Reaction of Sulfur Chlorides with Metal β-Diketonates

Abstract

Metal b-diketonates react with sulfur dichloride to form sulfenyl chlorides irrespective of b-substituent. Bulky phenyl and tert-butyl groups do not prevent formation of fully substituted complexes. The possibility of preparing sulfenyl chloride derivatives of rhodium, ruthenium, and vanadium b-diketonates was demonstrated. A new procedure was suggested for preparing chlorosulfenyl-substituted b-diketonates. Disulfur dichloride reacts with metal chelates with the substitution of both chlorine atoms and formation of polynuclear complexes in which the diketonate groups are linked by disulfide bridges.It was shown previously that sulfur dichloride reacts with metal acetylacetonates with the substitution of one chlorine atom and formation of sulfenyl chloride derivatives [1]: % , 0 D ? B M O O H n + nSCl 2 76 % , 0 D ? B M O O SCl n + nHCl, I!IV (1) M = Cr (I), Co (II), Al (III), n = 3; M = Be (IV), n = 2.Sulfur dichloride was added to a suspension of acetylacetonate in pentane. The reactant ratio chelate : SCl 2 : pentane (g/ml/ml) was 1 : 1 : 10, which corresponded to a 1.8-fold excess of SCl 2 . After stirring for 10 min, the product was filtered off.The procedure is simple and convenient. However, it is applicable to only a limited range of metal complexes, namely, to those exhibiting high kinetic stability. Iron(III) and copper(II) acetylacetonates decompose under the conditions of reaction (1). Among compounds I3IV, the chromium complex I is the most stable. It can be stored for an unlimited time and can be purified by recrystallization. The cobalt (II) and aluminum (III) chelates decompose during storage or recrystallization. Collman et al. [2] prepared an SCl-substituted acetylacetonate by reaction (1) starting from dichlorosubstituted chromium acetylacetonate. The high reactivity of the SCl group was used to prepare chromium and cobalt acetylacetonates containing at the central carbon atom the thiophosphate [1, 3], thioamide [3], vinylthio [4], or chloroethylthio [5] group, and also siloxane polymers containing metal chelate groups [6].Our goal was to apply reaction (1) to complexes of other b-diketones and to extend the range of metals whose complexes can be brought into this reaction. We obtained the SCl derivatives of the following metal chelates:M = Cr, R 1 = R 2 = Ph (V); M = Co, R 1 = R 2 = Ph (VI); M = Al, R 1 = R 2 = Ph (VII); M = Cr, R 1 = CH 3 , R 2 = Ph (VIII); M = Cr, R 1 = t-Bu, R 2 = CH 3 (IX); M = Cr, R 1 = CH 3 , R 2 = H (X); M = Co, R 1 = CH 3 , R 2 = H (XI); M = Cr, R 1 = R 2 = H (XII); M = Rh, R 1 = CH 3 , R 2 = CH 3 (XIII); M = Ru, R 1 = CH 3 , R 2 = CH 3 (XIV); M = V, R 1 = CH 3 , R 2 = CH 3 (XV).b-Phenyl substituents drastically decrease the reactivity of the chelate ring. In the reaction of chromium dibenzoylmethanate [Cr(dbmH) 3 ] with sulfur dichloride under the conditions described in [1], the conversion of the starting chelate was incomplete (TLC monitoring). The decreased reactivity of dibenzoylmethanates in halogenation and nitration was reported previously [7, 8].The fully subst...