我們知道當配基的立體阻礙效應增大時，過渡金屬有機會和配基形成低配位數金屬中心的錯合物，而金屬空出的d軌域可能重疊並形成鍵結；不同配基與金屬的鍵結模式不同，也影響金屬之間鍵結的強度。而我們的興趣在於合成低配位數多金屬錯合物。根據文獻，我們成功合成出H2[2,6-(NDipp)2-4-MeC5H2N]及H2[Me2Si(NDipp)2] (Dipp = 2,6-i-propylphenyl)。使用甲基鋰當鹼將兩者除氫後，嘗試和金屬起始物反應，我們成功得到低配位數金屬錯合物。兩配基和碘化銅以四氫呋喃為溶劑下反應，我們成功分離出多銅金屬錯合物： Li(THF)3{Cu3[μ3-η1:η1:η1-2,6-(NDipp)2-4-MeC5H2N]2} (3)和 [K(18-crown-6)]{Cu4[μ4-η2:η2-Me2Si(NDipp)2]2(μ-I)} (4)。因為上述金屬中心d軌域全填滿沒有鍵結，但推測有d10-d10交互作用力造成其雙銅金屬距離縮短為2.4 Å；兩錯合物具有螢光發光性質，但量子產率低。而與二氯化鎘和二溴化鋅以乙醚為溶劑下反應，可得到雙鎘和雙鋅錯合物：Cd2[μ-η2-Me2Si(NDipp)2]2 (5)、Zn2[μ-η2-Me2Si(NDipp)2]2 (7)和Zn2[μ-η1:η2-2,6-(NDipp)2-4-MeC5H2N]2(THF)2 (9)。我們嘗試用KH以四氫呋喃為溶劑還原錯合物5，可以得到具有鎘-鎘鍵的四鎘多金屬結構[K(18-crown-6)]2{Cd[(μ-Me2Si(NDipp)2)Cd(η2-Me2Si(NDipp)2)]}2 (6)：具有三配位鎘(II)和二配位鎘(I)金屬中心。我們利用113Cd-NMR推測其反應機制。[K-C-2,2,2]2[Zn(η2-Me2Si(NDipp)2)]2 (8)和[K-18-crown-6]{KZn2[μ-η1:η2-2,6-(NDipp)2-4-MeC5H2N]2} (10)可由錯合物7和9與KC8以四氫呋喃為溶劑下反應而得。錯合物8具有三配位鋅(I)金屬中心形成的鋅-鋅鍵(2.36 Å)，我們利用DFT理論計算去解釋其配基鍵結模式由架橋到箝合的轉變。錯合物10經過X-ray吸收近緣光譜確定具有鋅(I)鋅金屬中心，而兩金屬中間鍵結一個鉀原子，鋅和鉀之間的距離(約2.46 Å)小於其共價半徑，形成三金屬中心兩電子的鍵結結構，目前文獻並沒有記載有關鋅和第一族和第二族的鍵結。我們也發現錯合物10雖然具有螢光發光性質，但量子產率仍低。

In order to synthesize low-coordinate multi-nuclear complexes, we prepared two sterically demanding ligands, H2[2,6-(NDipp)2-4-MeC5H2N] and H2[Me2Si(NDipp)2] (Dipp = 2,6-i-propylphenyl). Their corresponding dilithiated salts were subsequently prepared and then reacted with copper(I) iodide in tetrahrdrofuran, cadmium(II) chloride in ether, and zinc(II) bromide in ether, respectively. From these said reactions, we successfully isolated multi-nuclear complexes and they are fully characterized by multi-nuvlear NMR spectroscopy and single crystal X-ray diffraction. Li(THF)3{Cu3[μ3-η1:η1:η1-2,6-(NDipp)2-4-MeC5H2N]2} (3) and [K(18-crown-6)]{Cu4[μ4-η2:η2-Me2Si(NDipp)2]2(μ-I)} (4) exhibit fluorescence with low quantum yield. Due to the d10-d10 interactions, the Cu-Cu distances in complexes 3 and 4 are short ( 2.426(1)-2.486(2) Å). On the other hand, two iso-structure dicadmium and dizinc complexes Cd2[μ-η2-Me2Si(NDipp)2]2 (5) and Zn2[μ-η2-Me2Si(NDipp)2]2 (7) supported by two sterically encumbered diamido ligands Me2Si(NDipp)2 could be isolated in good yields, in which the metal-metal axes are perpendicular to the Si-Si linkage. Upon reduction of 5, a novel tetracadmium complex, [K(18-crown-6)]2{Cd[(η-Me2Si(NDipp)2)Cd(η2-Me2Si(NDipp)2)]}2 (6), with a Cd-Cd bond was prepared. It is interesting to note that complex 6 displays two different types of cadmium metal centers. One, Cd(II), is ligated by three nitrogen atoms, and the other, Cd22+, is coordinated by two nitrogen atoms. A possible mechanism to explain the formation of complex 6 was proposed based on 113Cd-NMR data. On the other hand, while complexes Zn2[μ-η2-Me2Si(NDipp)2]2 (7) and Zn2[μ-η1:η2-2,6-(NDipp)2-4-MeC5H2N]2(THF)2 (9) were also treated with KC8 in tetrahydrofuran, we obtained [K-C-2,2,2]2[Zn(η2-Me2Si(NDipp)2)]2 (8), where the Zn-Zn bond is parallel with the Si-Si linkage, and [K-18-crown-6]{KZn2[μ-η1:η2-2,6-(NDipp)2-4-MeC5H2N]2} (10) exhibiting a remarkable three-center and two-electron Zn-K-Zn bonding. The mechanism for the interesting structural transformations from 7 to 8 involving Zn-Zn bonds was proposed to proceed through an intermediate {Zn2[μ-η2-Me2Si(NDipp)2]2}‾ which was verified with the aid of DFT calculations. Complex 10 displays fluorescence property with low quantum yield.

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