Carbon monoxide hybrid orbitals

Formally, the lone pairs on molecular nitrogen, hydrogen cyanide, and carbon monoxide are sp hybrid orbitals, whereas NLMO hybridizations calculated even lower p contributions. Hence, these lone pairs have low directionality, the electron density remains close to the coordinating atom and interaction between the lone pair and the Be2+ is comparatively weak. The Be-L bonds are easily disrupted and ligand exchange consequently can proceed with a low activation barrier. A high degree of p character, on the other hand, means that the lone pair is directed toward beryllium, with electron density close to the metal center, and thus well suited for coordination. 

Considering the molecular orbital diagram of carbon monoxide (Fig. 5.201 and the discussion concerning hybridization and energy (pages 225-227). predict which end of the carbon monoxide molecule will be the more basic (i.e., will donate electrons more readily and form the stronger, direct covalent bond)... 

The adsorption of carbon monoxide on metal surfaces can be qualitatively understood using a model originally formulated by Blyholder [45]. A simplified molecular orbital picture of the interaction of CO with a transition metal surface is given in Figure 6. The CO frontier orbitals 5a and 2n interact with the localized d metal states by splitting into bonding and antibonding hybridized metal-... 

The first generalization is confirmation of the well-known influence of crystal orientation in catalytic activity. The (100) and (112) faces of tungsten are found by LEED to be reactive towards NHg decomposition, and the W(llO) face is apparently passive. Similarly the Cu(lOO) and Cu(llO) surfaces are efficient in the oxidation of carbon monoxide, while the activity of the Cu(lll) surface is much lower. The reasons for these variations of catalytic power are not yet understood. Variation of atomic structure with surface orientation, and differences of hybridization of surface orbitals on different faces suggest themselves as primary causes, but more experiments are required before judgment can be made. 

The overlapping of an empty hybrid orbital, which is a blend of d-, s- and p-orbitals on a metal atom with the filled hybrid orbital (HOMO) on a carbon atom of carbon monoxide molecule, results into the formation of an M<—CO a-bond, as shown in Figure 4. 

The structure of dimanganese decacarbonyl can be explained using d sp hybridization, as shown in Figure 16. Out of the six hybrid orbitals on each manganese atom, five orbitals accept a lone pair of electrons from the carbon monoxide molecules to form 10 Mn<—CO coordinate bonds. While, the remaining one half-filled orbital on each manganese overlap to form a Mn—Mn bond. 

Isocyanides, also known as isonitriles or carbylamines, are characterized by a primary isocyanide (R-NC) functional group and pungent odor. According to the Hiickel, MNDO, and ab initio molecular orbital calculations, the electronic configuration of isocyanide is represented by an iminocarbene resonance hybrid (Eq. 7.1) [1]. Experimental studies have confirmed that the resonance hybrid is closely represented by the triple-bonded resonance structure [2], Electronically, isocyanides resemble that of carbon monoxide (Eq. 7.2) and recently, isocyanides have been used as substitutes for carbon monoxide in organometallic transformations [3]. 

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