Cumulated double bond systems as ligands : IV. 1H and 13C NMR studies of the intra- and inter-molecular exchange processes of cationic dialkylsulfurdiimine compounds of RhI,IrI and PtII

The preparation and properties are described of trans-[(Ph₃P)₂(CO)M(RNSNR)] [ClO₄] (M  Rh^I, Ir^I; R  Me, Et, i-Pr, t-Bu) and of cis- or trans-[L₂Pt(RNSNR)X] [ClO₄] (X  Cl^?, L  Et₂S, PhMe₂As, PhMe₂P, R  Me, t-Bu; X  CH₃, L  PhMe₂P, R  Me).¹H and ¹³C NMR data show the existence of various isomers in solution which may interconvert via intra- and inter-molecular exchange processes. A general reaction scheme for the intramolecular exchange processes is discussed.     

New biimidazole and bibenzimidazole derivatives: mono and binuclear palladium(II) or platinum(II) complexes and heterobinuclear palladium(II)-rhodium(I) or platinum(II)-rhodium(I) complexes

Novel neutral biimidazolate or bibenzimidazolate palladium(II) and platinum(II) complexes of the type M(NN)₂(dpe) [M = Pd, Pt; (NN)₂^2? = BiIm^2?, BiBzIm^2?. dpe = 1,2-bis(diphenylphosphino) ethane] have been obtained by reacting MCl₂(dpe) with TI₂(NN)₂. Complexes M(NN)₂(dpe) which are Lewis bases react with HClO₄ or [M(dpe)(Me₂CO)₂](ClO₄)₂ to yield, respectively, mononuclear cationic complexes of general formula [M{H₂(NN)₂](dpe) (M = Pd, Pt; H₂(NN)₂ = H₂BiIm, H₂BiBzIm) and homobinuclear palladium(II) or platinum(II) cationic complexes of the type [M₂{μ - (NN)₂}(dpe)₂](ClO₄)₂. Reactions of M(BiBzIm)(dpe) with [Rh(COD) (Me₂CO)_X](ClO₄) render similar heterobinuclear palladium(II)-rhodium(I) and platinum(II)-rhodium(I) cationic complexes, of general formula [(dpe)M(μ-BiBzIm)Rh(COD)](ClO₄) (M = Pd, Pt; COD = 1,5-cyclooctadiene). Di- and mono-carbonyl derivatives [(dpe)M(μ-BiBzIm)Rh(CO)L](ClO₄) (M = Pd, Pt; L = CO, PPh₃) have also been prepared. The structures of the resulting complexes have been elucidated by conductance studies and IR spectroscopy.     

The syntheses and coordination properties of M(CO)3X(DAB) (M = Mn,Re; X = Cl,Br, I; DAB = 1,4-diazabutadiene)

M(CO)₅X (M = Mn, Re; X = Cl, Br, I) reacts with DAB (1,4-diazabutadiene = R₁N=C(R₂)C(R₂)′=NR′₁) to give M(CO)₃X(DAB). The ¹H, ¹³C NMR and IR spectra indicate that the facial isomer is formed exclusively. A comparison of the ¹³C NMR spectra of M(CO)₃X(DAB) (M = Mn, Re; X = Cl, Br, I; DAB = glyoxalbis-t-butylimine, glyoxyalbisisopropylimine) and the related M(CO)₄DAB complexes (M = Cr, Mo, W) with Fe(CO)₃DAB complexes shows that the charge density on the ligands is comparable in both types of d⁶ metal complexes but is slightly different in the Fe-d⁸ complexes. The effect of the DAB substituents on the carbonyl stretching frequencies is in agreement with the A′(cis) > A″ (cis) > A′(trans) band ordering.Mn(CO)₃Cl(t-BuNCHCHNt-Bu) reacts with AgBF₄ under a CO atmosphere yielding [Mn(CO)₄(t-BuNCHCHN-t-Bu)]BF₄. The cationic complex is isoelectronic with M(CO)₄(t-BuNCHCHNt-Bu) (M = Cr, Mo, W).     

