, effectively lowering its oxidation state. The orbital nature of the lowest (3)MLCT manifold is fully corroborated by a molecular orbital diagram derived from quantum chemical modeling studies, while the existence of the localization, localized mixed valency, and second-order charge transfer rely on spectral evidence alone. This work makes use of low-temperature time-resolved infrared (TRIR) techniques as well as a luminescence study. Many of the nuances of the luminescence and TRIR data interpretation are extracted from statistical analysis and quantum chemical modeling studies. The relative concentrations of the dominant conformers that exist for Re(4)(CO)(12)(4,4'-bpy)(4)Cl(4) have also been estimated from Boltzmann statistics.     

1/1-komplexe des trimethylphosphinimino-pentamethyldisiloxans und des bis(trimethylphosphinimino)-dimethylsilans mit aluminium-, gallium- und indiumtrimethy. Verbindungen mit stationärem bzw. Oszillierendem akzeptor

(CH₃)₃P&zdbnd;NSi(CH₃)₂OSi(CH₃)₃ reacts with (CH₃)₃Al, (CH₃₃Ga, or (CH₃)₃In to give rigid 1/1-adducts. On the contrary, the analogous 1/1-complexes of(CH₃)₃P&.zdbndNSi(CH₃)₂-N&.zdbndP(CH₃)₃ exhibit a nonrigid behavior as shown by the temperature dependence of the ¹H NMR spectra.     

Untersuchungen an Metallchelaten mit Liganden des Cuproin- und Ferrointyps. XXI. Struktur und Bindung der Dinitrato-mono(cuproin)- und Dinitrato-mono(ferroin)kupfer(II)-Chelate

Studies on Metal Chelates with Ligands of the Cuproin and Ferroin Type. XXI. Structure and Bonding of Dinitrato-mono(cuproin)- and Dinitrato-mono(ferroin)-copper(II) Chelates Chelates of the type Cu(N? N)(NO₃)₂ (N? N = bipy, phen, dmp, dmch, dpch, and bich) are characterized by means of e.s.r., u.v.-vis, i.r., and conductivity measurements. On the basis of these results the possible structures of these chelates both in solution and in the solid state are discussed. The MO coefficients, which could be obtained by e.s.r. measurements, are indicating a high covalency of the out-of-plane π-bonding, but only low covalency of the σ-bonding and the in-plane π-bonding.