# Trick to Find STYX Number of Boranes

## How to calculate STYX Number of Boranes easily?

STYX number is used to understand the types of bonds in boranes.

S = Three center-two electrons B-H-B bond

T = Closed and/or open three center-two electrons B-B-B bond

Y = Two center-two electrons B-B bond

X = Two center-two electrons B-H terminal bond

You can easily find out the STYX number of Boranes without knowing the structure by using this trick.

**Step-1:**

Subtract the number of B from number of H atom. The number obtained is now divided into two parts in the following way-

A. If number of B and H are even then divided into two even numbers such as 1st number must be greater than the 2nd number.

B. If no. of B and H are odd then divided into two equal parts.

C. If given Boranes are nido then do not divided and write for S, and for X write zero.

Now the two numbers obtained by the above process is write first number for S and the second number for X.

For nido Boranes, the number is for S.

**Step-2:**

The number of S is subtracted from the number of B. The number obtained is for T.

**Step-3:**

The average of given Borane is equal to the sum of the STYX number. So, the number for Y is

Y = average of Borane – sum of the numbers of S, T and X.

**1. B _{5}H_{9}**

Step-1:

Value for S:

9 - 5 = 4

This Borane is NIDO so we can not divide this number.

So the number for S is 4 and for X is 0

Step-2:

Value for T:

5 - 4 = 1

Step-3:

Value for Y:

(5 + 9)/2 = S + T + Y + X = 4 + 1 + Y + 0

7 = 5 + Y

or Y = 2

so the STYX number for B

_{5}H

_{9}is 4120.

**2. B _{4}H_{10}**

**CSIR-NET/JRF: Dec. 2011**

Value for S:

10 -4 = 6

Since this is not nido Boran and the no. of B and H are even so it is divided into two even no as 1st is greater than 2nd. So we get 4 and 2, 4 for S and 2 for X.

Value for T:

4 – 4 = 0

Value for Y:

(4 + 10)/2 = 4 + 0 + Y + 2

Y= 1

Now we have STYX no. for B

_{4}H

_{10}is 4012.

**3. B _{5}H_{11}**

Value for S:

11 - 5 = 6

Since this is not nido Boran and the no. of B and H are odd so it is divided into two equal numbers. So we get 3 and 3, So, both S and X have the same value 3.

Value for T:

5 – 3 = 2

Value for Y:

(5 + 11)/2 = 3 + 2 + Y + 3

Y= 0

Now we have STYX no. for B

_{5}H

_{11}is 3203.

STYX Number for Other Boranes:

B_{2}H_{6}------ 2002

B_{5}H_{11}------ 3203

B_{6}H_{10}----- 4220

B_{9}H_{15}-------3603

B_{10}H_{14}----- 4620

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