Phosphinsubstituierte chelatliganden: XI. NMR-spektroskopische untersuchungen (1H, 13C, 31P, 55Mn) an halogentricarbonylmangan-chelatkomplexen mit phosphino-thioformamid- und -thioformimidoester-liganden

A series of halotricarbonylmanganese chelate complexes, fac-(CO)₃Mn(X)L (X = Cl (a), Br (b), I (c)), with thioformamide (L = Ph₂PC(S)NRMe; R = H (1), Me (2), Ph (3)) and the isomeric thioformimidoester (L = Ph₂PC(NR)SMe; R = Me (4), Ph (5)) ligands were prepared by thermal CO substitution of the pentacarbonylmanganese halides. The IR and NMR data indicate P,S-coordination of the ambidentate ligands and uniform Z configuration in 3–5. Due to the large linewidth of the NMR signals, the ⁴J(PH) and ³J(PC) coupling constants could not be determined for the thioamide complexes 1–3. Coordination of the thioimide 4 causes an increase in ⁴J(PH) whereas ³J(PC) remains unchanged. δ(³¹P) shows a downfield coordination shift as usual for manganese complexes. The broad ⁵⁵Mn NMR signals cover a range of +90 to ?730 ppm (rel. KMnO₄) with the imidoester complexes 4 and 5 at the low-field side. The normal halogen dependence Cl < Br < I is observed for ⁵⁵Mn shielding.     

Metallacumulenylidene complexes in the [(η5-C5Me5)(η2-dppe)Fe(=C(=C)nR2)]X (n = 0, 1, 2) series: investigations of the iron-carbon bonding by Mössbauer spectroscopy and X-ray analyses

The synthesis of the iron allenylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Ph)Ph)][X] (5a, X = PF₆, 95%; 5b, X = BPh₄, 91%; dppe = 1,2-bis(diphenylphosphino)ethane) was achieved by reacting the complex (η⁵-C₅Me₅)(η²-dppe)FeCl (10) with 1 equiv of 1,1-diphenyl-prop-2-yn-1-ol in methanol in the presence of KPF₆ or NaBPh₄. Surprisingly, when the reaction was carried out in the presence of the tetraphenylborate anion, the final product contained both 5b and the hydroxyvinylidene [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C(H)C(OH)(Ph)₂)][BPh₄] (14b) in the 1:1 ratio. Further treatment of the mixture with Amberlyst 15 in methanol provided the allenylidene 5b as a pure sample. The allenylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Me)Ph)][PF₆] (6) and [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C=C(Me)Et)][PF₆] (7) were prepared according to the same procedure and they were isolated as purple powders in 90% yield. The X-ray crystal structures were determined for the vinylidene complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=CH₂)][PF₆] (3) and [(η⁵-C₅Me₅)(η²-dppe)Fe(=C=C(Ph)H)][PF₆] (4), and the allenylidene derivative 5a. In the homogeneous series of complexes [(η⁵-C₅Me₅)(η²-dppe)Fe(=(C)_n(R)R’)][PF₆], (n = 1, R = H, R′ = Me, X = PF₆, 1; n =1, R = H, R’ = OMe, X = PF₆, 2a; n = 1, R = H, R’ = OMe, X = CF₃OSO₂, 2b; n = 2, R = R′ = H, X = PF₆, 3; n = 2, R = H, R′ = Ph, X = PF₆, 4; n = 3, R = R′ = Ph, X = PF₆, 5a; n = 3, R = R′ = Ph, X = BPh₄, 5b; n = 3, R = Me, R′ = Ph, X = PF₆, 6; n = 3, R = Me, R′ = Et, X = PF₆, 7; n = 3, R = Me, R′ = OMe, X = BPh₄, 8), an empiric relationship between the Mössbauer parameters, δ and QS, was found. This observation would indicate that the positive charge on the iron nucleus decreases with the Fe=C bond order. Moreover, in this series of iron cumulenylidene derivatives, comparison of the variation of the metal–carbon bond distances determined by X-ray analyses with the Mössbauer QS values allows the observation of a linear correlation (R = 0.99). To cite this article: G. Argouarch et al., C. R. Chimie 6 (2003).     

