Mechanism and selectivity of methyl and phenyl migrations in hypervalent silylated iminoquinones.

Chlorosilanes R(X)(Y)SiCl (R = Me, Ph; X, Y = Me, Ph, Cl) have been reported to react with Pb(ONO(Q))2 (ONO(Q) = 3,5-di-tert-butyl-1,2-quinone-(3,5-di-tert-butyl-2-oxy-1-phenyl)imine) to give five-coordinate (X)(Y)Si(ON[R]O), in which the R group has migrated from silicon to nitrogen. This migration is intramolecular, as confirmed by the lack of crossover between (CH3)3SiCl and (CD3)3SiCl in their reaction with Pb(ONO(Q))2. Reaction of PhSiMeCl2 takes place with high kinetic stereoselectivity to produce isomer Ph(Cl)Si(ON[Me]O) in which the phenyl is axial in the trigonal bipyramid, which subsequently isomerizes to the thermodynamic isomer with axial chlorine.

Mixed amidophenolate-catecholates of molybdenum(VI).

The dioxomolybdenum(vi) complex ((t)BuClipH2)MoO2 ((t)BuClipH4 = 4,4'-di-tert-butyl-N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl) reacts with 3,5-di-tert-butylcatechol to form oxo-free ((t)BuClip)Mo(3,5-(t)Bu2Cat). The bis(amidophenoxide)-monocatecholate complex is monomeric and exhibits a cis-β geometry in the solid state. Variable-temperature NMR data are consistent with two fluxional processes, one that interconverts several geometric isomers at low temperature, and a second that interchanges the ends of the (t)BuClip ligand at ambient temperatures.

Molybdenum(VI) complexes of a 2,2'-biphenyl-bridged bis(amidophenoxide): competition between metal-ligand and metal-amidophenoxide π bonding.

The 2,2'-biphenyl-bridged bis(2-aminophenol) ligand 4,4'-di-tert-butyl-N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-2,2'-diaminobiphenyl ((t)BuClipH(4)) reacts with MoO(2)(acac)(2) to form ((t)BuClipH(2))MoO(2), where the diarylamines remain protonated and bind trans to the terminal oxo groups. This complex readily loses water on treatment with pyridine or 3,5-lutidine to form mono-oxo complexes ((t)BuClip)MoO(L), which exhibit predominantly a cis-β geometry with an aryloxide trans to the oxo group. Exchange of the pyridine ligands is rapid and takes place by a dissociative mechanism, which occurs with retention of stereochemistry at molybdenum.

Synthesis of aryloxyaluminium hydrides and their conversion into aryloxyalumoxanes (ArOAlO)n.

The reaction of bulky phenols with H(3)Al x NMe(3) afforded the new primary phenoxyalanes Mes*OAlH(2) x NMe(3), 2 (Mes* = 2,4,6-(t)Bu(3)-C(6)H(2)-), 2,6-Dipp(2)C(6)H(3)OAlH(2) x NMe(3), 3 (Dipp = 2,6-(i)Pr(2)C(6)H(3)-), and 2,6-Trip(2)C(6)H(3)OAlH(2) x NMe(3), 4 (Trip = 2,4,6-(i)Pr(3)C(6)H(2)-) as colorless crystalline solids. Subsequent reactions of 2,6-(t)Bu(2)-4-MeC(6)H(2)OAlH(2) x NMe(3), 1, and 2 with oxygen sources such as (Me(2)HSi)(2)O or Me(2)SO gave the disiloxyalane 2,6-(t)Bu(2)-4-Me-C(6)H(2)OAl(OSiHMe(2))(2) x NMe(3), 5, and the alumoxane (Mes*OAlO.OSMe(2))(4), 6.

Facile synthesis of monoazidotitanium isopropoxides.

The monoazidotitanium trisisopropoxide {(N(3))Ti(OiPr)(3)}(4) (2) was obtained by the reaction of (N(3))(2)Ti(OiPr)(2) (1) with Ti(OiPr)(4). Colorless 2 possesses an interesting tetrameric structure featuring bridging azide and isoproxide ligands and five- and six-coordinate titanium centers. It can be sublimed in vacuo at ca.

Aluminumoxyhydride: improved synthesis and application as a selective reducing agent.

Aluminumoxyhydride (HAlO) has been obtained by the reaction of aluminum hydride with the siloxane (Me2HSi)2O or the stannoxane (Bu3Sn)2O as an amorphous colorless insoluble powder. The highest-purity product resulted from the reaction of H3Al.NMe3 with (Me2HSi)2O.