Transition Metal compoundsIons
Transition metal complex ions are called as d-block elements. Transition metal complex ions have an incompletely filled d sub shell. Atoms in the periodic table have a single d electron in their outermost shell i.e. from scandium and yttrium thus those elements are considered as transition metals complex ions. Complex ions are those ions which are having a metal ion at its centre with a number of other molecules or anion surrounding it and this complex which is formed is called as co ordination complex. Metal complex and the surrounding ligands are attached to each other by the co ordinate bonds.
Characteristics of complex ions in Transition metal:
• Variable oxidation states
• Magnetic properties
• Formation of colored compounds
• Formation of complexes
• Electrode potential and low reactivity
Ex: water, ammonia and chloride ions.
All these ions have active lone pairs of electrons in the outer energy level which are used to form co-ordinate bonds with the metal ion.
Examples for Transition Metal with Complex Ions
1. [Fe (H2O)6]2+
2. [Co (NH3)6]2+
3. [Cr (OH) 6]3-
4. [CuCl4]2-
Properties of transition metal
1. The color of the transition metal complex ions is due to d - d electronic transitions.
2. Formation of complexes in many oxidation states, due to the relatively low reactivity of unpaired d electrons.
3. Formation of paramagnetic compounds due to the presence of unpaired d electrons.
Color and Oxidation State of Transition Metal with Complex Ions:
Color of transition metal with complex ions:
An electron jumps from one d- orbital to another d-orbital due to d-d transition. In transition metal complex ions, the d orbitals don’t have the same energy. The splitting pattern of the d orbitals can be calculated by using crystal field theory. The theory in which the extent of the splitting depends on the particular metal, its oxidation state and the nature of the ligands. Color of the transition metal ion is also due to charge transfer because an electron jumps from ligand to metal orbital gives rise to ligand to metal charge transfer. Color of the dichromate and permanganate ions is due to ligand to metal charge transfer.
Colors for some common transition metal
Oxidation states of the transition metal with complex ions:
Transition metal complex ions exhibits two or more oxidation states. For example, compounds of vanadium are known in all oxidation states between −1, such as [V(CO)6] − , and +5, such as VO43- . The element which belongs to groups between 13-17 exhibits multiple oxidation states. Common oxidation state of all the transition metal complex ions differs by two. The maximum oxidation states of transition metal complex ions is +7 for manganese and the minimum oxidation state is -2 for [Fe (CO)4]2− complex.