Chelate complexes of some NNO tridentate Schiff bases with iron(II), cobalt(II), nickel(II) and copper(II)

Summary The Schiff bases a-(C₅H₄N)CMe=NNHCOR (R = Ph, 2-thienyl or Me), prepared by condensation of 2-acetylpyridine with the acylhydrazines RCONHNH₂, coordinate in the deprotonated iminol form to yield the octahedral complexes, M[NNO]₂ M = Co or Ni; [NNOH] = Schiff base and the square-planar complexes, Pd[NNO]Cl. The Schiff bases also coordinate in the neutral keto form yielding the octahedral complexes (M[NNOH]2)Z2 (M = Ni, Co or Fe; Z = C104, BF₄ or N03) and complexes of the type M[NNOH]X2 (M = Ni, Co, Fe or Cu; X = Cl, Br or NCS). Spectral and x-ray diffraction data indicate that the complexes M[NNOH]X2 (M = Ni or Fe) are polymeric octahedral, as are the corresponding cobalt complexes having R = 2-thienyl. However, the cobalt complexes Co[NNOH]X2 (X = CI or Br; R = Ph or Me) and the copper complexes Cu[NNOH]CI₂ (R = Ph, 2-thienyl or Me) are five-coordinate, while the thiocyanato complex Co[NNOH](NCS)₂ (R = 2-thienyl) is tetrahedral.     

Chemistry of Fischer-type rhenacyclobutadiene complexes. II. Reactions with alkynes and sulfonium ylides, and rearrangements induced by nitriles and pyridine

Further investigations into the chemistry of the rhenacyclobutadiene complexes (CO)₄Re(η²-C(R)C(CO₂Me)C(X)) (1: R=Me, X=OEt (1a), O(CH₂)₃CCH (1b), NEt₂ (1c); R=CHEt₂, X=OEt (1d); R=Ph, X=OEt (1e)) are reported. Reactions of 1 with alkynes at reflux temperature of toluene and at ambient temperature either under photochemical conditions or in the presence of PdO yield ring-substituted η⁵-cyclopentadienylrhenium tricarbonyl complexes, 2. The symmetrical alkynes R^′CCR^′ (R^′=Ph, Me, CO₂Me) afford the pentasubstituted complexes (η⁵-C₅(Me)(CO₂Me)(OEt)(Ph)(Ph))Re(CO)₃ (2d), (η⁵-C₅(Me)(CO₂Me)(OEt)(Me)(Me))Re(CO)₃ (2e), (η⁵-C₅(Me)(CO₂Me)(OEt)(CO₂Me)(CO₂Me))Re(CO)₃ (2f), and (η⁵-C₅(Me)(CO₂Me)(NEt₂)(CO₂Me)(CO₂Me))Re(CO)₃ (2i) on reaction with the appropriate 1, whereas the unsymmetrical alkynes R^′CCR″ (R^′=Ph; R″=H, Me) give either only one, (η⁵-C₅(Me)(CO₂Me)(OEt)(Ph)H)Re(CO)₃ (2a)), or both, (η⁵-C₅(Me)(CO₂Me) (OEt)(Ph)(Me))Re(CO)₃ (2b) and (η⁵-C₅(Me)(CO₂Me)(OEt)(Me)(Ph))Re(CO)₃ (2c), (η⁵-C₅(Ph)(CO₂Me)(OEt)(Ph)H)Re(CO)₃ (2g) and (η⁵-C₅(Ph)(CO₂Me)(OEt)(H)(Ph))Re(CO)₃ (2h), of the possible products of [3 + 2] cycloaddition of alkyne to η²-C(R)C(CO₂Me)C(X). Thermolysis of (CO)₄Re(η²-C(Me)C(CO₂Me)C(O(CH₂)₃CCH)) (1b) containing a pendant alkynyl group proceeds to (η⁵-C₅(Me)(CO₂Me)(O(CH₂)₃)H)Re(CO)₃ (2j), a η⁵-cyclopentadienyl-dihydropyran fused-ring product. Competition experiments showed that each of PhCCH and MeO₂CCCCO₂Me reacts faster than PhCCPh with 1a. The results with unsymmetrical alkynes are rationalized by steric properties of substituents at the CC and ReC bonds and by a preference of ReC(Me) over ReC(OEt) to undergo alkyne insertion. A mechanism is proposed that involves substitution of a trans CO by alkyne in 1, insertion of alkyne into ReC bond to give a rhenabenzene intermediate, and collapse of the latter to 2. Complexes 1a and 1d undergo rearrangement in MeCN at reflux temperature to give rhenafuran-like products, (CO)₄Re(κ²-OC(OMe)C(CHCR₂)C(OEt)) (R=H (3a) or Et (3b)). The reaction of 1d also proceeds in EtCN, PhCN, and t-BuCN at comparable temperature, but is slower (especially in t-BuCN) than in MeCN. In pyridine at reflux temperature, 1a undergoes a similar rearrangement, with CO substitution, to give (CO)₃(py)Re(κ²-OC(OMe)C(CHCEt₂)C(OEt)) (4). A mechanism is proposed for these reactions. The sulfonium ylides Me₂SCHC(O)Ph and Me₂SC(CN)₂ (Me₂SCRR^′) react with 1a in acetonitrile at reflux temperature by nucleophilic addition of the ylide to the ReC(Me) carbon, loss of Me₂S, and rearrangement to a rhenafuran-type structure to yield (CO)₄Re(κ²-OC(OMe)C(C(Me)CRR^′)C(OEt)) (R=H, R^′=C(O)Ph (5a); R=R^′CN (5b)). All new compounds were characterized by a combination of elemental analysis, mass spectrometry, and IR and NMR spectroscopy.     

