Synthesis of Novel Pseudocloso Ruthenacarboranes based on an Unsubstituted nido‐C₂B₉H₁₁²⁻ Ligand

Abstract

The reaction of the known closo-ruthenacarborane 3-H-3-Cl-3,3-(PPh 3 ) 2 -closo-3,1,2-RuC 2 B 9 H 11 with tridentade nitrogen-based ligands of the general formula (C 5 NH 4 CH 2 ) 2 NR (R=H, Me, Et, iPr, Bu t ) in benzene solution at 60 °C allowed us to isolate novel ruthenacarborane clusters 3,3,3-(2'-NC 5 H 4 CH 2 ) 2 NR-pseudocloso-3,1,2-RuC 2 B 9 H 11 . According to the performed X-ray study, the obtained compounds are the first examples of pseudoclosometallacarboranes bearing unsubstituted C 2 B 9 2À nido-carborane ligand. In spite of the determined pseudocloso structure of the complexes in the solid state, the recorded 11 B{ 1 H} NMR spectra indicate that some of them are converted into the closo isomers in solution. The conducted quantum-chemical calculations have confirmed the subtle difference between two configurations and possible rearrangement in solution. The performed electrochemical investigations show the ability of the formed ruthenacarboranes to undergo reversible oxidation to Ru(III) species.

Cyclic Voltammetry Study of Closo-Ruthenacarboranes

“…Ruthenacarboranes 11a-11e exhibit 18-e species and contain tridentate nitrogen-based ligands in their structure. Another peculiarity of the mentioned compounds is a so-called pseudocloso conformation of carborane ligand with enlarged C-C distance exceeding the sum of covalent radii [35]. These compounds are capable of reversible reduction at potentials close to E 1/2 of the Fc|Fc + couple.…”