含N,N’−二(2−嘧啶)甲咪配位基與多核金屬化合物之研究

Chemistry of Polynuclear Metal Complexes Containing anions of N,N’-bis(pyrimidine-2-yl)formamidine Ligands

詹智剴(Zhi-Kai Chan)

指導教授 ： 陳志德

中原大學/理學院/化學研究所/博士(2007年)

https://doi.org/10.6840/cycu200700643

摘要

中文摘要
本論文主要討論含N,N’-bis(pyrimidine-2-yl)formamidine配位基與過渡金屬之化學。
將KL1 (L1 = N,N’-bis(pyrimidine-2-yl)formamidine, HL1的陰離子) 分別與具有d10電子的金屬鹽類在THF中反應，可獲雙核金屬化合物[M2(L1)3](X) (M = Zn(II), X = I3-, 1a; M = Zn(II), X = NO3-, 1b; M = Zn(II), X = ClO4-, 1c; M = Cd(II), X = NO3-, 2a; M = Cd(II), X = ClO4-, 2b) 與Hg2(L1)2X2 (X = Cl, 3a; Br, 3b; I, 3c)。化合物1a - c與3a - c中L1配位基分別以四配位或三配位的模式與金屬鍵結，而在化合物2a與2b中配位基皆是以四配位模式與金屬鍵結。由變溫之液態1H NMR可知，L1配位基鍵結在金屬後，其pyrimidyl環可自由旋轉，而化合物2a與2b擁有較大的活化能(孱c╪)。在含formamidinate配位基中，化合物1a - c與3a - c是第一個具有雙核鋅與雙核汞金屬之化合物。化合物3a - c中兩個汞金屬的距離分別為3.47(1)、3.49(1)和3.53(1) Å與兩個汞金屬的凡得爾半徑和3.50(7) Å相近。在化合物1 - 3中放光光譜的範圍為391到472 nm，且在相同的金屬中心裡改變不同的陰離子對並放光之波長不會有太大的影響。
將KL1與二價的銅金屬鹽類在THF中反應，可獲得具有直線型的三核銅金屬化合物[Cu3(L1)4](X)2 (X = NO3-, 4a; ClO4-, 4b)。在此類型化合物中四個L1配位基分別是利用橋接或螯合的型式以螺旋方式與銅原子進行鍵結。其中有三個L1配位基與銅金屬是以四配位的模式形成鍵結，而另一L1配位基則是以三配位的模式與銅金屬鍵結，而剩下一個嘧啶環上的氮原子則未與金屬形成鍵結。在四配位的鍵結模式中，有兩個配位基利用兩個氨基上的氮原子以螯合的方式與銅金屬鍵結。另一個則是利用配位基上一個嘧啶環上的氮原子與一個氨基上的氮原子以螯合的方式與銅金屬鍵結。
以K[Cu4(L1)3(SCN)2]為起始物，分別與二價的Cu(CH3COO)2和Mo2(CH3COO)4進行反應，可獲得直線型四核金屬化合物Cu2(M)2(L1)4(SCN)2 (M = Cu(II), 5; M = Mo(II), 6)。在化合物5與6中L1配位基均是利用橋接的型式與四個中心金屬原子以螺旋方式進行鍵結。化合物6在液態中其結構會有所改變。藉由變溫1H NMR的測量得知，在分裂溫度(Tc)為275 K時，活化能(孱c╪)為13.65 kcal mol−1，而互變常數為77.71 s−1。
將NaL1分別與AgSCN、Co(SCN)2與CoBr2進行反應，可獲得化合物Ag4(L1)4, 7; 化合物Co2(L1)4, 8; 化合物Na2[Co6(L1)6(μ3-O)2(μ4-O)(Br)2], 9。化合物7為環狀結構，L1配位基氨基上的氮原子以橋接的方式與銀金屬形成二配位的鍵結模式，而嘧啶環上的氮原子則未與金屬進行鍵結。化合物8為雙核鈷金屬化合物，其L1配位基是以三配位的型式與鈷金屬形成鍵結。此外，在化合物8中兩個鈷的距離為3.504(1) Å。在化合物9結構中發現靠近中心的兩個鈷金屬會有disorder現象，因而解出兩個六核化合物結構。結構中含有三個氧原子，其中心的氧原子是以四配位的型式與四個鈷金屬原子形成一個扭曲的平面四邊形，另外兩個氧原子則是與三個鈷金屬原子形成一個扭曲的平面三角形。
利用Mo2(CR3COO)4 (R = H or F)為起始物，分別以不同比例的NaL1、HL1 與 N-(2-pyrimidinyl)formamide (HL2)進行反應，可獲得雙核鉬金屬化合物NaMo2(CF3COO)(L1)4, 10、Mo2(CH3COO)(L1)2(L2), 11、trans-Mo2(L1)2(L2)2, 12、cis-Mo2(L1)2(L2)2, 13與Mo2(L2)4, 14。化合物12 與13是含formamidinate配位基中第一對同時具有trans與cis構形的雙核鉬金屬化合物。化合物10 - 13中L1配位基是利用中心的兩個氨基上的氮原子以橋接的方式與鉬金屬進行鍵結，而化合物11 - 14中L2配位基則是利用嘧啶環上的氮原子與氨基上的氮原子以橋接的方式與鉬金屬進行鍵結。在化合物10 - 13中隨著Mo---N與Mo---O的作用力導致Mo-Mo之間的距離有所改變：化合物10 [2.1084(6) Å]、化合物11 [2.0951(17) Å]、化合物12 [2.103(1) Å]與化合物13 [2.1017(3) Å]。由於化合物14僅有Mo---O之間的作用力，故化合物10 - 13的Mo-Mo距離均較化合物14 [2.0826(12) - 2.0866(10) Å]長。