Alkynylcarbyne complexes containing various tri- and bidentate ligands such as cyclopentadienide,tris(pyrazolyl)borate,bis(pyrazolyl)acetate and tmeda: synthesis and spectroscopic properties

The (alkynylcarbyne)tungsten complexes [L₃(CO)₂WCCCR] (3a,b–6a,b) [L₃=hydro[tris(3,5-dimethylpyrazol-1-yl)]borato (Tp′, 3), hydro[tris(pyrazol-1-yl)]borato (Tp, 4), cyclopentadienyl (Cp, 5), bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza, 6); R=SiMe₃ (a), Ph (b)] were prepared in a stepwise fashion from [W(CO)₆] and Li[CCR], (CF₃CO)₂O and M[L₃] (M=Na, K). The formation of 6a,b was highly selective, only complexes with a trans arrangement of the carboxylate group of bdmpza and the alkynylcarbyne ligand were detected. The reaction of [W(CO)₆] with Li[CCR], C₂O₂Cl₂ and tmeda afforded trans-[Cl(CO)₂(tmeda)WCCCR] (7a,b). The electron-donating potential of the different tripodal ligands L₃ was studied by IR- and ¹³C-NMR spectroscopy and compared to that of the ligand combination Cl/tmeda. The IR data suggest that in these complexes bdmpza is a weaker electron donor than Tp′ and Tp but displays stronger electron-donating abilities than Cp. The structures of 6b and 7b were established by X-ray structural analyses.     

Hydrazinocarben-Metallkomplexe—synthese aus allenylidenkomplexen und hydrazinen, umlagerung und cyclisierung

