$\bf X$ is a 1:1 type salt (quaternary compound) with a carbon mass fraction of 4.35% and a boron mass fraction of 43.09%. Treatment of $\bf X$ with excess $\rm ICl$ in glyme yields the anion $\bf B^-$ in good yield, which has a boron mass fraction of 13.24%. The reaction of $\rm CPh_3^+\bf B^-$ with $\rm ^iPr_3SiH$ in toluene gives pale yellow microcrystals of $\bf C$, and the reaction of $\bf C$ with anhydrous liquid hydrogen chloride gives $\bf A$.

Which of the following statements are correct:

1. The quotient of the number of possible structures with the highest symmetry of $\bf B^-$ and its point group order is 0.4.
2. The mass fraction of boron in $\bf A$ is approximately 13.22%.
3. Under different reaction conditions, $\bf C \rm _{Cl}$, $\bf C \rm _{Br}$, and $\bf C \rm _I$ can be obtained respectively, then the order of the magnitude of the cation-anion interaction in $\bf C$ is $\bf C \rm _{Cl}$>$\bf C \rm _{Br}$>$\bf C \rm _I$.
4. Similarly, $\bf A \rm _{Cl}$, $\bf A \rm _{Br}$, and $\bf A \rm _I$ exist, and the order of their acidity is $\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$.
$\bf X$是一种1:1型盐（四元化合物），碳的质量分数为4.35%，硼的质量分数为43.09%。在乙二醇二甲醚中用过量的$\rm ICl$处理$\bf X$可以以很好的产率得到阴离子$\bf B^-$，该阴离子中硼的质量分数为13.24%。$\rm CPh_3^+\bf B^-$在甲苯中与$\rm ^iPr_3SiH$作用，可以得到浅黄色微晶$\bf C$，$\bf C$与无水的液态氯化氢反应则可以得到$\bf A$。

下列说法正确的有：

1. $\bf B^-$的对称性最高的可能结构数量与其点群阶数之商为0.4
2. $\bf A$中硼的质量分数约为13.22%
3. 不同反应条件下可以分别得到$\bf C \rm _{Cl}$、$\bf C \rm _{Br}$、$\bf C \rm _I$，则$\bf C$中阴阳离子相互作用的大小顺序为$\bf C \rm _{Cl}$>$\bf C \rm _{Br}$>$\bf C \rm _I$
4. 类似地存在$\bf A \rm _{Cl}$、$\bf A \rm _{Br}$、$\bf A \rm _I$，它们的酸性大小顺序为$\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$
All other options are incorrect
1
2
3
4
1,2
1,3
1,4
2,3
2,4
3,4
1,2,3
1,2,4
1,3,4
2,3,4
1,2,3,4
其他选项均不正确
1
2
3
4
1,2
1,3
1,4
2,3
2,4
3,4
1,2,3
1,2,4
1,3,4
2,3,4
1,2,3,4
From the mass fraction, it can be known that in $\bf X$, $\rm B:C=11:1$. At this time, one can think of carborane. Since the following is a halogenation process, it can be assumed that the anion is $\rm CB_{11}H_{12}^-$ first. Substituting into the mass fraction calculation, it can be known that the remainder is about 133, i.e., $\rm Cs$, which is consistent with the conditions of the problem. Therefore, $\bf X$ is $\rm Cs[CB_{11}H_{12}]$.

<Checkpoint>[$\bf X$ is $\rm Cs[CB_{11}H_{12}]$](1)</Checkpoint>

According to the question, $\bf B^-$ must contain $\rm C$, $\rm B$, and $\rm I$ elements, and may also contain $\rm H$ element.

Consider from the simplest case, considering that the carborane skeleton remains unchanged, that is, $\bf B^-$ still contains 11 $\rm B$s. Since the mass fraction of $\rm B$ is 13.24%, the molar mass of $\bf B^-$ is $\rm 898.1~g\cdot mol^{-1}$.

Removing 1 $\rm C$ and 11 $\rm B$s, the remainder is $\rm 767.2~g\cdot mol^{-1}$, corresponding to 6 $\rm I$s and 6 $\rm H$s. Therefore, the chemical formula of $\bf B^-$ is $\rm CB_{11}H_6I_6^-$.

<Checkpoint>[$\bf B^-$ is $\rm CB_{11}H_6I_6^-$](2)</Checkpoint>

When $\rm CPh_3^+\bf B^-$ reacts with $\rm ^iPr_3SiH$ in toluene, the negatively charged hydrogen combines with $\rm CPh_3^+$, and $\bf C$: $\rm ^iPr_3Si[CB_{11}H_6I_6]$ is obtained at the same time. $\bf C$ reacts with anhydrous liquid hydrogen chloride to undergo protonation to obtain $\bf A$: $\rm H[CB_{11}H_6I_6]$.

