Skeletal geometries

Table 4.42. Skeletal geometries and charges of equilibrium and transition-state species in the model propagation reaction (4.106) cf. Fig. 4.74...

Table 4.43. Skeletal geometries and atomic charges of the alternative secondary-Cp (Hsec) andprimary-Cp (IIpri) propylene complexes, as well as of the transition state (IIpri ) and actual product (IIIpri) of the model propylene-polymerization reaction (4.107) cf Figs. 4.79 and4.80...

Figure 5.30 Alternative water pentamer isomers having partial anticooperativity, (a)-(c), or higher coordination and ring strain, (d). Labels in (a)-(c) correspond to clockwise monomer numbering from the top (see the text). (Species (a)-(c) have been optimized under the constraint of planar equilateral skeletal geometry to prevent rearrangement to Wsc [Fig. 5.29(a)] and are therefore only near-stationary points on the potential-energy surface.)...

These crude approximations allow the C—C skeletal geometry variations to be simply estimated from the bond-order variations in Figs. 5.61 and 5.62. 

M[N(SiMe3)2 ] 3, M = Sc, Ti, Cr, and Fe, are stable, relatively volatile compounds that proved suitable for UPS measurements (200). With the exception of Sc[N(SiMe3)2 ] 3, which possesses a pyramidal (C3) structure (143), these compounds are expected to adopt Z)3 MN3 skeletal geometries. The dihedral angle 0 between the NSi2 and MN3 planes is not generally known for all the compounds however, 0 is 49° for Fe[N(SiMe3)2 ] 3 (41). Crystal field calculations... 

Significant substituent effects on the skeletal geometry of trisilaallene have been revealed theoretically by Apeloig et al. 72 trisilaallene 121 having electron-donating boryl-substituents is designed theoretically as a linear trisilaallene. 

Assignments of electronic origins can also be colored by expectations based on the spectra of related compounds. One must be extremely cautious here not to make a false comparison. As discussed in Sect. 5, a tris complex of 2,2 -bipyridine is not similar to a tris complex of ethylenediamine, even though the skeleton is MN6 in both cases, and the skeletal geometry may be comparable. 

Cluster Spectroscopic data reported Crystal structure determined Skeletal geometry adopted Ref. 

Interestingly, in the solid state, [Au2Ru6C(CO)16(PEt3)2] is thought to adopt the same structure as that of isomer A, whereas [Au2Ru5M(CO)17-(PEt3)2] (M = Cr, Mo, or W) exhibit skeletal geometries similar to that of isomer B (133). 

Fig. 15. Structures of the clusters [h R HzfCOlufPPlb ] and [M2Ru4(m-CO)3-(CO)10(PPh3)2] (M = (Cu, Ag, or Au), showing the change in skeletal geometry when two hydrido ligands are formally replaced by a CO group. [Reprinted with permission of the Royal Society of Chemistry 142) and Elsevier Sequoia S.A. (44).]...

Fig. 16. Structures of the clusters (Cu2Ru6C(CO) 16(NCMe)2] and [Cu2Ru6(CO),8-(C6H5Me)2], with the CO ligands omitted for clarity, showing the change in skeletal geometry when an interstitial carbido ligand is formally replaced by two CO groups. [Reprinted with permission of Freund Publishing House Ltd. (11).]...

Fig. 26. Structures of the clusters [Au3Ru4(/i3-H)(CO)12(PPh3)3] and [Au3Ru4(/a-H)-(li-Ph2PCH2PPh2)(CO)12(PPh3)], with the phenyl groups in the former species omitted for clarity, showing the change in skeletal geometry when two PPh3 groups are formally replaced...

The clusters [AuOs3(/A-X)(CO)10(PPh3)] have been attached to phosphine-functionalized silica for X = H or Cl (175,176) or polymer (styrene-divinylbenzene) for X = H (176). On both supports, the immobilized hyd-rido cluster was found to be inactive for alkene hydrogenation and isomerization, whereas the supported Cl-containing species catalyzed alkene hydrogenation. The different behavior was initially incorrectly attributed to different metal framework structures for the two clusters, but, in fact, both species adopt similar butterfly skeletal geometries (12,54). 

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