A Basic Strategy for Functionalization of Metal Cyclopentadienyl Complexes: Synthesis, Characterization, and Reactivity of Linear, Butterfly, and Cubic Chromium/Selenium Complexes Containing Functionally Substituted Cyclopentadienyl Ligands

The first examples of linear, butterfly, and cubic Cr/Se complexes containing functionally
substituted Cp ligands have been successfully synthesized by skeleton and functional
transformations of the prefunctionalized Cp metal precursors. For example, (i) the prefunctionalized Cp metal precursors [η5-RC5H4Cr(CO)3]2 (1, R = MeCO; 2, R = MeO2C) reacted
with elemental selenium under the given conditions to afford linear complexes [η5-RC5H4Cr(CO)2]2Se (3, R = MeCO; 4, R = MeO2C), butterfly complexes [η5-RC5H4Cr(CO)2]2Se2 (5,
R = MeCO; 6, R = MeO2C), and cubane clusters (η5-RC5H4)4Cr4Se4 (7, R = MeCO; 8, R =
MeO2C), whereas the linear complexes 3/4 reacted with elemental selenium under appropriate conditions to produce butterfly complexes 5/6 or cubane clusters 7/8; (ii) thermolysis of
a THF solution of butterfly complex 5 or 6 gave rise to cubane cluster 7 or 8, whereas the
THF solution of two butterfly complexes [CpCr(CO)2]2Se2 and 6 under reflux afforded cubane
clusters (η5-MeO2CC5H4)nCp4-nCr4Se4 (n = 0, Cp4Cr4Se4; n = 1, 9; n = 2, 10; n = 3, 11; n =
4, 8); (iii) while cluster 7 reacted with excess NaBH4 to give secondary hydroxy derivative
[η5-MeCH(OH)C5H4]4Cr4Se4 (12), it reacted with Grignard reagent MeMgI and subsequent
hydrolysis of the addition intermediate to afford tertiary hydroxy derivative [η5-Me2C(OH)C5H4]4Cr4Se4 (13); and (iv) the functional transformation of cluster 7 under the action of
Wittig reagent Ph3PCHPh produced cubane cluster [η5-PhCHC(Me)C5H4]4Cr4Se4 (14),
whereas the condensation reaction of 7 with 2,4-dinitrophenylhydrazine yielded phenylhydrazone derivative [η5-2,4-(NO2)2C6H3NHNC(Me)C5H4]4Cr4Se4 (15). Possible pathways for
the reactions leading to functionalized cubane clusters 7−11 are suggested. Furthermore,
77Se NMR techniques were utilized to characterize the new functionalized complexes, whereas
single-crystal X-ray diffraction was employed to confirm the structures of complexes 4, 7, 8,
11, and 12.

首例通过预功能化环戊二烯基（Cp）金属前驱体的骨架与官能团转化，成功合成了带有功能取代基Cp配体的线性、蝶形与立方型铬/硒配合物。具体示例如下：(i) 预功能化Cp金属前驱体[η⁵-RC₅H₄Cr(CO)₃]₂（1，R=MeCO；2，R=MeO₂C）在指定条件下与单质硒反应，得到线性配合物[η⁵-RC₅H₄Cr(CO)₂]₂Se（3，R=MeCO；4，R=MeO₂C）、蝶形配合物[η⁵-RC₅H₄Cr(CO)₂]₂Se₂（5，R=MeCO；6，R=MeO₂C）以及立方烷团簇(η⁵-RC₅H₄)₄Cr₄Se₄（7，R=MeCO；8，R=MeO₂C）；而线性配合物3/4在适宜条件下与单质硒反应，可生成蝶形配合物5/6或立方烷团簇7/8。(ii) 对蝶形配合物5或6的四氢呋喃（THF）溶液进行热解，可得到立方烷团簇7或8；而将[CpCr(CO)₂]₂Se₂与6两种蝶形配合物的THF溶液回流，可得到混合配体立方烷团簇(η⁵-MeO₂CC₅H₄)ₙCp₄₋ₙCr₄Se₄（n=0时为Cp₄Cr₄Se₄；n=1时为9；n=2时为10；n=3时为11；n=4时为8）。(iii) 当团簇7与过量硼氢化钠（NaBH₄）反应，可得到仲羟基衍生物[η⁵-MeCH(OH)C₅H₄]₄Cr₄Se₄（12）；而其与格氏试剂（Grignard reagent）MeMgI反应后，再对加成中间体进行水解，可得到叔羟基衍生物[η⁵-Me₂C(OH)C₅H₄]₄Cr₄Se₄（13）。(iv) 团簇7在维蒂希试剂（Wittig reagent）Ph₃P=CHPh作用下发生官能团转化，可得到立方烷团簇[η⁵-PhCH=C(Me)C₅H₄]₄Cr₄Se₄（14）；而7与2,4-二硝基苯肼发生缩合反应，可得到苯腙衍生物[η⁵-2,4-(NO₂)₂C₆H₃NHNC(Me)C₅H₄]₄Cr₄Se₄（15）。本文提出了生成功能化立方烷团簇7~11的可能反应路径。此外，本研究采用⁷⁷Se核磁共振（NMR）技术对新型功能化配合物进行了表征，并通过单晶X射线衍射确认了配合物4、7、8、11及12的晶体结构。