Chromium, molybdenum, and tungsten zerovalent complexes of the nitrogen chelating ligand 2-(phenylazo)pyridine (2-PAP), including air-stable cis-M(CO)2(2-PAP)2 and M(2-PAP)3

Ackermann, Martin N.; Barton, Carolyn R.; Deodene, Charles J.; Specht, Elizabeth M.; Keill, S. C.; Schreiber, William E.; Kim, Hidong

doi:10.1021/ic00302a006

Cited by 40 publications

(9 citation statements)

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“…However, three successive one-electron-transfer processes were observed in our experimental conditions. Notably, the ligand reductions in the tris-chelate 2 were systematically cathodic 10 as compared to those in [Cr(pap) 3 ]. This may be attributed to the strong inductive effect of p-NH(Ar) substitution in 2.…”

Section: Resultsmentioning

confidence: 99%

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Chromium Complexes of an Isomeric N-Donor Ligand, 2-[(N-Arylamino)phenylazo]pyridine: Amination Reactions, X-ray Structure, and Redox Properties

et al. 2002

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The chromium chemistry of two positional isomers of the ligand 2-[(N-arylamino)phenylazo]pyridine (HL(1)and HL(2)) are described. While the ligand HL(1) coordinates as a bischelating tridentate N,N,N-donor, [L(1)](-), with deprotonation of the amine nitrogen, its isomer HL(2) coordinates as a neutral bidentate N,N-donor. The amine nitrogen in this case remains protonated. Thus the reaction of CrCl(3).nH(2)O with HL(1) produced the brown cationic complex, [Cr(L(1))(2)](+), [1](+). The representative X-ray structure of [1a](ClO(4)) is reported. The two azo nitrogens of the anioinc tridentate ligand approach the metal center closest with Cr(1)-N(azo) av 1.862(6) A. There is a significant degree of ligand backbone conjugation in the coordinated ligands, which resulted in shortening of the C-N distances and also in lengthening of the diazo (N=N) distances. Two synthetic approaches for the synthesis of chromium complexes of HL(2) are investigated. The first approach is based on the substitution reaction, wherein all the coordinated CO ligands of Cr(CO)(6) were completely substituted by the three bidentate HL(2) ligands to produce a violet complex [Cr(HL(2))(3)]. The second approach is based on para-amination reaction of coordinated 2-(phenylazo)pyridine (pap). Thus the reaction of an inert complex, [CrCl(2)(pap)(2)], with ArNH(2) yields a mixed ligand complex, [CrCl(2)(pap)(HL(2))], 3. In this reaction one of the two coordinated pap ligands in [CrCl(2)(pap)(2)] undergoes amination at the para carbon (with respect to the diazo function) to yield HL(2) in situ. This metal-promoted transformation is authenticated by the X-ray structure determination of a representative complex, [CrCl(2)(pap)(HL(2a))], 3a. Notable differences in bond distances along the ligand backbones of the two coordinated ligands in 3a indicate different levels of metal-ligand overlap in this complex. All the chromium complexes of HL(2) are characterized by their intense blue-violet color. The frequencies of the visible range transitions in these complexes linearly correlate with the Hammett's substitution constant. Intraligand charge-transfer transitions in the visible region are believed to be responsible for the intense color. Redox properties of all these complexes are reported.

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Section: Resultsmentioning

confidence: 99%

“…Herein we describe the synthesis and properties of a series of chromium(II) and chromium(III) complexes of the isomeric 2-[( N -arylamino)phenylazo]pyridine ligands. Optical properties of these are markedly different than those of the parent chromium−pap complexes, − which are highlighted in this paper.…”

Section: Introductionmentioning

confidence: 85%

Chromium Complexes of an Isomeric N-Donor Ligand, 2-[(N-Arylamino)phenylazo]pyridine: Amination Reactions, X-ray Structure, and Redox Properties

et al. 2002

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“…As the copper(II) ion in a octahedral geometry exhibits Jahn–Teller distortion, generation of tris complexes of copper(II) ion with bidentate ligands is a challenge to synthetic inorganic chemists. Moreover, tris complexes of transition metal ions with abpy, one of the stronger π acidic bidentate and bridging ligands, are limited, while tris(bpy) and tris(2-phenylazopyridine) complexes are numerous. So far only a tris(abpy) complex of ruthenium(II) ion of type [Ru(abpy) 3 ] 2+ has been reported in literature .…”

Section: Introductionmentioning

confidence: 99%

Tris(2,2′-azobispyridine) Complexes of Copper(II): X-ray Structures, Reactivities, and the Radical Nonradical Bis(ligand) Analogues

Maity¹,

Kundu²,

Weyhermüller

et al. 2015

Inorg. Chem.

