The expected color of the transition metal complex [Fe H2O 6]Cl3 can be determined using crystal field theory principles. In this complex, the central metal ion is Fe III , which has a d5 electron configuration.In an octahedral crystal field, the d orbitals split into two sets: the lower energy t2g set dxy, dyz, and dxz and the higher energy eg set dx^2-y^2 and dz^2 . The energy difference between these two sets is called the crystal field splitting energy o .For the [Fe H2O 6]3+ complex, the Fe III ion has five d electrons. According to Hund's rule, these electrons will fill the lower energy t2g orbitals first. Since there are five d electrons, all three t2g orbitals will be filled, and the two eg orbitals will remain empty.When the complex absorbs light, electrons can be excited from the t2g orbitals to the eg orbitals. The energy of the absorbed light corresponds to the energy difference between these orbitals o . The color of the complex is complementary to the color of the absorbed light.The energy difference o corresponds to the energy of light in the visible region of the electromagnetic spectrum. If the absorbed light has a higher energy shorter wavelength , the complex will appear more red. If the absorbed light has a lower energy longer wavelength , the complex will appear more blue.For the [Fe H2O 6]3+ complex, the crystal field splitting energy o is relatively small due to the weak field ligands H2O . This means that the complex will absorb lower energy light longer wavelengths and thus appear more blue. Therefore, the expected color of the [Fe H2O 6]Cl3 complex is pale blue to violet.In summary, the [Fe H2O 6]Cl3 complex is expected to be pale blue to violet in color due to the small crystal field splitting energy o caused by the weak field ligands H2O and the d5 electron configuration of the Fe III ion.