Fluorescent sensors based on controllable conformational change for discrimination of Zn2+ over Cd2+

A new coumarin-derived imine IC1 was designed for highly selective sensing of Zn²⁺ over Cd²⁺ ions in aqueous solution based on a controllable CN isomerization mechanism. Methyl as a fine controllable unit was incorporated into IC1 to tune the conformational change of imine and thus significantly improve its selectivity to Zn²⁺ compared with methyl-free imine IC2. Sensor IC1 was also utilized to image intracellular Zn²⁺ ions in HepG2 cells with a good performance.     

Site selectivity in the reactions of 1,3-dipoles with norbornadiene derivatives

The cycloadditions of arylazides, benzonitrile oxides and diphenylnitrile imine to norbotnadiene derivatives 1a–c showed varying degree of site- and stereo-selectivity. With dipolarophile 1a arylazides and benzonitrile oxides attack, preferentially, the electron-poor tetrasubstituted double bond, while in the case of 1b and 1c is the substituted double bond which enters the cycloaddition. By contrast, 2-diazopropane and C-pnenyl-N-methyl-nitrone react with the sole tetrasubstituted double bond of 1a–c in stereo- and site-specific cycloadditions. The quantitative evaluation of the two possible reaction paths was performed by glc analysis. The compounds detected were those arising from Diels-Alder cycloreversions of the thermally labile intermediate adducts 2 and 3 (Scheme 1). The results were rationalized on the basis of a qualitative perturbation treatment which considers frontier orbital interactions only.     

Rifamycin antibiotics—new compounds and synthetic methods. Part 3: Study of the reaction of 3-formylrifamycin SV with primary amines and ketones

In the third stage of our study concerning the search for new antibacterial rifamycin antibiotics, the reactions of 3-formylrifamycin SV (1) with a range of primary alkylamines and ketones of general structure R₁–CH₂–CO–R₂ (R₁H or alkyl and R₂alkyl or aryl) has been investigated. A new synthetic method for the preparation of a new group of rifamycin derivatives with an α,β-unsaturated imine substituent at C-3 has been developed.These compounds showed a tendency to reversibly isomerise in organic solvents and, in the presence of water, to rapidly hydrolyse. The structures of four isolated microcrystalline compounds 2, 3, 4, 5 and a reaction's mechanism have been proposed on the basis of mass spectrometry results as well as (1D) and (2D) ¹H and ¹³C NMR analysis. The new synthetic route reported herein is a promising pathway to new reactive rifamycins displaying broader capabilities than the plain 3-formylrifamycin SV.     

1,3-Dipolar cycloaddition of diaryldiazomethanes across N-ethoxy-carbonyl-N-(2,2,2-trichloroethylidene)amine and reactivity of the resulting 2-azabutadienes towards thiolates and cyclic amides

1,3-dipolar cycloaddition of diaryldiazomethanes Ar₂CN₂ across Cl₃C–CHN–CO₂Et 1 yields Δ³-1,2,4-triazolines 2. Thermolysis of 2 leads, via transient azomethine ylides 3, to diaryldichloroazabutadienes [Ar(Ar')CN–CHCCl₂] 4. Treatment of 4a (Ar = Ar' = C₆H₅) and 4c (Ar = Ar' = p-ClC₆H₄) with NaSR in DMF yields 2-azabutadienes [Ar₂CN–C(H)C(SR)₂] 5. In contrast, nucleophilic attack of NaStBu on 4 affords azadienic dithioethers [Ar₂CN–C(S^tBu)C(H)(S^tBu)] (7a Ar = C₆H₅; 7b Ar' = p-ClC₆H₄). The reaction of 4a with NaSEt conducted in neat EtSH produces [Ph₂CN–C(H)(SEt)–CCl₂H] 8, which after dehydrochloration by NaOMe and subsequent addition of NaSEt is converted to [Ph₂CN–C(SEt)C(H)(SEt)] 7c. Upon the reaction of 4c with NaSⁱPr, the intermediate dithioether [(p-ClC₆H₄)₂CN–CHC(SⁱPr)₂] 5k is converted to tetrakisthioether [(p-ⁱPrSC₆H₄)₂CN–CHC(SⁱPr)₂] 6. Treatment of 4a with the sodium salt of piperidine leads to [Ph₂CN–CHC(NC₅H₁₀)₂] 10. The coordination of 6 on CuBr affords the macrocyclic dinuclear Cu(I) complex 11. The crystal structures of 5i, 7a,b, 10 and 11 have been determined by X-ray diffraction.     

