Synthesis and X-ray crystal structure of 3-cyclopentadienyl- 9-(acetomercuro)-3-cobalta-1,2-dicarba-closo-dodecaborane

Abstract

with (AcO) 2 Hg in CH 2 Cl 2 /AcOH (7:1) leads mainly to 9-acetomercuro-cobaltacarborane 2. In addition, 8-mono-and 9,12-dimercurated products 3 and 4 were isolated in small yields. The XRay structural analysis of 2 reveals the Hg-B bond length of 2.10(1) Å.

Substitution reactions at boron atoms in metallacarboranes

“…77 Mercuration of compound 7 was examined in the studies. 75,78 It was noted that different products can be prepared by varying the reaction conditions. For example, mercuration under severe conditions, i.e., the reaction of cobaltacarborane 7 with mercury trifluoroacetate in trifluoroacetic acid followed by treatment with NaCl in a water ± acetone system, afforded the disubstituted derivative 9,12-(ClHg) 2 -3-Cp-3,1,2-CoC 2 B 9 H 9 (20) and polymercuration products (Scheme 5).…”

“…The structure of the 9-substituted monomercury derivative was confirmed by X-ray diffraction analysis. 78 A diacetomercury-substituted derivative was prepared by the reaction of compound 7 with mercury acetate in acetic acid, whereas the reaction in the CH 2 Cl 2 ± AcOH system gave rise to a disubstituted complex along with two isomeric 8-and 9-substituted monomercury derivatives. The 9-chloromercury derivative 9-ClHg-3-Cp- dichloromethane mixture followed by the replacement of the trifluoroacetoxy group with chlorine (Scheme 6).…”

“…Its structure was determined by X-ray diffraction analysis. 118 The reactions with an excess of alkyne RC:CH (R = Bu t , Me (78). 118 Interestingly, the reaction of ruthenacarborane 3-CO-3-Ph 3 P-3-THF-3,1,2-RuC 2 B 9 H 11 (79) containing the triphenylphosphine ligand with a threefold excess of PhC:CH is accompanied by the selective replacement of the hydrogen atom at position 4 nearest to the carbon atom of the dicarbollyl ligand to form the 4,3-(s,Z 2 -PhCH=CH)-3-CO-3-Ph 3 P-3,1,2-RuC 2 B 9 H 10 complex (80), whose structure was established by X-ray diffraction analysis.…”

“…{ The synthesis of derivatives 21 and 28 was described in the studies. 78,83 Analysis of the published data on substitution in metallacarboranes makes it possible to compare these reactions with analogous reactions of other polyhedral boron hydrides and draw a conclusion about the influence of the metal atom and the coordinated ligands as well as of the substituents in the polyhedral moiety on the direction of substitution and possible mechanisms of the process.…”