Kinetic Investigation of Electron TransFer Reaction between trans - [(en)_2(NO_2)Co(O_2CC_5H_5N)]--(2+)/Fe（Ⅱ）

合成了新型CO(Ⅲ)配合物TrAnS-[(En)_2(nO_2)CO(O_2CC_5H_5n)](ClO_4)_2,并通过紫外可见光谱、红外光谱、元素分析和X射线单晶衍射分析进行了表征.同时分别以[fE(Cn)_6]--(4-)和[fE(Cn)_5(H_2O)]--(3-)作为还原剂,考察了该配合物被还原的反应动力学行为.结果表明两反应体系分别按外配位界机理和内配位界机理进行电子传递.在25℃,I=0.5MOl·l--(-1),TrAnS-[(En)_2(nO_2)CO(O_2CC_5H_5n)]--(2+)/[fE(Cn)_6]--(4-)反应体系的前驱配合物离子对形成常数Q_(IP)=29MOl--(-1)·l,电子转移速率常数k_(ET)=2.4x10--(-4)S--(-1),电子转移过程的活化焓△H_(ET)--≠和活化熵△S_(ET)--≠分别为1.2x10--2kJ·MOl--(-1)和5.0x10--2J·MOl--(-1)·k--(-1)在40℃,PH=8.0,I=0.1MOl·l--(-1),TrAnS-[(En)_2(nO_2)CO(O_2CC_5H_4n)]--(2+)/[fE(Cn)_5(H_2O)]--(3-)反应体系前驱双核配合物分子内电子转移速率常数为7.0x10--(-5)S--(-1).最后讨论了分子轨道对称性,两金属中心氧化还原电势差等因素对电子转移速率的影响.trans - [(en)2(NO2)Co(O2CC5H5N) ]2+ (C1O4)2, which is First reported, has been synthesized and characterized by elemental analysis, UV - Vis and IR spectra, and X - ray structural analyses.Kinetic behaviours of the Co( III) complex reduced by [Fe(CN)6]4- and [Fe (CN)5 (H2O)]3- have been investigated.The results indicated the electron transFer (ET) reactions Followed the outer- sphere mechanism or the inner- sphere mechanism respectively.At25℃ ,I= 0.50mol L-1, the ion - pair Formation constant Qip and ET rate constant ket of theprecursor complex For trans - [ (en)2 ( NO2 ) Co( O2CC5H5N) ]2+ /[ Fe(CN)6 ]4- are 29mol-1·Land 2.4 × 10-1s-1, the activation enthalpy △H≠er and the activation entropy △S≠er of this ETprocess are 1.2 × 102kJ·mol-1 and 5.0 ×102kJ·mol-1·K-1 respectively.The intramolecular ET rate constant of the precursor binuclear complex For trans - [(en)2(NO2)Co(O2CC5H4N) ] + /[Fe(CN)5(H2O)]3- is 7.0×10-5 at 40℃ , pH=8.0 and I= -0.10mol L-1.Finally the inFluence of the moar orbital symmetry and the redox potentials on ET rate have been discussed.国家自然科学基金资助的项

Kinetic investigation of electron transfer reaction between trans- (en)(2)(NO2)Co(O2CC5H5N) (2+)/Fe(II)

trans - [(en)(2)(NO2)Co(O2CC5H5N)](2+) (ClO4)(2), which is first reported, has been synthesized and characterized by elemental analysis, UV - Vis and IR spectra, and X - ray structural analyses. Kinetic behaviours of the Co(III) complex reduced by [Fe(CN)(6)](4-) and [Fe(CN)(5)(H2O)](3-) have been investigated. The results indicated the electron transfer (ET) reactions followed the outer-sphere mechanism or the inner-sphere mechanism respectively. At 25 degrees C, I = 0.50mol . L(-1), the ion-pair formation constant Q(ip) and ET rate constant k(et) of the precursor complex for trans - [(en)(2)(NO2)Co(O2CC5H5N)](2+)/[Fe(CN)(6)](4-) are 29mol(-1). L and 2.4 x 10(-1) s(-1), the activation enthalpy Delta H-et(not equal) and the activation entropy Delta S-et(not equal) of this ET process are 1.2 x 10(2)kJ . mol(-1) and 5.0 x 10(2)kJ . mol(-1). K-1 respectively. The intramolecular ET rate constant of the precursor binuclear complex for trans - [(en)(2)(NO2)Co(O2CC5H4N)](+)/[Fe(CN)(5)(H2O)](3-) is 7.0 x 10(-5) s(-1) at 40 degrees C, pH = 8.0 and I = -0.10mol . L(-1). Finally the influence of the molecular orbital symmetry and the redox potentials on ET rate have been discussed