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Orbitals in Transition Metal Bonding

The bonding in transition metal complexes has been elucidated in some detail by Albright et al. [58]. The reader is directed to that source for a thorough development [Pg.176]

Manganese pentacarbonyl is a free radical and spontaneously dimerizes to dimanganese decacarbonyl. Iron pentacarbonyl is a weak Lewis base and can be protonated by sulfuric acid, forming a metal-hydrogen bond. We will make extensive use of the isolobal [Pg.177]

The orbital interaction theoretical approach requires an appreciation of the effective overlap of the interacting orbitals, their relative energies, and the amount of interaction which ensues. We here attempt to place the transition metal orbitals on the same energy scale as was found useful for the first- and second-row elements. [Pg.178]

It is clear that while the early transition elements, Sc and Ti, have 3d orbital energies which are higher than the 2p orbital energy of C, the 3d orbital energies fall sharply across the row, with the later energies comparable to the 2p orbital energies of and F. [Pg.178]


Commercial catalysts consists of two main classes organometallics and tertiary amines. Both classes have features in common in that the catalytic activity can be described as a combination of electronic and steric effects. Electronic effects arise as the result of the molecule s ability to donate or accept electrons. For example, in the tertiary amines, the stronger the Lewis base, generally the stronger the polyurethane catalyst. Empty electronic orbitals in transition metals allow reactants to coordinate to the metal center, activating bonds and placing the reactants in close proximity to one another. [Pg.695]

We consider first some experimental observations. In general, the initial heats of adsorption on metals tend to follow a common pattern, similar for such common adsorbates as hydrogen, nitrogen, ammonia, carbon monoxide, and ethylene. The usual order of decreasing Q values is Ta > W > Cr > Fe > Ni > Rh > Cu > Au a traditional illustration may be found in Refs. 81, 84, and 165. It appears, first, that transition metals are the most active ones in chemisorption and, second, that the activity correlates with the percent of d character in the metallic bond. What appears to be involved is the ability of a metal to use d orbitals in forming an adsorption bond. An old but still illustrative example is shown in Fig. XVIII-17, for the case of ethylene hydrogenation. [Pg.715]

The detailed theory of bonding in transition metal complexes is beyond the scope of this book, but further references will be made to the effects of the energy splitting in the d orbitals in Chapter 13. [Pg.60]

Bond angles in transition-metal tricarbonyl compounds A test of the theory of hybrid bond orbitals ... [Pg.242]

Pauling, L. Bond Angles in Transition-Metal Tricarbonyl Compounds A Test of the Theory of Hybrid Bond Orbitals Proc. Natl. Acad. Sci. (USA) 1978, 75, 12-15. [Pg.340]

Two other, closely related, consequences flow from our central proposition. If the d orbitals are little mixed into the bonding orbitals, then, by the same token, the bond orbitals are little mixed into the d. The d electrons are to be seen as being housed in an essentially discrete - we say uncoupled - subset of d orbitals. We shall see in Chapter 4 how this correlates directly with the weakness of the spectral d-d bands. It also follows that, regardless of coordination number or geometry, the separation of the d electrons implies that the configuration is a significant property of Werner-type complexes. Contrast this emphasis on the d" configuration in transition-metal chemistry to the usual position adopted in, say, carbon chemistry where sp, sp and sp hybrids form more useful bases. Put another way, while the 2s... [Pg.25]

Thus, the calculations show that the outer ns(np) atomic orbitals can play a significant role in the formation of M-M bonds in transition metal acido-clusters. The probability that these atomic orbitals will participate in the formation of M-M bonds is maximal for elements of Group 7, particularly, for technetium, in whose clusters Zeff for technetium atoms is the lowest of those observed in all known acido-clusters. [Pg.235]

What are the expected hybrids for transition-metal bonding In analogy with the treatment of Section 2.4, we expect that the pF ligand donor orbital can interact with a general spM hybrid mixture of valence s, p, d orbitals of the form (cf. Eq. (2.3))... [Pg.81]

In 1937 Jahn and Teller applied group-theoretical methods to derive a remarkable theorem nonlinear molecules in orbitally degenerate states are intrinsically unstable with respect to distortions that lower the symmetry and remove the orbital degeneracy.37 Although Jahn-Teller theory can predict neither the degree of distortion nor the final symmetry, it is widely applied in transition-metal chemistry to rationalize observed distortions from an expected high-symmetry structure.38 In this section we briefly illustrate the application of Jahn-Teller theory and describe how a localized-bond viewpoint can provide a complementary alternative picture of transition-metal coordination geometries. [Pg.467]

A persistent feature of qualitative models of transition-metal bonding is the supposed importance of p orbitals in the skeletal hybridization.76 Pauling originally envisioned dsp2 hybrids for square-planar or d2sp3 hybrids for octahedral bonding, both of 50% p character. Moreover, the 18-electron rule for transition-metal complexes seems to require participation of nine metal orbitals, presumably the five d, one s, and three p orbitals of the outermost [( — l)d]5[ s]1[ p]3 quantum shell. [Pg.570]


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