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Bis(imino)aryl NCN pincer cobalt complexes: synthesis and disproportionation.
Dalton Transactions ( IF 3.5 ) Pub Date : 2020-04-28 , DOI: 10.1039/d0dt00747a Li-Cheng Huang 1 , Jing-Shun Zhang 1 , Teng Jia 1 , Ying Mu 1 , Wei Gao 1
Dalton Transactions ( IF 3.5 ) Pub Date : 2020-04-28 , DOI: 10.1039/d0dt00747a Li-Cheng Huang 1 , Jing-Shun Zhang 1 , Teng Jia 1 , Ying Mu 1 , Wei Gao 1
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Treatment of iPr[NCN]Br (2,6-(2,6-iPr2C6H3C[double bond, length as m-dash]N)2C6H3Br) with nBuLi in THF and the subsequent addition of 1 equiv. of CoCl2, CoCl2(Ph3P)2, and CoBr2 gave pincer Co(ii) complexes {iPr[NCN]Co(μ-Cl)}2 (1d), iPr[NCN]CoClPh3P (1d-Ph3P), and iPr[NCN]CoBr2·Li(THF)4 (1d-LiBr) respectively in moderate yields, whereas the slow addition of in situ prepared iPr[NCN]Li to CoCl2 in THF afforded an unexpected mixed-valence cobalt(i/ii) complex κ2C,N,η6-iPr[NCN]Co-κN-CoCl3·Li(THF)4 (2d). Complex 2d was probably formed via a disproportionation reaction of the iPr[NCN]Co(ii) species with excess CoCl2 during the reaction. Nevertheless, addition of CoCl2 to in situ formed 1d-THF at room temperature did not lead to 2d but gave a trinuclear Co(ii) complex {iPr[NCN]Co(μ-Cl)(μ-Br/Cl)}2Co (1d-CoCl2) in moderate yield. Similar reactions using ligands containing small ortho groups in the imine moieties R[NCN]Br (2,6-(2,6-Me2C6H3C[double bond, length as m-dash]N)2C6H3Br, Me[NCN]Br; 2,6-(2,6-Et2C6H3C[double bond, length as m-dash]N)2C6H3Br, Et[NCN]Br; 2,6-(2,4,6-Me3C6H2C[double bond, length as m-dash]N)2C6H3Br, Mes[NCN]Br) and CoBr2, regardless of the reactant addition sequence, afforded mixed-valence cobalt(i/ii) complexes {κ2C,N,η6-R[NCN]Co-κN-CoBr(μ-Br)}2 (Me[NCN] (2a), Et[NCN] (2b), and Mes[NCN] (2c)), suggesting that the bulkiness of the ortho-groups in the imine moieties of the ligands plays an important role in the disproportionation reaction. In the presence of PMe3, Co(ii) complexes κ2C,N-R[NCN]CoBr(PMe3)2 (3a-d) and a bisligated cobalt(ii) complex κ3N,C,N-κ2C,N-iPr[NCN]2CoPMe3 (4d) can be prepared respectively in high yields. The molecular structures of 1d-LiBr, 1d-CoCl2, 2b, 2d, 3a, and 4d were confirmed by X-ray crystallographic analysis and the detailed mechanisms of the disproportionation reaction were proposed.
