Carbon−Sulfur Bond Cleavage in Bis(N-alkyldithiocarbamato)cadmium(II) Complexes:  Heterolytic Desulfurization Coupled to Topochemical Proton Transfer

Abstract

Three bis(N-alkyldithiocarbamato)cadmium(II) complexes [Cd(S(2)CNHR)(2)] (1, R = n-C(3)H(7); 2, R = n-C(5)H(11); 3, n-C(12)H(25)) were prepared by metathesis of the corresponding lithium salt, Li[S(2)CNHR], with cadmium chloride. The crystal structures of 2 and 3 consist of planar molecular units of [Cd(S(2)CNHR)(2)] connected by intermolecular Cd.S interactions to give a one-dimensional chain. The chains are connected by a network of intermolecular N-H.S hydrogen bonds between the dithiocarbamato nitrogen atom and bridging sulfur atoms in neighboring chains. In solution, the (113)Cd NMR spectrum of 2 is dependent on concentration and temperature, indicative of a dimerization equilibrium mediated by similar Cd.S intermolecular bridging interactions. In the solid state, thermal gravimetric analyses show that all three complexes decompose smoothly via a heterolytic C-S bond cleavage reaction to give the corresponding alkyl isothiocyanate and cadmium sulfide as the primary products, with the formation of primary amine and CS(2) as coproducts. These products can result only from the net transfer of protons between N-alkyldithiocarbamato ligands in the solid state. Thus, the C-S bond cleavage reaction is interpreted in terms of the topochemical arrangement of molecular units in the crystalline state, which provides a pathway for proton transfer between ligands via N-H.S hydrogen bonds. Decomposition was also initiated by addition of a tertiary amine to a solution of [Cd(S(2)CNHR)(2)]. This confirms that C-S bond cleavage must be coupled to deprotonation of the -NH group, and explains why dialkylated derivatives [Cd(S(2)CNR(2))(2)] are inert to this particular mode of C-S bond cleavage. This system thus constitutes an unusual example of heterolytic, nonoxidative C-S bond cleavage that appears to proceed by a topochemical transfer of protons, which has implications for C-S bond cleavage processes in single-source precursors for II-VI semiconductor materials.

Bis[bis(N-2-hydroxyethyl,N-isopropyl-dithiocarbamato)mercury(II)]2: crystal structure and Hirshfeld surface analysis

“…The polymeric form mimics the recently reported structure of [Cd(S2NMe2)2]n [6] as well as those of {Cd[S2N(H)R]2}n, R = n-C5H11 and n-C12H25 [7], for which no bi-nuclear species have been reported.…”

Indirect evidences of desulfurization of a thiosemicarbazonecopper(II) system in aqueous basic medium

“…In some cases, the attack of a basic reactive as sodium methoxide to the thioamide carbon atom has been proposed [32]. Recently, desulfurization of dithiocarbamatocadmium(II) complexes in the presence of amines has been reported [33]. However, as far as we are aware desulfurization reactions induced by basic media have not been referenced for thiosemicarbazone compounds in aqueous solutions up to date.…”

Exploring the crystallization landscape of cadmium bis(N-hydroxyethyl, N-isopropyldithiocarbamate), Cd[S2CN(iPr)CH2CH2OH]2

“…For completeness, it is noted that the nonalkyl species, {Cd[S2CN(H)R]2}∞ R = n-C5H11 and n-C12H25, are linear coordination polymers with octahedrally coordinated cadmium atoms [52]. (37) mother liquor over a period of several days it transformed to {Cd[S2CN(iPr)CH2CH2OH]2}2·2H2O·2MeCN, which has the normally adopted binuclear motif [50].…”