The diarylallenylidene pentacarbonyl complexes (CO)₅M=C=C=C(C₆H₄NMe₂-p)₂ (M = W (1), Cr (2)) add 1,2,-disubstituted hydrazines RNH-HNR to form alkenyl hydrazino carbene complexes (CO)₅M=C(C(H)=C(C₆H₄NMe₂-p)₂) NR-N(H)R (M = W, R = Bn (3b), ⁱPr (3c), ^cHex (3d); M = Cr, R = Me (4a), ⁱPr (4b)) in good yield. 3c and 4b are formed selectively as E-conformers (E arrangement of N_βHR and (CO)₅M with respect to the C(carbene)-N_α bond). In contrast, all other derivatives of 3 and 4 are obtained as a mixture of E/Z-isomers. On heating, E-3a and E-3b rearrange to give the acrylamidine complexes (CO)₅W-NR=C(NHR)C(H)=C(C₆H₄NMe₂-p)₂ (R = Me (5a), Bn (5b). The structure of complex 5b was established by X-ray analysis. Acid-catalyzed, the alkenyl hydrazino carbene complexes E-3a, E-3b and 3c are transformed by intramolecular cyclization into the pyrazolidinylidene complexes

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(R =Me (6a), Bn (6b), ⁱPr (6c)).

Zusammenfassung

Die Diarylallenyliden(pentacarbonyl)komplexe (CO)₅M=C=C=C(C₆H₄NMe₂-p)₂ (M = W (1), Cr (2)) addieren 1,2-disbustituierte Hydrazine RNH-HNR in guten Ausbeuten zu Alkenylhydrazinocarbenkomplexen (CO)₅M=C(C(H)=C(C₆H₄NMe₂p)₂) NR-N(H)R (M = W, R = Bn (3b), ⁱPr (3c), ^cHex (3d); M = Cr, R =Me(4a), ⁱPr (4b)). 3c und 4b entstehen hierbei selektiv in der E-Konformation (E-Anordnung von N_βHR und (CO)₅M bezülich der C(Carben)-N_α-Bindung). Alle anderen Derivate von 3 und 4 werden dagegen als E/Z-Isomerengemisch gebildet. E-3a und E-3b lagern sich beim Erwärmen in die Acrylamidinkomplexe (CO)₅W-NR=C(NHR)C(H)=C(C₆H₄NMe₂-p)₂ (R = Me (5a), Bn (5b)) um. Die Struktur von 5b wurde anhand einer Röntgenstrukturanalyse gesichert. Säurekatalysiert cyclisieren die Alkenylhydrazinocarbenkomplexe E-3a, E-3b und 3c zu den Pyrazolidinylidenkomplexen

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(R = Me (6b), ⁱPr (6c)).     

Relative dioxygenation rates of some trans-Ir(CO)X(PR3)2 complexes: The effect of phosphine and halogen changes

Relative rates of dioxygen uptake by the complexes trans-Ir(CO)X(PPh₂R)₂ (R = Ph, Me, Et; X = F, Cl, Br, I) have been measured in dichloromethane and found to follow the order R = Ph<Et<Me and X = F <Cl<Br<I. The basicity of these trans-Ir(CO)X(L)₂ complexes, as measured by their affinity for dioxygen, is not reflected in the energy of the ν(CO) absorption in the parent compounds; a previous report that complex basicity ∝1/ν(CO) does not hold for the complexes reported here.     

Alkoxy,amido and thiolato complexes of tris (3, 5-dimethylpyrazolyl)borato(nitrosyl) molybdenum fluoride,chloride and bromide

The complexes Mo{HB(Me₂pyz)₃}(NO)XY {HB(Me₂pyz)₃  HB(3, 5-Me₂C₃HN₂)₃; X=Y=F, Cl or Br; X=F, Y=OEt, NHMe or SBuⁿ; X=Cl, Y=NHR (R=Me Et, Buⁿ, Ph, p-MeC₆H₄), NMe₂ and SR (R=Buⁿ, C₆H₁₁, CH₂Ph, Ph); X=Br, Y=NHMe, NMe₂ and SBuⁿ} have been prepared and characterised spectroscopically. Their properties are generally similar to those of their iodo-analogues.     

