Alkenyl and alkynyl complexes of osmium(II) derived from [OsH(Cl)(CO)(BTD)(PPh3)2] (BTD = 2,1,3-benzothiadiazole)

Abstract

Treatment of [OsH(CA)(NCMe)₂(PPh₃)₂]⁺ (A = O or S) with [NEt₄]Cl and 2,1,3-benzothiadiazole (BTD) provided [OsH(Cl)(CA)(BTD)(PPh₃)₂] (A = O or S). Under mild conditions, the complex [OsH(Cl)(CO)(BTD)(PPh₃)₂] hydro-osmiates ethynyltoluene, ethyne and di(4-tolyl)butadiyne to provide vinyl complexes [Os(CHCHR)Cl(CO)(BTD)(PPh₃)₂] (R = C₆H₄Me-4), [Os(CHCH₂)Cl(CO)(BTD)(PPh₃)₂] and [Os{C(CCR)CHR}Cl(CO)(BTD)(PPh₃)₂]. Complex [OsH(CO)(NCMe)₂(PPh₃)₂]⁺ reacted with HCCR to provide [Os(CHCHR)(CO)(NCMe)₂(PPh₃)₂]⁺ which is converted by [NEt₄]Cl into [Os(CHCHR)Cl(CO)(NCMe)(PPh₃)₂]. Treatment of [Os(CHCHR)Cl(CO)(BTD)(PPh₃)₂] with CNCMe₃ or CO provided [Os(CHCHR)Cl(CO)(L)(PPh₃)₂] (L = CNCMe₃ or CO). The dithiocarbamate complex [Os(CHCHR)(S₂CNMe₂)(CO)(PPh₃)₂] and the osmatetraborane [Os(CHCHR)(B₃H₈)(CO)(PPh₃)₂] resulted from the reactions of [Os(CHCHR)Cl(CO)(BTD)(PPh₃)₂] with Na[S₂CNMe₂] and [NBuⁿ₄][B₃H₈], respectively, whereas with K[HB(pz)₃] (pz = pyrazolyl) initially [Os(CHCHR)(CO)(PPh₃)₂{η²-HB(pz)₃}] was formed which is converted into [Os(CHCHR)(CO)(PPh₃){HB(pz)₃}] on heating. No intermediates are however observed in the corresponding reaction with 1,4,7-trithiacyclononane ([9]aneS₃) to provide [Os(CHCHR)(CO)(PPh₃)([9]aneS₃)]⁺. The alkynyl complex [Os(CCR)Cl(CO)(BTD)(PPh₃)₂] was obtained from either (i) the reaction of [OsH(Cl)(CO)(BTD)(PPh₃)₂] with [Hg(CCR)₂] or (ii) [Os(CHCHR)Cl(CO)(BTD)(PPh₃)₂] with an excess of HCCR. Treatment of [Os(CCR)Cl(CO)(BTD)(PPh₃)₂] with Na[S₂CNMe₂] or alternatively [Os(CHCHR)(S₂CNMe₂)(CO)(PPh₃)₂] with an excess of HCCR provided [Os(CCR)(S₂CNMe₂)(CO)(PPh₃)₂], which can also be obtained from [OsH(S₂CNMe₂)(CO)(PPh₃)₂] and [Hg(CCR)₂]. The BTD in [Os(CCR)Cl(CO)(BTD)(PPh₃)₂] is substituted by CNCMe₃ to provide [Os(CCR)Cl(CO)(CNCMe₃)(PPh₃)₂]. The reaction of [OsH(Cl)(CS)(BTD)(PPh₃)₂] with HCCR provided [Os(CHCHR)Cl(CS)(BTD)(PPh₃)₂] which in contrast to [Os(CHCHR)Cl(CO)(BTD)(PPh₃)₂] reacts with carbon monoxide to provide the thiocinnamoyl complex [Os(η²-SCCHCHR)Cl(CO)(PPh₃)₂].