The spin-only magnetic moment value of $M^{n+}$ ion formed among $\mathrm{Ni}, \mathrm{Zn}, \mathrm{Mn}$ and Cu that has the least enthalpy of atomisation is $\_\_\_\_$ . (in nearest integer) Here n is equal to the number of diamagnetic complexes among $\mathrm{K}_{2}\left[\mathrm{NiCl}_{4}\right],\left[\mathrm{Zn}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right] \mathrm{Cl}_{2}, \mathrm{~K}_{3}\left[\mathrm{Mn}(\mathrm{CN})_{6}\right]$ and $\left[\mathrm{Cu}\left(\mathrm{PPh}_{3}\right)_{3} \Gamma\right]$