Syntheses, structural characterisation and electronic structures of some simple acyclic amino carbene complexes

Eaves, Samantha G.; Yufit, Dmitry S.; Skelton, Brian W.; Howard, Judith A. K.; Low, Paul J.

doi:10.1039/c5dt01806d

Cited by 20 publications

(10 citation statements)

References 68 publications

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“…The formation of 5 a from 3 a is believed to proceed through protonation of the acetylide ligand by NH 4 PF 6 , an acidic salt, to afford 2 a , followed by the subsequent addition of NH 3 at Cα. The 1 H NMR spectrum of 5 a displays two characteristic broad singlets at δ= 8.97 and 6.91 ppm assigned to the NH 2 group . In the 13 C NMR spectrum, the resonance of Cα appears as a triplet at δ= 251.8 ppm, with 2 J (C,P)=13.5 Hz, which shifts upfield significantly relative to the Cα signal of 2 a at δ= 345.4 ppm.…”

Section: Resultsmentioning

confidence: 96%

“…[19] However,i nt he presence of NH 4 PF 6 ,a ttempted alkylationso f3a with haloacetates afforded the aminocarbenec omplex 5a,w hich wasa lso obtained from the direct reaction of 2a with NH 3 (0.5 m in tetrahydrofuran (THF)) in CH 2 Cl 2 .T he formation of 5a from 3a is believed to proceedt hrough protonation of the acetylide ligand by NH 4 PF 6 ,a na cidic salt, to afford 2a,f ollowed by the subsequent addition of NH 3 at Ca.T he 1 HNMR spectrum of 5a displays two characteristicb road singlets at d = 8.97 and 6.91 ppm assigned to the NH 2 group. [20] In the 13 CNMR spectrum, the resonance of Ca appears as at riplet at d = 251.8 ppm, with 2 J(C,P) = 13.5 Hz, which shifts upfield significantly relative to the Ca signal of 2a at d = 345.4 ppm. The singlet 31 PNMR signal of 5a at d = 49.2 ppm is considerably different from that of 2a at d = 42.3 ppm.…”

Section: Alkylation Versus Nucleophilic Additionmentioning

confidence: 96%

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Reactions of a Ruthenium Complex with Substituted N‐Propargyl Pyrroles

Chia

Huang

Liu

et al. 2016

Chemistry An Asian Journal

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In an investigation into the chemical reactions of N-propargyl pyrroles 1 a-c, containing aldehyde, keto, and ester groups on the pyrrole ring, with [Ru]-Cl ([Ru]=Cp(PPh3 )2 Ru; Cp=C5 H5 ), an aldehyde group in the pyrrole ring is found to play a crucial role in stimulating the cyclization reaction. The reaction of 1 a, containing an aldehyde group, with [Ru]-Cl in the presence of NH4 PF6 yields the vinylidene complex 2 a, which further reacts with allyl amine to give the carbene complex 6 a with a pyrrolizine group. However, if 1 a is first reacted with allyl amine to yield the iminenyne 8 a, then the reaction of 8 a with [Ru]-Cl in the presence of NH4 PF6 yields the ruthenium complex 9 a, containing a cationic pyrrolopyrazinium group, which has been fully characterized by XRD analysis. These results can be adequately explained by coordination of the triple bond of the propargyl group to the ruthenium metal center first, followed by two processes, that is, formation of a vinylidene intermediate or direct nucleophilic attack. Additionally, the deprotonation of 2 a by R4 NOH yields the neutral acetylide complex 3 a. In the presence of NH4 PF6 , the attempted alkylation of 3 a resulted in the formation the Fischer-type amino-carbene complex 5 a as a result of the presence of NH3, which served as a nucleophile. With KPF6, the alkylation of 3 a with ethyl and benzyl bromoacetates afforded the disubstituted vinylidene complexes 10 a and 11 a, containing ester groups, which underwent deprotonation reactions to give the furyl complexes 12 a and 13 a, respectively. For 13 a, containing an O-benzyl group, subsequent 1,3-migration of the benzyl group was observed to yield product 14 a with a lactone unit. Similar reactivity was not observed for the corresponding N-propargyl pyrroles 1 b and 1 c, which contained keto and ester groups, respectively, on the pyrrole ring.