Acyl-platinum(II) and -palladium(II) complexes derived from 2-hydroxybenzaldehyde derivatives. X-ray structure of [Pt(OC6H4CO) (P(p-CH3C6H4)3)2]

Platinum(II) and palladium(II) complexes containing chelating acyl ligands have been synthesized from salicylaldehyde, 2-hydroxynaphthaldehyde and 2-hydroxy-3-methoxybenzaldehyde. The platinum(II) complexes [Pt(acyl)L₂], acyl  OC₆H₄CO, OC₁₀H₆CO, O(m-CH₃OC₆H₃CO), L  tertiary phosphine, 1/2 diphenylphosphinoethane, can be isolated with both monodentate and chelating diphosphines, whereas for palladium only the compounds with chelating phosphines are readily obtainable. The reactions of [Pt(OC₆H₄CO)L₂] with HCl afford trans-[PtCl(OHC₆H₄CO)L₂], L  monodentate tertiary phosphine and cis-[PtCl(OHC₆H₄CO)L₂], L2  1,2-bis-diphenylphosphinoethane, in which the metal—carbon bond remains intact. The structure of [Pt(OC₆H₄CO)-(P(p-CH₃C₆H₄)₃)₂] has been determined by X-ray diffraction methods and found to have the expected square planar structure. Some relevant bond lengths and angles are: PtP; 2.271(4) and 2.348(5) Å; PtC; 1.96(2) Å and PtO; 2.07(1) Å; PPtP  101°, CPtO  82°.     

Synthesis and structure of FeRu3(CO)13(μ-PPh2)2; A “64-electron” cluster complex with a planar triangulated rhomboidal array of metal atoms

The species FeRu₃(CO)₁₃(μ-PPH₂)₂, synthesized from Ru₃(CO)₁₂ and Fe(CO)₄(Ph₂PPPh₂),has been characterized both spectroscopically and via a single-crystal X-ray structural analysis. This complex crystallizes in the centrosymmetric triclinic space group P$\text{1}$ [No. 2, C_i¹] with a  10.066(3), b  12.899(3), c  17.003(4) Å, α  111.89(2), β  91.02(2), γ  102.00(2)°, V  1992.7(9) ų, Z  2, ?(obsd)  1.79(2) g cm^-3 and ?(calcd)  1.82 cm^-3. Diffraction data were collected with a Syntex P2₁ automated four-circle diffractometer and the structure was refined to R_F  6.0% and R_WF  3.6% for all 5213 reflections (R_F  3.8%, R_WF  3.6% for those 4140 reflections with |F_o|> 3σ(|F_o|).The metal atoms define a planar triangulated rhombus, with atoms Ru(1) and Ru(2) at the bridgehead, and Fe(1) and Ru(3) at the acute apices. Fe(1) is linked to four terminal carbonyl ligands and is associated with the heteronuclear bonds Fe(1)Ru(1)  2.861(1) Å and Fe(1)Ru(2)  2.868(1) Å. The ruthenium atoms are each bonded to three terminal carbonyl groups. The retheniumruthenium distances are Ru(1)Ru(2)  3.098(1), Ru(1)Ru(3)  3.147(1), and Ru(2)Ru(3)  3.171(1) Å. The structure is completed by Ph₂P bridges across the Ru(1)Ru(3) and Ru(2)(ru(3) vectors (<Ru(1)P(1)Ru(3)  84.89(5)° and <Ru(2)P(2)Ru(3)  85.56(6)°).     

Carbonylrhodium(I) complexes with heterocyclic nitrogen compounds

Crystalline complexes of rhodium(I) of the type [Rh(CO)₂(NN)] [RhX₂-(CO)₂] (NN  2,2'-bipyridyl, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 4,7-dipheynl-1,10-phenanthroline; X = Cl, Br) have been prepared. An ionic chain-like structure involving metal-metal interactions has been established by measurement of the reflectance spectra, absorption electronic spectra and electrical conductivities. The IR spectra have been examined over the 50–4000 cm^-1 range.     

Synthesis of ylideplatinum(II) complexes via α-functionalised alkylplatinum(II) intermediates and some comparative data on palladium(II) complexes; X-ray structure of trans-[Pt(CH2PEt3)I(PEt3)2]I