Synthesis of tungsten compounds with Schiff base ligands prepared from ferrocenecarboxaldehyde: Observation of the migration of an imine double bond

The one-pot reactions of ferrocenecarboxaldehyde, W(CO)₄(pip)₂ (pip = piperidine) and either 2-(aminomethyl)pyridine or 2-(2-aminoethyl)pyridine lead to clean formation of pyridine imine products W(CO)₄(η²-NC₅H₄CHNCH₂C₅H₄FeCp) (1) and W(CO)₄(η²-NC₅H₄C₂H₄NCHC₅H₄FeCp) (2), respectively. Crystal structures of the two compounds show that in 1 the imine double bond has migrated so that it is conjugated with the pyridine ring while in 2 the imine double bond remains conjugated with the cyclopentadienyl ring. This finding is reinforced by a comparison of dihedral angles in each molecule. IR, NMR and electronic spectra each highlight the differences between the two compounds. Crystal data for C₂₁H₁₆FeN₂O₄W (1): monoclinic P2(1)/c, a = 12.768(2) Å, b = 13.593(2) Å, c = 12.981(2) Å, β = 119.46°, V = 1961.6(4) Å³, Z = 4; C₂₂H₁₈FeN₂O₄W (2): monoclinic P2(1)/c, a = 16.759(1) Å, b = 8.8612(7) Å, c = 13.802(1) Å, β = 95.998(1)°, V = 2038.4(3) Å³, Z = 4.     

Structural and spectral studies of 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one and its diorganotin(IV) complexes

Two diorganotin(IV) complexes of the general formula R₂Sn[Ph(O)CCH-C(Me)N-C₆H₄(O)] (R = Ph, 1a; R = Me, 1b) have been synthesized from the corresponding diorganotin(IV) dichlorides and the ligand, 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (1) in methanol at room temperature in presence of triethylamine. Both compounds have been characterized by elemental analyses, IR and ¹H, ¹³C, ¹⁵N, ¹¹⁹Sn NMR spectra. The structures of the free ligand and the complexes have been confirmed by single crystal X-ray diffraction. There are three independent molecules in the crystal structure of the ligand 1 and in all three the O-bound proton is transferred to the imine nitrogen and makes an intramolecular N-H?O hydrogen bond with the carbonyl oxygen. In turn this makes an intermolecular hydrogen bond with the phenolic H atom. The crystal structure of 1 is trigonal and a new polymorph; triclinic and monoclinic forms have already been published. In 1a, the central tin atom adopts distorted trigonal-bipyramidal coordination geometry whereas in dimeric 1b it is distorted octahedral when including the intermolecular Sn-O(phenolic) bond [2.7998(20) Å]. The δ (¹¹⁹Sn) values for the complexes 1a and 1b are −306.6 and −127.9 ppm, respectively, thus indicating penta-coordinated Sn centres in solution.     

