422. An infrared study of pentacyano-, hexacyano-, and chloropentacyano-nickelate(II) in aqueous solution

Penneman, R. A.; Bain, R. L.; Gilbert, G. P.; Jones, Llewellyn H.; Nyholm, R. S.; Reddy, G.K.N.

doi:10.1039/jr9630002266

Cited by 13 publications

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“…The overall formation constant of [Ni(CN) 4 ] 2- (yellow) in aqueous solution has been determined by UV−visible and IR spectroscopy and leads to a log β 4 = 30.3 ± 0.1 . At high CN - concentration, a pentacoordinated [Ni(CN) 5 ] 3- (red) species is formed, and the formation constant K 5 is small ( K 5 ≈ 0.15 mol l -1 ) and depends slightly on the ionic strength The [Ni(CN) 4 ] 2- ion is very stable in water (nickel bis(dimethyl)glyoximate, for instance, is soluble in aqueous cyanide solution).…”

Section: Resultsmentioning

confidence: 99%

“… The populations were calculated as functions of C tot , C Ni , K 5 , and pH. K 5 was fixed to the value found by Hugel, 0.168 ± 0.003 mol -1 kg 28c. A Lorentzian function was fitted to each spectrum, and the analysis of the dependence of the resonance frequency on the concentratin of CN - led to the adjusted resonance frequency of δ Ni(5) = 230 ± 26 for [Ni(CH) 5 ] 3- .…”

Section: Resultsmentioning

confidence: 99%

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Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)₄]^2- (M = Ni, Pd, and Pt)¹

et al. 2002

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Kinetic studies of cyanide exchange on [M(CN)(4)](2-) square-planar complexes (M = Pt, Pd, and Ni) were performed as a function of pH by (13)C NMR. The [Pt(CN)(4)](2-) complex has a purely second-order rate law, with CN(-) as acting as the nucleophile, with the following kinetic parameters: (k(2)(Pt,CN))(298) = 11 +/- 1 s(-1) mol(-1) kg, DeltaH(2) (Pt,CN) = 25.1 +/- 1 kJ mol(-1), DeltaS(2) (Pt,CN) = -142 +/- 4 J mol(-1) K(-1), and DeltaV(2) (Pt,CN) = -27 +/- 2 cm(3) mol(-1). The Pd(II) metal center has the same behavior down to pH 6. The kinetic parameters are as follows: (k(2)(Pd,CN))(298) = 82 +/- 2 s(-1) mol(-1) kg, DeltaH(2) (Pd,CN) = 23.5 +/- 1 kJ mol(-1), DeltaS(2) (Pd,CN) = -129 +/- 5 J mol(-1) K(-1), and DeltaV(2) (Pd,CN) = -22 +/- 2 cm(3) mol(-1). At low pH, the tetracyanopalladate is protonated (pK(a)(Pd(4,H)) = 3.0 +/- 0.3) to form [Pd(CN)(3)HCN](-). The rate law of the cyanide exchange on the protonated complex is also purely second order, with (k(2)(PdH,CN))(298) = (4.5 +/- 1.3) x 10(3) s(-1) mol(-1) kg. [Ni(CN)(4)](2-) is involved in various equilibrium reactions, such as the formation of [Ni(CN)(5)](3-), [Ni(CN)(3)HCN](-), and [Ni(CN)(2)(HCN)(2)] complexes. Our (13)C NMR measurements have allowed us to determine that the rate constant leading to the formation of [Ni(CN)(5)](3-) is k(2)(Ni(4),CN) = (2.3 +/- 0.1) x 10(6) s(-1) mol(-1) kg when the following activation parameters are used: DeltaH(2)() (Ni,CN) = 21.6 +/- 1 kJ mol(-1), DeltaS(2) (Ni,CN) = -51 +/- 7 J mol(-1) K(-1), and DeltaV(2) (Ni,CN) = -19 +/- 2 cm(3) mol(-1). The rate constant of the back reaction is k(-2)(Ni(4),CN) = 14 x 10(6) s(-1). The rate law pertaining to [Ni(CN)(2)(HCN)(2)] was found to be second order at pH 3.8, and the value of the rate constant is (k(2)(Ni(4,2H),CN))(298) = (63 +/- 15) x10(6) s(-1) mol(-1) kg when DeltaH(2) (Ni(4,2H),CN) = 47.3 +/- 1 kJ mol(-1), DeltaS(2) (Ni(4,2H),CN) = 63 +/- 3 J mol(-1) K(-1), and DeltaV(2) (Ni(4,2H),CN) = - 6 +/- 1 cm(3) mol(-1). The cyanide-exchange rate constant on [M(CN)(4)](2-) for Pt, Pd, and Ni increases in a 1:7:200 000 ratio. This trend is modified at low pH, and the palladium becomes 400 times more reactive than the platinum because of the formation of [Pd(CN)(3)HCN](-). For all cyanide exchanges on tetracyano complexes (A mechanism) and on their protonated forms (I/I(a) mechanisms), we have always observed a pure second-order rate law: first order for the complex and first order for CN(-). The nucleophilic attack by HCN or solvation by H(2)O is at least nine or six orders of magnitude slower, respectively than is nucleophilic attack by CN(-) for Pt(II), Pd(II), and Ni(II), respectively.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)₄]^2- (M = Ni, Pd, and Pt)¹

et al. 2002

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“…The overall observed rate of the reaction is significantly reduced and it is observed kinetically as the second reaction. The CN" suppression operates through the series of reactions given by eq [26][27][28][29] . A steady-state approximation in Ni(en)-(CN)3" using eq 25 and 26 leads to eq 30.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of tetracyanonickelate(II) reactions

Crouse¹,

Margerum²

1974

Inorg. Chem.

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“…Phosphine association in step (5) gives an 18-electron hydrido-alkyl which produces alkane by reductive elimination, regenerating RhCI(PPh3),. Wilkinson's isolation of (C2H4)RhClL2 and observation that the ethylene complex is not readily hydro-genatedq6 suggest that step (9) is very slow, so that the bulk of the reaction goes via the loop which contains steps (1)- (6). The inhibition of hydrogenation on addition of triphenylphosphine to the system can be understood in terms of its suppression of ligand dissociation in step (2).…”

Section: C02 Etmentioning

confidence: 99%

The 16 and 18 electron rule in organometallic chemistry and homogeneous catalysis

Tolman¹

1972

Chem. Soc. Rev.

377

157

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422. An infrared study of pentacyano-, hexacyano-, and chloropentacyano-nickelate(II) in aqueous solution

Abstract: Chloropentac yano-nickelate( 11) in Aqueous Solution.

Cited by 13 publications

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Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)₄]^2- (M = Ni, Pd, and Pt)¹

Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)₄]^2- (M = Ni, Pd, and Pt)¹

Kinetics of tetracyanonickelate(II) reactions

The 16 and 18 electron rule in organometallic chemistry and homogeneous catalysis

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422. An infrared study of pentacyano-, hexacyano-, and chloropentacyano-nickelate(II) in aqueous solution

Abstract: Chloropentac yano-nickelate( 11) in Aqueous Solution.

Cited by 13 publications

References 0 publications

Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)4]2- (M = Ni, Pd, and Pt)1

Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)4]2- (M = Ni, Pd, and Pt)1

Kinetics of tetracyanonickelate(II) reactions

The 16 and 18 electron rule in organometallic chemistry and homogeneous catalysis

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Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)₄]^2- (M = Ni, Pd, and Pt)¹

Mechanistic Diversity Covering 15 Orders of Magnitude in Rates: Cyanide Exchange on [M(CN)₄]^2- (M = Ni, Pd, and Pt)¹