Metalmetal bonded triazenido compounds : II. Compounds with M = RhI,IrI; R = Me,aryld and X = Cl,Br, I Cl,Br, I

Complexes

(M = Rh, X = Cl, M = Ir, X = Cl, Br, I and R = CH₃, R′ = CH₃, p-tolyl) have been made by the reaction of (Ph₃P)₂(CO)MX with

. The proposed structure is analogous to that of the related copper derivatives and contains a five-membered ring in which an M^I to Ag^I donor bond is bridged by an azenido group, while the halide atom X has migrated from M^I to Ag^I.Carbon monoxide at 1 atm reacts rapidly and quantitatively with the iridium compounds to give novel acyltriazenido compounds {Ph₃P(CO)₂ - Ir[OCN(R)N=NR′]} (R = CH₃, p-tolyl; R′ = CH₃, p-tolyl).     

The preparation of fluxional tetrahydrides, (R  H or Me) and their reactions with CO,ButNC or HBr

The cyclometallated monohydrides

(R  H or Me) react with NaOPrⁱ/PrⁱOH/H₂ to give fluxional tetrahydrides, probably

. These are highly fluxional having magnetically equivalent hydridic hydrogens, even at ---100°C. When treated with HBr,

, gives

and with CO it gives a mixture of complexes which are probably

(2 isomers) and

. When treated with Bu^tNC this tetrahydride undergoes similar reactions but another (major) product is formed which appears to be binuclear and fluxional and is probably of type

, with four bridging hydrogens.     

Tiazenido complexes with M = Mo or W and R = aryl OR alkyl

The preparation, structure and some properties of compounds

(M = Mo, W; R = aryl and R′ = aryl or alkyl) are reported. Temperature dependent ¹³C NMR spectra show that for R ≠ R′ = aryl the complexes are fluxional, but not when one of the R groups is an alkyl group. The fluxional mechanism involves an interchange of the two CO groups via Berry type pseudorotations.Mass spectrometric measurements show the formation of nitrene type species [(η⁵-C₅H₅)(CO)_nM=NR]⁺ with n = 0, 1, 2.     

Zur ursache der extremen 31P-NMR-verschiebungen von phosphinidenkomplexen

Phosphinidene complexes RP[ML_n]₂ (R = univalent residue; L_nM = 16 electron fragment e.g. (CO)₅Cr, Cp(CO)₂Mn) show extremely paramagnetic ³¹P NMR shifts (884 to 1362 ppm). The values of these NMR shifts are strongly correlated with the energy of the electroic ππ^* transition in

π-systems. The large paramagnetic ³¹P NMR shifts is caused by the small

HOMO-LUMO separation specific for these compounds.     

Niederkoordinierte phosphorverbindungen: LIII. 1,3-Diphosphaallyl-nickelkomplexe

(R = 2,4,6-tri-t-butylphenyl) and

(R = 2,4,6-tri-t-butylphenyl) are two new nickel complexes with a 1,3-diphosphaallyl ligand. Both structures have been determined by X-ray analysis.     

Synthese de composes a liaison MIVBmercure. Precurseurs d'especes monovalentes (germynes), et bivalentes (germylenes), de radicaux centrometalles et d'intermediaires

Polynuclear germylmercury compounds are obtained from the reaction of organohydrogermanes Ph_nGeH_4?n or digermanes Ph_2nGe₂H_4?n (n = 1, 2) with dialkylmercury R₂Hg. Di- or tri-mercurated geminal polygermates thus synthesized generally present a low stability and undergo thermal- or photo-decompositions leading to the corresponding monovalent (germynes), divalent (germylenes) or, trivalent (germanium centered radicals) species and also to intermediate

biradicals which could be considered as limit forms of germanium doubly-bonded compounds

. Such intermediates have been chemically and spectroscopically characterized.Extension of these reactions to the silicon analogs met with difficulties, and thus previously observed differences between silicon and germanium chemistry were confirmed.     

Spectres de vibration de composes organiques des elements de la colonne IVB : VIII. Derives organometalliques a liaison germanium—azote: Trialkylgermyl-et bis(trialkylgermyl)-amines

We have examined in the 3600–100 cm^?1 region the IR and Raman spectra of three bis(trialkylgermyl)amines (R₃Ge)₂NR′ (R = Me, Et; R′ = H, C₆H₅), of three dialkyl(trialkylgermyl)amines R₃GeNR′₂ (R = Me, Et; R′ = Me, n-Bu) and of two triethylgermylpyrazoles:

Assignments are discussed for the characteristic vibrations of these derivatives.     