<Checkpoint>[$\bf A$: $\rm H[CB_{11}H_6I_6]$](1)</Checkpoint>

<Checkpoint>[$\bf C$: $\rm ^iPr_3Si[CB_{11}H_6I_6]$](1)</Checkpoint>

Statement 1: The highest symmetry requires placing 1 $\rm H$ and 1 $\rm I$ on the $\rm C$ or $\rm B$ that are farthest apart, with the 5 $\rm B$s close to $\rm H$ connected to $\rm I$, and the 5 $\rm B$s close to $\rm I$ connected to $\rm H$; or the 5 $\rm B$s close to $\rm H$ connected to $\rm H$, and the 5 $\rm B$s close to $\rm I$ connected to $\rm I$. This is the $\rm C_{5v}$ point group, a total of $2 \times 2 =4$ types, and the quotient is $4/10=0.4$. Statement 1 is correct.

<Checkpoint>[The quotient of the number of possible structures with the highest symmetry of $\bf B^-$ and the order of its point group is 0.4](2)</Checkpoint>

Statement 2: $(11 \times 10.81) / 898.1 ≈ 13.22%$, statement 2 is correct.

Statement 3: The order of polarizability is $\rm I>Br>Cl$, so the electron donating ability is $\rm I>Br>Cl$. The interaction between anions and cations is $\rm Si-X$ coordination, so $\bf C \rm _{Cl}$<$\bf C \rm _{Br}$<$\bf C \rm _I$, statement 3 is incorrect.

<Checkpoint>[The order of the magnitude of the interaction between anions and cations is $\bf C \rm _{Cl}$>$\bf C \rm _{Br}$>$\bf C \rm _I$](1)</Checkpoint>

Statement 4: The electron withdrawing ability is $\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$, so the order of acidity is $\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$, statement 4 is correct.

<Checkpoint>[The order of acidity is $\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$](1)</Checkpoint>

Therefore, choose M
由质量分数可知$\bf X$中$\rm B:C=11:1$，此时可以联想到碳硼烷，由于后面是卤代过程，因此可以先假设阴离子为$\rm CB_{11}H_{12}^-$，代入质量分数计算可知剩余约133，即$\rm Cs$，与题目条件吻合，故$\bf X$为$\rm Cs[CB_{11}H_{12}]$

<Checkpoint>[$\bf X$为$\rm Cs[CB_{11}H_{12}]$](1)</Checkpoint>

由题意，$\bf B^-$中必然含有$\rm C$、$\rm B$、$\rm I$元素，还可能含有$\rm H$元素

从最简单情况开始考虑，考虑碳硼烷骨架保持不变，即$\bf B^-$中仍含有11个$\rm B$。由$\rm B$的质量分数为13.24%，$\bf B^-$的摩尔质量为$\rm 898.1~g\cdot mol^{-1}$
  
除去1个$\rm C$，11个$\rm B$，剩余$\rm 767.2~g\cdot mol^{-1}$，对应6个$\rm I$、6个$\rm H$。因此，$\bf B^-$的化学式为$\rm CB_{11}H_6I_6^-$

<Checkpoint>[$\bf B^-$为$\rm CB_{11}H_6I_6^-$](2)</Checkpoint>

$\rm CPh_3^+\bf B^-$在甲苯中与$\rm ^iPr_3SiH$作用时，带负电的氢与$\rm CPh_3^+$结合，同时得到$\bf C$：$\rm ^iPr_3Si[CB_{11}H_6I_6]$。$\bf C$与无水的液态氯化氢反应发生质子化得到$\bf A$：$\rm H[CB_{11}H_6I_6]$

<Checkpoint>[$\bf A$：$\rm H[CB_{11}H_6I_6]$](1)</Checkpoint>

<Checkpoint>[$\bf C$：$\rm ^iPr_3Si[CB_{11}H_6I_6]$](1)</Checkpoint>

说法1：对称性最高要求把1个$\rm H$和1个$\rm I$放在相距最远的$\rm C$或$\rm B$上，靠近$\rm H$的5个$\rm B$连接$\rm I$，靠近$\rm I$的5个$\rm B$连接$\rm H$；或是靠近$\rm H$的5个$\rm B$连接$\rm H$，靠近$\rm I$的5个$\rm B$连接$\rm I$。这样为$\rm C_{5v}$点群，共$2 \times 2 =4$种，商为$4/10=0.4$。说法1正确

<Checkpoint>[$\bf B^-$的对称性最高的可能结构数量与其点群阶数之商为0.4](2)</Checkpoint>

说法2：$(11 \times 10.81) / 898.1 ≈ 13.22%$，说法2正确

说法3：极化能力排序为$\rm I>Br>Cl$，故给电子能力$\rm I>Br>Cl$，阴阳离子间的相互作用为$\rm Si-X$配位作用，故$\bf C \rm _{Cl}$<$\bf C \rm _{Br}$<$\bf C \rm _I$，说法3错误

<Checkpoint>[阴阳离子相互作用的大小顺序为$\bf C \rm _{Cl}$>$\bf C \rm _{Br}$>$\bf C \rm _I$](1)</Checkpoint>

说法4：吸电子能力$\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$，故酸性大小顺序为$\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$，说法4正确

<Checkpoint>[酸性大小顺序为$\bf A \rm _{Cl}$>$\bf A \rm _{Br}$>$\bf A \rm _I$](1)</Checkpoint>

故选M