New Look into the Synthesis of Polyhalogenoarylphosphanes

The present study shows new aspects of the synthesis of polyhalogenoarylphosphanes. The sterically hindered anions Ph(R)P-Y^? (1a–c, Y = O, lone pair; R = Ph, Bu^t) have been used to show the complexity of the reaction between phosphorus nucleophiles and hexahalogenobenzenes or 9-bromofluorene (E3). The Ph(Bu^t)P-O^? (1a) anion reacts with hexachlorobenzene (E1), hexafluorobenzene (E2), or E3 to give Ph(R)P(O)X (4a–c, X = F, Cl, Br) with the release of the corresponding carbanion as a nucleofuge, followed by side reactions. In contrast, the lithium phosphides Ph(R)PLi (1b,c) react with hexahalogenobenzenes to give the corresponding diphosphanes 5a,b as the main product and traces of P-arylated products, i.e., Ph(R)P-C₆X₅ (10a,b, X = Cl, F). Unexpectedly, Ph(Bu^t)PLi (1b) reacts with an excess of 9-bromofluorene to give only halogenophosphane Ph(Bu^t)P-X.     

Reaction of ruthenium complexes containing heterocyclic thiazine–thione ligand

Treatment of the ruthenium complex [Ru]---

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(3, [Ru]=Cp(dppe)Ru) containing a heterocyclic [1,3]-thiazine-4-thione six-membered-ring ligand with various organic halides results in alkylation at the thione sulfur terminus of the ligand to yield [Ru]---

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][X] (4a, R=CN, X=I; 4b, R=Ph, X=Br; 4c, R=CH=CH₂, X=I, 4d, R=p-C₆H₄CF₃, X=Br). Similarly the reaction of 3 with HgCl₂ at room temperature affords [Ru]---

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][Cl] (5). Transformation of 5 to the cationic vinylidene complex {[Ru]=C=C(Ph)C(O)NHPh}₂[Hg₂Cl₆] (6) readily occurred in the air. The structures of 4c and 6 are determined by single crystal X-ray diffraction analysis.     

Synthesis,structural characterisation and reactivity of molybdenum half-sandwich complexes containing keto- and amido-phosphines

The keto-functionalised N-pyrrolyl phosphine ligand PPh₂NC₄H₃{C(O)CH₃-2} L¹ reacts with [MoCl(CO)₃(η⁵-C₅R₅)] (R=H, Me) to give [MoCl(CO)₂(L¹-κ¹P)(η⁵-C₅R₅)] (R=H 1a; Me 1b). The phosphine ligands PPh₂CH₂C(O)Ph (L²) and PPh₂CH₂C(O)NPh₂ (L³) react with [MoCl(CO)₃(η⁵-C₅R₅)] in an analogous manner to give the compounds [MoCl(CO)₂(L-κ¹P)(η⁵-C₅R₅)] (L=L², R=H 2a, Me 2b; L=L³, R=H 3a, Me 3b). Compounds 1–3 react with AgBF₄ to give [Mo(CO)₂(L-κ²P,O)(η⁵-C₅R₅)]BF₄ (L=L¹, R=H 4a, Me 4b; L=L², R=H 5a, Me 5b; L=L³, R=H 6a, Me 6b) following displacement of chloride. The X-ray crystal structure of 4a revealed a lengthening of both Mo–P and CO bonds on co-ordination of the keto group. The lability of the co-ordinated keto or amido group has been assessed by addition of a range of phosphines to compounds 4–6. Compound 4a reacts with PMe₃, PMe₂Ph and PMePh₂ to give [Mo(CO)₂(L¹-κ¹P)(L)(η⁵-C₅H₅)]BF₄ (L=PMe₃ 7a; PMe₂Ph 7b; PMePh₂ 7c) but does not react with PPh₃, 5a reacts with PMe₂Ph, PMePh₂ and PPh₃ to give [Mo(CO)₂(L²-κ¹P)(L)(η⁵-C₅H₅)]BF₄ (L=PMe₂Ph 8b; PMePh₂ 8c; PPh₃ 8d), and 6a reacts with PMe₃, PMe₂Ph, PMePh₂ and PPh₃ to give [Mo(CO)₂(L³-κ¹P)(L)(η⁵-C₅H₅)]BF₄ (L=PMe₃ 10a; PMe₂Ph 10b; PMePh₂ 10c; PPh₃ 10d). No reaction was observed for the pentamethylcyclopentadienyl compounds 4b–6b with PMe₃, PMe₂Ph, PMePh₂ or PPh₃. These results are consistent with the displacement of the co-ordinated oxygen atom being influenced by the steric properties of the P,O-ligand, with PPh₃ displacing the keto group from L² but not from the bulkier L¹. In the reaction of [Mo(CO)₂(L²-κ²P,O)(η⁵-C₅H₅)]BF₄ (5a) with PMe₃ the phosphine does not displace the keto group, instead it acts as a base, with the only observed molybdenum-containing product being the enolate compound [Mo(CO)₂{PPh₂CHC(O)Ph-κ²P,O}(η⁵-C₅H₅)] 9. Compound 9 can also be formed from the reaction of 2a with BuLi or NEt₃, and a single crystal X-ray analysis has confirmed the enolate structure.     

