Methylsulfanyl‐Stabilized Rotamers of Cobalt Bis(dicarbollide)

Abstract

Methylsulfanyl derivatives of cobalt bis(dicarbollide), [8,

Dimethyloxonium and Methoxy Derivatives of nido-Carborane and Metal Complexes Thereof

“…In the 1 H NMR spectra of K [3] and K [4] the signals of methoxy groups are shifted to high field in comparison with 1 and 2 up to 3.22 and 3.17 ppm, respectively, and appear as 1:1:1:1 quartets due to long-range B-H coupling ( 3 J B,H = 3.7-3.8 Hz). Such coupling has also been previously observed for some organoboron compounds [29][30][31][32], methylsulfanyl derivatives of the closo-dodecaborate anion [33,34] and B-methysulfanyl derivatives of cobalt bis(dicarbollide) anion [35].…”

Synthesis and study ofC-substituted methylthio derivatives of cobalt bis(dicarbollide)

“…This nonequivalence can be caused by the participation of the CH groups in the formation of intramolecular CH carb /S hydrogen bonds between the ligands similar to found in the B-substituted methylthio derivatives. 24 In this case, in the rac-isomer [1,1 0 -(MeS) 2 -3,3 0 -Co(1,2-C 2 B 9 H 10 ) 2 ] À both CH groups can form intramolecular CH carb /S hydrogen bonds, while in the meso-isomer…”

“…[32][33][34][35][36] This prompted us to synthesize similar compounds with methylthio derivatives of cobalt bis(dicarbollide). It should be noted that our initial attempt to obtain the BEDT-TTF salt with the with [8,8 0 -(MeS) 2 -3,3 0 -Co(1,2-C 2 B 9 H 10 ) 2 ] À anion was unsuccessful due to the ease of oxidation of sulfur atoms, 24 which, probably, can be explained by the strong electrondonating effect of the cobaltacarborane cage bound via boron atom. On the other hand, in the case of the MeS group attached to the carbon atom, the electron-withdrawing nature of the cobaltacarborane cage should result in an increase of the oxidative stability of the substituent.…”

“…To the best of our knowledge, there are only a few examples of the formation of chalcogen bonds with boron hydrides as acceptors and all them were found in the MeS derivatives of transition metal bis(dicarbollide) complexes. 24,40,41 In the crystal structure, the pairs of A and B enantiomers alternate with the BEDT-TTF radical-cation dimers. In the dimers, the radical-cations are bound by shortened S/S intermolecular contacts in the range 3.378-3.380Å (the sum of the van der Waals radii S/S is 3.60Å).…”

“…In the case of the 4,7 0 -isomer [4,7 0 -(MeS) 2 -3,3 0 -Co(1,2-C 2 B 9 H 10 ) 2 ] À , due to steric reasons the gauche conformation is stabilized by only one pair of the CH carb /S hydrogen bonds. 24 The addition of an external metal of labile metallacomplex to the 8,8 0 -isomer leads to the breaking weak hydrogen bonds and the appearance of stronger dative S/M bonds that accompanies by a change in conformation from transoid to cisoid one. 25 In this contribution we report the synthesis and study of C-methylthio derivatives of cobalt bis(dicarbollide).…”