Synthesis, structures, and some reactions of [(Thioacyl)thio]- and (Acylseleno)antimony and -bismuth derivatives ((RCSS)xMR 3-x1 and (RCOSe)xMR3-x1 with M=Sb, Bi and x=1-3)

Abstract

A series of [(thioacyl)thio]- and (acylseleno)antimony and [(thioacyl)thio]- and (acylseleno)bismuth, i.e., (RCSS)xMR 3-x1 and (RCOSe)xMR3-x1 (M = Sb, Bi, R1 = aryl, x = 1 - 3), were synthesized in moderate to good yields by treating piperidinium or sodium carbodithioates and -selenoates with antimony and bismuth halides. Crystal structures of (4-MeC 6H4CSS)2Sb(4-MeC6H4) (9b′), (4-MeOC6H4COSe)2Sb(4-MeC 6H4) (12c′), (4-MeOC6H 4COS)2Bi(4-MeC6H4) (15c′), and (4-MeOC6H4CSS)2BiPh (18c) along with (4-MeC6H4COS)2SbPh (6b) and (4-MeC 6H4COS)3Sb (7b) were determined (Figs. 1 and 2). These compounds have a distorted square pyramidal structure, where the aryl or carbothioato (=acylthio) ligand at the central Sb- or Bi-atom is perpendicular to the plane that includes the two carbodithioato (=(thioacyl)thio), carboselenato (=acylseleno), or carbothioato ligand and exist as an enantiomorph pair. Despite the large atomic radii, the C=S⋯Sb distances in (RCSS)2MR1 (M = As, Sb, Bi; R1 = aryl) and the C=O⋯Sb distances in (RCOS)xMR3-x1 (M = As, Sb, Bi; x = 2, 3) are comparable to or shorter than those of the corresponding arsenic derivatives (Tables 2 and 3). A molecular-orbital calculation performed on the model compounds (MeC(E)E1) 3-xMMex (M = As, Sb, Bi; E = O, S; E1 = S, Se; x = 1, 2) at the RHF/LANL2DZ level supported this shortening of C=E⋯Sb distances (Table 4). Natural-bond-orbital (NBO) analyses of the model compounds also revealed that two types of orbital interactions nS → σ*MC and nS → σ* MS(1) play a role in the (thioacyl)thio derivatives (MeCSS) 3-xMMex (x = 1, 2) (Table 5). In the acylthio- MeCOSMMe2 (M = As, Sb, Bi), nO → σ* MC contributes predominantly to the orbital interactions, but in MeCOSeSbMe2, none of nO → σ*MC and nO → σ*MSe contributes to the orbital interactions. The nS → σ*MC and nS → σ*MS(1) orbital interactions in the (thioacyl)thio derivatives are greater than those of nO → σ*MC and nO → σ*ME in the acylthio and acylseleno derivatives (MeCOE)3-xMMex (E = S, Se; M = As, Sb, Bi; x = 1, 2). The reactions of RCOSeSbPh2 (R = 4-MeC6H4) with piperidine led to the formation of piperidinium diphenylselenoxoantimonate(1-) (=piperidinium diphenylstibinoselenoite) (H2NC5H10) +Ph2SbSe-, along with the corresponding N-acylpiperidine (Table 6). Similar reactions of the bis-derivatives (RCOSe)2SbR1 (R, R1 = 4-MeC6H 4) with piperidine gave the novel di(piperidinium) phenyldiselenoxoantimonate(2-) (=di(piperidinium) phenylstibonodiselenoite), [(H2NC5H10)+] 2(PhSbSe2)2-, in which the negative charges are delocalized on the SbSe2 moiety (Table 6). Treatment of RCOSeSbR21 (R, R1=4-MeC6H 4) with N-halosuccinimides indicated the formation of Se-(halocyclohexyl) arenecarboselenoates (Table 8). Pyrolysis of bis(acylseleno)arylbismuth at 150° gave Se-aryl carboselenoates in moderate to good yields (Table 9). © 2006 Verlag Helvetica Chimica Acta AG.