本實驗室使用雙氮基脒為配基與鉻金屬成功合成出雙鉻金屬五重鍵錯合物Cr2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (1),其具有低配位數以及低價數的特性,我們嘗試著利用錯合物 1 與小分子進行反應,由於雙鉻金屬五重鍵錯合物具有δ鍵,可與碳-碳多重鍵的π鍵作比較,觀察與碳-碳多重鍵與小分子間的反應性有何異同。 將錯合物 1 與四當量的乙腈反應,可得到錯合物{Cr2[μ-κ2-HC(NDipp)2][μ-HC(NDipp)2][η2-NC(CH3)C(CH3)N]}2 (2) 以及錯合物(μ-η2,η2-MeCN)2(MeCN)2Cr2[μ-κ2-HC(NDipp)2]2 (3) ,而與丙腈和異丁腈反應可得與錯合物 3 相似結構的錯合物(μ-η2,η2-EtCN)2(EtCN)2Cr2[μ-κ2-HC(NDipp)2]2 (4) 以及錯合物(μ-η2,η2-iPrCN)2(iPrCN)2Cr2[μ-κ2-HC(NDipp)2]2 (5),其中令人意外的是與三甲基腈甲矽烷的反應,與上述所得到的結果完全不同,得到鉻零價單核錯合物Cr(Me3SiNC)6 (6) ,六鉻金屬環化錯合物{Cr(μ-CN)2[μ-HC(NDipp)2]}2{[Cr(CN(TMS)2)(μ-HC(NDipp)2)]2(μ-CN)4[Cr(CN)]2} (7) 以及四個三甲基腈甲矽烷配位在鉻上的錯合物Cr[μ-HC(NDipp)2][CN(TMS)2](CNTMS)3 (8) ,錯合物 6-8 鉻鉻五重鍵皆被打斷,三甲基腈甲矽烷的碳-氮鍵反轉,以碳配位在鉻金屬上。 而將錯合物 1 與9-borabicyclo[3.3.1]nonane進行反應,成功的得到十分少見的鉻硼鍵錯合物,最後合成出錯合物Cr2[HC(NDipp)2](9-borabicyclo[3.3.1]nonyl)2(μ2-O-9-borabicyclo[3.3.1]nonyl)(μ2-THF) (9) 。 另外,我們嘗試著用錯合物 1 和疊氮化合物進行反應,與兩當量的叠氮苯甲酰反應,卻無法得到推測中的雙核金屬錯合物,而是形成一單核的錯合物Cr{[HC(NDipp)2]C(NPh)O}2 (10) 。 除了利用雙氮基脒外,本實驗室還嘗試其他配基與不同金屬進行反應,實驗能否能合成出相似的燈籠型金屬多重鍵錯合物,我們利用Li2[HB(N-2,6-iPr2C6H3)2]配基,與鉻、鉬、鎢等金屬進行反應,嘗試其可行性。
The low-coordinate and low-valent quintuply-bonded dichromium complex Cr2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (1) characterized by our group behaves like alkynes, so we further examine reactivity of 1 with small molecules. Treatment of 1 with four equiv of acetonitrile respectively results in a complexation product {Cr2[μ-κ2-HC(NDipp)2][μ-HC(NDipp)2][η2-NC(CH3)C(CH3)N]}2 (2) and (μ-η2,η2-MeCN)2(MeCN)2Cr2[μ-κ2-HC(NDipp)2]2 (3).Complex 2 is formed via C-C coupling of two molecules of MeCN. On the other hand, the C-N triple bond of MeCN is activated via coordination to the Cr2 unit in 3. Treatment of 1 with propiononitrile or isobutyronitrile gives complexes (μ-η2,η2-EtCN)2(EtCN)2Cr2[μ-κ2-HC(NDipp)2]2 (4) and (μ-η2,η2-iPrCN)2(iPrCN)2Cr2[μ-κ2-HC(NDipp)2]2 (5). Both structures of 4 and 5 are similar to that of complex 3. Surprisingly, reaction of complex 1 with trimethylsilyl cyanide (Me3SiCN) is complicated and results in three products: Cr(Me3SiNC)6 (6), {Cr(μ-CN)2[μ-HC(NDipp)2]}2 {[Cr(CN(TMS)2)(μ-HC(NDipp)2)]2(μ-CN)4[Cr(CN)]2} (7) and Cr[μ-HC(NDipp)2][CN(TMS)2](CNTMS)3 (8). The characterization of complexes 6-8 indicates this reaction proceeds through cleavage of Cr-Cr quintuple bond, inversion of C-N functionality of Me3SiCN and Si-N bond cleavage. In all complexes 6, 7 and 8, trimethylsilyl cyanide binds the metal center through its C instead of N atom. Treatment of 1 with 9-borabicyclo[3.3.1]nonane(9-BBN) gives Cr2[HC(NDipp)2] (9-borabicyclo[3.3.1]nonyl)2(μ2-O-9-borabicyclo[3.3.1]nonyl)(μ2-THF) (9).Treatment of the 1 with benzoyl azide results in the formation of the mononuclear complex Cr{[HC(NDipp)2]C(NPh)O}2 (10). We recently succeeded in characterizing boron-containing diamido transition-metal complexes. Therefore, we tried to employ the boron-containing diamido ligand Li2[HB(N-2,6-iPr2C6H3)2] to react with chromium, molybdenum and tungsten species.