Synthesis and Characterization of Alkyltris(2-pyridyl)phosphonium Salts

Alkytris(2-pyridyl)phosphonium salts [(2-Py) ₃ PR]X 1 [1a, R = Et, X = Br; 1b, R = Pr, X = Br; 1c, R = Bu, X = Br; 1d, R = CH₂Ph, X = Br; 1e, R = CH ₂ Ph, X = Cl] were synthesised from (2-Py) ₃ P and an excess of RCl. 1c and 1e were found to rapidly decompose in hot acetone to 2,2′-bipyridinium(+1) bromide 2 and (2-Py)P(O)(CH ₂ Ph)C(OH)Me ₂ 3, respectively. A reaction mechanism for both products is proposed. All compounds were fully characterized, including X-ray crystallography for 1a and 3 with 1a being the first representative of this class of compounds characterized by this technique.     

Synthesis and characterisation of mixed ligand Pt(II) and Pt(IV) oxadiazoline complexes

The nitrile ligands in trans-[PtX2(PhCN)2] (X = Cl, Br, I) undergo sequential 1,3 dipolar cycloadditions with nitrones R1R2C=N+(Me)-O(-) (R1 = H, R2 = Ph; R1 = CO2Et, R2 = CH2CO2Et) to selectively form the Delta4-1,2,4-oxadiazoline complexes trans-[PtX2(PhCN) (N=C(Ph)-O-N(Me)-CR1R2)] or trans-[PtX2(N=C(Ph)-O-N(Me)-CR1R2)2] in high yields. The reactivity of the mixed ligand complexes trans-[PtX2(PhCN)(N=C(Ph)-O-N(Me)-CR1R2)] towards oxidation and ligand substitution was studied in more detail. Oxidation with Cl2 or Br2 provides the Pt(IV) species trans-[PtX2Y2(PhCN)(N=C(Ph)-O-N(Me)-CH(Ph))] (X, Y = Cl, Br). The mixed halide complex (X = Cl, Y = Br) undergoes halide scrambling in solution to form trans-[PtX(4-n)Yn(PhCN)(N=C(Ph)-O-N(Me)-CH(Ph))] as a statistical mixture. Ligand substitution in trans-[PtCl2(PhCN)(N=C(Ph)-O-N(Me)-CR1R2)] allows for selective replacement of the coordinated nitrile by nitrogen heterocycles such as pyridine, DMAP or 1-benzyl-2-methylimidazole to produce mixed ligand Pt(II) complexes of the type trans- [PtX2(heterocycle)(N=C(Ph)-O-N(Me)-CR1R2)]. All compounds were characterised by elemental analysis, mass spectrometry, IR and 1H, 13C and 195Pt NMR spectroscopy. Single-crystal X-ray structural analysis of (R,S)-trans-[PtBr2(N=C(Ph)-O-N(Me)-CH(Ph))2] and trans-[PtCl2(C5H5N)(N=C(Ph)-O-N(Me)-CH(Ph))] confirms the molecular structure and the trans configuration of the heterocycles relative to each other.     

