Question

Which of the following is borane? (1) \(\mathrm{B}_{5} \mathrm{H}_{9}\) (2) \(\mathrm{B}_{5} \mathrm{H}_{10}\) (3) \(\mathrm{B}_{5} \mathrm{H}_{11}\) (4) \(\mathrm{B}_{6} \mathrm{H}_{10}\) (a) \(1,2,3\) (b) \(1,3,4\) (c) \(2,3,4\) (d) \(1,2,4\)

Short answer

The correct answer is (c) 2, 3, 4.

Step-by-step solution

Definition of Boranes

Boranes are a specific type of chemical compound that includes the element boron and hydrogen. They follow the general formula \(B_xH_y\), where \(x\) and \(y\) are integers. Typical boranes have the form \(B_nH_{n+4}\), \(B_nH_{n+6}\), or \(B_nH_{n+10}\).

Analyze Each Option

We need to determine which of the given options in the problem fit the general formulas for boranes.1. \(B_5H_9\) does not match the standard borane formula for any common \(n\).2. \(B_5H_{10}\) matches the formula \(B_nH_{n+5}\), which can fit borane types that deviate from strict standards, sometimes noted in literature.3. \(B_5H_{11}\) matches the formula \(B_nH_{n+6}\), also fitting boranes that may deviate slightly.4. \(B_6H_{10}\) matches the formula \(B_nH_{n+4}\), which is a standard borane formation.

Identify Correct Answer

Based on the analysis above, \(B_5H_{10}\), \(B_5H_{11}\), and \(B_6H_{10}\) all have matching formulas aligned with borane structures. Therefore, options 2, 3, and 4 are forms of borane.

Match with Answer Choices

Comparing against the given answer options:- (1,2,3) does not include all correct choices- (1,3,4) does not include all correct choices- (2,3,4) is a complete match with our correct options 2, 3, and 4- (1,2,4) includes an incorrect optionTherefore, the correct answer is choice (c) \(2,3,4\).

Key concepts

Understanding Borane Structure

Boranes are fascinating clusters of boron and hydrogen atoms, and their structures play a vital role in understanding their chemical behavior.
These compounds are defined by specific stoichiometric formulas, commonly represented as \(B_nH_{n+4}\), \(B_nH_{n+6}\), or sometimes even \(B_nH_{n+10}\).
These structures are not just a random assembly but a well-organized arrangement of atoms.

To grasp the structure of boranes, it's important to think of them as consisting of "closo," "nido," and "arachno" frameworks:

• Closo: These structures are closed and are highly symmetrical polyhedral forms containing \(n+1\) boron atoms themselves, and they fall under the \(B_nH_{n+2}\) formula.
• Nido: These are derived by removing one vertex from a closo structure, leading to an open structure, falling under the \(B_nH_{n+4}\) type.
• Arachno: These forms arise from removing two vertices, resulting in a more open, often larger framework, typically aligning with \(B_nH_{n+6}\) compounds.

These unique structures often contribute to the distinct reactivity and properties of boranes. Understanding the structure in terms of closo, nido, and arachno can help in visualizing these intriguing compounds.

The Role of Boranes in Chemical Compounds

Boranes are unique chemical compounds that mainly consist of boron atoms bonded to hydrogen.
These compounds have gained significant interest due to their unusual bonding and structure. They're not just limited to single types but can manifest in various stoichiometries and geometries.

In most common chemical compounds composed of boron and hydrogen, boranes exhibit fascinating bonding patterns:

• They employ what is known as multi-center bonding where electrons are shared among more than two atoms, which is unlike traditional covalent bonding.
• Some boranes are known to form electron-deficient compounds, where there are fewer electrons than would be required for conventional two-electron bonds for each bond.

This property makes boranes very reactive and useful in various applications including reaction intermediates, and they often serve as precursors in organic synthesis.
Borane clusters not only demonstrate unusual chemistry but also lay the groundwork for understanding more complex boron hydride derivatives.

Interplay of Boron and Hydrogen

The relationship between boron and hydrogen in boranes is a perfect example of how two elements can form stable yet diverse structures.
Boron is capable of forming compounds with hydrogen that defy traditional chemical rules.

The ability for boron to bond with hydrogen results in several unique features:

• Electron-Deficient Bonding: Boron has fewer valence electrons than are needed for conventional bonding, which leads to the formation of multi-center bonds as seen in boranes.
• Diverse Structures: Boron and hydrogen form a wide range of structures from simple diborane \((B_2H_6)\) to complex polyhedral boranes.

Such combinations between boron and hydrogen create possibilities for varied types of chemical reactions and industrial applications.
Boranes with their unique boron-hydrogen interaction showcase the versatility and adaptability of boron in nature and synthetic chemistry.