Heterobimetallic aluminium and zinc complex with N-arylanilido-imine ligand: Synthesis, structure and catalytic property for ring-opening polymerization of ε-caprolactone

Treatment of a N-arylanilido-imine ligand [ortho-C₆H₄(NHAr)CHN]₂CH₂CH₂ (Ar = 2,6-Me₂C₆H₃) (LH₂) with one equiv. of AlMe₃ affords a monometallic complex [C₆H₄(NHAr)–CHN)]CH₂CH₂(C₆H₄(NAr)CHNAlMe₂) (1). The monometallic complex 1 reacts with one equiv. of ZnEt₂ to give a heterobimetallic complex [C₆H₄(NAr)–CHNZnEt]CH₂CH₂[C₆H₄(NAr)–CHNAlMe₂] (2). Both complexes were characterized by ¹H and ¹³C NMR spectroscopy and elemental analyses, and the molecular structures of 1 and 2 were determined by X-ray diffraction analysis. The complexes 1 and 2 both are efficient catalysts for ring-opening polymerization of ε-caprolactone in the presence of benzyl alcohol yielding polymers with narrow polydispersity values and complex 2 initiates the polymerization in a controllable manner.     

Coordination of reduced Schiff base anion to Pd(II): Synthesis,characterization, DFT calculation and catecholase activity

The article reports the synthesis and characterization of a new palladium(II) complex of type [(L_NNN¹⁻)PdCl] (1) where L_NNN¹⁻ is a mono anionic Schiff's base having a imine bond in reduced state. The L_NNN¹⁻ is generated from a tridentate NNN donor ligand (L_NNN) through in-situ reduction using sodium borohydride, where L_NNN is [(E)-N-(phenyl(pyridine-2-yl)methylene)quinoline-8-amine)]. 1 is characterized by the single crystal X-ray diffraction study, IR, mass and UV–Vis spectroscopy. The X-ray bond parameter authenticates the imine bond of the coordinated Schiff's base anion is in reduced state. 1 exhibits catalytic activity towards the oxidation of 3,5-ditertiarybutyl catechol(3,5-DTBC) with turnover number (K_cat) ​= ​135.6 h^-1. The catalytic oxidation of 3,5-DTBC is authenticated by the UV–Vis, mass and EPR spectroscopy. An isotropic EPR signal with g ​= ​2.011 of a solution containing 1 and 3,5-DTBC authenticating the generation of organic radical during the oxidation process. Cyclic voltammogram of 1 displays an irreversible anodic wave at +0.22 ​V may be due to the oxidation of N⁻ to N^•−. The atomic spin density of 1⁺ obtained from DFT calculation is also supporting the N-centre oxidation process.     

Cyclobutane-bicyclobutane system—I : The relative reactivity of the central bond in bicyclobutanecarbonitrile and the double bond in crotononitrile in nucleophilic reactions

The ease of nucleophilic cleavage of the central bond of bicyclo[1.1.0]butanecarbonitrile 1 by alkoxides was compared to that of the double bond in crotononitrile 2. With both MeO^? /MeOH and i-PrO^?/PrOH, 2 reacts faster than 1 (by a factor of ca. 8 and 3 respectively). Analysis of the activation parameter reveals that in MeO^?/MeOH, both substrates have about the same activation energy and the reaction rate of 1 is markedly retarded by entropy effect. In i-PrO-/i-PrOH the entropy of activation is in favour of the reaction of 1 white its activation energy is higher than that of 2. Considering the steric and electronic effects of the substituents, it is concluded that the central bond of bicyclobutanecarbonitrile is more susceptible to nucleophilic attack than the analogous double bond.     

A comparative study of neighbouring group effects on the isomerization of imines in platinum-imine complexes by 1H, 13C, 31P and 195Pt NMR spectroscopy

¹⁹⁵Pt-, ³¹P-, ¹³C- and ¹H-chemical shifts are reported for the first time for complexes of the type trans-[PtCl₂ (η²-C₂H₄) (imine)], I, trans-[PtCl₂ (η²-C₂H₄) (amine)] II, and trans-[PtCl₂(PR′₃) (imine)] III (the imine ligand being derived from cyclopropyl-2-thienylketone and primary amines; PR′₃ = PBuⁿ₃ and PPh₃; amine; the amine ligand obtained by the reduction of the appropriate imine). The use of multinuclear spectroscopy provides strong evidence for E-Z isomerization of imine ligands coordinated to platinum (II) of the type trans-[PtCl₂ (η²-C₂H₄)(imine)]. Tertiary phosphine ligands trans to imine ligand (III) are not strongly labilizing groups, in contrast to η²-C₂H₄, which shows a strong labilizing effect. The effect of neighbouring groups on E-Z isomerization indicates that increase of the bulky substituents close to the imino group tends to increase the rate of isomerization, and increasing the degree of substitution on the imine carbon atoms slows the rate of isomerization. Furthermore, addition of a trace of amine will catalyze the E-Z isomerization. Also, isomerization takes place in the liquid state to give one isomer during the coordination with platinum.     

