Polyimido sulfur anions and ylides

Abstract

Isovalent electronic replacement of the oxygen atoms in the classic SO(n)(m-) molecules and ions by NR imido groups yields the polyimido sulfur species S(NR)(n)(m-), n = 2, 3, 4 and m = 0, 2. The crucial cornerstone to the richness of SN chemistry is the access to sulfur diimides S(NR)(2) and triimides S(NR)(3). While the syntheses of the first are well established the preparations of the second were hazardous and of poor yields. A new facile, safe and elaborated route to give quantitative yields is presented. It involves the synthesis of triimido sulfites S(NR)(3)(2-), which are versatile ligands in their own right. With a trigonal pyramidal shape, containing three basal negatively charged nitrogen atoms, they are rare examples of dianionic tripodal ligands. Various (mixed) metal complexes are presented. Lithium coordination at the N-S-N bisections converts the dianion into the inverse tripod ligand Li(3)(NR)(3)S(+), capable of anion solvation. Among others, this motif stabilizes unprecedented monomeric methyllithium and lithium enolate. In the reaction of sulfur diimides S(NR)(2) and triimides S(NR)(3) with organometallics the diimidosulfinates RS(NR)(2)(-) and triimidosulfonates RS(NR)(3)(-) are synthesised. Both display a rich coordination chemistry to various metals, which is discussed in the review. Furthermore, the S-organo substituent can be modified in various ways. It can be a linker between two SN moieties or can be shaped to a R(2)N- or R(2)P-donating side arm of any form or length to give hemilabile scorpionates. Their ample application in metal coordination and anion solvation is presented. These monoanions can be converted to the related ylides by deprotonation of the S-alkyl group. The diimidosulfur(IV) ylides (R(2)C)S(NR)(2)(2-) and triimidosulfur(VI) ylides (R(2)C)S(NR)(3)(2-) contain the CR(2) methylene group, isoelectronic to the NR imido group. Their coordination behaviour and reactivity are discussed. In addition to the rich SN chemistry the S-N and S-C bonding is elucidated by means of theoretical and experimental charge density investigations and topological analyses on the basis of multipole refinement. As the most important result hypervalency at sulfur and S=N(C) double bonding are ruled out as superfluous concepts.

Polyimido Sulfur(VI) Phosphanyl Ligand in Metal Complexation

“…The out-of-plane arrangement of the heavier alkaline earth-metal cations and the Ni 2 + and the Zn 2 + dications demonstrates the preference of the easier-to-polarize metal ions to interact with p-electron density located at the imide nitrogen atoms. Remarkable, the sum of all SÀN distances in all three transition metal complexes is almost constant at 4.72 (1) . [11a] The CSN 3 unit responds flexibly to different electronic requirements induced by the various metal cations in terms of the sulfur atom being shifted relative to an otherwise fixed N 3 environment.…”

“…The wide range of coordination numbers one to six and oxidation states (+ I to + VI) affords an enormous variety of covalent molecules. [1] Ever since, the synthesis of polymeric (SN) x [2] and the discovery of its high-temperature superconducting properties, [3] the nature of the SÀN bond was under constant debate and the synthesis of SÀN multiple bonds was a rapidly emerging area. [4] Originally, sulfur dioxide SO 2 and diimide S(NR) 2 were believed to be hypervalent species with one lone pair and two S=O or S=N double bonds.…”

“…[9] After the syntheses to triimidosulfites S(NR) 3 2À [Eq. (1)] and their oxidation to sulfur triimides S(NR) 3 by halogens [Eq. (2)], [10] the triimidosulfonate anion RS(NR) 3 À is accessible in the reaction of sulfur triimide S(NR) 3 with any organometallics, such as methyllithium [Eq.…”

Manipulation of Phosphorescence Efficiency of Cyclometalated Iridium Complexes by Substituted o‐Carboranes

“…; R″ = Me, Ph, t Bu, etc; b in Scheme ) have proved to be valuable starting materials in the synthesis of, for example, digermylenes5a,8 and distannylenes 8b. To further this endeavor we wished to develop an N , N′ ‐chelating ligand with an anchoring central sulfur atom ( c in Scheme ) provided by sulfur diimides S(NR′) 2 9,10 and triimides S(NR′) 3 .…”

Lithium Complexes of Asymmetric Hydrogen Tetraimido Sulfate

“…The covalent nature of S-N bonds enhances the coexistence to other bonds (i.e., S-C, S-O, or S-F). [1] Ever since the synthesis of polymeric (SN) x [2] and the discovery of its high-temperature superconducting properties, [3] the nature of the S-N bond has been under constant debate and the synthesis of S-N multiple bonds has been a rapidly emerging area. [4] Originally, sulfur dioxide SO 2 and sulfur diimide S(NR) 2 were believed to be hypervalent species with one lone pair and two oxygen or imide groups doublebonded to the sulfur atom.…”