Brief Summary
This video provides solutions to inorganic chemistry questions from the CSIR NET exam held in December 2019. It covers topics such as bond order calculation, IR spectra of metal carbonyl complexes, molar extinction coefficients, redox reactions of main group elements, hapticity in buckminsterfullerene complexes, EPR spectra of copper complexes, K-electron capture, stability of vanadium species in aqueous solutions, NMR spectroscopy of phosphorus complexes, bond angle trends, and properties of oxy myoglobin, cytochrome p450, and lanthanide ions.
- Bond order can be determined by calculating total valence electrons.
- Symmetry influences the number of IR bands in metal carbonyl complexes.
- Molar extinction coefficient is proportional to molar absorptivity and intensity of absorption bands.
- Redox titrations of iodine with thiosulfate involve specific reactions and standardization processes.
- Hapticity in buckminsterfullerene complexes relates to the number of carbon atoms coordinating to a metal center.
- EPR spectra can provide information about the electronic structure and geometry of metal complexes.
- K-electron capture involves the absorption of an electron by a proton in the nucleus, forming a neutron and a neutrino.
- Stability of vanadium species in aqueous solutions depends on oxidation state and the formation of vanadyl ions.
- NMR spectroscopy can be used to determine the number and types of phosphorus atoms in a complex.
- Bond angles are influenced by the electronegativity of central and surrounding atoms.
- Oxy myoglobin and cytochrome p450 have distinct structural and electronic properties.
- Experimental magnetic moments of samarium and europium deviate significantly from calculated values.
Bond Order Calculation
The video explains how to determine the ion with the highest bond order by calculating the total valence electrons. For diatomic molecules, a total valence electron count of 14 corresponds to a bond order of 3. The bond order decreases by 0.5 for each electron added or subtracted from this count. For example, NO+ has 14 valence electrons (7 from nitrogen, 8 from oxygen, minus 1 for the positive charge), resulting in a bond order of 3, which is the highest among the options provided.
IR Spectra of Metal Carbonyl Complexes
The video discusses how to determine the expected number of carbonyl bands in the IR spectra of facial and trans metal carbonyl complexes. It emphasizes the importance of considering the point group symmetry of the molecule. Lower symmetry leads to a higher number of IR bands. For a facial complex with C3v symmetry, two carbonyl bands are expected due to the different environments of the carbonyl ligands. In contrast, a trans complex with higher symmetry (D4h) exhibits only one carbonyl band because all carbonyls are equivalent.
Molar Extinction Coefficient and Selection Rules
The video explains the relationship between molar extinction coefficient, molar absorptivity, and the intensity of absorption bands in transition metal complexes. Molar extinction coefficient is proportional to molar absorptivity, which in turn is proportional to the intensity of the absorption band. The intensity of a band depends on selection rules, including spin and Laporte rules. Spin-allowed and Laporte-allowed transitions result in the highest intensity, followed by spin-allowed but Laporte-forbidden transitions. Non-centrosymmetric molecules give more intense bands than centrosymmetric molecules.
Redox Titration of Iodine with Thiosulfate
The video discusses a question based on the redox titration of iodine with thiosulfate. The reaction involves the standardization of thiosulfate using potassium iodate (KIO3) in the presence of potassium iodide (KI) and an acidic medium (HCl). This reaction produces iodine, which then reacts with sodium thiosulfate (Na2S2O3) to form sodium iodide and tetrathionate (S4O62-). The video identifies the reactants and products in the given scenario, emphasizing the importance of understanding the standardization process.
Hapticity in Buckminsterfullerene Complexes
The video addresses the common hapticity observed for the coordination of C60 (buckminsterfullerene) to a metal center. It explains that C60 typically coordinates through an η2 fashion, where the pi electrons of a carbon-carbon double bond are shared with the metal. This is due to the peripheral aromaticity of C60, where certain carbon-carbon double bonds are available for coordination.
EPR Spectra of Copper Complexes and Jahn-Teller Distortion
The video explains how to determine the geometry and electronic configuration of an octahedral copper(II) complex based on its axial EPR spectrum. Given that G parallel is greater than G perpendicular, it indicates that the electron density is higher along the z-axis. This implies a tetragonal elongation due to the Jahn-Teller distortion, where the dz2 orbital is lower in energy than the dx2-y2 orbital. The unpaired electron resides in the dx2-y2 orbital.
K-Electron Capture
The video defines K-electron capture as a process where a proton in the nucleus absorbs an electron from the K or L shell, resulting in the formation of a neutron and the emission of an electron neutrino. The process leads to the conversion of a proton into a neutron and the release of a neutrino.
Stability of Vanadium Species in Aqueous Solutions
The video discusses the most stable vanadium species in aqueous solutions. The most stable oxidation state of vanadium is +4, and the most stable form is the vanadyl ion (VO2+). Therefore, the correct answer is the vanadium species with vanadium in the +4 oxidation state and bonded to oxygen.
NMR Spectroscopy of Phosphorus Complexes
The video explains how to determine the expected 31P NMR spectrum for a given complex. By identifying the number of different types of phosphorus atoms in the molecule and applying the 2nI+1 rule, the splitting pattern can be predicted. In this case, there are two types of phosphorus atoms, each resulting in a doublet due to coupling with the other phosphorus atom.
Bond Angle Trends
The video discusses the factors affecting bond angles in molecules. Bond angle is directly proportional to the electronegativity of the central atom and inversely proportional to the electronegativity of the surrounding atoms. For molecules with different central atoms, the electronegativity of the central atom is the primary factor. For molecules with the same central atom, the electronegativity of the surrounding atoms determines the bond angle.
Properties of Oxy Myoglobin and Cytochrome P450
The video compares the properties of oxy myoglobin and cytochrome P450. Both contain iron bound to a porphyrin ring and have a single active site. However, they differ in their fifth ligand: oxy myoglobin has an imidazole ring from histidine, while cytochrome P450 has a cysteine ligand. In the resting state, both contain iron in the +3 oxidation state.
Exceptional Behavior of Lanthanide Ions
The video identifies the pair of lanthanide ions that show significant deviation between experimental and calculated magnetic moments. Samarium(III) and europium(III) exhibit observed magnetic moments that are much higher than their expected values, due to factors not accounted for in simple ground-state calculations.
