Nitrogen has electronic configuration [He]2s22p3, and accessible oxidation states from -3 to +5. It has more valence electrons than orbitals (2x2s and 3x2p = 5, in 4 orbitals), so lone pairs play an important role in its chemistry. N2 is inert; the very strong N-N triple bond is very stable towards decomposition and reaction, and this means that nitrogen gas is … Read more
The effects of the application of a field to a metal ion, in the formation of a complex, whether examined through the Crystal Field Theory of the Ligand Field Theory, have so far been limited to octahedral complexes. This is because it is easy to visualize the orientation of ligands and orbitals in the octahedral symmetry environment, and the points at … Read more
The magnitude of the ligand field splitting parameter in the octahedral field can be determined from the frequency of maximum absorption in the optical absorption spectrum. This absorption arises from an electronic transition from the t2g level to the eg level. This is the most important form of electronic transition in the transition metal complexes, but others are also observed, and these … Read more
The enthalpies of hydration of d-metal complexes The trend in observed hydration enthalpies of the hexa-aquo transition metal complexes of the first row transition metals can be explained in terms of the ligand field stabilization energy. The enthalpies of hydration for [M(H2O)6]2+The arrow denotes the LFSE for the hexa-aquo VII complex. In the plot, the dashed line is the enthalpy of hydration expected … Read more
Crystal Field Theory describes the interactions between the ligands and the metal ion orbitals on an electrostatic basis, and examines the effect the ligands have on the metal center as a result. However, the interaction between the ligands and the metal is generally stronger than simply an electrostatic interaction. There is generally some sharing of electrons between the … Read more
When a metal is subjected to the perturbation of an octahedral field, the energies of the d-orbitals split into two groups, the lower energy t2g, at -0.4Δo, and the higher energy eg, at 0.6Δo, where Δo is the ligand field splitting parameter. When electrons are put into these orbitals, the orbitals which become occupied depend on the value of Δo. … Read more
he value of the ligand field splitting parameter, ie. the amount by which the degeneracy of the d-orbitals is disturbed by the effect of the electrostatic field generated by the ligands, depends upon the identity of the ligands. The ligand field splitting parameter can be measured by recording the optical absorption spectrum of the complex. The first absorption maximum in … Read more
Ligand and Crystal Field theories are used to describe the nature of the bonding in transition metal complexes. Crystal Field Theory is based upon the effect of a perturbation of the d-orbitals consisting of electronic interaction between the metal cation nucleus and the negatively charged electrons of the ligands: the metal-ligand interactions are electrostatic only. Ligand Field Theory treats the metal-ligand interaction as a covalent bonding interaction, … Read more
Diamond is an insulator, but silicon is a semiconductor. This is because the band gap in Si is smaller than that in C. There is no Si analogue of graphite; the larger size if the Si atom means that the overlap of the Si p-orbitals is poor, and hence that Si pπ-pπ bonding is poor. Si forms strong bonds to … Read more
There are two main forms of the oxides of Carbon: Carbon Monoxide (CO) and Carbon Dioxide (CO2). Carbon Monoxide This is formed when carbon is burned with a deficiency of oxygen. There is a formal triple bond thereby completing the octet around each of the atoms, and this results in formal charges of -1 for C and +1 for … Read more