Seeking new metalloligands: Synthesis and reactivity of palladacycles with pyridine and pyrimidine rings

Treatment of the Schiff base ligands 4-(NC₅H₄)C₆H₄C(H)N[2′-(OH)C₆H₄] (a), 3,5-(N₂C₄H₃)C₆H₄C(H)N[2′-(OH)-C₆H₄] (b) and 3,5-(N₂C₄H₃)C₆H₄C(H) N[2′-(OH)-5′-^tBuC₆H₃] (c) with palladium (II) acetate in toluene gave the poly-nuclear cyclometallated complexes [Pd{4-(NC₅H₄)C₆H₃C(H)N[2′-(O)C₆H₄]}]₄ (1a), [Pd{3,5-(N₂C₄H₃)C₆H₃C(H)N[2′-(O)-C₆H₄]}]₄ (1b) and [Pd{3,5-(N₂C₄H₃)C₆H₃C(H)N[2′-(O)-5′-^tBuC₆H₃]}]₄ (1c) respectively, as air stable solids, with the ligand acting as a terdentate [C,N,O] moiety after deprotonation of the –OH group. Reaction of the cyclometallated complexes with triphenylphosphine gave the mononuclear species [Pd{4-(NC₅H₄)C₆H₃C(H) N[2′-(O)C₆H₄]}(PPh₃)], (2a), [Pd{3,5-(N₂C₄H₃)C₆H₃C(H) N[2′-(O)C₆H₄]}(PPh₃)], (2b) and [Pd{3,5-(N₂C₄H₃)C₆H₃C(H)N[2′-(O)-5′-^tBuC₆H₃)}(PPh₃)], (2c) in which the polynuclear structure has been cleaved and the coordination of the ligand has not changed [C,N,O]. When the cyclometallated complexes 1b and 1c were treated with the diphosphines Ph₂P(CH₂)₄PPh₂ (dppb), Ph₂PC₅H₄FeC₅H₄PPh₂ (dppf) and Ph₂P(CH₂)₂PPh₂ (t-dppe) in a 1:2 molar ratio the dinuclear cyclometallated complexes [{Pd[3,5-(N₂C₄H₃)C₆H₃C(H)N{2′-(O)C₆H₄}]}₂(μ-Ph₂P(CH₂)₄PPh₂)], (3b), [{Pd[3,5-(N₂C₄H₃)C₆H₃C(H) N{2′-(O)-5′-^tBuC₆H₃}]}₂(μ-Ph₂P(CH₂)₄PPh₂)], (3c), [{Pd[3,5-(N₂C₄H₃)C₆H₃C(H)N{2′-(O)C₆H₄}]}₂(μ-Ph₂P(η⁵-C₅H₄)Fe(η⁵-C₅H₄)PPh₂)], (4b), [{Pd[3,5-(N₂C₄H₃)C₆H₃C(H) N{2′-(O)-5′-^tBuC₆H₃}]}₂(μ-Ph₂P(η⁵C₅H₄)Fe(η⁵C₅H₄)P-Ph₂)], (4c) and [{Pd[3,5-(N₂C₄H₃)C₆H₃C(H)N{2′-(O)-5′-^tBuC₆H₃}]}₂(μ-Ph₂P(CHCH)PPh₂)], (5c) were obtained as air stable solids.     