The reaction of [Pt(PEt₃)₃] with CH₂I₂ affords trans-[Pt(CH₂PEt₃)I(PEt₃)₂]I and is believed to proceed via the α-functionalised alkyl cis-[Pt(CH₂I)I(PEt₃)₂], because similar ylides are obtained from cis- or trans-[PT(CH₂X)(PPh₃)₂X] (XCl, Br, or I) with PR₃ (PEt₃, PBu₃ⁿ, PMePh₂, PEtPh₂, or PPh₃); cis-[Pd(CH₂I)-I(PPh₃)₂] does not react with excess PPh₃, but with PEt₃ yields trans-[Pd(CH₂PEt₃)I(PPh₃)₂]I; the X-ray structure of trans-[Pt(CH₂PEt₃)I(PEt₃)₂]I (current R = 0.045) shows PtP(1) 2.332(7), PtP(2) 2.341(8), PtC 2.08(2), and PtI 2.666(2) Å, and angles (a) C(1)PtI, P(1), P(2): 176.9(8), 91.6(6), 93.4(6), (b) IPtP(1), P(2): 87.1(2), 88.5(2), and (c) P(1)P(2), 166.8(3), and (d) PtC(1)P(3), 118(1)°.     

Synthesis and reactivity of formamidinato rhodium(I) complexes

The syntheses of [Rh(diol)(formamidine)]₂ complexes (diol  cycloocta-1,5-diene (1); diol  norbornadiene (2); formamidine  N,N′-di-p-tolylformamidine) are reported. These complexes are dimeric and contain the bridging formamidino ligand. They react with CO, dppe and PPh₃ with displacement of the diene ligand to yield the known [Rh(CO)₂(formamidine)]₂, [Rh(dppe)₂]⁺ and [Rh(PPh₃)₂(formamidine)], respectively; the last complex, in which the formamidine acts as a chelating ligand, was isolated only as the O₂ adduct. With HCl or HBF₄ aqueous 1 and 2 do not form hydrides but instead the formamidino cation [p-tolyl-NHCHNHtolyl-p]⁺ and the complexes [Rh(diol)X]₂ (X  Cl, F); a possible scheme for the reaction with HCl is proposed. The [Rh(C₈H₁₂)(formamidine)]₂ complex reacts with heterocumulenes as CS₂, SO₂, PhNCS and PhNCO with diene displacement; the only product isolated was [Rh(CS₂)₂(formamidine], to which a polymeric structure is assigned.     

A convenient synthetic route to new bis(arenediazo) complexes of molybdenum and tungsten

Complexes of the type [(C₅H₅)Mo(N₂Ar)(N₂Ar′)(PPh₃)] [PF₆] have been prepared and shown to be useful starting materials for the synthesis of a variety of neutral, cationic or anionic compounds containing [cis-Mo(N₂Ar)(N₂Ar′)]²⁺ units.     

Stepwise reduction of the thiocarbonyl ligand: hydride transfer to CS: thioformyl,thioformaldehyde, methylthiolato,secondary carbene,formyl and iminoformyl complexes of osmium

The complexes OsHX(CS)L(PPh₃)₂ (X  Cl, Br; L  CO and X  Cl; L  CN-p-tolyl), which contain mutually cis hydrido and thiocarbonyl ligands, undergo transfer of the hydrido ligand to CS when treated with CO to give blue complexes containing the thioformyl ligand [OsCHS]. OsCl(CHS)(CO)₂(PPh₃)₂ reacts with borohydride to give the first metal complex of the thioformaldehyde monomer, viz. Os(η²-CH₂S)(CO)₂(PPh₃)₂, which reacts rapidly with HCl to give OsCl(SCH₃)(CO)₂(PPh₃)₂ and then, by a slower reaction, OsCl₂(CO)₂(PPh₃)₂ and CH₃SH. The ligands produced in this stepwise reduction have possible relevance as models for postulated intermediates in the Fischer—Tropsch synthesis. Synthetic routes to formyl [OsCHO], iminoformyl [OsCHNMe] and secondary carbene complexes [OsCHSMe, OsCHNMe₂, OsCHOMe] are also demonstrated.     

Low frequency vibrational spectra of zirconocene and hafnocene sulfide [Cp2M(μ-S)]2 (MZr4+, Hf4+)

Metallocene sulfides [Cp₂M(μ-S)]₂ (I, M  Zr⁴⁺; II, M  Hf⁴⁺ and Cp = cyclopentadienyl) have been synthesized. I and II show charge transfer absorption in the visible region. FT-Raman, Raman and IR spectra of these compounds are reported for the first time. The MS stretching bands have been assigned with the help of a pre-resonance effect. The approximate normal coordinate analysis of the coordination skeleton (D_2h symmetry) aids the detailed assignment in the low frequency spectral region. Force constants of MCp and MS stretching imply that the bond order of HfL is higher than that of ZrL.     

