A diphenylboron chelate of anN-alkyl-2,2-diarylglycolohydroxamic acid

Abstract

Cyclohexyl-5-[hydroxy-bis(4-methoxyphenyl)methyl]-2,2diphenyl-1,3-dioxa-4-azonia-2-borata-4-cyclopentene, C 34 H 36-BNO 5 , contains a ®ve-membered heterocyclic ring with a Benvelope conformation. Bond lengths and angles are similar to those in related hydroxamatoboron chelates.

Diphenylboron chelate of an 3-hydroxy-N-(2-hydroxyalkyl)hydroxamic acid

“…The detailed structure of the chelate ring system in (II) is very similar to that found in related hydroxamatoboron chelates (Kliegel et al, 1996(Kliegel et al, , 2001(Kliegel et al, , 2002, and references therein), the BONCO ring having a slight B-envelope conformation [dihedral angle magnitudes 1.5 (3)±6.9 (3) ]. The short C1Ð N1 bond distance of 1.297 (3) A Ê corresponds to a high amount of double-bond character, with a %-bond order of around 0.8, similar to the hydroxamatoboron complex reported recently (Kliegel et al, 2002). Comparable to the latter is also the retention of about 50% of the double-bond character of the C1ÐO2 carbonyl bond of the hydroxamate moiety.…”

“…In the course of our research on the formation of boron complexes with functionally modi®ed hydroxamic acids (Kliegel et al, 1996(Kliegel et al, , 2001(Kliegel et al, , 2002, and references therein), the tetradentate ligand (I), obtained from (AE)tropic acid and 1-(N-hydroxyaminomethyl)cyclohexanol, was reacted with diphenylborinic acid (anhydride).…”