三吡啶二胺配基之四核異金屬(鈷/鎢及鎳/鉬)串錯合物的合成及研究

Abstract

本論文為利用三吡啶二胺為配基(Tripyridyldiamino ligand 簡稱H2tpda)與6B 以及9B ˴ 10B金屬在高溫萘燒法條件下進行反應，成功合成出不對稱四核混金屬串錯合物[CoWCo2(μ5-tpda)4(Cl)2](BF4) (1)、 [CoWCo2(μ5-tpda)4(Cl)2] (2)、[CoWCo2(μ5-tpda)4(NCS)2](PF6) (3)以及[Mo2Ni2(μ5-tpda)4(Cl)(O)](PF6) (4)。並對這類含八配位構型之金屬串錯合進行其結構、磁性及電化學進行探討。 由X-ray單晶繞射解析可知，所有產物皆是以四片tpda2- 配基以全順向式之模式螺旋纏繞在四個金屬離子外圍，中間的鉬˴鎢金屬離子是以四方反稜柱的配位模式與氮原子鍵結，其他的鈷˴鎳金屬離子則是平面四方以及四角的配位構型。中間的鉬、鎢與旁邊金屬的距離大於3.0 A，超過金屬單鍵的共價半徑，推斷其金屬間的作用力是非常弱的。 以超導量子干涉測量磁性，可知(1)、(3)在300K時的μeff為2.59及2.44 B.M ，推測(1) ˴(3)金屬電子自旋為 Co2+ (S = 1/2) ; W4+ (S = 0) ; Co25+ (S = 1/2)，接近於純自旋理論μeff = 2.45 B.M。錯合物(2)的還原的電子應是位於雙核鈷的單元，因此推測其只有一個磁性中心Co2+ (S = 1/2)，300 K時的μeff為2.01 B.M.，接近於純自旋理論的 1.73 B.M。錯合物(4)在300 K時的μeff為3.04 B.M ，推測其自旋組態為Mo4+(1) (S = 0) ; Mo4+ (2) (S = 0) ; Ni2+(1) (S = 0) ; Ni2+(2) (S = 1)，接近於純自旋理論μeff = 2.83 B.M.。

A series of tetranuclear heterometallic string complexes, [CoWCo2 (μ5-tpda)4(Cl)2](BF4) (1) , [CoWCo2(μ5-tpda)4(Cl)2] (2) , [CoWCo2 (μ5-tpda)4(NCS)2](PF6) (3) and [Mo2Ni2(μ5-tpda)4(Cl)(O)](PF6) (4) (tpda = tripyridyldiamino anion) were synthesized and characterized. The X-ray structural studies showed that all of them are helically wrapped by four all syn type H2tpda ligand, and have one 6B metal ion with square anti-prismatic geometry chelated by one pyridine N atom and the amido N atom of each of tpda2-. Axial ligands Cl- and NCS- are bonded to two Co ions for (1), (2) and (3), Cl- and O2- are bonded to Ni and Mo for (4). The distance between the middle 6B and nearby metal is larger than 3.0 A , which is elongated beyond the single-bond covalent radii of the metal atoms. The magnetic susceptibility showed that the μeff values of (1), (2), (3) and (4) at 300K are 2.59 , 2.44 and 2.01 B.M. respectively. The spin state of (1), (3) are the same, with Co2+ (S = 1/2), W4+ (S = 0), Co25+ (S = 1/2) configuration, which is close to the spin-only value 2.45 B.M. (2) is Co2+ (S = 1/2), W4+ (S = 0), Co2+(2) = Co2+(3) (S = 0) ,which is close to (1.73 B.M.) of spin-only value. The μeff of (4) is 3.04 B.M. , corresponding to Mo4+(1) (S = 0) , Mo4+ (2) (S = 0) , Ni2+(1) (S = 0) ; Ni2+(2) (S = 1) spin state.