Activation catalytique des réactifs de grignard par les complexes du nickel en sèrie organosilicièe : II. Rèduction des organosilanes fonctionnels avec les rèactifs de grigrand saturès

A silicon deuteride DH exchange reaction demonstrates the reductive characteristics of saturated Grignard reagents catalytically activated by nickel complexes. Application of this reaction to the organosilanes R₁R₂R₃SiX(X=OCH₃,F,Cl) provides a new method for their reduction.

The reduction takes place with retention of configuration at the silicon atom for methoxy. and fluorosilanes. However inversion of configuration occurs in the case of chlorosilanes.The new type of reaction can also be used for the reduction of vinylsilanes

The results show the reductive properties of the Ni-H bond formed by β-elimination of the Ni-R intermediate.     

Nature of the hydrogen bridge in transition metal complexes: II. Molecular orbital calculations of binuclear carbonyls of Mn,Re, Cr,Mo and W with double hydrogen bridges

To throw more light on the nature and character of the metalhydrogenmetal bond we carried out the electronic structure calculations by use of the parameter-free Fenske-Hall method and the semi-empirical EHT method for

complexes (M = Mn, Re, Cr, Mo, W and n = −2,0). The character and stability of the double hydrogen bridges in these complexes and in

and

were compared. The effects that type of transition metal has on the character and stability of double hydrogen bridges in carbonyl dimers are described. The electronic structures of the bridge cores in the double-and single-hydrogen bridge binuclear carbonyls of chromium and molybdenum were compared.     

η2-acylcarbonylvanadium-verbindungen

Substituted vanadium carbonyl compounds with η²-bonded acyl ligands (η²-RCO)V(CO)₃

(

= ditertiary phosphines or arsines: dppe, dppp, dppm, diars, arphos, dpase) have been prepared by photochemical reaction of [V(CO)₄

] with various substituted benzoyl chlorides and cyclopropanylcarbonyl chloride.Effects of aromatic substituents and

upon the thermal stability of the η²-acylcarbonylvanadium compounds are discussed. IR ν(CO) force constants and ⁵¹V NMR signals are linearly correlated with Hammett's σ constants of the aromatic substituents.The preparation of V(CO)₂Cl(diars)₂ is described.     

Darstellung und eigenschaften cyclischer silylamide des berylliums. Kristall- und molekülstruktur eines dimeren diaza-disila-berylla-cyclohexans

Four novel cyclic beryllium silylamides (I–IV; R = CH₃) were obtained by reaction of BeMe₂ with the appropriate aminosilanes. In solution and in the solid state they form dimers and probably higher associated oligomers, which,

according to their ¹H NMR spectra, interconvert depending on temperature and solvent. Crystallic II dimerizes via a centrosymmetric BeNBe′N′ four-membered ring, the BeN and BeN′ distances being 1.714(3) and 1.683(3) Å. The CN and SiN bonds of the tetracoordinate N atom (1.502(3) and 1.752(3) Å) are longer than those formed by the tricoordinate N atom (1.473(3) and 1.722(2) Å); the BeN (tricoordinate N) distance is 1.550(4) Å.     

Reaktionen von carbonylcyclopentadienylhydriden des molybdäns und des wolframs mit inaminen

The hydrides (η⁵-C₅H₅)(CO)₃MH (M = Mo, W) react with ynamines R′CCNR₂ under mild conditions to form 1 : 1 adducts. According to the ¹H and ¹³C NMR spectra depending on the metal and the ynamine substituents carbene acyl chelate or complexes with η³-aminoacryloyl ligands are formed:

A Dicarbene chelate compound is obtained by alkylation of I, R = Et, R′ = Me. CC-η² keteneimmonium complexes are formed in the reaction of the phosphite substituted hydrides (η⁵-C₅H₅)(CO)₂P(OMe)₃MH (M = Mo, W) with MeCCN Et; an intermediate 1-aminovinyl compound has been isolated.     

Sussex-N.P.L. computer analysed thermochemical data: Organic and organometallic compounds : J.B. Pedley and J. Rylance,University of Sussex, 1977 £10.00

The formation of new

intermediates and especially germaimines R₂GeNR′ has been observed in the reaction of germylenes with phenyl azide (precursor of phenylnitrene). These transient derivatives lead, by polycondensation reactions, to the corresponding cyclic or linear germazanes

, and are characterized by insertion reactions into the germanium—nitrogen bond, cleavage and addition reaction with tetrahydrofuran, and pseudo-Wittig reactions with benzaldehyde. The latter produces the corresponding germoxanes via new

intermediates and phenyl benzaldimine.     

