Synthesis and structures of β-dialdiminatoantimony(iii) halides and β-dialdiminium hexahalogenoantimoniates

Abstract

From SbCl₃, SbBr₃ or SbI₃ and an equivalent portion of the β-dialdiminatopotassium compound K[{N(C₆H₃Prⁱ₂-2,6)C(H)}₂CPh] [ K(L)] in Et₂O there was obtained in good yield the crystalline yellow [SbCl₂(L)]·(0.5thf)·(0.5Et₂O) (1) and the bis(bromo) analogue 2, or the orange [{SbI(L)(μ-I)}₂]·(0.5Et₂O) (3). Each of 1–3 was treated with the appropriate dihalogen (X₂) in Et₂O. Thus, whereas 1 or 2 furnished the corresponding β-dialdiminium hexahalogenoantimoniate [Et₂O⋯H(L)H⋯OEt₂][SbX₆] (4, X = Cl; 6, X = Br), the iodo compound 3 afforded the known pyrazolium salt [N(C₆H₃Prⁱ₂-2,6)C(H)C(Ph)C(H)N(C₆H₃Prⁱ₂-2,6)][I₅]. It is suggested that the source of the additional 2HX, required to convert 1 or 2 with X₂ in Et₂O into 4 or 6, was derived from halogenation of the N-aryl groups of L. The formation of 4 or 6 was achieved by the alternative synthesis from equivalent portions of [H₂(L)]X, SbX₃ and X₂ in diethyl ether. The X-ray structures of the isomorphous compounds 1 and 2 and 4 and 6, as well as of 3, are reported.