Metal-Promoted Aromatic Ring Amination Reactions following Carbon−Nitrogen Bond Formation. Proof of Amine Coordination for <i>ortho </i>Amination

Saha, Amrita; Ghosh, Amit; Majumdar, Partha; Mitra, Kedar Nath; Mondal, Sujit; Rajak, Kajal Krishna; Falvello, Larry R.; Goswami, Sreebrata

doi:10.1021/om9903341

Cited by 52 publications

(38 citation statements)

References 12 publications

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“…[13] The labile cobalt complex [Co(L 1 ) 3 ] 2ϩ reacts smoothly with primary aromatic amines (ArNH 2 ), without solvent, to produce [6] green, crystalline complexes [Co III (L 2 ) 2 ] ϩ . [13] The labile cobalt complex [Co(L 1 ) 3 ] 2ϩ reacts smoothly with primary aromatic amines (ArNH 2 ), without solvent, to produce [6] green, crystalline complexes [Co III (L 2 ) 2 ] ϩ .…”

Section: Iron-and Nickel-promoted Aromatic Ring Amination Of Coordinamentioning

confidence: 99%

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Transition-Metal-Promoted C−N Bond-Formation Processes − Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine − X-ray Structure, Redox- and Spectroelectrochemistry

Saha

Majumdar

Peng

et al. 2000

Eur. J. Inorg. Chem.

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Keywords: Transition-metal-promoted reactions / Aminations / Iron / Nickel / Electrochemistry / N ligandsThe metal-promoted amination of an aromatic ring of coordinated L 1 [L 1 , pap = 2-(phenylazo)pyridine] is described. Whereas the labile cobalt complex [Co(L 1 ) 3 ] 2+ prefers orthoamination, yielding L 2 H {2-[2-(arylamino)phenylazo]-pyridine}, the corresponding [Fe(L 1 ) 3 ] 2+ complex produces the para-aminated product L 3 H {2-[4-(arylamino)phenylazo]pyridine}. Both L 2 H and L 3 H have been isolated in the pure state and were fully characterised. They have low pK a values, for example pK a (L 2a H) = 8.5 ± 1 and pK a (L 3a H) = 9.1 ± 1. Upon deprotonation, the ligand L 2 H behaves as a potential tridentate N,N,N donor. It reacts with anhydrous FeCl 3 and NiCl 2 ·6H 2 O to produce cationic [Fe(L 2 ) 2 ] + (1 + ) and neutral [Ni(L 2 ) 2 ] (2), respectively. The cationic ferric complex has been isolated as its perchlorate salt, which is paramag- [a]

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Section: Iron-and Nickel-promoted Aromatic Ring Amination Of Coordinamentioning

confidence: 99%

“…[6] The tridentate ligand [L 2 ] Ϫ has a unique combination of hard as well as netic with one unpaired electron (1.66 µ B ). [6] The tridentate ligand [L 2 ] Ϫ has a unique combination of hard as well as netic with one unpaired electron (1.66 µ B ).…”

Section: Introductionmentioning

confidence: 99%

Transition-Metal-Promoted C−N Bond-Formation Processes − Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine − X-ray Structure, Redox- and Spectroelectrochemistry

Saha

Majumdar

Peng

et al. 2000

Eur. J. Inorg. Chem.

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“…[13] The labile cobalt complex [Co(L 1 ) 3 ] 2ϩ reacts smoothly with primary aromatic amines (ArNH 2 ), without solvent, to produce [6] green, crystalline complexes [Co III (L 2 ) 2 ] ϩ . The free ligand [L 2 H] has been isolated [9] by the removal of the metal ion from [Co(L 2 ) 2 ] ϩ (Scheme 2).…”

Section: Iron-and Nickel-promoted Aromatic Ring Amination Of Coordinamentioning

confidence: 99%

Transition-Metal-Promoted C−N Bond-Formation Processes − Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine − X-ray Structure, Redox- and Spectroelectrochemistry

Saha

Majumdar

Peng

et al. 2000

Eur. J. Inorg. Chem.