Pentacoordinated iridium(I) complexes incorporating azopyridine chelation. Synthesis,structure and bonding

The reaction of [Ir(COD)Cl]₂ with 2-(arylazo)pyridine (L) in dichloromethane solution has afforded the nonelectrolytic pentacoordinated species of type Ir(L)(COD)(Cl) from which the corresponding bromides and iodides have been synthesised by metathesis (COD=1,5-cyclooctadiene). L ligands used are: 2-(phenylazo)pyridine (L¹); 2-(m-tolylazo)pyridine (L²) and 2-(p-chlorophenylazo)pyridine (L³). The X-ray structures of Ir(L²)(COD)(Cl)·0.5 CH₂Cl₂ and Ir(L³)(COD)(I) have been determined revealing square-pyramidal geometry. The relatively short IrN(azo) lengths (∼2.00 Å) and the relatively long NN bond distance (∼1.30 Å) are consistent with significant dππ* (azo) back-bonding. The HOMO (50% Ir and 15% azo character) and LUMO (50% azo and 30% Ir character) are primarily localised in the IrL fragment and the absorption bands near 600 nm is assigned tentatively to the HOMO→LUMO transition. The stability of the pentacoordinated structures and the inertness to oxidative addition of the present complexes in contrast to the behaviour of corresponding 2,2′-bipyridine species (tetracoordinated, reactive) is rationalised in terms of π-acidity order L≫bpy.     

Binuclear platinum(I) complexes with bis(dimethylphosphino)methane ligands: evidence for both short- and long-range NMR trans-influences

The diplatinum(I) complexes or complex ions [Pt₂X₂(μ-dmpm)₂] (X = Cl or I), [Pt₂X(PPh₃)(μ-dmpm)₂]⁺] (X = I, Br or Me), and [Pt₂(PPh₃)₂(μ-dmpm)₂]²⁺, where dmpm = Me₂PCH₂PMe₂, have been prepared and characterized by ¹H and ³¹P NMR spectroscopy. In the linear X-Pt-Pt-Y unit the trans-influence of X is felt primarily at the PtPt bond, but groups X having a very high trans-influence (X = H or Me) can also exert a weaker long-range trans-influence on the PtY bond.     

[Rh12Sb(CO)27]3-. an example of encapsulation of antimony by a transition metal carbonyl cluster

The reaction of Rh(CO)₂acac with triphenylantimony in the presence of cesium benzoate in tetraethylene glycol/dimethyl ether solution resulted in the selective formation of [Rh₁₂Sb(CO)₂₇]^3- (66% yield) after 3 h of contact time under ≈400 atm of carbon monixide and hydrogen (CO/H₂  1) at 140–160°C. The cluster has been isolated as the [Cs(18-Crown-6)₂]⁺, [(CH₃)₄]⁺, [(C₂H₅)₄N]⁺, (Ph₃P)₂N]⁺ and [PhCH₂N(C₂H₅)₃]⁺ salts. The [(C₂H₅)₄N]₃ [Rh₁₂Sb(CO)₂₇] complex has been characterized via a complete three-dimensional X-ray diffraction study. The complex crystallizes in the space group R$\text{3}$c with a  23.258(13) Å, c  22.811(4) Å, V  10 686 ų and p(calcd.)  2.334 g cm^-3 for mol.wt. 2503.66 and Z  6. Diffraction data were collected with an Enraf-Nonius CAD 4 automated diffractometer using graphite-monochromatized Mo-Kα radiation. The structure was solved by direct methods and refined by difference-Fourier and least-squares techniques. All non-hydrogen atoms have been located and refined: final discrepancy indices are R_f  3.5% and R_wf  4.6% for 3011 reflections. The anion's structure consists of twelve rhodium atoms situated at the corners of a distorted icosahedron with contacts of 2.807(1), 2.861(1), 2.874(1), 2.999(1), 3.017(1) and 3.334(1) Å and rhodium—antimony contacts of 2.712(0) Å. Rhodium—rhodium bond distances of 2.807 and 3.017 Å are in the range usually found for these complexes although a distance of 3.334 Å may be longer than expected from bonding interactions. The sum of the covalent radii of antimony and rhodium, 2.80 Å, is intermediate between the two observed RhSb contacts. The anion cluster structure is that of distorted icosahedron. This polyhedron has previously been found in [B₁₂H₁₂]^2- but not with transition metal clusters. A comparison between the structures of rhodium carbonyl clusters and boranes shows the occurrence of similar structural features. Applications of bonding theories based on the boranes, such as Wade's rules, to rhodium carbonyl clusters shows the extent in which these rules are obeyed.     

