Rare-earth metal boroxides are not only rare and of great synthetic challenge but also important theoretically due to their unrevealed bonding characteristics. In this paper, we report the synthesis, characterization, and bonding characteristics of the 4f-block metal boroxide complexes ^MesDAD₂ LuOB(C₆F₅)X ( 4-Lu, X = C₆F₅; 5-Lu, X = NC₁₃H₁₀) with two chelating radical-anionic 1,4-diazabutadiene (DAD) ligands. The synthesis of 4-Lu or 5-Lu involved three steps, during which the radical-anionic DAD ligands could be kept stable: (1) the reaction of LuCl₃, ^MesDAD, and potassium graphite (KC₈) afforded the diradical rare-earth metal chloride ^MesDAD₂ LuCl· tetrahydrofuran (THF) ( 1-Lu); (2) the salt metathesis of 1-Lu with two alkali metal amides gave lutetium bis(diazabutadiene) amides 2-Lu or 3-Lu, respectively; and (3) 2-Lu or 3-Lu reacted with B(C₆F₅)₃·H₂O, resulting in the formation of rare-earth metal boroxides 4-Lu or 5-Lu. The radical-anionic nature of DAD ligands in these complexes were proven by their bond lengths and coordination modes in single-crystal structures. DFT calculations clearly show the bonding of 4-Lu can be divided into three major types of Lu–O orbital interactions, which can be categorized as σ-donation, π-donation, and d-π-conjugation. The triple Lu–O orbital interactions cooperatively make a Lu–O single bond and contribute to the linear Lu–O–B structure.

稀土金属硼氧化物不仅罕见，而且面临巨大的合成挑战，而且由于其未揭示的键合特性，在理论上也很重要。在本文中，我们报告了4f-嵌段金属硼氧化物配合物^Mes DAD ₂的合成，表征和键合特性 鲁OB（C ₆ F ₅）X（ 4路，X = C ₆ F ₅ ; 5路，X ＝ NC ₁₃ H ₁₀），具有两个螯合的自由基-阴离子1，4-二氮杂丁二烯（DAD）配体。的合成 4路 要么 5路 涉及三个步骤，在此期间，自由基-阴离子DAD配体可以保持稳定：（1） 鲁Cl ₃，^Mes DAD和碳酸钾（KC ₈）提供了双自由基稀土金属氯化物^Mes DAD ₂ 鲁Cl·四氢呋喃（THF）（ 1路）; （2）盐的复分解 1路 用两种碱金属酰胺得到gave双（二氮杂丁二烯）酰胺 2路 要么 3路， 分别; 和（3） 2路 要么 3路与B（C ₆ F ₅）₃ ·H ₂ O反应，形成稀土金属硼氧化物 4路 要么 5路。这些配合物中DAD配体的自由基-阴离子性质已通过其单晶结构中的键长和配位模式得到证明。DFT计算清楚地表明了 4路可以将Lu-O轨道相互作用分为三种主要类型，可以将其分为σ-给体，π-给体和d-π-共轭。三重Lu–O轨道相互作用共同构成了Lu–O单键并有助于线性Lu–O–B结构。