關鍵字

多核化合物 ； 互變常數 ； 甲咪配位基 ； 變溫核磁共振實驗 ； 自由能

並列摘要

Abstract
This dissertation discusses the chemistry of polynuclear metal complexes containing anion of N,N’-bis(pyrimidine-2-yl)formamidine ligand.
The salts of d10-metal react instantaneously with KL1 (L1 = anion of N,N’-bis(pyrimidine-2-yl)formamidine, HL1) in THF, producing bimetallic complexes of the types [M2(L1)3](X) (M = Zn(II), X = I3-, 1a; M = Zn(II), X = NO3-, 1b; M = Zn(II), X = ClO4-, 1c; M = Cd(II), X = NO3-, 2a; M = Cd(II), X = ClO4-, 2b) and Hg2(L1)2X2 (X = Cl, 3a; Br, 3b; I, 3c). New tridentate and tetradentate coordination modes were observed for the L1 ligands and their fluxional behaviors investigated by measuring variable- temperature 1H NMR spectra. Complexes 2a and 2b, which possess only tetradentate coordination modes for the L1 ligands in the solid state show larger free energy of activation (孱c╪) for the exchange than complexes 1a - c and 3a - c with tetradentate and/or tridentate coordination modes. Complexes 1a - c and 3a - c are the first dinuclear Zn(II) and Hg(II) complexes containing formamidinate ligands. Moreover, the separation between the two Hg(II) atoms are 3.47(1), 3.49(1) and 3.53(1) Å for complexes 3a - c, respectively, similar to the sum of van der Waals radii of two Hg(II) atoms which is 3.50(7) Å. All the complexes exhibit emissions with λem in the range form 391 to 472 nm and the nature of the anions hardly change the emission wavelengths of the complexes with the same metal centers.
Reactions of KL1 with divalent copper salt CuX2 afforded linear trinuclear complex of the type [Cu3(L1)4](X)2 (X = NO3-, 4a; ClO4-, 4b). The copper atoms of complexes 4a and 4b are helically bridged and/or chelated by four L1 ligands, resulting in four different coordination modes for the L1 ligands. While three of the four L1 ligands in complexes 4a and 4b are coordinated to the copper atoms in tetradentate fashions, the other one is coordinated to the copper atoms in a tridentate fashion, leaving one of the pyrimidyl nitrogen atom uncoordinated. In the tetradentate fashion, a pair of the L1 ligands form the coordination, with the two amine nitrogen atoms chelating to the central copper atom, while one L1 ligand forms the coordination mode, which features chelation by one pyrimidyl and one adjacent amine nitrogen atoms.
Reactions of K[Cu4(L1)3(SCN)2] with Cu(CH3COO)2 and Mo2(CH3COO)4 afforded linear tetranuclear complexes of the type Cu2(M)2(L1)4(SCN)2 (M = Cu(II), 5; M = Mo(II), 6). The four metal atoms of complexes 5 and 6 are helically bridged by four tetradentate L1 ligands. Fluxional behavior was observed for complex 6 in solution. By the DNMR analysis, the free energy of activation (孱c╪) for the exchange is 13.65 kcal mol−1 at 275 K (Tc), and the rate constant of exchange (Kc) is 77.71 s−1 for 6.
Reactions of NaL1 with AgSCN, Co(SCN)2 and CoBr2 afforded complexes Ag4(L1)4, 7; Co2(L1)4, 8 and Na2[Co6(L1)6(μ3-O)2(μ4-O)(Br)2], 9, respectively. The complex 7 is a cyclic tetranuclear complex containing only Ag(I) atoms and the L1 ligands are coordinated to the silver atoms in bidentate fashion through the two central amine nitrogen atoms, leaving the pyrimidyl nitrogen atoms uncoordinated. Complex 8 is a bimetallic complex with the L1 ligands coordinating to the metal centers in a tridentate fashion. The separation between the two Co(II) atoms is 3.504(1) Å. Complex 9 is a hexanuclear complex with four disordered Co atoms. Each structure consists of three oxygen atoms, where one oxygen atom is centered in a square planar of four Co atoms and the other two oxygen atoms are centered in a trigonal planar of three Co atoms.
The reactions of Mo2(CR3COO)4 (R = H or F) with different equivalents of HL1 and N-(2-pyrimidinyl)formamide (HL2) afforded dimolybdenum complexes of the types NaMo2(L1)4(CF3COO), 10; Mo2(L1)2(L2)(CH3COO), 11; trans-Mo2(L1)2(L2)2, 12; cis-Mo2(L1)2(L2)2, 13 and Mo2(L2)4, 14. Complexes 12 and 13 establish the first pair of trans and cis forms of dimolybdenum complexes containing formamidinate ligands. The L1 ligands in 10 - 13 are bridged to the metal centers through two central amine nitrogen atoms, while the L2 ligands in 11 - 14 are bridged to the metal centers via one pyrimidyl nitrogen atom and the amine nitrogen atom. The Mo-Mo distances of complexes 10 [2.1084(6) Å], 11 [2.0951(17) Å], 12 [2.103(1) Å] and 13 [2.1017(3) Å], which contain both Mo---N and Mo---O axial interactions, are slightly longer than those of complex 14 [2.0826(12) - 2.0866(10) Å] which has only Mo---O interactions.

並列關鍵字

polynuclear complexes ； free ； VT-NMR ； formamidine ligand

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