Carbon-13 and proton NMR parameters of neopentyl-and trimethylsilylmethyl-thallium(III) derivatives and the x-ray crystal structure of bis(trimethylsilylmethyl)chlorothallium(III)

Carbon-13 and proton NMR spectra have been determined for organothallium (III) derivatives of the types RTlX₂ and R₂ TlX (R  (CH₃)₃CCH₂ or (CH₃)₃SiCH₂; X  Cl, Br or O₂CCH(CH₃)₂). The dependence of coupling of ¹³C and ¹H to thallium on the number and nature of R groups is discussed in terms of the Fermi contact mechanism for spinspin coupling.The crystal structure of [(CH₃)₃SiCH₂]₂ TlCl has been determined. The compound crystallises in the monoclinic space group P2₁/n, with a 10.618, b 24.492, c 6.017 Å, β 99.76°. The molecule is dimeric with each four-coordinate thallium atom bonded unequally to two bridging chlorine atoms. The CTlC angle is 168°.     

Synthesis and properties of alkylvanadium(III) alkoxides

The reactions of R₃V · THF (R  C₆F₅, CH₂SiMe₃) with one t-BuOH equivalent result in formation of unstable R₂V(Ot-Bu)·THF, which disproportionates readily to V^IV and V^II compounds. The interaction of V(Ot-Bu)₃ with Me₃SiCH₂Li in diethyl ether is accompanied by formation of the at-complex [Me₃SiCH₂V(Ot-Bu)₃]^-Li⁺ which decomposes with formation of (Me₃SiCH₂)₂V(Ot-Bu)₂ and [V(Ot-Bu)₃]^-Li⁺. As a result of exchange reaction of V(Ot-Bu)₃ with one mole of RMgX, the complexes RV(Ot-Bu)₂·XMgOt-Bu (R  Me, X  Br, R  CH₂Ph, CH₂SiMe₃, C₆F₅, X  Cl) have been obtained. The insertion of carbon dioxide in vanadiumcarbon and vanadiumoxygen bonds has also been investigated.     

Die FIR-Spektren gemischter Hexahalogeno-Osmate (IV) vom OsCl6-nXn-Typ (X = Br,I) und ihre Normalkoordinatenanalyse

The far infrared (FIR) spectra of [OsCl₅I]²⁻, cis-[OsCl₄I₂]²⁻, fac-[OsCl₃I₃]²⁻, [OsCl₅Br]²⁻ and cis-[OsCl₄Br₂]²⁻ (Cs-salts) have been recorded at temperatures down to 35 K. The measured band peaks are assigned to symmetry levels using group theory arguments and normal coordinate analyses starting from corresponding octahedral OsX²⁻₆ compounds. In general, OsX bonding properties can be transferred from one compound to another except for XOsY axes where distinct trans-effects are operative. Normal coordinates are also able to explain weak oscillator strengths when predicting small changes of transition dipole moments.     

Permetalloplumbanes: Preparation of [Pb{Co(CO)3(L)}4] and [Pb{Fe(CO)2(NO)(L)}4].: Complexes containing four transition metal to lead bonds (L = tertiary arsine,phosphine or phosphite).

The sole and unexpected products from the reactions of a variety of lead (II) and lead (IV) compounds with [Co₂(CO)₆(L)₂] complexes (L = tertiary arsine, phosphine, or phosphite) in refluxing benzene solution are the blue, air-stable percobaltoplumbanes [Pb{Co(CO)₃(L)}₄]. These have also been obtained from the reaction of Na[Co(CO)₃(L)] (L  PBu₃ⁿ) with lead (II) acetate which with Na[Fe(CO)₂(NO)(L)] forms the isoelectronic [Pb{Fe(CO)₂(NO)(L)}₄] [L  P(OPh)₃]. The IR spectra of the complexes in the v(CO) and v(NO) regions are consistent with tetrahedral PbCo₄ or PbFe₄ fragments, trigonal bipyramidal coordination about the cobalt or iron atoms and linear PbCoAs, PbCoP, or PbFeP systems. Unlike [Pb{Co(CO)₄}₄], our complexes do not dissociate to [Co(CO)₃(L)]^? or [Fe(CO)₂(NO)(L)]^? ions when dissolved in donor solvents.