Natural Bond Orbital Analysis of creatinine: A DFT Approach Study

We have studied different interactions on the basis of the NBO analysis of both conformer of creatinine by using density function theory method. The energy between donor of C1-C3 and acceptor of C2-N8 is 1.69 kcal/mol, donor of C1 - C3 and acceptor of N6 - C11 is 3.96 kcal/mol for amino isomer. However we found the energy difference between C1 - N 6 and C 2 - N9 is 3.90 kcal/mol, C2 - N6 and N7 - H8 is 2.42 kcal/mol and C3 - N7 and C2 - N9 is 3.61 kcal/mol. The occupancy for C1-C3, C1-H4,C1-H5 and C1-N6 are 1.98294,1.97219,1.97491 and1.98091 respectively for amino isomer. For imino isomer we found the occupancy for C1 - C3, C1 - H4, C1 - N6, C3- O11 are 1.97607, 1.97033,1.98459 and 1.99574 respectively. These interaction energies are responsible for stabilization and also some nonbonding interactions enhance the stability.