萘啶吡啶胺及其多核金屬串錯合物之合成及研究

Abstract

以萘啶吡啶胺配基 (2-α-Pyridylamino-1,8-Naphthyridine ligand) 為配基, 簡稱Hpyany, 成功地合成出錯合物 [Mo2(Hpyany)2(pyany)2](PF6)2 與第一個偶數核的異核金屬串 [Mo2Ni2(pyany)4(Cl)2](ClO4)。[Mo2(Hpyany)2(pyany)2](PF6)2 有兩個配基未脫氫，而 Mo-Mo(A)距離為約2.09A, 顯示 Mo24+ 單元有著金屬-金屬四重鍵 。[Mo2Ni2(pyany)4(Cl)2](ClO4) 金屬以 Mo1-Mo2-Ni1-Ni2 的方式排列，兩端皆有軸向配基氯，被四個 pyany- 配基以螺旋式纏繞成全順向式配位包覆著金屬軸。 電化學分析下, 在氧化的部份有兩組氧化還原對，其中一組氧化還原對位於 E1/2 = +0.130V、+0.248V、0.386V,另有一組氧化還原對, 位於 E1/2 = +0.834V、+0.934V、+1.024V, 兩組推測為配基失序導致有較多對氧化還原對。由 OTTLE、UV-Vis 光譜可以發現較低氧化電位組其氧化是在Ni23+ 單元上，而較高氧化電位組是氧化在 Mo24+ 上。 以超導量子干涉儀量測磁性可知 [Mo2Ni2(pyany)4(Cl)2](ClO4) 錯合物為順磁性 (paramagnetism) 物質，300K 時的 μeff = 4.08 B.M.，與純自旋理論 μspin-only = 3.87 B.M. 接近。Mo24+ 電子組態 (S = 0) 為逆磁四重鍵的雙金屬簇，而因為萘啶的關係，在反應的過程中將 Ni24+ 還原成 Ni23+ 單元，其電子組態為 S = 3/2。

The goal of this thesis is to synthesize heteronuclear metal string including nickel and molybdenum with 2-α-pyridylamino-1,8-naphthyridine (Hpyany) . The Mo -Mo bond distance of [Mo2(Hpyany)2(pyany)2](PF6)2 is about 2.09 A which corresponds to a metal - metal quadruple bond. There are two ligands without deprotonation. The tetranuclear linear metal chain, [Mo2Ni2(pyany)4(Cl)2](ClO4), is helically wrapped by four all syn form type ligands. The metals of nickel and molybdenum arrange in order of Mo1-Mo2-Ni1-Ni2 with Cl- axial ligands both at two side of metal string. In the CV analysis, the [Mo2Ni2(pyany)4(Cl)2](ClO4) have two regions of oxidative potentials and each region has three pairs of redox couples. The E1/2 of potentials at lower oxidative region is 0.130V、0.248V and 0.386V; the E1/2 of potentials at higher oxidative region is 0.834V、0.934V and 1.024V, respectively, with OTTLE and UV/vis spectrum, the lower region is assigned as oxidation on Ni23+ to Ni24+，and the higher region is assigned as oxidation on Mo24+, respectively. The magnetic susceptibility shows that [Mo2Ni2(pyany)4(Cl)2](ClO4) is paramagnetic. The μeff values of Mo2Ni2(pyany)4(Cl)2](ClO4) is 4.08 B.M. which is smiliar to the μspin-only value 3.87 B.M. in 300K. The electronic configuration (S = 0) of Mo24+ bimetal clusters is the diamagnetic quadruple bond, and the Ni23+ ion is consistent with the mixed valence unit comparison to the electronic configuration (S = 3/2).