Structural and energetic aspects of hydrogen bonding and proton transfer to ReH2(CO)(NO)(PR3)2 and ReHCl(CO)(NO)(PMe3)2 by IR and X-ray studies

The interaction of rhenium hydrides ReHX(CO)(NO)(PR₃)₂ 1 (X=H, R=Me (a), Et (b), iPr (c); X=Cl, R=Me (d)) with a series of proton donors (indole, phenols, fluorinated alcohols, trifluoroacetic acid) was studied by variable temperature IR spectroscopy. The conditions governing the hydrogen bonding ReHHX in solution and in the solid state (IR, X-ray) were elucidated. Spectroscopic and thermodynamic characteristics (−ΔH=2.3–6.1 kcal mol⁻¹) of these hydrogen bonded complexes were obtained. IR spectral evidence that hydrogen bonding with hydride atom precedes proton transfer and the dihydrogen complex formation was found. Hydrogen bonded complex of ReH₂(CO)(NO)(PMe₃)₂ with indole (2a–indole) and organyloxy-complex ReH(OC₆H₄NO₂)(CO)(NO)(PMe₃)₂ (5a) were characterized by single-crystal X-ray diffraction. A short NHHRe (1.79(5) Å) distance was found in the 2a–indole complex, where the indole molecule lies in the plane of the Re(NO)(CO) fragment (with dihedral angle between the planes 0.01°).     

Siliciumhaltige carben-komplexe: VIII. HSiR3-eliminierung aus carben-komplexen des typs (CO)5MC(NHR′)SiR3 (M = Cr,Mo, W)

Upon heating solid monoalkylamino(silyl)carbene complexes (CO)₅MC(NHR′)SiR₃ (M = W: SiR₃ = SiPh₃, R′ = Me, Et, Buⁿ, C₆H₁₁, Ph; SiR₃ = SiMePh₂, R′ = Me, Et. M = Mo, Cr: R = Ph, R′ = Me, Et) beyond their melting points, HSiR₃ elimination with formation of the isonitrile complexes (CO)₅MNCR′ and (CO)₄M(CNR′)₂ and (CO)₆M takes place quantitatively. Deuteration experiments show that the silane hydrogen stems from the NH group and that the reaction partially or exclusively proceeds by an intermolecular pathway.     

Cyclopentadienyl tungsten complexes with thiocarboxylate and thiosulfonate ligands: Structures of CpW(CO)3SCOPh and CpW(CO)3SSO2-4-C6H4Cl

Treatment of the hydrosulfido tungsten complex CpW(CO)₃SH with acid chlorides (RCOCl) or sulfonyl chlorides (RSO₂Cl) affords CpW(CO)₃SCOR (1) [R = Me (a), CH₂Cl (b), Ph (c), 4-C₆H₄NO₂ (d)] and CpW(CO)₃SSO₂R (2) [R = Me (a), Ph (b), 4-C₆H₄Cl (c), 4-C₆H₄NO₂ (d)], respectively. The novel complexes, 1 and 2, were fully characterized by elemental analyses, IR and ¹H NMR spectroscopy. The solid state structures of CpW(CO)₃SCOPh (1c) and CpW(CO)₃SSO₂-4-C₆H₄Cl (2c) were determined by an X-ray crystal structure analysis.     

Synthese und Reaktivität von Silicium-übergangsmetall-Komplexen: XXI. Ferrio-azidosilane and Ferriosilyl-iminophosphorane

Reaction of the ferriochlorosilanes R₅C₅(CO)₂FeSiR′_3-nCl_n (1a–1f) with sodium azide in tetrahydrofuran yields the ferrio- (mono-, bis-, and tris-azido)silanes R₅C₅(CO)₂FeSiR′_3-n(N₃)_n (R = H, Me; R′ = Me, H; n = 1–3) (2a–2f). CCl₄ converts Cp(CO)₂FeSiMe(H)N₃ (2a) into the ferrioazido(chloro)silane Cp(CO)₂-FeSiMe(Cl)N₃ (3). Treatment of 2d, 2f with Me₃P results in the formation of the ferriosilyl-iminophosphoranes Cp(CO)₂FeSi(N₃)(R)NPMe₃ (R = Me, N₃), (4a, 4b) by N₂ elimination.     