Réactions des céténes et du dicéténe avec les germyl- et silylphosphines

Ketenes add to germyl- and silylphosphines R₃MPEt₂ with opening of the carbonyl group and formation of phosphorylated alkenoxygermanes or -silanes

(R′H, Ph). These adducts are thermally stable and only the addition derivative of diphenylketene and Me₃SiPEt₂ exhibits metallotropic isomerization to a C-derivative after prolonged heating. Hydrolysis of these addition compounds is a new approach to the acylphosphines R₂CH-CO-PEt₂. Diketene also reacts with germyl- and silylphosphines with acyloxygen bond cleavage and formation of metallated and phosphorylated ketoenolates of the type

. These derivatives isomerize either partially (MSi) or completely (MGe) into R₃MOC(CH₃)CHCOPEt₂. Their hydrolysis constitutes a new method of synthesis of the phosphorylated β-diketone

. The ketoenolates from the addition reaction of the hydrosilylphosphine, Me₂Si(H)PEt₂, cyclize readily after partial isomerization by the intramolecular addition SiH to CO, to give phosphorylated siladioxane and siladioxene. The conformation of these heterocyclic compounds has been studied.     

Complexes chiraux derives du monocyclopentadienyltitane(IV). Diastereotopie et diastereoisomerie des complexes Cp′TiA(ZZ′) presentant un ligand bidente σ

The reaction 1 has been used to obtain monocyclopentadienyltitanium(IV)

(HZZ′H = disymmetric diphenol or dithiol; R^? = Cl^? or SR^? from CCl₄ or RSSR) chiral complexes with three σ bonds. The chirality at the titanium atom is detected either by NMR analysis (diastereotopy of methyl groups when Cp′ = η⁵-C₅H₄CHMe₂) and by characterization of diastereoisomer pairs (Cp′ = η⁵-C₅H₄$\text{C}\text{*}$CHMeC₆H₅).     

The reaction of triphenylcarbinol with HCo(CO)4

The reaction of Ph₃COH with 2 mol of HCo(C0)₄ gives Ph₃CH in quantitative yield. The reaction is cleanly second order (κ₂  2.50 X 10^-4 1 mol^-1 s^-1, in CH₂Cl₂ at 20°C), first order with respect to each reactant. The rate increases markedly with increase in solvent polarity, suggesting Ph₃C⁺ as an intermediate. The rate of the reaction of HCo(C0)₄ with

is more than 10³ as fast as with Ph₃COH. No evidence for the functioning of HCo(C0)₄ as a hydride donor could be secured.     

Zur komplexchemie von 4-zentren-π-systemen : XII. Glyoxaldiiminkomplexe: 1H-nmr-spektren und long range-kopplungen

Glyoxaldiimines (I) RN=CHCH=NR show in the NMR a downfield shift of glyoxalic protons (H_gly) when complexed to

(II: M = Mo, W), but increasing high field shifts when going to

(III) and

complexes (IV). In the tungsten complexes II H_glyW coupling satellites are resolved (J(WH) ≈4–6 Hz); in the phosphine compounds III, IV long range PH_gly coupling is clearly visible. Mechanisms of spinspin interaction are briefly discussed in connection with the EPR results on monoanionic radicals of II–IV.     

Organoboron compounds: XXVII. A13C NMR Study of PhB(NMe2NHBut and PhB(NMe2)NHSiMe3

The rotational barriers (ΔG) about the

bond in PhB(NMe₂)NHBu^t and PhB(NMe₂)NHSiMe₃ have been determined by variable temperature ¹³C NMR.     

Nouveaux complexes π-allyliques cationiques du nickel(II)

The air stable complexes

are readily obtained in high yields by reaction of tetracarbonylnickel and allyloxytris(dimethylamino)phosphonium salts, R²CHCR¹CH₂OP(NMe₂)₃A^?, in acetonitrile, followed by addition of triphenylphosphine.     

Etude en resonance magnetique nucleaire du carbone-13 de complexes η-1,5-cyclooctadiene β-dicetonato iridium(I)

The ¹³C NMR spectra of iridium complexes of 1,5-cyclooctadiene are reported and discussed. For compounds containing β-diketonato ligands, a correlation is found between the ethylenic carbon chemical shifts and the Swain and Lupton

and

values of the substituents of the β-diketonato ligand. The relationship is satisfactorily explained by considering the Dewar, Chatt and Duncanson model of bonding. Tentative interpretation of the observed chemical shifts of the other carbons is presented.