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Ligand cone angle shows how much space is taken up by a ligand coordinated to a metal center. In coordination chemistry, the ligand cone angle (θ) is a measure of the steric bulk of a ligand in a transition metal coordination complex. It is defined as the solid angle formed with the metal at the vertex of a cone and the outermost edge of the ...
The Tolman electronic parameter (TEP) is a measure of the electron donating or withdrawing ability of a ligand. It is determined by measuring the frequency of the A 1 C-O vibrational mode (ν (CO)) of a (pseudo)-C 3v symmetric complex, [LNi (CO) 3] by infrared spectroscopy, where L is the ligand of interest. [LNi (CO) 3] was chosen as the model ...
The Tolman cone angle and Tolman electronic parameter [3] are named after him. In 1972, he proposed the 16 and 18 electron rule , extending Irving Langmuir 's 18-Electron rule to include the many examples of stable 16 electron square planar d 8 complexes. [ 4 ]
Sterimol parameters are built upon the Corey-Pauling-Koltun atomic models, which take into consideration the Van der Waals radii of each atom in the molecule. Unlike most other steric parameters such as A-value, Taft parameters and Tolman cone angle, which group all the spatial information into a single cumulative value, Sterimol parameters consist of three sub-parameters: one length parameter ...
A metal-phosphine complex is a coordination complex containing one or more phosphine ligands. Almost always, the phosphine is an organophosphine of the type R 3 P (R = alkyl, aryl). Metal phosphine complexes are useful in homogeneous catalysis. [ 1 ][ 2 ] Prominent examples of metal phosphine complexes include Wilkinson's catalyst (Rh (PPh 3) 3 ...
A double cone (not shown infinitely extended) 3D model of a cone. A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines connecting a common point, the apex, to all of ...
The Tolman length is thus defined as the leading order correction in an expansion in /. The equimolar radius is defined so that the superficial density is zero, i.e., it is defined by imagining a sharp mathematical dividing surface with a uniform internal and external density, but where the total mass of the pure fluid is exactly equal to the ...
As a ligand, trimethylphosphine's Tolman cone angle is 118°. [7] This angle is an indication of the amount of steric protection that this ligand provides to the metal that to which it is bound. Being a relatively compact phosphine, several can bind to a single transition metal, as illustrated by the existence of Pt(PEt 3) 4. [8]