New cyclometalated palladium(II) complexes with iminophosphines: Crystal structures of [Pd(C^N)(o-Ph2PC6H4–CH=NR)][PF6] (C^N=azobenzene,R=Et; C^N=2-phenylpyridine,R=Me)

The synthesis of new cyclometalated compounds of palladium(II) with the mixed-donor bidentate ligands o-Ph₂PC₆H₄–CH=NR is described. Two series of complexes [Pd(C^N)(o-Ph₂PC₆H₄–CH=NR)][PF₆] have been prepared using either azobenzene or 2-phenylpyridine as cyclometalated ligands [C^N=azobenzene (azb); R=Me (1a), Et (2a), ⁿPr (3a), ⁱPr (4a), ^tBu (5a), Ph (6a), NH–Me (7a); C^N=2-phenylpyridine (phpy); R=Me (1b), Et (2b), ⁿPr (3b), ⁱPr (4b), ^tBu (5b), Ph (6b), NH–Me (7b)]. The new complexes were characterized by partial elemental analyses and spectroscopic methods (IR, FAB, ¹H and ³¹P NMR). The molecular structures of compounds 2a (monoclinic, P 2₁/n) and 1b (monoclinic, C 2/c) have been determined by a single-crystal diffraction study. In both cases this technique revealed the relative trans configuration between the phosphorus atom and the nitrogen atom of the ortho-metalated ligand.     

Reactions of a phosphido-bridged unsymmetrical diiron complex (η-C5Me5)Fe2(CO)4(μ-CO)(μ-PPh2) with various alkynes

A phosphido-bridged unsymmetrical diiron complex (η⁵-C₅Me₅)Fe₂(CO)₄(μ-CO)(μ-PPh₂) (1) was synthesized by a new convenient method; photo-dissociation of a CO ligand from (η⁵-C₅Me₅)Fe₂(CO)₆(μ-PPh₂) (2) that was prepared by the reaction of Li[Fe(CO)₄PPh₂] with (η⁵-C₅Me₅)Fe(CO)₂I. The reactivity of 1 toward various alkynes was studied. The reaction of 1 with ^tBuCCH gave a 1:1 mixture of two isomeric complexes (η⁵-C₅Me₅)Fe₂(CO)₃(μ-PPh₂)[μ-CHC(^tBu)C(O)] (3) containing a ketoalkenyl ligand. The reactions of 1 with other terminal alkynes RCCH (R=H, CO₂Me, Ph) afforded complexes incorporating one or two molecules of alkynes and a carbonyl group. The principal products were dinuclear complexes bridged by a new phosphinoketoalkenyl ligand, (η⁵-C₅Me₅)Fe₂(CO)₃(μ-CO)[μ-CR¹CR²C(O)PPh₂] (4a: R¹=H, R²=H; 4b: R¹=CO₂Me, R²=H; 4c: R¹=H, R²=Ph). In the cases of alkynes RCCH (R=H, CO₂Me), dinuclear complexes having a new ligand composed of two molecules of alkynes, a carbonyl group, and a phosphido group; i.e. (η⁵-C₅Me₅)Fe₂(CO)₃[μ-CRCHCHCRC(O)PPh₂] (5a: R=H; 5b: R=CO₂Me), were also obtained. In all cases, mononuclear complexes, (η⁵-C₅Me₅)Fe(CO)[CR¹CR²C(O)PPh₂] (6a: R¹=H, R²=H; 6b: R¹=H, R²=CO₂Me; 6c: R¹=H, R²=Ph) were isolated in low yields. The structures of 1, 4c, 5b, and 6a were confirmed by X-ray crystallography. The detailed structures of the products and plausible reaction mechanisms are discussed.