Lead aryloxides

The U ion displacement from the aryloxide plane in addition to the increased steric bulk provided by the adamantane substituents of lead to a narrow and approximately 4.7A deep cylindrical... 

Several unique synthetic strategies for bidentate(amino)(oxy)- and (amino)(aryl) carbenes have been described (Scheme 10). For the former, the reaction of the amino(phosphino)carbene with an ort/io-quinone leads to the transient formation of a zwitterionic species featuring both a phosphonio nucleofuge and an aryloxide nucleophile that allow for a subsequent intramolecular substitution process. The... 

Scheme 2 Bond homolysis in bismuth aryloxides leading to Bi radicals...

The complete replacement of the chlorine substituents in cyclotriphosphazenes (ClaPhOs by nucleophilic reagents, e.g. sodium alkoxides or aryloxides, primary or secondary amines, leads to a variety of other cyclotriphosphazenes, as illustrated in Scheme 11.5. Of particular interest is the synthesis of the hexaazido derivative... 

The dihalides react with alcohols leading to the formation of an enormous range of alkoxides and even aryloxides [Mo(NO)(Me2pzb)X(OR)] as detailed in Table 7, The crystal structure of [Mo(NO)(Me2pzb)a(OPr1)] has been determined,125 and the molybdenum shows normal octahedral six-coordination, albeit with a very short Mo-O bond. 

Alkoxides and aryloxides demonstrate similar chemistry to that of hydroxides in that it is possible to prepare mixed metal or double metal derivatives similar to hydroxo salts such as Na2[Sn(OH)6]. The formation of mixed metal alkoxides, e.g. Na2[Zr(OEt)6] and Ln[Al(OPri)4]3, is typically a result of the electron deficiency (Lewis acidity) of the metal centers in units of the type M(OR)x or M(OAr)JC (x < 5). This then leads either to oligomerization via alkoxide bridges or, in the presence of other alkoxides, to the formation of mixed metal compounds. 

The coordination of an alkoxide or aryloxide can lead to a mixed metal derivative.149 In some cases, ligand exchange can take place to generate a neutral adduct (equation 55).IS4... 

C H activation using the aryloxide supported Ta complexes has been discussed in Section 6.3. Additional examples include the thermal conversion of the hydride Ta(0-2,6-Ph2-C6H3)2(H)2Cl(PMe3)2 into the monocyclometalated complex (94). Reaction of Cp TaCU with (cb)K (>3 equiv) leads to the species (C5Me4CH2)Ta(cb)2Cl, in which one ofthe ring methyl C-H bonds of the Cp ligand has been cleaved. ... 

A range of aryloxides exists. With 2,6-dimethylphenoxide, six-coordinate Y(OR)3(thf)3 (and dimeric [Y(OR)3(thf)]2 with five- coordination) are formed replacement of methyl by phenyl substituents leads to the isolation of the 2,6-diphenylphenolates [Ln(OC6H3Ph2-2,6)3] (Ln = La, Ce, Pr, Nd, Gd, Ho, Er, Ln, Y), which have monomeric structmes with the lanthanide slightly out of the O3 plane, but with some additional ring-metal interactions. [Ln(OC6H3Ph2-... 

Structure. The presence of an oxygen atom directly bound to zinc increases both the electron deficiency of the zinc and the donor character of the oxygen atom. This condition will inevitably result in intermolecular (see Intermolecular) association increasing the coordinative saturation of zinc and leading to high thermal stability and low sensitivity towards oxygen and moisture. Organozinc alkoxides and aryloxides... 

A combination of two square-pyramids of [Ln5((jt4-OH)( X3-OH)4] with one hollow octahedron of [Ln6([X3-OH)8] by vertex-sharing leads to the assembly of esthetically pleasing tetradecanuclear complexes with a rod-like cluster core (Figure 6.16). Complexes characterized by such a core have been successfully prepared using aryloxide [34, 35], P-diketonate [87], and amino acid ligands [104],... 

ATPH (Scheme 2-5). Aluminum tris(2,6-di-/er/-butyI-4-methylphenoxide) (ATD) [15, 16] was first reported by Barron and co-workers. They exploited a two-step synthesis of ATD starting from LiAlH4 as an aluminum source. Apparently the structural modification of aluminum aryloxides that leads to numerous variants offers real advantages over conventional Lewis acids regarding preparation and handling. 

The syntheses, physical properties, and molecular structures of alkoxides and aryloxides have been discussed in CCC (1987).161 The alkoxides of scandium and yttrium were reviewed in CCC (1987).1 There have been more recent developments in this area and the impetus for this chemistry has been the developments in materials research. Metal alkoxides and /3-diketonates can be used as precursors for oxide and nonoxide thin films.162 The stable M—O bond and the volatility of the metal alkoxides are important features of this area of chemistry. This has lead to more research in this area particularly in synthesis, NMR, and X-ray crystallography. 

In order to prepare hydrolytically stable polythionyiphosphazenes the perchlo-rinated polymers were reacted with nucleophiles to substitute the hydrolytically sensitive main group-element halogen bonds [2]. This type of post-polymerization structural modification is well-established in polyphosphazene chemistry [2,8]. Thus, aryloxide nucleophiles or primary amines were used to substitute the polymers leading to poly(aryloxythionylphosphazenes) 24 and poly(amino-thionylphosphazenes) 25 respectively [35,37] ... 

---