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The system most often studied for the cis effect is an octahedral complex M(CO) 5 X where X is the ligand that will labilize a CO ligand cis to it. Unlike the trans effect, which is most often observed in 4-coordinate square planar complexes, the cis effect is observed in 6-coordinate octahedral transition metal complexes.
For a free ion, e.g. gaseous Ni 2+ or Mo 0, the energy of the d-orbitals are equal in energy; that is, they are "degenerate". In an octahedral complex, this degeneracy is lifted. The energy of the d z 2 and d x 2 −y 2, the so-called e g set, which are aimed directly at the ligands are destabilized.
Another example of this is the relationship between oleic acid and elaidic acid; oleic acid, the cis isomer, has a melting point of 13.4 °C, making it a liquid at room temperature, while the trans isomer, elaidic acid, has the much higher melting point of 43 °C, due to the straighter trans isomer being able to pack more tightly, and is solid ...
For example, in the rock salt ionic structure each sodium atom has six near neighbour chloride ions in an octahedral geometry and each chloride has similarly six near neighbour sodium ions in an octahedral geometry. In metals with the body centred cubic (bcc) structure each atom has eight nearest neighbours in a cubic geometry.
In organic structural chemistry, the configuration of a double bond can be described with cis and trans, in case it has a simple substitution pattern with only two residues. The position of two residues relative to one another at different points in a ring system or a larger molecule can also be described with cis and trans if the structure's ...
The polyhedral symbol is sometimes used in coordination chemistry to indicate the approximate geometry of the coordinating atoms around the central atom. One or more italicised letters indicate the geometry, e.g. TP -3 which is followed by a number that gives the coordination number of the central atom. [ 1 ]
Cisplatin, PtCl 2 (NH 3) 2, is a coordination complex of platinum(II) with two chloride and two ammonia ligands.It is one of the most successful anticancer drugs. A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands ...
The ligand can bend so that one donor atom is at the pole and the remaining three are on the equator of the central atom. This is called cis-β (beta). The remaining octahedral positions are cis (adjacent) to each other. The triangles of coordinating atoms and the central atom have two coplanar atoms, and one perpendicular atom.