Chemistry of vinylidene complexes. XX. Intramolecular carbonylation of vinylidene on the MnFe center: Spectroscopic and structural study. X-ray structure of the new trimethylenemethane type MnFe complex

Reactions of Fe₂(CO)₉ with Cp(CO)₂MnCCHPh (1) and Cp(CO)(PPh₃)MnCCHPh (3) gave the heterometallic trimethylenemethane complexes η⁴-{C[Mn(CO)₂Cp](CO)CHPh}Fe(CO)₃ (2) and η⁴-{C[Mn(CO)(PPh₃)Cp](CO)CHPh}Fe(CO)₃ (4), respectively. The formation of the benzylideneketene [PhHCCCO] fragment included in complexes 2 and 4 occurs via intramolecular coupling of the carbonyl and vinylidene ligands. The structures of 3 and 4 were determined by single crystal XRD methods. The influence of the nature of the L ligands at the Mn atom on the structural and spectroscopic characteristics of η⁴-{C[Mn(CO)(L)Cp](CO)CHPh}Fe(CO)₃ (L = CO (2), PPh₃ (4)) is considered. According to the VT ¹H and ¹³C NMR spectra, complex 2 reversibly transforms in solution into μ-η¹:η¹-vinylidene isomer Cp(CO)₂MnFe(μ-CCHPh)(CO)₄ (2a), whereas complex 4 containing the PPh₃ ligand is not able to a similar transformation.     

Cyclometallated platinum(II) compounds with imine ligands derived from amino acids: Synthesis and oxidative addition reactions

The reactions of [PtMe₂(μ-SMe₂)]₂ with imines 4-ClC₆H₄CHNCHRCO₂Me (R = H (1a), Me (1b), ⁱPr (1c), CH₂C₆H₄(4’-OH) (1d), C₆H₅ (1e), CH₂C₆H₅(1f)) derived from natural amino acids produced under mild conditions cyclometallated platinum(II) compounds [PtMe{κ²-(C,N)-4-ClC₆H₃CHNCHRCO₂Me}(SMe₂)] (2a-2f). These compounds gave the corresponding phosphine derivatives [PtMe{κ²-(C,N)-4-ClC₆H₃CHNCHRCO₂Me}(PPh₃)] (3a-3f). The corresponding cyclometallated platinum(IV) compounds [PtMe₂I{κ²-(C,N)-4-ClC₆H₃CHNCHRCO₂Me}(PPh₃)] (4) arising from intermolecular oxidative addition of methyl iodide were obtained with a high degree of stereo selectivity. Analogous results were obtained for imine 2,6-Cl₂C₆H₃CHNCH(CH₂C₆H₅)CO₂Me (1g) in a process involving intramolecular oxidative addition of a C-Cl bond. The obtained compounds were fully characterized including structure determinations for compounds 3f, 4d and 4f.     

H NMR Dynamic study of thermal Z/E isomerization of 5-substituted 2-alkylidene-4-oxothiazolidine derivatives: Barriers to rotation about CC bond

The rotational barriers between the configurational isomers of two structurally related push–pull 4-oxothiazolidines, differing in the number of exocyclic CC bonds, have been determined by dynamic ¹H NMR spectroscopy. The equilibrium mixture of (5-ethoxycarbonylmethyl-4-oxothiazolidin-2-ylidene)-1-phenylethanone (1a) in CDCl₃ at room temperature to 333 K consists of the E- and Z-isomers which are separated by an energy barrier ΔG^# 98.5 kJ/mol (at 298 K). The variable-temperature ¹H NMR data for the isomerization of ethyl (5-ethoxycarbonylmethylidene-4-oxothiazolidin-2-ylidene)ethanoate (2b) in DMSO-d₆, possessing the two exocyclic CC bonds at the C(2)- and C(5)-positions, indicate that the rotational barrier ΔG^# separating the (2E,5Z)-2b and (2Z,5Z)-2b isomers is 100.2 kJ/mol (at 298 K). In a polar solvent-dependent equilibrium the major (2Z,5Z)-form (>90%) is stabilized by the intermolecular resonance-assisted hydrogen bonding and strong 1,5-type S · · · O interactions within the SCCCO entity. The ¹³C NMR Δδ_C(2)C(2′) values, ranging from 58 to 69 ppm in 1a–d and 49-58 ppm in 2a–d, correlate with the degree of the push-pull character of the exocyclic C(2)C(2′) bond, which increases with the electron withdrawing ability of the substituents at the vinylic C(2′) position in the following order: COPh COEt > CONHPh > CONHCH₂CH₂Ph. The decrease of the Δδ_C(2)C(2′) values in 2a–d has been discussed for the first time in terms of an estimation of the electron donor capacity of the S fragment on the polarization of the CC bonds.     