中文翻译：
双（亚氨基）芳基NCN钳制钴配合物：合成和歧化。
在THF中用nBuLi处理iPr [NCN] Br（2,6-（2,6-iPr2C6H3C [双键，长度为m-虚线N] 2C6H3Br），然后加入1当量。CoCl2，CoCl2（Ph3P）2和CoBr2的合成得到钳制的Co（ii）络合物{iPr [NCN] Co（μ-Cl）} 2（1d），iPr [NCN] CoClPh3P（1d-Ph3P）和iPr [NCN ] CoBr2·Li（THF）4（1d-LiBr）的产率中等，而将原位制备的iPr [NCN] Li缓慢添加到THF中的CoCl2中，则得到了出乎意料的混合价钴（i / ii）复合物κ2C， N，η6-iPr[NCN]Co-κN-CoCl3·Li（THF）4（2d）。在反应过程中，iPr [NCN] Co（ii）物种与过量的CoCl2发生歧化反应，可能形成络合物2d。不过，在室温下向原位添加CoCl2形成1d-THF并不会导致2d，而是产生了三核Co（ii）络合物{iPr [NCN] Co（μ-Cl）（μ-Br/ Cl）} 2Co（ 1d-CoCl2），收率中等。使用亚胺部分R [NCN] Br（2,6-（2,6-Me2C6H3C [双键，长度为m-N] N）2C6H3Br，Me [NCN] Br; 2 6-（2,6-Et2C6H3C [双键，长度为m-破折号] N）2C6H3Br，Et [NCN] Br; 2,6-（2,4,6-Me3C6H2C [双键，长度为m-破折号] N）2C6H3Br，Mes [NCN] Br）和CoBr2，无论反应物的添加顺序如何，均可提供混合价的钴（i / ii）配合物{κ2C，N，η6-R[NCN]Co-κN-CoBr（μ- Br）} 2（Me [NCN]（2a），Et [NCN]（2b）和Mes [NCN]（2c）），表明配体亚胺部分中邻位基团的体积很大在歧化反应中的作用。在存在PMe3的情况下，Co（ii）配合物κ2C，NR [NCN] CoBr（PMe3）2（3a-d）和双键钴（ii）配合物κ3N，C，N-κ2C，N-iPr [NCN] 2CoPMe3 （4d）可以分别以高产率制备。
更新日期：2020-03-25
中文翻译：
双（亚氨基）芳基NCN钳制钴配合物：合成和歧化。
在THF中用nBuLi处理iPr [NCN] Br（2,6-（2,6-iPr2C6H3C [双键，长度为m-虚线N] 2C6H3Br），然后加入1当量。CoCl2，CoCl2（Ph3P）2和CoBr2的合成得到钳制的Co（ii）络合物{iPr [NCN] Co（μ-Cl）} 2（1d），iPr [NCN] CoClPh3P（1d-Ph3P）和iPr [NCN ] CoBr2·Li（THF）4（1d-LiBr）的产率中等，而将原位制备的iPr [NCN] Li缓慢添加到THF中的CoCl2中，则得到了出乎意料的混合价钴（i / ii）复合物κ2C， N，η6-iPr[NCN]Co-κN-CoCl3·Li（THF）4（2d）。在反应过程中，iPr [NCN] Co（ii）物种与过量的CoCl2发生歧化反应，可能形成络合物2d。不过，在室温下向原位添加CoCl2形成1d-THF并不会导致2d，而是产生了三核Co（ii）络合物{iPr [NCN] Co（μ-Cl）（μ-Br/ Cl）} 2Co（ 1d-CoCl2），收率中等。使用亚胺部分R [NCN] Br（2,6-（2,6-Me2C6H3C [双键，长度为m-N] N）2C6H3Br，Me [NCN] Br; 2 6-（2,6-Et2C6H3C [双键，长度为m-破折号] N）2C6H3Br，Et [NCN] Br; 2,6-（2,4,6-Me3C6H2C [双键，长度为m-破折号] N）2C6H3Br，Mes [NCN] Br）和CoBr2，无论反应物的添加顺序如何，均可提供混合价的钴（i / ii）配合物{κ2C，N，η6-R[NCN]Co-κN-CoBr（μ- Br）} 2（Me [NCN]（2a），Et [NCN]（2b）和Mes [NCN]（2c）），表明配体亚胺部分中邻位基团的体积很大在歧化反应中的作用。在存在PMe3的情况下，Co（ii）配合物κ2C，NR [NCN] CoBr（PMe3）2（3a-d）和双键钴（ii）配合物κ3N，C，N-κ2C，N-iPr [NCN] 2CoPMe3 （4d）可以分别以高产率制备。
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