Preparation and molecular structure of the dimeric arylstibonic monoethylester [2,6-Mes2C6H3Sb(O)(OEt)(OH)]2

Abstract

Heating of the arylstibonic acid [2,6-Mes 2 C 6 H 3 Sb(O)(OH) 2 ] 2 in refluxing ethanol gave rise to the esterification and formation of the monoethyl ester [2,6-Mes 2 C 6 H 3 Sb(O)(OEt)(OH)] 2 , the molecular structure of which was established by X-ray crystallography.Despite being known for more than 100 years ( Hasenb ä umer, 1898), the chemistry of arylstibonic acids began to develop at a rapid pace only within the last 5 years. For a long time, progress in the field has arguably been delayed by the fact that most previously known arylstibonic acids are high-melting amorphous polymers that are only poorly soluble in most common solvents.

Chemical Structure Elucidation in the Development of Inorganic Drugs: Evidence from Ru‐, Au‐, As‐, and Sb‐based Medicines

“…[139] Although the compound was initially described as a monomeric stibonic acid, it is now known that, like arylstibine oxides, [101][102][103][140][141][142] arylstibonic acids can self-associate into higher-nuclearity structures. [143][144][145][146] In the absence of oligomerization, they may also remain monomeric but expand their coordination sphere, possibly with ligand exchange occurring. [147] As a result, the molecular structure of stibamine remains unknown.…”

“…Among the first to be prepared was the antimony analog of arsanilic acid, which was described as “ para ‐aminophenylstibinic acid” (although it would now be called para ‐aminophenylstibonic acid) and given the moniker stibamine [139] . Although the compound was initially described as a monomeric stibonic acid, it is now known that, like arylstibine oxides, [101–103,140–142] arylstibonic acids can self‐associate into higher‐nuclearity structures [143–146] . In the absence of oligomerization, they may also remain monomeric but expand their coordination sphere, possibly with ligand exchange occurring [147] .…”

A tetranuclear arylstibonic acid with an adamantane type structure

“…2 In preceding work we used the kinetic stabilization of a bulky m-terphenyl substituent for the preparation of the first well-defined arylstibonic acid and derivatives thereof. Thus, the controlled base hydrolysis of 2,6-Mes 2 C 6 H 3 SbCl 4 afforded the dinuclear arylstibonic acid [2,6-Mes 2 C 6 H 3 Sb(O)(OH) 2 ] 2 3 and the related mono ethyl ester [2,6- 4 The reaction of [2,6-Mes 2 C 6 H 3 Sb(O)(OH) 2 ] 2 with H 2 SO 4 and NaOH confirmed the amphoteric character of the arylstibonic acid. 5 Notably, similar base hydrolysis of 2,6-Mes 2 C 6 H 3 SbCl 2 under aerobic conditions produced mixed-valent arylstiboxane clusters (2,6-Mes 2 C 6 H 3 Sb V ) 2 (ClSb III ) 4 O 8 and (2,6-Mes 2 C 6 H 3 Sb V ) 4 (ClSb III ) 4 (HOSb III ) 2 O 14 , which evolved from partial Sb-C bond cleavage.…”