Transition Metal Synthesis
Post Lab Assignment
Post Lab Questions: Diethylenetramine is a chelating tridentate ligand. The nitrogen atoms are involved in binding to a central metal ion to form a coordination complex.
NH2 – CH2 – CH2 – NH – CH2 – CH2 – NH2
Salen is a tetradentate chelating ligand. The nitrogen atoms and oxygen atoms are involved in binding to the central metal ion in order to form a coordination complex.
Acetylacetone is a chelating bidentate ligand. The oxygen atoms are involved in binding to a central metal ion to form a coordination complex. d. Pyrazine is a bidentate bridging ligand. The two nitrogen atoms are involved in bridging two metal ions together.
Copper has a ground state configuration…show more content… In the first step of the copper cycle, copper is oxidized by nitric acid to form a Cu+2 metal complex, Cu(NO3)2. Then copper is oxidized again to form Cu(H2O)62+ in the presence of water. Cu2+ has an unfilled d subshell containing 9 electrons. The transitions in this experiment are due to MLCT transitions from the d orbital to the pi orbital of the ligand. Cu(NO3)2 has a green appearance, therefore it absorbs in the red region (~800nm). Cu(H2O)62+ looks blue, and so it absorbs in the orange region (~600nm). Energy is inversely related to the wavelength because all light travels at the same speed (E=1/λ), therefore the longer the wavelength, the less energy the electron had during transition. NH3 is a stronger ligand than H2O, therefore the d splitting of the copper when in complex with the NH3 will be larger (higher ∆_O), which results in a shorter wavelength because less energy is needed to promote the electron via MLCT. H2O is a weaker ligand, which results in smaller d splitting. As the water replaces NH3 as the ligand, the distance between the d orbitals decreases, meaning more energy is needed to promote an electron from the HOMO to the…show more content… A paramagnetic species contains unpaired electrons, and thus is attracted to a magnetic. Ligand strength plays a role in determining magnetism because strong field ligands result in low spin electron configurations (all electrons paired) and weak field ligands result in high spin configurations (some electrons paired and some not paired, or no paired). NH3 is a strong field ligand, which likely produces a low spin complex. If the energy needed to promote an electron to the next orbital is too high (larger d splitting), then the electrons will pair via Hund’s Rule and the Aufbau principle in the d orbitals with lower energy. As seen in the spectrochemical series, H2O is a weaker field, small splitting ligand. In addition, Co+3 has a higher ∆O than Fe+2. According to the spectrochemical series, both the NH3 ligand and Co+3 metal are higher on the scale, thus indicating that there is larger d splitting and it is more likely the electrons will pair than be excited to the next