Kinetics of chromium(II) reduction of nitrile-bonded cyanoacetate complexes of pentaaminecobalt(III)

Kupferschmidt, W. C.; Jordan, R. B.

doi:10.1021/ic50224a061

Cited by 8 publications

(4 citation statements)

References 2 publications

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“…The Co(III) products are the pentaammineaqua (83%) and the nitrile-bonded 2-cyanoacetamide (17%) complexes. The latter complex was characterized by its IR and 1 H and 13 C NMR spectra, and the identification was confirmed by preparation of the nitrile-bonded complex directly from 2-cyanoacetamide . The two complexes were spectroscopically identical.…”

Section: Resultsmentioning

confidence: 87%

“…Visible (M -1 cm -1 , 0.10 M HClO 4 ): ε 466 64, ε 332 63 ( cf. ε 467 62.9, ε 334 63.6; ε 474 72, ε 341 82; and ε 465 84 ). IR (cm -1 ): nitrile stretch 2340 (coord.…”

Section: Methodsmentioning

confidence: 96%

“…Pentaamminecobalt(III) complexes of phthalonitrile (1,2-dicyanobenzene) ( 4 ), fumaronitrile ( 5 ), malononitrile ( 6 ), succinonitrile ( 7 ), glutaronitrile ( 8 ), and adiponitrile ( 9 ) were used. In the first two, the functional groups are fixed in their orientation to each other, cis and trans , respectively, and in the malononitrile species the distance between the functional groups is invariant.…”

Section: Introductionmentioning

confidence: 99%

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Occurrence of Neighboring Group Participation Reactions in Amide-N and Amidine Complexes Derived from Pentaammine(dinitrile)cobalt(III) Ions

1996

Inorg. Chem.

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N-Bonded pentaamminecobalt(III) complexes of 2-cyanobenzamide, 2-cyanoacetamide, and fumaric, succinic, glutaric, and adipic amide-nitriles have been prepared. The kinetics of the base hydrolysis of (succinonitrile)pentaamminecobalt(III) have been measured: k(obsd) = k(OH) [OH(-)]; k(OH) = 1.23 x 10(3) {I = 1.00 M (NaCH(3)COO), 25 degrees C}. Amido-N-coordinated 2-cyanobenzamide cyclized in aqueous base, and it forms [(1-oxo-3-iminoisoindolino-endo-N)pentaamminecobalt(III). In aqueous acid it protonates on the exo-imine and solvolyzes (k(H) = 7.9 x 10(-)(5) s(-)(1)), forming the pentaammineaquacobalt(III) complex and 1-oxo-3-iminoisoindoline. In aqueous acid the amido-N complexes are protonated on the amide oxygen. The 2-cyanobenzamide species rearranges to form the nitrile-bonded linkage isomer in aqueous acid and also in Me(2)SO-d(6), while the succinic amide nitrile complex rearranges more slowly in aqueous acid to form solely the nitrile-bonded linkage isomer. The kinetics of the reaction were k(obsd) = f(k(H)[H(+)]/(K(a) + [H(+)])) where k(H) = 3.4 x 10(-)(4) M(-)(1) s(-)(1) and K(a) = 6.76 x 10(-)(2) M, pK(a) 1.2; pK(a) 1.3 (spectrophotometric) {I = 1.00 M (LiClO(4).3H(2)O), 25 degrees C}. In Me(2)SO-d(6) this amide-N complex reacts by three pathways: solvolysis, amide-N to -O isomerization, and amide-N to nitrile-bonded rearrangement (10%). The conjugate acid of the 2-cyanoacetamido-N complex reacted in both aqueous acid and acidified Me(2)SO-d(6) by solvolysis, amide N to O isomerization, and amide-N to nitrile-bonded rearrangement (17% in each solvent). The fumaric, glutaric, and adipic amide-nitrile complexes bonded through the amide nitrogen react only by solvolysis and amide-N to -O isomerization. Pentaamminecobalt(III) complexes of 2-cyanobenzamidine and succinic, glutaric, and adipic amidine-nitriles bonded through the amidine secondary nitrogen have been prepared. The 2-cyanobenzamidine complex undergoes rapid ligand cyclization to form the corresponding complex of 1,3-diiminoisoindoline bonded through the deprotonated endocyclic nitrogen. In aqueous acid the complex is protonated on one of the exo-imines, and this solvolyzes to form the pentaammineaquacobalt(III) complex and 1,3-diiminoisoindoline {k(H) = 1.7 x 10(-)(3) s(-)(1) (0.5 M HCl, 25 degrees C). Coordinated succinic amidine-nitrile also cyclizes in liquid ammonia to yield the complex of 2,5-diiminopyrrolidine bonded through the deprotonated endocyclic nitrogen. This is stable in aqueous base but solvolyzes rapidly (t(1/2) (s)) in aqueous acid to the aqua complex and succinimide; the latter is formed by hydrolysis of the free 2,5-diiminopyrrolidine. The dinuclear complex &mgr;-decaammine(succinonitrile)dicobalt(III) was synthesized; in aqueous base it forms &mgr;-(succinamido-N)decaamminecobalt(III). The dinuclear dinitrile complex reacts in liquid ammonia to form the corresponding succinic amidine-nitrile species which cyclizes rapidly to form &mgr;-decaammine(2,5-diiminopyrrolidino)cobalt(III) in which the ligand is bonded to cobalt(III)...

