TY - JOUR
T1 - A kinetic study of the reactions of dimethyl sulfide bridged tetramethylplatinum(II) and octamethylplatinum(IV) complexes with dimethyl sulfide and bidentate ligands
AU - Nakayama, Katsuyuki
AU - Kondo, Yuichi
AU - Ishihara, Koji
PY - 1998/1/1
Y1 - 1998/1/1
N2 - Kinetics for the reactions of [1] [PtIV2Me8 (μ-SMe2)2] + 2 Me2S kf⇌kd 2 [PtIVMe4(SMe2)2] [2] [PtII2Me4 (μ-SMe2)2] + 2 Me2S kf→ 2 [PtIIMe2(SMe2)2] and [3] [PtIV2Me8 (μ-SMe2)2] + 2NN → 2 [PtIVMe4(NN)] + 2 Me2S where NN = bipy or 4,4′-Me2-bipy, have been studied at various temperatures and pressures. Reaction [3] was shown to consist of the rapid conversion of the dimer to a monomer and the much slower subsequent substitution of the dimethyl sulfide with bidentate ligand NN: [PtIV2Me8(μ-SMe2)2] + 2 Me2S ⇌ 2 [PtIVMe4(SMe2)2] and [PtIVMe4(SMe2)2] + NN → [PtIVMe4(NN)] + 2 Me2S The rate constants and activation parameters for the reactions areas follows: kf= 3.16 ± 0.06 M-1 s-1 (25°C), ΔH≠f = 51.8 ± 1.7 kJ mol-1, ΔS≠f = -61.0 ± 5.8 J mol-1 K-1, kd= 1.18 ± 0.22 M-1 s-1 (25°C), ΔH≠d = 65 ± 22 kJ mol-1, ΔS≠d = -26 ± 73 J mol-1 K-1 for reaction [1] in n-hexane; kf = 6.68 ± 0.06 M-1 s-1 (25°C), ΔH≠f = 58.0 ± 3.1 kJ mol-1, ΔS≠f = -34.5 ± 10.5 J mol-1 K-1, ΔV≠f = -10.7 ± 1.3 cm3 mol-1 for reaction [2] in dichloromethane; k2= (7.09 ± 1.89) × 10-4 M-1 s-1, ΔH≠2 = 95 ± 21 kJ mol-1, and ΔS≠2 = 18 ± 70 J mol-1 K-1, ΔV≠2 = 9 ± 9 cm3 mol-1 for reaction [3] with bipy, and kl = (1.10 ± 0.10) × 10-2 s-1, k3/k-1 = (4.33 ± 0.30) × 10-2, and k2= (6.09 ± 1.35) × 10-4 M-1 s-1 for reaction [3] with 4,4′-Me2-bipy. It was shown that reactions [1] and [2] proceed nucleophilically without any intermediates, and reaction [3] proceeds through a mainly k2 path for NN = bipy and through both k1 and k2 paths for NN = 4,4′-Me2-bipy, without appreciable participation of the direct reaction between the dimer and NN as shown by the following reaction scheme.
AB - Kinetics for the reactions of [1] [PtIV2Me8 (μ-SMe2)2] + 2 Me2S kf⇌kd 2 [PtIVMe4(SMe2)2] [2] [PtII2Me4 (μ-SMe2)2] + 2 Me2S kf→ 2 [PtIIMe2(SMe2)2] and [3] [PtIV2Me8 (μ-SMe2)2] + 2NN → 2 [PtIVMe4(NN)] + 2 Me2S where NN = bipy or 4,4′-Me2-bipy, have been studied at various temperatures and pressures. Reaction [3] was shown to consist of the rapid conversion of the dimer to a monomer and the much slower subsequent substitution of the dimethyl sulfide with bidentate ligand NN: [PtIV2Me8(μ-SMe2)2] + 2 Me2S ⇌ 2 [PtIVMe4(SMe2)2] and [PtIVMe4(SMe2)2] + NN → [PtIVMe4(NN)] + 2 Me2S The rate constants and activation parameters for the reactions areas follows: kf= 3.16 ± 0.06 M-1 s-1 (25°C), ΔH≠f = 51.8 ± 1.7 kJ mol-1, ΔS≠f = -61.0 ± 5.8 J mol-1 K-1, kd= 1.18 ± 0.22 M-1 s-1 (25°C), ΔH≠d = 65 ± 22 kJ mol-1, ΔS≠d = -26 ± 73 J mol-1 K-1 for reaction [1] in n-hexane; kf = 6.68 ± 0.06 M-1 s-1 (25°C), ΔH≠f = 58.0 ± 3.1 kJ mol-1, ΔS≠f = -34.5 ± 10.5 J mol-1 K-1, ΔV≠f = -10.7 ± 1.3 cm3 mol-1 for reaction [2] in dichloromethane; k2= (7.09 ± 1.89) × 10-4 M-1 s-1, ΔH≠2 = 95 ± 21 kJ mol-1, and ΔS≠2 = 18 ± 70 J mol-1 K-1, ΔV≠2 = 9 ± 9 cm3 mol-1 for reaction [3] with bipy, and kl = (1.10 ± 0.10) × 10-2 s-1, k3/k-1 = (4.33 ± 0.30) × 10-2, and k2= (6.09 ± 1.35) × 10-4 M-1 s-1 for reaction [3] with 4,4′-Me2-bipy. It was shown that reactions [1] and [2] proceed nucleophilically without any intermediates, and reaction [3] proceeds through a mainly k2 path for NN = bipy and through both k1 and k2 paths for NN = 4,4′-Me2-bipy, without appreciable participation of the direct reaction between the dimer and NN as shown by the following reaction scheme.
KW - High-pressure kinetics
KW - Octamethylplatinum(IV) dimer
KW - Reaction mechanism
KW - Tetramethylplatinum(II) dimer
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U2 - 10.1139/v97-203
DO - 10.1139/v97-203
M3 - Article
AN - SCOPUS:0031652296
SN - 0008-4042
VL - 76
SP - 62
EP - 70
JO - Canadian Journal of Chemistry
JF - Canadian Journal of Chemistry
IS - 1
ER -