Abstract <p>Density functional investigation of weaker noncovalent interactions of 2nd transition metal series with electron donating Lewis base (MX_n−−L, M = transition metal, X= F, Cl, Br &amp; I and L= Pyridine &amp; Furan) has been performed. Conclusive evidence has been provided by analysis of molecular electrostatic potential (MEP) surfaces, noncovalent bond length, interaction energy (∆E), second order perturbation energy (E⁽²⁾), charge transfer (∆q), quantum theory of atom in molecules (QTAIM) and noncovalent interaction (NCI) plots for 24 complexes with varying Lewis base (L) and halogen atom (X). The noncovalent bond length varies from 2.23 to 2.48 Å in complexes containing pyridine and 2.29 to 2.83 Å in complexes containing furan at PBE0-D3 functional. The magnitude of <i>σ</i>-hole present on the transition metal (M) has a bargaining effect on the strength of noncovalent bond which can be fine-tuned by switching the halogen atom (X).</p> Graphical abstract <p>Synopsis: Density functional investigation of weaker noncovalent interactions of 2nd transition metal series with electron donating Lewis base (MXn−−L, M = transition metal, X= F, Cl, Br &amp; I and L= Pyridine &amp; Furan) to rationalise the elusive behaviour of NCIs in complexes of 2nd transition metal halides with Lewis base.</p>