【摘要】 采用密度泛函理论DFT/BP86方法研究金属串配合物[MM’M″（dpa）₄（Cl）₂][MM’M″=CoCoCo（1）,CoCoRh（2）,CoRhRh（3）,Ni CoRh（4）]的结构和电子输运性质.结果表明,配合物1,2和4的最稳定自旋态均存在1个（MM’M″）6+的离域σ33键（σ2σnb1σ*0）;但配合物3具有1个（MM’M″）6+的离域σ34键（σ2σnb2σ*0）和2个π35键（π4πnb4π*2）,故Rh—Rh键和Co—Rh键较强; Rh的引入使M—M键增强,Ni的引入则使M—M键减弱,键强次序为Rh—Rh>Co—Rh>Co—Co>Ni—Co.配合物1～4的传输通道均含有π和σ型轨道.正偏压下,配合物2和3的电流大于配合物1和4的.负偏压下,配合物4中出现负微分电阻效应.配合物3中形成传输通道的σnbα/β和π*α/β轨道能级分裂明显,（MM’M″）6+对β自旋的π*轨道的贡献（88%）比α自旋（74%）的大,使β自旋的电子更易传输,具有较好的自旋过滤效应（70%～80%）.更多还原

【Abstract】 The electronic structures and transmission properties of metal string complexes [MM’M″(dpa)4·(Cl)2][MM’ M″ = CoCoCo(1); CoCoRh(2); CoRhRh(3); Ni CoRh(4) ] were investigated by density functional theory BP86 method. The results show that there is a delocalized 3-center-3-lectron σ bond of(MM’M″)6+among complexes 1,2 and 4,while there are one delocalized 3-center-4-electron σ bond of(MM’M″)6+and two 3-center-5-electron π bonds in complex 3. The Rh—Rh bond of complex 3 is the strongest among complexes 1—4 and the Co—Rh bond is second on account of above-mentioned information.The substitution of Rh enhanced the M—M bond,and the replace of Ni weakened the M—M bond. In conclusion,the order of bond is Rh—Rh>Co—Rh>Co—Co>Ni—Co. The transport channels of complexes 1—4 contain π-type and σ-type orbitals. Under positive bias,the currents in complexes 2 and 3 are greater than complexes 1 and 4. Under negative bias,there is a negative differential resistance effect in complex 4. The energy splitting of σnbα/β and π*α/β orbit as transport channels in complex 3 are the most obvious among complexes1—4. Moreover,the contribution of(MM’M″)6+to the π*orbit of β spin(up to 88%) is larger than that of α(up to 74%). Thus,the electronic transmission of β spin channel is stronger than α spin. To sum up,the complex 3 has significant spin filter effect(up to 70%—80%).更多还原