Tris-thiobenzoates, Arsenic, Antimony, BismuthTris-thiobenzoates o f arsenic, antimony and bismuth, M(SOCR)3 have been obtained from their oxides and characterized. In the X-ray crystal structure determinations of these, the group 15 atom and the three covalently bonded sulfur atoms are found to constitute a trigonal pyramid, the central atoms lie at a C3 axis. In the bismuth complex the thiobenzoate ligand tends to chelate. However, three comparatively short intermolecular M---S interactions are significant features for these molecules resulting in stacking of trigonal prisms providing an essentially six coordinate environment around arsenic and antimony and a nine-coordinate one for bismuth. The structure of PhSb(SOCPh)2 can be considered Metal carboxylates [1] are known to display in teresting structural features arising from the varying modes of bonding of the carboxylate anions. The monothiocarboxylates can be classified as asymetrical sulfur ligands [2] with the potential of bind ing metal ions depending upon their hardness and softness. Surprisingly, few metal thiocarboxylates [3 -5 ] have been prepared so far and even fewer ones [5-9] have been examined for structural de tails. Amongst group 15 elements, there are two reports on the structures of thioacetate complexes. In antimony tris-thioacetate [10] antimony is found to possess eight-fold coordination, and the resultant geometry is best described as a distorted dodeca hedron. A bidentate bonding pattern of the thioac etate group is also present in phenylantimony bisthioacetate [11] whose geometry is o f a distorted square-pyramidal shape.Our systematic efforts in main group metal com plexes of asymmetrical sulfur ligands such as thio-ß-diketonate [12-16] and thiocarbamate [17][18][19][20][21][22][23][24][25][26][27][28][29] have provided many discernible and interesting structural features. Thiocarboxylates are the natu ral extension of this thematic approach [8], and we report here on the synthesis and structure of the trismonothiobenzoates o f arsenic, antimony and bis muth as well as of PhSb(SOCPh)2.* Reprint requests to Dr. V. D. Gupta or Prof. H. Nöth.to be distorted trigonal bipyramidal.
ExperimentalAll experiments were carried out under anhydrous conditions. Solvents were purified and dried by stan dard methods. Arsenic, antimony and bismuth oxides (Fluka) were used without further purification. PhSbCb and PhaSbCl were prepared by literature methods [21], as well as monothiobenzoic acid (b. p. 85 -87 °C/10 mm Hg) and potassium thiobenzoate [22], Sulfur was estimated by Messenger's method. IR spectra were recorded in the re gion 4000-400 cm-1 on a JASCO FT/IR-5300 spectrom eter on KBr disks. Elemental analyses were carried out on a Perkin-Elmer 240C model analyzer. NM R spectra were recorded in CDC13 using SiMe4 as an internal reference on a JEOL 270 spectrometer.Preparation o f compounds 1 -3 (Table I ) A solution of the respective thiobenzoic acid in dichloromethane (~ 20 cm3) in appropriate molar ra tio was added dropwise with constant stirri...