To build an input Gaussian, the charge must always be zero (S=0) (the system must be neutral). So, the multiplicity that obtained from the following equation will be 1=Singlet.
Did it actually worked?. I tried the same but just after a few intermediates, I observed a cleavage in the molecule. I understood that the multiplicity is 1 as it is neutral...is there any issue with my basis set (Pople).
Here you can see the disconnection in my molecule, just after a few steps