A supramolecular 1D ferromagnetic system was studied experimentally as well as theoretically.Hybrid density functional theory(DFT) calculations were based on the X-ray analysis.The results of DFT calculations and McConnell mechanism have contributed to the understanding of the factors governing the exchange coupling of magnetism in the crystal packing.Both the experimental evidence and theoretical calculation indicate that spin density in 2-iodo nitronyl nitroxide(INN) radicals confirms 1D ferromagnetic chain with inter-chain antiferromagnetic interaction. A supramolecular 1D ferromagnetic system was studied experimentally as well as theoretically. Hybrid density functional theory (DFT) calculations were based on the X-ray analysis. The results of DFT calculations and the McConnell mechanism have contributed to the understanding of the factors governing the exchange coupling. of magnetism in the crystal packing. Both the experimental evidence and theoretical calculation indicate that spin density in 2-iodo nitronyl nitroxide (INN)