Kinetic study of the reaction betweentrans-aquanitridotetra-cyanorhenate(V) and different cyanide species

Damoense, Llewellyn; Purcell, Walter; Leipoldt, J. G.

doi:10.1007/bf00980416

Cited by 30 publications

(27 citation statements)

References 29 publications

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“…The protonated oxygen bond length increased from 2.077 (7) 4 ] 2-, respectively [2][3][4]. The same tendency was observed for the corresponding complexes of tungsten(IV), rhenium(V) and technetium(V) [5][6][7][8][9].…”

Section: Introductionsupporting

confidence: 75%

“…A good example of the large impact of the trans ligand on the physical and chemical behaviour of these complexes is illustrated by the iso-electronic rhenium(V) complexes, T [9,10], the Re-OH 2 bond length increases from 2.142(7) to 2.496(7) Å [8,12] and the rate of aqua substitution decreases from 3.48(4) 9 10 -3 M -1 s -1 (NCS -) to 7.2(4) 9 10 3 M -1 s -1 (CN -) for the oxo and nitrido complexes, respectively [10,13].…”

Section: Introductionmentioning

confidence: 99%

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A novel rhenium-aqua structure: the synthesis and structural characterization of (PPh4)4[ReN(H2O)(CN)3-μ-CN-ReN(CN)4] · 5H2O

Mtshali

Purcell

Visser

et al. 2008

Transition Met Chem

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A novel cyano bridged rhenium nitrido complex, [ReN(H 2 O)(CN) 4 -l-CN-ReN(CN) 4 ] 4-(I) was isolated during a kinetic study of the reaction of ReN(H 2 O)(CN) 4 ] 2-with pyridine-2,3-dicarboxylic acid. Yellow crystals of (I), suitable for X-ray structure determination were isolated and the structural data showed an unsymmetrical binuclear rhenium complex with a cyano ligand acting as a bridge between two metal atoms, Re(1) and Re(2). The nitrogen of the bridged cyano ligand coordinates trans to the nitrido ligand of Re(1). The rhenium-nitrido bond distances are 1.657(4) and 1.656(5) Å for Re(1)-N(9) and Re(2)-N(10) respectively. Re(1) and Re(2) are displaced from the planes formed by the four carbon atoms of the cyano ligands towards the nitrido ligands by 0.348(2) and 0.3403(2) Å , respectively.

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Section: Introductionsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

A novel rhenium-aqua structure: the synthesis and structural characterization of (PPh4)4[ReN(H2O)(CN)3-μ-CN-ReN(CN)4] · 5H2O

Mtshali

Purcell

Visser

et al. 2008

Transition Met Chem

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“…These values may be compared with the values of 1.00(2) M -1 , 2.10(1) 9 10 -2 M -1 s -1 and 2.11(5) 9 10 -2 s -1 reported for the reaction between [ReN(H 2 O)(CN) 4 ] 2-and the pyridine-2-carboxylate anion [21]. The k 1 value of 2.17(1) 9 10 -2 M -1 s -1 is substantially slower (factor 10 5 ) than the corresponding reaction when CN -was the incoming group [8]. This is due to the difference in the coordination capability of the two ligands which is also manifested in the stability constant for the two different complexes compared to the rate with CN -as incoming group [19].…”

Section: Discussionmentioning

confidence: 86%

“…These investigations have shown that these complexes undergo stepwise protonations to form the corresponding oxo-hydroxo, [MO(OH)(CN) 4 ] (n -1)-, and oxo-aqua, [MO(H 2 O)(CN) 4 ] (n -2)-, complexes with dissociation constants for the latter species: pK a1 = 10.0, pK a2 [ 14 (Mo); pK a1 = 7.8, pK a2 = 14.5 (W); pK a1 = 1.4, pK a2 = 3.7 (Re) [6]. Similarly, the nitrido complexes, [MN(CN) 4 (H 2 O)] n-(where M = Re(V) or Os(VI)), can also undergo deprotonation reactions to form nitridohydroxo complexes, [MN(CN) 4 (OH)] (n + 1)-with dissociation constants: pK a1 = 11.7 (Re) [7] and pK a1 = 7.6 (Os) [8], except that the [MN(O)(CN) 4 ] n-type complex was never observed. The hydroxo complexes are mostly inert towards substitution, whereas aqua complexes are reactive species.…”

Section: Introductionmentioning

confidence: 97%

Kinetic study of reaction of [ReN(H2O)(CN)4]2− with quinoline-2-carboxylate and pyridine-2,3-dicarboxylate anions

