本實驗室利用雙氮基脒Li[HC(N-2,6-iPr2C6H3)2]為配基合成出第一個雙鉬五重鍵錯合物Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (1)，其具有低價數、低配位的特性，其中錯合物1擁有兩個δ鍵兩個π鍵及一個σ鍵，因此我們好奇是否能進行一些類似炔類的配位化學。錯合物1與一當量的Co2(CO)8反應，可得錯合物(OC)3Co(μ-κ2-CO){κ1-Mo[(OC)3Co(μ-κ2-CO)]Mo(CO)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2} (2)與[(OC)3Co(μ-κ2-CO)][μ-κ2-HC(N-2,6-iPr2C6H3)2]Mo(μ-CO)Co(μ-CO)(κ1-CO)Mo[μ-κ2-HC(N-2,6-iPr2C6H3)2] (3)其中2是動力學產物而3是熱力學產物，在此我們無法得到以六羰基二鈷當保護基形成Mo2Co2(CO)6[μ-κ2-HC(N-2,6-iPr2C6H3)2]2的結構。
將錯合物1與一當量的W(CO)5THF反應，1在此為配位基，配位在鎢金屬上，得到 (OC)4W{κ2-Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2]} (4)，錯合物1為四個電子的予體配位基。將錯合物1與一當量的Fe2(CO)9沒有得到類似4的產物而單離出產物[(OC)3Fe](μ-κ2-CO)MoMo(CO)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (5)，Fe(CO)4與其中一個鉬原子有雙鍵的鍵結。為了得到以多重鍵配位在鐵金屬上，改成使用雙鉬四重鍵錯合物Mo2[μ-κ2-PhB(N-2,6-iPr2C6H3)2]2 (6)當配位基，令人高興的是在6與Fe2(CO)9 的反應中產生錯合物 (OC)4Fe{κ2-Mo2[μ-κ2-PhB(N-2,6-ίPr2C6H3)2]2} (7)，而且鐵金屬的π反饋能力會讓錯合物7變回雙鉬四重鍵錯合物。
三核金屬錯合物5中的鉬原子具缺電子的性質，錯合物5與兩當量苯甲腈反應產生[(OC)3Fe](μ-κ2-CO)Mo(κ1-NCPh)Mo(CO)(κ1-NCPh) [μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (8)，但是苯甲腈的碳-氮三鍵並沒有被削弱，因此改用推電子能力較強的2,4,6-三甲基苯甲腈，得到了[(OC)3Fe](μ-κ2-CO)Mo(CO) Mo(κ1-NC-2,4,6-(Me)3C6H2)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (9)，可能由於立體阻礙的因素，5只與一當量的2,4,6-三甲基苯甲腈反應，最後我們嘗試用較缺電子的苯甲醯氰與5反應，得到了與錯合物9類似的化合物[(OC)3Fe](μ-κ2-CO)Mo(κ1-NCC(O)Ph)Mo(CO) [μ-κ2-HC(N-2,6-iPrC6H3)2]2 (10)。另一方面，錯合物1與具有較強推電子能力的二甲基氰胺反應產生兩分子的二甲基氰胺經碳-氮耦合反應形成一新穎胍基接在錯合物1上，最後得到了一個雙鉬配位有三個配基的錯合物Mo2[μ-κ2-NCNMe2]2[μ-κ3-N(Me2)CNC(NMe2)N][μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (11)。

The low-coordinate and low-valent quintuple bonded dimolybdenum complex Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (1) has two Mo-Mo δ bonds, two Mo-Mo π bonds and one Mo-Mo σ bond, so we wondered that if complex 1 is chemically similar to alkynes, particularly, the coordinating ability. Accordingly, we treated complex 1 with 1 equiv of Co2(CO)8 and we isolated two products, (OC)3Co(μ-κ2-CO){κ1-Mo[(OC)3Co(μ-κ2-CO)]Mo(CO)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2} (2) and [(OC)3Co(μ-κ2-CO)][μ-κ2-HC(N-2,6-ίPr2C6H3)2]Mo(μ-CO)Co(μ-CO)(κ1-CO)Mo [μ-κ2-HC(N-2,6-iPr2C6H3)2] (3). Complex 2 is a kinetic product, while 3 is a thermodynamic product. Attempts to isolate the targeted complex Mo2Co2(CO)6[μ-κ2-HC(N-2,6-iPr2C6H3)2]2, which is conceptually similar to Co2(CO)6(μ-κ2-alkyne), have failed.
The reaction of 1 with 1 equiv W(CO)5(THF) produced (CO)4W[κ2-Mo2[μ-κ2-HC(N-2,6-iPr2C6H3)2]2] (4), in which 1 donates four electrons to the W(CO)4 fragment to make it an 18-electron species. Furthermore, treatment of 1 with Fe2(CO)9 led to the isolation of the complex [(OC)3Fe](μ-κ2-CO)MoMo(CO)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (5), where one Mo atom has a double bond to the Fe atom. To synthesize a heterotrinuclear FeMo2 complex similar to 4, we then use the quadruple bonded dimolybdenum complex Mo2[μ-κ2-PhB(N-2,6-iPr2C6H3)2]2 (6) to react with Fe2(CO)9. To our delight, we obtained the targeted compound ((OC)4Fe){κ2-Mo2[μ-κ2-PhB(N-2,6-iPr2C6H3)2]2} (7), where the bonding between two Mo atoms could have a quadruple bond character due to back π donation from Fe to the LUMO (δ character) of 6.
It turns out that the Mo centers of the heterotrinuclear complex 5 are electron deficient. Treatment of complex 5 with 2 equiv of benzonitrile generated [(OC)3Fe](μ-κ2-CO)Mo(κ1-NCPh)Mo(CO)(κ1-NCPh)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (8). Two nitriles are simply two-electron σ donors, and the nitrile functionalities of PhCN are not activated judged by their bond lengths. When a bulky nitrile 2,4,6-trimethylbenzonitrile and an electron deficient benzoyl cyanide was employed to react with 5, two structurally similar compounds [(OC)3Fe](μ-κ2-CO)Mo(κ1-NCR)Mo(CO)[μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (R = 2,4,6-Me3C6H2 (9), C(O)C6H5 (10)). On the basis of the reactions above, we surmise that the C-N triple bond of nitriles cannot be activated by complex 5. We then treated 1 with a more electron-donating substrate dimethylcyanamide and isolated the complex Mo2[μ-κ2-NCNMe2]2[μ-κ3-N(Me2)CNC(NMe2)N][μ-κ2-HC(N-2,6-iPr2C6H3)2]2 (11), in which a new guanidinate ligand was formed by two molecules of dimethylcyanamide via a C-N coupling.

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