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The metal‐promoted amination of an aromatic ring of coordinated L1 [L1, pap = 2‐(phenylazo)pyridine] is described. Whereas the labile cobalt complex [Co(L1)3]2+ prefers ortho‐amination, yielding L2H {2‐[2‐(arylamino)phenylazo]pyridine}, the corresponding [Fe(L1)3]2+ complex produces the para‐aminated product L3H {2‐[4‐(arylamino)phenylazo]pyridine}. Both L2H and L3H have been isolated in the pure state and were fully characterised. They have low pKa values, for example pKa(L2aH) = 8.5 ± 1 and pKa(L3aH) = 9.1 ± 1. Upon deprotonation, the ligand L2H behaves as a potential tridentate N,N,N donor. It reacts with anhydrous FeCl3 and NiCl2·6H2O to produce cationic [Fe(L2)2]+ (1+) and neutral [Ni(L2)2] (2), respectively. The cationic ferric complex has been isolated as its perchlorate salt, which is paramagnetic with one unpaired electron (1.66 μB). It shows a rhombic EPR spectrum with g1 = 2.11, g2 = 2.08, g3 = 1.93. The room‐temperature magnetic moment of the nickel complex is 2.89 μB, which confirms the presence of two unpaired electrons. The representative X‐ray structures of [1]ClO4 and 2 are reported. In both cases the azo nitrogen atoms of the coordinated ligand, [L2]− approach the metal centres more closely, and there is a significant degree of ligand backbone conjugation. The complexes display multiple redox responses. Chemical reduction of 1+ with dilute hydrazine affords the corresponding ferrous complex [Fe(L2)2] (1) in almost quantitative yield. The spectral changes upon electrolysis of the above couples have been recorded in an OTTLE cell.

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“…Our interest in this work originated from our recent results on amine fusion reactions of pap coordinated to Ir(III) and Ir(V) centres. 13 6,7 Tetrabutylammonium perchlorate (TBAP) was prepared following the reported procedure. 15 All chromatographic purification has been carried out on alumina and column chromatographic purification has been done using silica gel (60-120 mesh) LR.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structure, redox and spectra of green iridium complexes of tridentate azo-aromatic ligands

et al. 2007

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Reactions of IrCl 3 ⋅xH 2 O with the ligands, 2-[(phenylamino)phenylazo]pyridine (HL 1a ) and 2-[(p-tolylamino)phenylazo]pyridine (HL 1b ) produce [Ir(L 1 ) 2 ]Cl (L 1 = L 1a , [1]Cl and L 1 = L 1b , [2]Cl) along with many unidentified products. The iridium complexes have been characterized by various techniques such as X-ray crystallography, mass spectrometry, 1 H and 13 C NMR, cyclic voltammetry and absorption studies. The complex [1]ClO 4 crystallises in triclinic space group. The crystallographic data have been determined. Notably, the Ir-N (azo) lengths are short (av. 1⋅9875(4) Å) as compared to the remaining four Ir-N lengths (av. 2⋅052(5) Å). There is significant degree of ligand backbone conjugation in the coordinated ligands, which result in shortening of the C-N lengths on the other side of the middle phenyl ring and also in lengthening of the diazo (N=N) lengths. The complexes display multiple low energy transitions ranging between 1010 and 450 nm. These are electro active and show three reversible redox responses in the potential range, +1⋅5 V to -1⋅5 V. The cathodic potential responses are ascribed as ligand reductions, while the redox process at the anodic potential occurs at a mixed metal-ligand (HOMO) orbital.

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Metal-Promoted Aromatic Ring Amination Reactions following Carbon−Nitrogen Bond Formation. Proof of Amine Coordination for ortho Amination

Abstract: The present report exemplifies two novel aromatic ring amination reactions via metal mediation. A rationale with respect to site selection for the above amination reactions, based on relative labilities of the coordinated coligands, has been established.

Cited by 52 publications

References 12 publications

Transition-Metal-Promoted C−N Bond-Formation Processes − Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine − X-ray Structure, Redox- and Spectroelectrochemistry

Transition-Metal-Promoted C−N Bond-Formation Processes − Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine − X-ray Structure, Redox- and Spectroelectrochemistry

Transition-Metal-Promoted C−N Bond-Formation Processes − Low-Spin FeIII, FeII, and NiII Complexes of 2-[(Arylamido)phenylazo]pyridine − X-ray Structure, Redox- and Spectroelectrochemistry

Synthesis, structure, redox and spectra of green iridium complexes of tridentate azo-aromatic ligands

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