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Section: Resultsmentioning

confidence: 87%

“…Visible (M -1 cm -1 , 0.10 M HClO 4 ): ε 466 64, ε 332 63 ( cf. ε 467 62.9, ε 334 63.6; ε 474 72, ε 341 82; and ε 465 84 ). IR (cm -1 ): nitrile stretch 2340 (coord.…”

Section: Methodsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Occurrence of Neighboring Group Participation Reactions in Amide-N and Amidine Complexes Derived from Pentaammine(dinitrile)cobalt(III) Ions

1996

Inorg. Chem.

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“…In this paper we wish to Electron transfer via "remote" substituents has been shown to repod on the preparation, characterization, and chromium (11) I occur in a wide variety of systems (1)(2)(3)(4)(5). For reduction of (NH3)5CoNC--C6H4-R complexes by chromium(II), innersphere remote attack by the reductant takes place for R = CN (6), C(0)CH3 (7), CHO (6), C02-(a), and 0- (9).…”

Section: Introductionmentioning

confidence: 99%

The reduction of (1-(4-cyanophenyl)-3-hydroxy-2-buten-1-one-N)pentaamminecobalt(III) by chromium(II)

Balahura¹,

Johnston²

1986

Can. J. Chem.

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. J. Chem. 64,841 (1986).The reduction of the title compound, I 1 by chromium(II) is first order in Cr(II) and obeys the rate law kobsd = klKa'/(Kaf + [H+]) at 25.0°C and I = 1.0molL-' I (LiC104) with kl = (2.9 + 0.1) X lo4 L mol-' s-I and K,' = 0.86 + 0.03 mol L-'. In the rate law, kl refers to reduction of the 3 + ion above and the K,' is the acid dissociation constant for the protonated form of 1. The reduction occurs by a remote attack inner-sphere mechanism with complete transfer of the organic ligand to chromium. ROBERT J. BALAHURA et A. JOHNSTON. Can. J. Chem. 64, 841 (1986).Le composC 1 mentionnC dans le titre est rCduit par le chrome(JI); la riaction est du premier ordre en Cr(I1) et, a 25,0°C, elle obCit a la loi de vitesse kobs = kl Kal/(Ka'1'Cquation de vitesse, kl se rapporte a la rkduction de l'ion 3+ mentionnk plus haut alors que K,' reprksente la constante de dissociation de la forme protonte du composk 1. La rkduction se produit par un mCcanisme d'attaque distance de la couche interne avec un transfert complet du ligand organique vers le chrome.[Traduit par la revue]

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ChemInform Abstract: KINETICS OF CHROMIUM(II) REDUCTION OF NITRILE‐BONDED CYANOACETATE COMPLEXES OF PENTAAMINECOBALT(III)

Kupferschmidt¹,

Jordan²

1982

Chemischer Informationsdienst

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Kinetics of chromium(II) reduction of nitrile-bonded cyanoacetate complexes of pentaaminecobalt(III)

Cited by 8 publications

References 2 publications

Occurrence of Neighboring Group Participation Reactions in Amide-N and Amidine Complexes Derived from Pentaammine(dinitrile)cobalt(III) Ions

Occurrence of Neighboring Group Participation Reactions in Amide-N and Amidine Complexes Derived from Pentaammine(dinitrile)cobalt(III) Ions

The reduction of (1-(4-cyanophenyl)-3-hydroxy-2-buten-1-one-N)pentaamminecobalt(III) by chromium(II)

ChemInform Abstract: KINETICS OF CHROMIUM(II) REDUCTION OF NITRILE‐BONDED CYANOACETATE COMPLEXES OF PENTAAMINECOBALT(III)

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