Search results
Results From The WOW.Com Content Network
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.
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 ...
One classic example of the trans effect is the synthesis of cisplatin and its trans isomer. [5] The complex PtCl 4 2− reacts with ammonia to give [PtCl 3 NH 3] −. A second substitution by ammonia gives cis-[PtCl 2 (NH 3) 2], showing that Cl- has a greater trans effect than NH 3. The procedure is however complicated by the production of ...
The term "octahedral" is used somewhat loosely by chemists, focusing on the geometry of the bonds to the central atom and not considering differences among the ligands themselves. For example, [Co(NH 3) 6] 3+, which is not octahedral in the mathematical sense due to the orientation of the N−H bonds, is referred to as octahedral. [2]
The insertion of carbon monoxide into a metal-carbon bond to form an acyl group is the basis of carbonylation reactions, which provides many commercially useful products. Mechanistic studies reveal that the alkyl group migrates intramolecularly to an adjacent CO ligand. [2] [3] CO Insertion reaction pathway for an octahedral complex
For octahedral mono- and dicationic aquo complexes, these exchange processes occur via an interchange pathway that has more or less dissociative character. [4] Rates vary by a factor of 10 18, [Ir(H 2 O) 6] 3+ being the slowest and [Na(H 2 O) 6] + being one of the fastest for octahedral complexes. Charge has a significant influence on these ...
(Similar procedures can give cis,trans isomers of 1,4-cyclooctadiene and 1,5-cyclooctadiene). [2] In addition, a photochemical method exists for the direct cis–trans isomerisation. Although this equilibrium strongly favours the more stable cis form, the reaction can be driven towards the trans form by trapping with silver ions. [11] [12]
The Eigen-Wilkins mechanism, named after chemists Manfred Eigen and R. G. Wilkins, [5] is a mechanism and rate law in coordination chemistry governing associative substitution reactions of octahedral complexes. It was discovered for substitution by ammonia of a chromium-(III) hexaaqua complex.