Synthesis and Reactivity of V2, Co2 and Ni2 Complexes

雙核釩、鈷、鎳錯合物的合成與化性研究

張凱傑(Kai-Chieh Chang)

指導教授 ： 蔡易州

國立清華大學/理學院/化學系/碩士(2009年)

摘要

將(Nacnac)DippCo(μ-Cl)2Li(THF)2 (Nacnac = HC(C(Me)NC6H3iPr2)2)在甲苯中利用KC8還原，可以成功的分離得到反三明治式雙核鈷錯合物－(μ-η2:η2-C7H8)[Co(Nacnac)Dipp]2 (1)，我們發現錯合物1對於小分子以及有機化合物皆有很好的反應性，產生許多新奇的鈷錯合物。利用1與白磷反應會得到以四個磷原子橋接的(μ-η4:η4-P4)[Co(Nacnac)Dipp]2 (2)，若再將2於100 ℃加熱四天，則會失去一個磷原子而產生(μ-η3:η3-P3)[Co(Nacnac)Dipp]2 (3)。另外利用1加入十六族元素後分別可分離得到[Co(Nacnac)Dipp(μ-X)]2 (4: X = S; 5: X = Se)與[Co(Nacnac)Dipp(μ-TeH)]2 (6)。而通入過量的一氧化氮則會得到逆磁性的Co(Nacnac)Dipp(NO)2 (7)。接著利用錯合物1和有機分子反應：加入對位疊氮甲苯後除了得到五員環單核的Co(Nacnac)Dipp(1,4-p-Tol2N4) (8)外，亦可分離出另一含量較少的雙核產物[Co(Nacnac)Dipp(μ-N-p-Tol)]2 (9)。和偶氮苯反應會得到將氮-氮雙鍵輕微活化的(μ-κ1:κ1-PhNNPh)[Co(Nacnac)Dipp]2 (10)。除此之外，1亦能催化末端炔類進行三聚合環化反應；而與立體阻礙較大的炔類如三甲基矽乙炔反應，則會生成三鍵配位於鈷上的錯合物－Co(Nacnac)Dipp(η2-Me3SiCCH) (12)。和1,3,5,7-環辛四烯反應會得到文獻上罕見的C16H16Co2(Nacnac)Dipp2 (13)，其中環辛四烯二聚合形成七六七的融合環連接兩個鈷；但加入1,3,5-環庚三烯卻得到把橋接的甲苯分子取代的錯合物－(μ-η4:η4-C7H8)[Co(Nacnac)Dipp]2 (14)。
除此之外，我們使用立體阻礙較小的配基與釩反應得到(Nacnac)ArVCl2 (Ar = Dmp or Dep)，接著再以四氫呋喃為溶劑在氮氣環境下還原，卻得到沒有固定氮氣的錯合物－[(Nacnac)ArV]2 (15: Ar = Dmp; 16: Ar = Dep)。
另一方面，利用amidinate配基與無水的氯化亞鈷和碘化鎳反應分別得到(DippNC(H)NDipp)Co(μ-Cl)2Li(THF)2 (18)和(η1-DippNC(H)NDipp)NiI3Li(THF)2(OEt2)2 (22)，分別將其還原可分離出無前例低配位的雙核錯合物－[M(μ-η2-DippNC(H)NDipp)]2 (20: M = Co; 24: M = Ni)。除此之外若利用22加入1.5當量的還原劑，則可分離得到(μ-I)[Ni(μ-η2-DippNC(H)NDipp)]2 (23)。

關鍵字

雙核 ； 雙核鎳 ； 雙核鈷 ； 雙核釩

並列摘要

Reduction of (Nacnac)DippCo(μ-Cl)2Li(THF)2 (Nacnac = HC(C(Me)NC6H3iPr2)2) by KC8 in toluene led to isolation of inverted-sandwich complex (μ-η2:η2-C7H8)[Co(Nacnac)Dipp]2 (1) in good yield. Then we found compound 1 able to activate small molecules and various organic functionalities, generating novel cobalt-containing complexes. Treatment of 1 with P4 afforded a P4-bridged compound (μ-η4:η4-P4)[Co(Nacnac)Dipp]2 (2), then we heat 2 for 4 days resulted in (μ-η3:η3-P3)[Co(Nacnac)Dipp]2 (3) with one phosphorus loss. Reaction with chalcogen elements furnished [Co(Nacnac)Dipp(μ-X)]2 (4: X = S; 5: X = Se) and [Co(Nacnac)Dipp(μ-TeH)]2 (6) respectively. While treatment of 1 with excess nitric oxide afforded diamagnetic compound Co(Nacnac)Dipp(NO)2 (7). Then we investigated the reactivity of 1 with organic functionalities. Reaction with p-TolN3 produced not only a five-membered-ring complex Co(Nacnac)Dipp(1,4-p-Tol2N4) (8), but a minor product [Co(Nacnac)Dipp(μ-N-p-Tol)]2 (9). Treatment of 1 with azobenzene led to isolation of (μ-κ1:κ1-PhNNPh)[Co(Nacnac)Dipp]2 (10), which had slightly activated N-N bond. Moreover, complex 1 can catalyze cyclotrimerization of alkynes and form C-C triple bond coordinated complexes while reaction with more steric hindered alkynes such as Me3SiCCH. The reaction of 1 with 1,3,5,7-cyclooctatetraene afforded novel compound C16H16Co2(Nacnac)Dipp2 (13), two COTs forming a new C16H16 skeleton containing 3 fused ring. While treatment with 1,3,5-cycloheptatiene produced (μ-η4:η4-C7H8)[Co(Nacnac)Dipp]2 (14) without dimerization of cycloheptatriene.

Moreover, we used less hindered ligand to synthesize vanadium complex (Nacnac)ArVCl2 (Ar = Dmp or Dep). Then we reduced it by KC8 in THF under N2 afforded [(Nacnac)ArV]2 (15: Ar = Dmp; 16: Ar = Dep) without N2 fixation.
Reaction of amidinate with anhydrous CoCl2 and NiI2 produced (DippNC(H)NDipp)Co(μ-Cl)2Li(THF)2 (18) and (η1-DippNC(H)NDipp)NiI3Li(THF)2(OEt2)2 (22) respectively. Reduction of 18 and 22 furnished unprecedented low-coordinate complex [M(μ-η2-DippNC(H)NDipp)]2 (20: M = Co; 24: M = Ni). Moreover, treatment of 22 with 1.5 equivalent KC8 produced mixed-valence (μ-I)[Ni(μ-η2-DippNC(H)NDipp)]2 (23).

參考文獻

(2) Holland, P. L. Acc. Chem. Res. 2008, 41, 905-914.

(9) Knobloch, D. J.; Toomey, H. E.; Chirik, P. J. J. Am. Chem. Soc. 2008, 130, 4248-+.

(12) Brosset, C. Nature (London) 1935, 135, 874.

(13) Cotton, F. A. L., S. J. J. Am. Chem. Soc. 1964, 86, 4497.

(22) Hsu, C. W.; Yu, J. S. K.; Yen, C. H.; Lee, G. H.; Wang, Y.; Tsai, Y. C. Angew. Chem. Int. Ed. 2008, 47, 9933-9936.