Metal center interaction

Thus, the bonding in metal compounds and complexes has traditionally been viewed as ionic, with a positive metal center interacting with negative ions, such as HO , 0 , Cl , AcO , and coordinate donor, Lewis acid-base interactions with a positive metal center interacting with negative ions and electron-pair Lewis bases, such as iNHs, iPPhs, HOH. Examples of ionic versus covalent bonding illustrate the tradition H+CH versus H-Cl (ls-3p), C +(C1 )4 versus C(-C1)4 [2sp -(3p)4], Fe +(C1 )3 versus Fe(-Cl)3 [3d sp2-(3p)3], H+-OH versus H-OH (ls-2p), C +(Q2-)2 versus 0=C=0 [2sp -(2p )2], and Fe +(0 ) versus Fe=0 [3d sp-(2p )]. Such ionic formulations for these molecules in an inert matrix are not consistent with their physical... 

In [M(Tmph)2] (M = Fe, Co) Tmph binds the metal through only two sulfur atoms, the tetrahedral metal centers interacting, however, also with the two B-H groups. Comparison of [M(Tmph)2] (M = Fe, Co) with the related [M(Tpph)2] counterparts indicates that TmR favors lower primary coordination numbers in divalent metal complexes.43... 

Ever since transition metal clusters have been discussed as catalysts, [4] there have been many attempts to develop catalytically active polynuclear complexes in which the metal centers interact during the formation of the target molecule ( cooperativity ) to control activity and selectivity of the catalytic process. In this way, a highly selective hydroformylation catalyst for propene was found in the cluster anion [HRu3(CO)n] (linear to branched product ration of butyraldehyde... 

As has been shown, binding of amino acids or peptides in the free form to monometallic complexes usually takes place via the carboxylate group or by simultaneous chelation of COO and -NH2 at the metal center. Interactions with side chains of substrates are typically secondary and weak in comparison to the chelation with the metallic ion, and they do not involve the coordination to the metal center of the organometallic complex. One approach followed by several groups to increase the importance of interactions with the side chains is to design receptors with two... 

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