Der hoch flexible Bis(hydroxylamin)-Ligand [ON(Me)]2CH22− und sein unterschiedliches Verhalten in der Chemie des Aluminiums und Galliums

Aluminum Complexes with Sulfide-Linked Bis(phenolato) Ligands: Unusual Structure and Reactivity of the Methyl Bis(phenolato) Complex “[Al(tbmp)Me]” (tbmp = 2,2‘-Thiobis(6-tert-butyl-4-methylphenolato))

“…Despite the unsymmetrical structure for 1 , as indicated by its 1 H NMR spectra, the 27 Al NMR spectra (CDCl 3 /CD 2 Cl 2 ) displayed only one very broad signal at 52 ppm ( w 1/2 = 4878 Hz). This chemical shift is within the range for five-coordinate aluminum centers according to literature reports. 10a,b,, When the temperature is lowered to −80 °C, this resonance is shifted to 62 ppm with slight broadening. No decoalescence was observed in the measured temperature range of 0 to −80 °C.…”

Expectation and surprise in group 13 organometallics: molecular vs. polymeric aggregation of Me2Ga and Me2In norcamphor oximates

“…1,2 Aggregates of even higher order are known, e.g. the bishydroxylamine-based 3 4 By contrast, in group 13 oximates the six-membered M 2 O 2 N 2 ring is found almost exclusively, 5-7 and we revealed just recently that it takes ligand skeletons that are both bulky and rigid to hamper aggregation by this motif. 8 In their landmark work on group 13 acetoximates 5 a and orthopyridylaldoximates about the crystallographic inversion centres.…”

Organoaluminium complexes with sterically demanding oximato ligands: does a bulky and rigid ligand backbone change the aggregation motif?

“…It could be shown that the hitherto solely found aggregation motif of such compounds, namely the Al 2 N 2 O 2 six-membered ring dimer, is no longer present when the backbone of the oxime used is both bulky and rigid. Whereas this dimerization motif is adopted by the dimethylaluminium complexes of diisopropyl oxime ( 5) and (rac)-norcamphor oxime (6) expectedly, the related derivatives of (R,R)-camphor oxime (7) and (R,S)-fenchone oxime (8) exhibit aggregation motifs that are new in organometallic oximate chemistry (Al 3 O 3 sixmembered ring trimer and Al 2 NO 2 five-membered ring dimer). The latter two chiral, rigid and highly substituted ketoxime ligands obviously account for steric congestion high enough to enforce aggregation changes in these cases.…”

“…9 2,4-Dimethylpentane-3-one oxime (5) was prepared according to the literature, 11a but was further purified by vacuum condensation (mp 34 • C; bp 25 • C, 1 mmHg; lit., 11b mp 34 • C; lit., 11b bp 82-85 • C, 12 mmHg); (rac)-norcamphor oxime (6) was prepared and purified analogously (mp 52 • C; bp 78 • C, 1 mmHg; lit., 13a mp 50-51.5 • C; lit., 13b bp 74-75 • C, 0.7 mmHg). (R,R)-Camphor oxime (7) was prepared according to the literature, 14 and recrystallized from ethanol (mp 119.5 • C; lit., 14 118-119 • C); (R,S)-fenchone oxime (8) was prepared and purified analogously (mp 168.5 • C; lit., 15 169-170 • C); this preparation proceeded only in moderate yield (47%), but unreacted starting material could satisfyingly be recovered (26%).…”

“…5 In comparison to related hydrazine species, group 13 organometallics of hydroxylamines show a limited tendency to form higher-order aggregates due to the lower valency of oxygen compared to nitrogen; nevertheless, with the aminal-type bis-hydroxylamine [HO-(Me)N] 2 CH 2 , 6 the trinuclear species [{Me 2 Al[O-(Me)N] 2 CH 2 } 2 AlMe] or the metalla-oxa-azanorbornanes {(Me 2 M) 2 [O-(Me)N] 2 CH 2 } (M = Al, Ga) are afforded, the latter (in case of Ga) showing intermolecular M-O contacts to yield a chain-like polymer aggregate in the solid state. 7 By sharp contrast, the chemically and structurally closely related group 13 organometallic oximates have in the past been shown to exhibit much less diverse aggregation types. Pioneering work a Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstr.…”