Notation bridging atoms

Fig. 12.12 29Si CP-MAS NMR spectra of star gels obtained from Star A and Star B precursors. Trifunctional silicon centers were named with the conventional T notation, where T refers to (SiO) R Si(OR)3 units and n to the number of bridging oxygen atoms surrounding the central silicon atom. In both BSC materials, the T2, T1 and T° relative contribution was...

Adsorbates may form ordered overlayers, which can have their own periodicity. The adsorbate structure is given with respect to that of the substrate metal. For simple arrangements the Wood notation is used some examples are given in Fig. A.3. The notation Pt (110) - c(2x2) O means that oxygen atoms form an ordered overlayer with a unit cell that has twice the dimensions of the Pt (110) unit cell, and an additional O in the middle. Note that this abbreviation does not specify where the O is with respect to the Pt atoms. It may be on top of the Pt atoms but also in bridged or fourfold sites, or in principle anywhere as long as the periodic... 

In compositional nomenclature, ligands are given in alphabetical order before central atoms. Central atoms are listed in alphabetical order as well. Bridging ligands to the extent known are indicated by the p notation (see Section 3.2.3.4). The numbers of ligands and central atoms are indicated by the appropriate numerical prefixes (see Section 3.3.2). Anions, cations, oxidation states and ionic charges are indicated in the same manner as in mononuclear compounds (see Section 3.3.3). For examples see Table 14. 

Bridging is indicated by the i prefix before the bridging ligand name, and unsymmetrical bridging by multiatom bridges is denoted by the ligating atom notation and central atom locant number separated by a colon x-(hydroxyamido)-2idV lK0-. For examples see Table 18. 

Figure 19. Molecular structures of the hydrogen-bridge diastereomers (a) (R,S)-(a a)-[p-N2H2 Fe(PPr3)(tpS4) 2] 2 THF and (b) (R,S)-(P P)-[p-N2H2 Fe(PPr3)(tpS4) 2] 4 CH2C12 [The notation (a a) and (P P) corresponds with the notation introduced in Section IV.D for the thiolate atoms involved in bridges.]...

Q notation specifies the number of oxygens of the SiO/ unit bridging to other Si (or Al) atoms (e.g., a Q silicate has three bridging and one nonbridging oxygen per silicate tetrahedron). 

The simplest explanation of the 86-electron count is as follows (7(g), 80,40) in Co6(C0)ie, for example, the metal atoms are all four-coordinate in CO. This accounts for their 4 s,p orbitals, which go to make 24 full metal-carbon tr-bonds (including the e face orbitals S) that overlap triply bridging CO). The d(xy, x —y ) orbitals (in the notation of Fig. 9) are not properly oriented for good metal-metal u-overlap, and... 

Figure 4. Comparison of 29Si NMR spectra of an add-catalyzed TEOS sol (H.20/Si = 2) and a commercial aqueous silicate (Ludox HS40) (a) TEOS sol after 3 h (b) TEOS sol after 3 days (c) TEOS sol after 14 days of reaction and (d) Ludox sol. Q notation refers to the number of bridging oxygens (-OSi) surrounding the central silicon atom (0-4). From Assink (41).

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