中科院上海有机化学研究所邓亮团队报道了印戒型八磷酸盐-钴络合物与卡宾类似物的合成、结构和功能化反应。相关研究成果发表在2022年11月2日出版的《美国化学会杂志》。

用低价金属物种激活白磷已被证明能够非常有效地将P4转化为含分子小Pn(n≤ 4)。金属介导的P4偶联反应很少发展，其可以选择性地产生大的多磷簇。

该文中，研究人员报道了与三种配位N-杂环卡宾（NHC）-钴（0）-烯烃配合物的P4活化反应，它们以高产率产生了钴的P8配合物[(NHC)2Co2(μ-η6:η6-P8)]（NHC=1,3-二甲基咪唑-2-亚基（IMes），1;1,3-双(2,6-二乙基苯基)咪唑-2-异丙烯(IDep)， 2)。1和2中的P8配体表现出理论研究预测的印戒型结构，但从未在合成分子中获得。

理论研究表明，[(NHC)2Co2(μ-η6:η6-P8)]最好描述为Co0-[P8]0-Co0络合物，其特征是Co–Coσ键和可识别的Co对P8的反配。通过用N-杂环硅烷、亚膦前体、有机叠氮化物和NHCs处理，络合物1转化为[(IMes)2Co2(μ-η6:η6-P8X)] (X = 1,3-双(叔丁基)-1,3-二氮-2-硅环戊-4-en-2-丙烯，3;PNMe2, 4), [（IMes）2Co2（σ：（μ-η4:η6）-RNPPPP6）]（R=SO2-C6H4-p-Me，5；C（CF3）2Ph，6）和[（IMe）2Co（μ-ε2:η2-环-P4P（IPri2））（μ-σ3:η3-P3）]（7）。

配合物3-7可以被视为1与相应的卡宾类似物SiR2、PR、NR和CR2的加合物，但它们的核心结构是不同的。在类似的条件下，白磷对这些试剂是惰性的。这些笼状官能化反应显示了P8配体在[（NHC）2Co2（μ-η6:η6-P8）]中的反应性比P4的反应性更强，并表明了P8配体对亲电试剂和亲核试剂的两亲性。

附：英文原文

Title: Signet-Ring-Shaped Octaphosphorus–Cobalt Complexes: Synthesis, Structure, and Functionalization Reactions with Carbene Analogs

Author: Chengbo Yang, Xuebin Jiang, Qi Chen, Xuebing Leng, Jie Xiao, Shengfa Ye, Liang Deng

Issue&Volume: November 2, 2022

Abstract: White phosphorus activation with low-valent metal species has proved to be very effective in converting P4 into small Pn-containing molecules with n ≤ 4. Much less developed are metal-mediated P4-coupling reactions that can yield selectively large polyphosphorus clusters. Herein, we report P4-activation reactions with three-coordinate N-heterocyclic carbene(NHC)-cobalt(0)-alkene complexes, which produce the P8 complexes of cobalt [(NHC)2Co2(μ-η6:η6-P8)] (NHC = 1,3-dimesitylimidazol-2-ylidene (IMes), 1; 1,3-bis(2,6-diethylphenyl)imidazol-2-ylidene (IDep), 2) in high yields. The P8 ligand in 1 and 2 exhibits a signet-ring type structure that was predicted by theoretical study but has never been obtained in synthetic molecules. Theoretical studies suggest that [(NHC)2Co2(μ-η6:η6-P8)] is best described as a Co0-[P8]0-Co0 complex featuring a Co–Co σ-bond and discernible Co-to-P8 back-donation. By treating with N-heterocyclic silylene, phosphinidene precursor, organic azides, and NHCs, complex 1 was transformed into [(IMes)2Co2(μ-η6:η6-P8X)] (X = 1,3-bis(tert-butyl)-1,3-diaza-2-silacyclopent-4-en-2-ylidene, 3; PNMe2, 4), [(IMes)2Co2(σ:(μ-η4:η6)-RNPPP6)] (R = SO2-C6H4-p-Me, 5; C(CF3)2Ph, 6), and [(IMes)2Co2(μ-η2:η2-cyclo-P4P(IPri2))(μ-η3:η3-P3)] (7), respectively. Complexes 3–7 can be viewed as the adducts of 1 with the corresponding carbene analogous SiR2, PR, NR, and CR2, but their core structures are distinct. Under similar conditions, white phosphorus is inert toward these reagents. These cage functionalization reactions showcase the enhanced reactivity of the P8 ligand in [(NHC)2Co2(μ-η6:η6-P8)] over that of P4, and indicate the amphiphilicity of the P8 ligand toward electrophiles and nucleophiles.

DOI: 10.1021/jacs.2c08647

Source: https://pubs.acs.org/doi/10.1021/jacs.2c08647