Cyclododecasulfur as a Ligand: From Gas‐Phase Experiments to the Crystal Structures of [Cu(S₁₂)(S₈)]⁺ and [Cu(S₁₂)(CH₂Cl₂)]⁺

Abstract

Sulfur is the element with the largest number of modifications and usually exists as S n ring molecules; those with n = 6-14, 18, and 20 [1,2] have been structurally characterized. Thermodynamically, the two most stable rings are D 4d S 8 and D 3d S 12 . [1a, 2] In contrast to the rich structural chemistry of elemental sulfur, the coordination chemistry of neutral sulfur molecules is underdeveloped and, to our knowledge, limited to [Ag (S 8 [5b] In agreement with this, the sulfur ring molecules usually undergo redox degradation when treated with transition metal cations, leading to simpler metal (poly-)sulfide complexes, rather than forming coordination compounds.[6] However, Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) gas phase investigations of transition metal monocations M + with sulfur vapor (mainly S 8 ) detected strong signals for [MS n ] + complexes (n = 2-4, 6-8, 10, 12, and 14), suggesting that such coordination complexes can exist.[7] However, it remains unclear, if the observed compounds are true coordination compounds of the S n molecule or if M + oxidatively added to the S À S bond, forming a (n + 1)-heterocycle. Recent quantum chemical studies on [MS n ] + complexes (M = Li, Ca, V, Cu) suggested complexation of the metal cation to the ring structures. [8] Another open question from the pioneering mass spectrometric study [7] is whether the [MS n ] + complexes contain a single S n molecule or two (or more) smaller molecules S x and S y (x + y = n). were only observed within the first ten seconds of the experiment, after which [CuS 12 ] + was the major peak. From the mass spectra it was not clear, if the S 12 ring was present as a ligand or if the detected mass corresponded to one S 4 and one S 8 , two S 6 , or even three S 4 units. Figure 1 gives an overview of PBE0/TZVPP calculated [Cu(S x )(S y )]+ (x + y = 12) species. These calculations indicate that that C 3v )]+ is the most stable cation in the gas phase.

Synthesis, Crystal, and Electronic Structure of Ba3Sb2Q7 (Q = S, Se)

“…This value is close to the sum of the corresponding Pauling single-bond radii of S (1.05 Å) [33] and similar to S-S distances in the crystal structures of different modifications of elemental sulfur: 2.03-2.08 Å. [34][35][36] The [S 2 ] 2-dumbbell is not a typical building block for compounds in the Ba-Sb-S system, but is present in barium polysulfides with S-S distances of 2.12 Å in BaS 2 [37] and 2.08 Å in BaS 3 , [38] as well as in the strontium antimony sulfide, Sr 6 Sb 6 S 17 , where the S-S distance is almost identical to the S-S distance found in Ba 3 Sb 2 S 7 . [30] In the crystal structure of Ba 3 Sb 2 S 7 the end member of the [S 2 ] 2-dumbbell is the S1 atom.…”

A copper(II) complex with a Cu–S8 bond. Attenuated total reflectance, electron paramagnetic resonance, resonance Raman and atoms-in-molecule calculations

“…Similarly the 153 cm À1 and the 84 cm À1 bands in S 8 is shifted to 152 cm À1 and 77 cm À1 , respectively. Similar redistribution of intensities of the totally symmetric bands and small shifts in the band positions have been reported for complexes where Ag + and Cu + are coordinated to S 8 [4][5][6][7]. Note that there is a weak band in the Raman spectrum of the complex at 109 cm À1 which is absent in the Raman spectrum of S 8 .…”

“…One of our relevant observations is that 1 crystallizes out from an acetonitrile solution of 2 leaving behind elemental sulfur in solution. It may be noted that in all the known complexes of S 8 , the metal ions [Cu(I), Ag(I) and Re(I)] are invariably soft [4][5][6][7][8].…”

“…Till now crystal structures of five metal complexes containing coordinated S 8 are known. In two cases [4,5], the metal is Cu(I) and in other cases [6,7], it is Ag(I). A structurally uncharacterized mixed ligand binuclear Re(I) complex of S 8 has been reported [8].…”

The Future of Main Group Chemistry

“…[63] A cogent example is the ring expansion observed in the formation of [Cu(cyclo-S 12 )] þ (22) from the reaction of cyclo-S 8 with [Cu(1,2-F 2 C 6 H 4 ) 2 ] þ [Al{OC(CF 3 ) 3 } 4 ] À . [64] In addition to their use as partners for the stabilization of unusual, highly electrophilic main group species, the use of known WCAs and the development of new examples of WCAs are likely to play an influential role in fields such as catalysis, as counter-ions for electrophilic transition-metal centers, in ionic liquids to generate low viscosities, [65] and in lithium batteries.…”