To calculate the crystal field stabilization energy CFSE for a tetrahedral complex, we need to consider the distribution of the unpaired electrons in the d-orbitals. In a tetrahedral complex, the d-orbitals are split into two groups: e dxy, dxz, dyz and t2 dx-y, dz .For a tetrahedral complex with three unpaired electrons, the electron configuration will be:e: 3 unpaired electrons t2: emptyNow, we can calculate the CFSE using the ligand field splitting parameter t and the number of unpaired electrons in each group:CFSE = -t * number of electrons in e + 2/3 t * number of electrons in t2 In this case, there are 3 electrons in the e orbitals and 0 electrons in the t2 orbitals:CFSE = -900 cm * 3 + 2/3 * 900 cm * 0CFSE = -2700 cmSo, the crystal field stabilization energy CFSE for this tetrahedral complex is -2700 cm.