[Re₁₂CS₁₇(CN)₆]ⁿ⁻ (n=6, 8): A Sulfido–Cyanide Rhenium Cluster with an Interstitial Carbon Atom

Abstract

The first compound with an octahedral sulfide-cyanide rhenium cluster, KCs 3 [Re 6 S 8 (CN) 6 ], was synthesized ten years ago.[1] Since then, the chemistry of chalcocyanide cluster complexes [Re 6 Q 8 (CN) 6 ] nÀ (Q = S, Se, Te; n = 3, 4) has developed intensively. [2][3][4][5][6] A remarkable feature of the [Re 6 Q 8 (CN) 6 ] nÀ complexes is their ability to coordinate the transition-metal and post-transition-metal atoms through ambidentate CN À ligands. Such coordination leads to the formation of cyanide-bridged polymeric structures with various dimensionalities and architectures. Many complex compounds containing similar octahedral chalcocyanide clusters have now been synthesized and their crystal structures and properties studied in detail. [7] The general approach for the synthesis of rhenium octahedral chalcocyanide complexes is to treat polymeric solids containing {Re 6 [2] as precursors. A few years ago, [9] it was found that ReS 2 and ReSe 2 react with molten KCN to form octahedral rhenium-cluster chalcocyanides with bridging S and Se 2 ligands in polymeric layered K 4 [{Re 6 S 8 }(CN) 4 S 4/2 ] and chainlike K 4 [{Re 6 Se 8 }(CN) 4 -(Se 2/2 ) 2 ] structures. Our further systematic study of phase formation in similar systems has culminated in the discovery of a unique rhenium sulfido-cyanide compound, K 8 [Re 12 CS 17 (CN) 6 ] (1), which contains a C-centered {Re 12 } cluster unit.The diamagnetic compound 1 was prepared by treating ReS 2 with molten KCN with a mass ratio ReS 2 /KCN of 1:2.[10]Single crystals suitable for a structural study were found in the reaction mixture and the single crystal structure of 1 has been solved by X-ray diffraction.[11] The cluster unit of 1 (Figure 1 a) consists of two {Re 6 } octahedra bonded by three m 2 -S bridges and one common m 6 -C atom. Each {Re 6 } cluster is capped by seven m 3 -S atoms and additionally by the centered m 6 -C ligand; thus, a typical octahedral cluster core analogous to {Re 6 Q 8 } (i.e., {Re 6 S 7 C}) is formed. Through such bonding and coordination, we recognize trigonal m 6 -C-centered prisms, {Re 6 C}, in which the triangle faces belong to two adjacent {Re 6 } octahedra. Six outward Re atoms (three from each {Re 6 } cluster unit) are coordinated by CN ligands.The ReÀRe interatomic distances in the {Re 6 S 7 C} fragments are comparable with those of {Re 6 Table 1). These values are within the range for ReÀRe single bonds observed in octahedral rhenium clusters (in [Re 6 (Q 8 (CN) 6 ] 4À mean ReÀRe distances are 2.599, 2.633, and 2.684 for Q = S, Se, and Te, respectively [7a] ). In the trigonal-prismatic {Re 6 C} units, the long Re···Re separations are 3.1576(17), 3.1722(17), and 3.1740(17) . ReÀ (m 3 -S) bond lengths range from 2.401 (6) [13] The mean ReÀ(m 2 -S) bond length of 1, 2.425 is close to ReÀS bond lengths found in numerous Bronger phases. [14] Re À (m 6 -C) bond lengths in the trigonal prism, {Re 6 C}, range from 2.16 (2) 6À anion in 3. For average bond lengths and angles, see Table 1. (Displacement ellipsoids are dra...

Computational Methods: Transition Metal Clusters

“…For the latter, no metal -metal bond exists between the Re 6 units. 67 The band structure of Ba 4 Mo 12 S 18 shows a similar behavior. The band lying at the bottom of the conduction band shows strong antibonding character between Mo 6 units.…”

“…The actual mve count of [Re 12 (µ 6 -C)(µ 2 -S) 3 (µ 3 -S) 14 (CN) 6 ] n− is 162 and 164 for n = 6 and 8, respectively. 67 This looks puzzling at first sight, but this kind of cluster is subject to relatively easy oxidation or reduction, indicating either a small HOMO -LUMO gaps or even open-shell electron configurations. Such an architecture is also exemplified in the superconducting compound Ba 4 Mo 12 S 18 that contains the Mo 12 (µ 6 -S)(µ-S) 3 (µ 3 -S) 14 S 6 cluster.…”

Low‐Dimensional Frameworks in Solid State Chemistry of Mo6 and Re6 Cluster Chalcohalides

“…However, in M 6 chalcogenide chemistry we can recall the two examples of S i-i ligands in Cs CN 6 ] in which two Re 6 clusters are connected by one C i-i ligand leading to a dimeric unit. [69] This unusual compound, at the border of the scope of this microreview, is obviously zero dimensional but one can speculate on the possible formation of chains such as ( with VEC values equal to 22.5 and 21.5, respectively. In 2D compounds, similar arrangements could be speculated.…”

Reversible Redox Transformations of Bridging Sulfide Ligands within Bioctahedral Rhenium Cluster Anions

“…As a result of the development of high‐nuclear rhenium clusters, the dodecanuclear anionic cluster complexes [Re 12 CS 14 (µ‐S) 3 (CN) 6 ] 6– were synthesised about ten years ago . This cluster can be considered to be a dimer composed of two {Re 6 } octahedrons face‐capped by seven inner sulfide µ 3 ‐S ligands and three terminal cyanide ligands.…”

“…Therefore, in the approach of a constant 6– charge of all [Re 12 CS 14 (µ‐L) 3 (CN) 6 ] 6– (L = S, SO, SO 2 ) clusters, the simplest scheme to represent the redox transformations can be written as (µ‐S 2+ O 2 ) 2– → (µ‐S 0 O) 2– → (µ‐S 2– ) 2– . However, this scheme does not reflect the real distribution of charge within the clusters . To evaluate the electron density localised on S‐atoms of bridging ligands, computational analysis of electron density distribution was carried out by using the Bader method for the [Re 12 CS 14 (µ‐L) 3 (CN) 6 ] 6– (L = S, SO, SO 2 ) cluster anions.…”