Experimental and Computational Studies of the Single-Molecule Conductance of Ru(II) and Pt(II) <i>trans</i>-Bis(acetylide) Complexes

The single-molecule conductance of metal complexes of the general forms trans-Ru­(CCArCCY)2(dppe)2 and trans-Pt­(CCArCCY)2(PPh3)2 (Ar = 1,4-C6H2-2,5-(OC6H13)2; Y = 4-C5H4N, 4-C6H4SMe) have been determined using the STM I(s) technique. The complexes display high conductance (Y = 4-C5H4N, M = Ru (0.4 ± 0.18 nS), Pt (0.8 ± 0.5 nS); Y = 4-C6H5SMe, M = Ru (1.4 ± 0.4 nS), Pt (1.8 ± 0.6 nS)) for molecular structures of ca. 3 nm in length, which has been attributed to transport processes arising from tunneling through the tails of LUMO states.本研究采用扫描隧道显微镜电流-距离（STM I(s)）技术，测定了通式为反式-Ru(C≡CArC≡CY)₂(dppe)₂与反式-Pt(C≡CArC≡CY)₂(PPh₃)₂的金属配合物的单分子电导，其中Ar=1,4-C₆H₂-2,5-(OC₆H₁₃)₂，Y=4-C₅H₄N、4-C₆H₄SMe。该类配合物在长度约为3 nm的分子结构下展现出较高的电导性能：当Y为4-C₅H₄N时，金属中心M为钌（Ru）时电导为(0.4±0.18) nS，为铂（Pt）时则为(0.8±0.5) nS；当Y为4-C₆H₅SMe时，钌对应的电导为(1.4±0.4) nS，铂对应电导为(1.8±0.6) nS。上述现象可归因于经由最低未占据分子轨道（LUMO）态的尾区隧穿所产生的电荷输运过程。