The complex with highest magnitude of crystal field splitting...

Crystal field stabilisation energy of the complex can be calculated as follows,

CFSE = $numberof{t}_{2g}electrons \times \left(- 0 . 4\right) + numberof{e}_{g}electrons \times \left(0 . 6\right)$

Complex CFSE

${\left[Ti{\left({OH}_{2}\right)}_{6}\right]}^{3 +}\left({{t}_{2g}}^{1}{{e}_{g}}^{0}\right)$– 0 . 4{∆}_{0}$</p><p>${\left[Cr{\left({H}_{2}O\right)}_{6}\right]}^{3 +}\left({{t}_{2g}}^{3}{{e}_{g}}^{0}\right)$– 1 . 2{∆}_{0}$

${\left[Mn{\left({H}_{2}O\right)}_{6}\right]}^{3 +}\left({{t}_{2g}}^{3}{{e}_{g}}^{1}\right)$– 0 . 6{∆}_{0}$</p><p>${\left[Fe{\left({H}_{2}O\right)}_{6}\right]}^{3 +}\left({{t}_{2g}}^{3}{{e}_{g}}^{2}\right)$0$