Mtshali

Purcell

Visser

et al. 2008

Transition Met Chem

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The kinetics of the reaction between [ReN(H 2 O)(CN) 4 ] 2-with different j 2 N,O-donor ligands (quin -and 2,3-dipic -, respectively) have been studied in the pH 4-12 range in aqueous solution. Two consecutive reaction steps with the formation of the [ReN(g 1 -quin)(CN) 4 ] 3-and [ReN(l 2 -quin) (CN) 3 ] 2-complexes, respectively, were spectrophotometrically observed and kinetically investigated. The same reaction mechanism is proposed for these two ligands. The first fast reaction (for quin -) is attributed to the aqua substitution of [ReN(H 2 O)(CN) 4 ] 2-with forward and reverse rate constants of 1.96(5) 9 10 -1 M -1 s -1 and 5.6(3) 9 10 -2 s -1 , while a rate of 2.64(3) M -1 s -1 was observed for the reaction between the conjugate base [ReN(OH)(CN) 4 ] 3-and quin -at 40.2°C. Due to small absorbance changes, it was difficult to obtain any good quality data for the fast reactions for 2,3-dipic -. The second, slower reaction is attributed to cyano substitution with rate constants (k 3 K 1 ) of 4.17(4) 9 10 -3 for quin -and 4.68(7) 9 10 -3 M -1 s -1 for 2,3-dipic -, at 80.02°C, respectively. The acid dissociation constant for the aqua complex was spectrophotometrically determined as 11.58(3) and 11.54(2) and kinetically as 11.51(8) and 11.41(1), at 80.4°C, respectively. Negative DS 6 ¼ values of -83.5(2) and -144.1(2) J K -1 mol -1 as well as the DH 6 ¼ of 71.4(3) and 47.3(3) kJ mol -1 , for the slow quin -and 2,3-dipic -reactions, respectively, point to an ordered transition state where bond formation is responsible for the major driving force of the reaction. The DH 6 ¼ ¼ 39:6ð2Þ kJ mol À1 and DS 6 ¼ ¼ À142:8ð1Þ J K À1 mol À1 for the fast forward reaction of quin -is indicative of expected associative activation in the transition state.

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“…This equilibrium between the different products and reactant rendered the isolation of any of the products not possible. However, due to the distinct infrared stretching frequency of CO groups [27,28], it was possible to clearly distinguish between alkyl and acyl products as described in the next section. In addition, the different products is further characterised by means of a computational chemistry study.…”

Section: Synthesis Of Complexesmentioning

confidence: 99%

A kinetic investigation of the oxidative addition reactions of the dimeric Bu4N[Ir2(μ-Dcbp)(CO)2(PCy3)2] complex with iodomethane

Grobbelaar¹,

Conradie²,

Venter³

et al. 2011

Journal of Organometallic Chemistry

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a b s t r a c tThe IR and UV/visible kinetic results of the oxidative addition of iodomethane to Bu 4 N[Ir 2 (m-Dcbp) (CO) 2 (PCy 3 ) 2 ] (Dcbp ¼ 3,5-dicarboxylatepyrazolate anion) showed three time separable reactions. The first, very fast reaction corresponds to the a Ir(I)eIr(III) alkyl species formation within 10 À3 s. The second, relative fast reaction corresponds to Ir(III)eIr(III) alkyl formation with a rate constant of 3.25(4) Â 10 À2 M À1 s À1 while the third and slowest reaction corresponds to Ir(III)eIr(III) acyl formation with a rate constant of 1.42 Â 10 À5 s À1 . The IR data clearly show the existence of a number of equilibria with the formation of an Ir (I)eIr(III) alkyl product which then react to form the Ir(III)eIr(III) which then slowly react to form the Ir(III)eIr(III) acyl product. A solvent study indicated increased oxidative addition activity in the presence of polar solvents, which is indicative of a polar transition state. The large negative entropy of activation for the Ir(III)eIr(III) alkyl formation step (k 2 ) of À178(23) JK À1 mol À1 is indicative of an associative process. DFT calculations successfully identified the stereochemistry of the starting complex, [Ir 2 (m-Dcbp)(CO) 2 (PCy 3 ) 2 ] À as well as that of the Ir-alkyl and acyl isomers. A reaction pathway, using the IR data and DFT calculations, is proposed for the reaction.

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Kinetic study of the reaction betweentrans-aquanitridotetra-cyanorhenate(V) and different cyanide species

Cited by 30 publications

References 29 publications

A novel rhenium-aqua structure: the synthesis and structural characterization of (PPh4)4[ReN(H2O)(CN)3-μ-CN-ReN(CN)4] · 5H2O

A novel rhenium-aqua structure: the synthesis and structural characterization of (PPh4)4[ReN(H2O)(CN)3-μ-CN-ReN(CN)4] · 5H2O

Kinetic study of reaction of [ReN(H2O)(CN)4]2− with quinoline-2-carboxylate and pyridine-2,3-dicarboxylate anions

A kinetic investigation of the oxidative addition reactions of the dimeric Bu4N[Ir2(μ-Dcbp)(CO)2(PCy3)2] complex with iodomethane

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