Aziridines-IV Catalytic decomposition of phenyldiazomethane in Schiff's bases

Catalytic decomposition of phenyldiazomethane in Schiff's bases is found to proceed via formation of trans-1,3-dipole (azomethine ylide) as an intermediate product. Depending on the size and quantity of the substituents, the ylide undergoes either cyclization in controtatory sense to cis-aziridine or cycloaddition[2+3]to the C=N bond of imine. The reactivity of double bonds to ylide decreases in the order C=C > C=O > C=N.     

Transformations of allylamine and N-allylacetamide on triosmium cluster complexes with hemilabile ligands

The cluster complexes (μ-H)Os₃(μ-OCR)(СО)₁₀ (R = Me (1); R = Ph (2)) catalyze the allylic rearrangement of N-allylacetamide at room temperature. Microwave irradiation greatly (by more than several thousand-fold) accelerates the reaction between the solution of 2 and allylacetamide. The interaction of cluster 2 with allylamine both at room and elevated temperatures results in cleavage of the C–N bond and coordination of the allylic fragment to one of the osmium atoms with the formation of Os₃(CO)₉(μ,η²-OC-Ph)(η³-C₃H₅) (4) cluster.     

Site specificity in cycloadditions of diphenylnitrile imine with 8-substituted-8-azaheptafulvenes and tricarbonyl (8-azaheptafulvene) iron complexes

The reaction of diphenylnitrile imine with 8-substituted-8-azaheptafulvenes is both site and regiospecific and resulted in a mixture of two [8+4]-adducts in high yield. The mechanism of the reaction was investigated. The [8+4]-adducts underwent easily a reversible thermal 1,7-sigmatropic shift involving an sp³ nitrogen centre. Diphenylnitrile imine reacted also with tricarbonyl(8-azaheptafutvene)iron complexes lo give adducts to the CN double bond, the degradative oxidation of which with trimethylamine-N-oxide was investigated. The specificity of the cycloadditions is briefly discussed on the basis of a simple perturbation theory approach.     

Étude de réactions photochimiques—XXIV: Réactions intramoléculaires de type ionique des alcools allyliques et homo-allyliques: Une approche vers l'étude conformationnelle des cholestènes-4 et cholestènes-5 excités

The C₅C₆ double bond of triplet-excited homoallylic alcohols 1, 5, 8, 10 and 13 is deactivated by protonation. Three secondary intramolecular processes follow: (a) addition to yield the oxetans 2, 6, 9, 11, 14; (b) fragmentation (followed by photocycloaddition which gives the oxetans 3, 12, 15); (c) isomérisation (Δ⁵ → Δ⁴). The C₄C₅ double bond of excited allylic alcohols 4, 16, 18, 20 and 7 is deactivated in the same way but only one secondary process is observed: fragmentation (followed by photocycloaddition giving rise to the oxetans 3, 12, 17, 19 and 21). Reactions in both homoallylic and allylic series have the same carbonium ion as intermediate. The triplet-excited homoallylic series have a conformation different from the triplet excited allylic series. The particular reactivity of each series is assigned to the conformational difference.     