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Tris(abpy) complexes of types mer-[Cu(II)(abpy)3][PF6]2 (mer-1(2+)[PF6(–)]2) and ctc-[Cu(II)(abpy)2(bpy)][PF6]2 (ctc-2(2+)[PF6(–)]2) were successfully isolated and characterized by spectra and single-crystal X-ray structure determinations (abpy = 2,2′-azobispyridine; bpy = 2,2′-bipyridine). Reactions of mer-1(2+) and ctc-2(2+) ions with catechol, o-aminophenol, p-phenylenediamine, and diphenylamine (Ph–NH–Ph) in 2:1 molar ratio afford [CuI(abpy)2](+) (3(+)) and corresponding quinone derivatives. The similar reactions of [Cu(II)(bpy)3](2+) and [Cu(II)(phen)3](2+) with these substrates yielding [Cu(I)(bpy)2](+) and [Cu(I)(phen)2](+) imply that these complexes undergo reduction-induced ligand dissociation reactions (phen = 1,10-phenanthroline). The average −N═N– lengths in mer-1(2+)[PF6(–)]2 and ctc-2(2+)[PF6(–)]2 are 1.248(4), while that in 3(+)[PF6(–)]·2CH2Cl2 is relatively longer, 1.275(2) Å, due to dCu → πazo* back bonding. In cyclic voltammetry, mer-1(2+) exhibits one quasi-reversible wave at −0.42 V due to Cu(II)/Cu(I) and abpy/abpy(•–) couples and two reversible waves at −0.90 and −1.28 V due to abpy/abpy(•–) couple, while those of ctc-2(2+) ion appear at −0.44, −0.86, and −1.10 V versus Fc(+)/Fc couple. The anodic 3(2+)/3(+) and the cathodic 3(+)/3 redox waves at +0.33 and −0.40 V are reversible. The electron paramagnetic resonance spectra and density functional theory (DFT) calculations authenticated the existence of abpy anion radical (abpy(•–)) in 3, which is defined as a hybrid state of [Cu(I)(abpy(0.5•–))(abpy(0.5•–))] and [Cu(II)(abpy(•–))(abpy(•–))] states. 3(2+) ion is a neutral abpy complex of copper(II) of type [Cu(II)(abpy)2](2+). 3 exhibits a near-IR absorption band at 2400–3000 nm because of the intervalence ligand-to-ligand charge transfer, elucidated by time-dependent DFT calculations in CH2Cl2.

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“…1) system have been undertaken and a number of studies of metal complexes containing this type of ligand have been reported. These include investigations of complexes of Fe(II) [1,2], Ni(II) [2], Hg(II) [3,4], Os(II) [5,6], Ru(II) [7][8][9][10][11][12][13][14][15][16][17][18][19], Cr(0), Mo(0), W(0) [20,21], Cr(II) [22], Cu(I) [23], Rh(III) [24,25], Rh(I) [26], Ag(I) [27], Re(III) [28], Co(II) [29], Mo(IV) [15], Ru(III) [30], Sn(IV) [31] and organometallic complexes of Re(I) [32] and Sn(IV) [33][34][35][36][37]. In spite of such a wide-ranging series of studies on a variety of metal complexes involving these ligands, the structures of the mer-0277-5387/$ -see front matter Ó 2004 Elsevier Ltd. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, X-ray crystal structures and multinuclear NMR characterization of Hg(II) complexes of 2-[(E)-2-(aryl)-1-diazenyl]pyridine

et al. 2004

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Chromium, molybdenum, and tungsten zerovalent complexes of the nitrogen chelating ligand 2-(phenylazo)pyridine (2-PAP), including air-stable cis-M(CO)2(2-PAP)2 and M(2-PAP)3

Abstract: Equimolar reaction of the title ligand (II) with the (norbornadiene)tetracarbonyls (I) results in the formation of the monosubstitution products (III).

Cited by 40 publications

References 0 publications

Chromium Complexes of an Isomeric N-Donor Ligand, 2-[(N-Arylamino)phenylazo]pyridine: Amination Reactions, X-ray Structure, and Redox Properties

Chromium Complexes of an Isomeric N-Donor Ligand, 2-[(N-Arylamino)phenylazo]pyridine: Amination Reactions, X-ray Structure, and Redox Properties

Tris(2,2′-azobispyridine) Complexes of Copper(II): X-ray Structures, Reactivities, and the Radical Nonradical Bis(ligand) Analogues

Synthesis, X-ray crystal structures and multinuclear NMR characterization of Hg(II) complexes of 2-[(E)-2-(aryl)-1-diazenyl]pyridine

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