computational chemistry - How to construct a QST2 input file for Gaussian16 for multiple reactants and products?

I am attempting to determine the transition state structure for the following reaction using the QST2 method on Gaussian 16:

$$\ce{CH3 + N -> HCN + H2 }$$

However, I am struggling to put together my input file. How do I format my z-matrices for multiple reactants and products? Here is what I have so far (though it is not running successfully):

%chk=sample2.chk
%mem=1500MB

#T UB3LYP/6-31G** opt=(qst2, redundant)

CH3 + N -> HCN + H2 reactants

0 3
C

X 1 1.0
H 1 r 2 90.0
H 1 r 2 90.0 3 120.0
H 1 r 2 90.0 3 -120.0

r 1.0828

CH3 + N -> HCN + H2 reactants

0 3

N

CH3 + N -> HCN + H2  products

0 1
C
X 1 1.0
H 1 rh 2 90.0
N 1 rn 2 90.0 3 180.0


rh 1.0587
rn 1.1326

0 1
H
H 1 r

r 0.741

I'm pretty new to this type of calculation on Gaussian so any help would be much appreciated!