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Section: Resultsmentioning

confidence: 96%

Section: Alkylation Versus Nucleophilic Additionmentioning

confidence: 96%

Reactions of a Ruthenium Complex with Substituted N‐Propargyl Pyrroles

Chia

Huang

Liu

et al. 2016

Chemistry An Asian Journal

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“…The NMR spectra show a single set of resonances, ascribable to the E configuration of substituents at the iminium moiety. The C 1 carbon resonates at 253.0 ppm, thus revealing its aminocarbene identity . Typical low field resonances feature also the C 2 and C 3 carbons (132.8 and 182.6 ppm, respectively).…”

Section: Resultsmentioning

confidence: 97%

Construction of a Functionalized Selenophene‐Allylidene Ligand via Alkyne Double Action at a Diiron Complex

et al. 2020

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The diiron µ‐vinyliminium compounds [Fe2Cp2(CO)(µ‐CO){µ‐η1:η3‐C3HC2HC1NMe(R)}]CF3SO3 (R = Me, 2a; R = Xyl = 2,6‐C6H3Me2, 2b; Cp = η5‐C5H5) reacted with grey selenium, in the presence of sodium methoxide, to give the corresponding Se‐functionalized derivatives [Fe2Cp2(CO)(µ‐CO){µ‐η1:η3‐C3HC2(Se)C1NMe(R)}], 3a–b, in ca. 50 % yields. The monoiron zwitterionic complex [FeCp(CO){SeC1(NMe2)C2HC3H}], 4, was obtained as a side‐product (31 %) of the reaction leading to 3a. The treatment of 3b with S8/NaOMe afforded the 2‐ferra‐thiophene [FeCp(CO){SC3HC2HC1NMe(Xyl)}], 5, in 49 % yield. The straightforward reactions of 3a with a two‐fold excess of dialkylacetylenedicarboxylates led to functionalized 3‐amino‐selenophenes appended to the diiron frame through a bridging allylidene ligand, [Fe2Cp2(CO)(µ‐CO){µ‐η1:η3‐C7(CO2R)C6(CO2R)C3HC2SeC5(CO2R)C4(CO2R)C1(NMe2)}] (R = Me, 6a; R = Et, 6b; R = tBu, 6c), in approximately 50 % yields. The synthesis of 6a–c is the result of two distinct modes of reactivity exhibited by the alkyne reactant in one pot, i.e. 1,3‐dipolar cycloaddition to C and Se atoms and insertion into Fe‐µ‐alkylidene. All the products were characterized by means of elemental analysis, IR and multinuclear NMR spectroscopy, and the molecular structure of 6a was elucidated by a single‐crystal X‐ray diffraction study.

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“…On the other hand, the introduction of basic amino-alkylidene group in half-sandwich iron complexes by classical methods requires the modification of a hydrocarbyl ligand, e.g. via aminolysis of an alkoxyalkylidene [26] or a vinylidene, [27] or derivatization of an isocyanide. [26a] The characterization was performed by means of Ft-IR and NMR spectroscopy, and the molecular structures of 5a, 5h, and 6b were ascertained by X-ray diffraction studies ( Figure 2, and Tables 1 and 5).…”

Section: Synthesis and Characterization Of Compoundsmentioning

confidence: 99%

Antiproliferative and bactericidal activity of diiron and monoiron cyclopentadienyl carbonyl complexes comprising a vinyl‐aminoalkylidene unit

Rocco

Busto

Pérez‐Arnaiz

et al. 2020

Applied Organom Chemis

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A series of diiron complexes with two cyclopentadienyls, two carbonyls, and one bridging vinyl-aminoalkylidene as ligands, [3a-h]CF 3 SO 3 and [4a-d] CF 3 SO 3 , was synthesized in 66-94% yields from diiron μ-aminocarbyne precursors. The subsequent reactions with pyrrolidine led to selective fragmentation to aminoalkylidene-ferracyclopentenone derivatives (5a-h and 6a-c) in 30-84% yields. The compounds were characterized by elemental analysis, Fourier transform infrared and NMR spectroscopy, and by single crystal X-ray diffraction in three cases. The stability in aqueous media relevant to biological trials, the carbon monoxide release, and the catalytic activity in NADH oxidation were evaluated for selected compounds by NMR spectroscopy and gas chromatography. The in vitro antiproliferative activity of the compounds was determined towards cancer (A2780, A2780cisR) and noncancer (HEK-293) cell lines. Moreover, the antibacterial activity was tested on Gram-positive (vancomycin-resistant E. faecium and methicillin-resistant S. aureus) and Gram-negative strains (A. baumannii and P. aeruginosa). K E Y W O R D S amino-alkylidene ligand, bioorganometallic chemistry, cytotoxic and antibacterial activity, diiron complexes, iron-carbonyl complexes Dalila Rocco and Natalia Busto contributed equally to the work.

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Syntheses, structural characterisation and electronic structures of some simple acyclic amino carbene complexes

Cited by 20 publications

References 68 publications

Reactions of a Ruthenium Complex with Substituted N‐Propargyl Pyrroles

Reactions of a Ruthenium Complex with Substituted N‐Propargyl Pyrroles

Construction of a Functionalized Selenophene‐Allylidene Ligand via Alkyne Double Action at a Diiron Complex

Antiproliferative and bactericidal activity of diiron and monoiron cyclopentadienyl carbonyl complexes comprising a vinyl‐aminoalkylidene unit

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