Electron‐Precise 1,3‐Bishomocubanes – A Combined Experimental and Theoretical Study

Stabilization of dichalcogenide ligands in the coordination sphere of a ruthenium system

The synthesis, structure and electronic properties of tetraruthenium dichalcogenide complexes displaying the exclusive coordination mode of dichalcogenide ligands have been discussed. The reactions of Li[BH₂E₃] (E = S or Se) with [ClRu(μ-Cl)(p-cymene)]₂ (p-cymene = η⁶-{p-C₆H₄(ⁱPr)Me}) at room temperature yielded tetrametallic dichalcogenide complexes [{Ru₂Cl₂(p-cymene)₂}₂(μ₄,η²-E₂)], 1-2 (E = S (1) and Se (2)). The solid-state X-ray structure of 1 shows that two {(p-cymene)RuCl}₂ moieties are bridged by a S-S bond. In addition to 2, the reaction of Li[BH₂Se₃] with [ClRu(μ-Cl)(p-cymene)]₂ also yielded a mononuclear tris-homocubane analogue [Ru(p-cymene){Se₇(BH)₃}] (3) which is an analogue of 1,3,3-tris-homocubane and possesses D₃ symmetry. In order to isolate the Cp* analogue of 1, the reaction of [Cp*Ru(μ-Cl)Cl]₂ with Li[BH₂S₃] was carried out, which led to the formation of bis/tris-homocubane derivatives [(Cp*Ru)₂{μ-S_n(BH)₂}] (n = 7 (4) and 6 (5)) along with the formation of ruthenium disulfide complexes [(RuCp*)₂(μ,η²:η²-S₂)(μ,η¹:η¹-S₂)] and [(RuCp*)₂(μ-SBHS-κ¹B:κ²S:κ²S)(μ,η¹:η¹-S₂)]. Complexes 1-5 have been characterized by multi-nuclear NMR, IR, UV-vis spectroscopy, and mass spectrometry and their molecular formulations (except 2) have been determined by single crystal X-ray crystallography. Furthermore, DFT calculations were performed that rationalize the stabilization of the dichalcogenide units (E₂^2-) by the tetrametallic systems in 1-2.

A combined experimental and theoretical study of bimetallic bis- and tris-homocubane analogues

Various bimetallic bis- and tris-homocubane analogues of group 9 transition metals have been isolated and structurally characterized employing Li[BH₂E₃] (E = S or Se).

Homocubane Chemistry: Synthesis and Structures of Mono- and Dicobaltaheteroborane Analogues of Tris- and Tetrahomocubanes

Room-temperature reactions between [Cp*CoCl]2 (Cp* = η5-C5Me5) and large excess of [BH2E3]Li (E = S or Se) led to the formation of homocubane derivatives, 1-7. These species are bimetallic tetrahomocubane, [(Cp*Co)2(μ-S)4(μ3-S)4B2H2], 1; bimetallic trishomocubane isomers, [(Cp*Co)2(μ-S)3(μ3-S)4B2H2], 2 and 3; monometallic trishomocubanes, [M(μ-E)3(μ3-E)4B3H3] [4: M = Cp*Co, E = S; 5: M = Cp*Co, E = Se and 6: M = {(Cp*Co)2(μ-H)(μ3-Se)2}Co, E = Se], and bimetallic homocubane, [(Cp*Co)2(μ-Se)(μ3-Se)4B2H2], 7. As per our knowledge, 1 is the first isolated and structurally characterized parent prototype of the 1,2,2',4 isomer of tetrahomocubane, while 3, 4, and 5 are the analogues of parent D 3-trishomocubane. Compounds 2 and 3 are the structural isomers in which the positions of the μ-S ligands in the trishomocubane framework are altered. Compound 6 is an example of a unique vertex-fused trishomocubane derivative, in which the D 3-trishomocubane [Co(μ-Se)3(μ3-Se)4B3H3] moiety is fused with an exopolyhedral trigonal bipyramid (tbp) moiety [(Cp*Co)2(μ-H)(μ3-Se)2}Co]. Multinuclear NMR and infrared spectroscopy, mass spectrometry, and single crystal X-ray diffraction analyses were employed to characterize all the compounds in solution. Bonding in these homocubane analogues has been elucidated computationally by density functional theory methods.

Chalcogen stabilized trimetallic clusters: synthesis, structures, and bonding of [(Cp*M)3(E)6+m(BH)n] (M = Nb or Ta; E = S or Se; m = 0 or 1 or 2; n = 0 or 1)

An unusual trimetallic octaselenide complex, [(Cp*Ta)₃(μ-Se)₄{μ-Se₂(Se₂)}], has been synthesized and structurally characterized.