Versatility in the mode of coordination {(N), (N,O), (C,N) or (C,N,O)} of [(η-C5H5)Fe{(η-C5H4)-CHN-(C6H4-2OH)}] to palladium(II)

The study of the reactivity of the ferrocenyliminoalcohol [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)-CHN-(C₆H₄-2OH)}] (1b) with Na₂[PdCl₄] or Pd(OAc)₂ has allowed the isolation and characterization of the heterotrimetallic complexes: trans-[Pd{(η⁵-C₅H₅)Fe[(η⁵-C₅H₄)-CHN-(C₆H₄-2OH)]}₂Cl₂] (2b), [Pd{[(η⁵-C₅H₃)-CHN-(C₆H₄-2O)]Fe(η⁵-C₅H₅)}{(η⁵-C₅H₅)Fe[(η⁵-C₅H₄)-CHN-(C₆H₄-2OH)]}] (3b) and trans-[Pd{(η⁵-C₅H₅)Fe[(η⁵-C₅H₄)-CHN-(C₆H₄-2O)]}₂] (4b). Ligand 1b acts as a (N) (in 2b) or a (N,O)⁻ (in 4b) ligand; while in 3b the two units of the iminoalcohol exhibit simultaneously different modes of binding {(N) and [C(sp², ferrocene),N,O]²⁻}. The crystal structures of 2b · 3H₂O and 3b · 1/2CHCl₃ are also reported and confirm the mode of binding of the ligand in these compounds. The relative importance of the factors affecting the preferential formation of products (2b-4b) is also discussed. The study of the reactivity of 3b with PPh₃ has enabled the obtention of the cyclopalladated complexes [Pd{[(η⁵-C₅H₃)-CHN-(C₆H₄-2O)]Fe(η⁵- C₅H₅)}(PPh₃)] (6b) and [Pd{[(η⁵-C₅H₃)-CHN-(C₆H₄-2OH)]Fe(η⁵-C₅H₅)}Cl(PPh₃)] (7b), in which 1b behaves as a [C(sp², ferrocene),N,O]²⁻ (in 6b) or [C(sp², ferrocene),N]⁻ (in 7b) ligand. Treatment of 3b with MeO₂C-CC-CO₂Me produces [Pd{[(MeO₂C-CC-CO₂Me)₂(η⁵-C₅H₃)-CHN-(C₆H₄-2O)]Fe(η⁵-C₅H₅)}] (8b), that arises from the bis(insertion) of the alkyne into the σ[Pd-C(sp², ferrocene)] bond. The comparison of the results obtained for 1b and [C₆H₅-CHN-(C₆H₄-2OH)] (1a) has allowed to establish the influence of the substituents on the imine carbon on their reactivity in front of palladium(II) as well as on the lability of the Pd-ligands bond. ⁵⁷Fe Mössbauer studies of 2b-4b and 6b provide conclusive evidence of the effect induced by the mode of binding of 1b on the environment of the iron(II).     

Übergangsmetall-heteroallen-komplexe XVII .Reaktionen des aza-allyl-komplexes (ketenimin)Fe2(CO)6 mit phosphanen

The aza-allyl complex (ketene imine)Fe₂(CO)₆ (3a) reacts with phosphanes PR₃ to give substitution products of the type (ketene imine)Fe₂(CO)₅PR₃ (4a,b). In addition, the phosphane PMe₃ yields a ferrole complex (5). Phosphites react with complex 3a to form mono- and di-substitution products (ketene imine)- Fe₂(CO)₅P(OR)₃ (4c,d) and (ketene imine)Fe₂(CO)₄(P(OR)₃)₂ (6). Diphosphanes yield substituted complexes of type (ketene imine)Fe₂(CO)₄(μ-Ph₂P ^⌢ PPh₂) (7). The structures of (ketene imine)Fe₂(CO)₅PMe₃ (4a), the ferrole complex 5, and (ketene imine)Fe₂(CO)₄(ν-Ph₂PCH₂CH₂PPh₂) (7b) were determined by X-ray analysis.