An element is named after a celestial body in the solar system, and the density of its simple substance exhibits an anomalous increase compared to its two adjacent elements. Now, by reacting a trifluoromethanesulfonate of a certain oxidation state of this element with potassium tris(3,5-dimethyl-1-pyrazolyl)hydroborate ($KTp^{3Me,5Me}$) under anhydrous and oxygen-free conditions, a mixed-ligand eight-coordinate complex was obtained. Please predict the ligands and metal center contained in this complex.
某元素以太阳系中的天体命名，其单质的密度相较于相邻的两个元素存在反常增大。现以该元素某一价态的三氟甲磺酸盐与三(3,5-二甲基-1-吡唑基)氢硼酸钾（$KTp^{3Me,5Me}$）在无水无氧条件下反应，得到了一种混配的八配位配合物，请预测该配合物中含有的配体与金属中心。
U(III) with the $Tp^{3Me,5Me}$ ligand and the 3,5-dimethylpyrazol-1-ide ligand
Pu(IV), featuring the $Tp^{3Me,5Me}$ ligand and bis(3,5-dimethyl-1-pyrazolyl)dihydroborate ($Bp^{3Me,5Me}$) ligand
Ce(III) with the ligand $Tp^{3Me,5Me}$ and the 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)diboroxane-1,3-diuide ligand
U(III), containing the $Tp^{3Me,5Me}$ ligand and the 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazolyl)diboroxane-1,3-diuide ligand
Ce(III) with the $Tp^{3Me,5Me}$ ligand and 3,5-dimethylpyrazol-1-ide ligand
All of the above options are incorrect.
U(III)，含有$Tp^{3Me,5Me}$配体与3,5-二甲基吡唑-1-负离子配体
Pu(IV)，含有$Tp^{3Me,5Me}$配体与二(3,5-二甲基-1-吡唑基)二氢硼酸根配体（$Bp^{3Me,5Me}$）
Ce(III)，含有$Tp^{3Me,5Me}$配体与1,1,3,3-四(3,5-二甲基-1-吡唑基)二硼氧烷-1,3-二负离子配体
U(III)，含有$Tp^{3Me,5Me}$配体与1,1,3,3-四(3,5-二甲基-1-吡唑基)二硼氧烷-1,3-二负离子配体
Ce(III)，含有$Tp^{3Me,5Me}$配体与3,5-二甲基吡唑-1-负离子配体
以上选项均不对
Based on the information that it is named after a celestial body, it can be inferred that the element is one of He, Se, Pd, Te, Ce, U, Np, or Pu.  

<Checkpoint>[The element is one of He, Se, Pd, Te, Ce, U, Np, or Pu](1)</Checkpoint>  

Furthermore, the abnormally increased density excludes He, Se, Pd, and Te. For U, Np, and Pu, since f-electrons can participate in metallic bonding, the density increases sequentially from Ac to Np, reaching its maximum at Np, and then decreases at Pu. Thus, the element is also not U, Np, or Pu.  
For Ce, since it can use four valence electrons to participate in metallic bonding, its density is nearly equivalent to that of Pr, which uses only three valence electrons for bonding. Therefore, the element is Ce.  

<Checkpoint>[The element is Ce](2)</Checkpoint>  

Regarding the formation of complexes, since the conditions are strictly anhydrous and oxygen-free, the $Tp^{3Me,5Me}$ ligand will not hydrolyze to produce oxygen-containing ligands but will instead undergo B-N bond cleavage to form a pyrazolyl anion ligand. Thus, the correct answer is E.  

<Checkpoint>[$Tp^{3Me,5Me}$ ligand does not hydrolyze to produce oxygen-containing ligands](1)</Checkpoint>  

<Checkpoint>[The ligand is $Tp^{3Me,5Me}$ and 3,5-dimethylpyrazolyl anion](1)</Checkpoint>
依据以天体命名这一信息，可知为He,Se,Pd,Te,Ce,U,Np,Pu中的某一元素

<Checkpoint>[该元素为He,Se,Pd,Te,Ce,U,Np,Pu中的某一元素](1)</Checkpoint>

而依据密度反常增大这一信息可以排除He,Se,Pd,Te，对于U,Np,Pu，由于f电子可以参与形成金属键，从Ac到Np密度依次增大且Np达到最大值，Pu处则减小，故同样不为U,Np,Pu
对于Ce，由于可以使用4个价电子参与形成金属键，其密度与仅使用3个价电子成键的Pr几乎相当，可知元素为Ce

<Checkpoint>[该元素为Ce](2)</Checkpoint>

对于形成配合物，由于严格无水无氧，$Tp^{3Me,5Me}$配体并不会水解产生含O配体，而会发生B-N键断裂形成吡唑负离子配体，可知答案选E

<Checkpoint>[$Tp^{3Me,5Me}$配体并不会水解产生含O配体](1)</Checkpoint>

<Checkpoint>[配体为$Tp^{3Me,5Me}$配体与3,5-二甲基吡唑负离子](1)</Checkpoint>