Synthesis, structure, and bonding of d(0)/f(n) metallacarboranes incorporating the eta(7)-carboranyl ligand

Treatment of 1,2-(C6H5CH2)(2)-1,2-C2B10H10 with excess Na or Li metal in TH F followed by reaction with MCl3 in the presence of excess alkali metal gav e novel 13-vertex closo-metallacarboranes {[(C6H5CH2)(2)C2B10H10]M(THF)}(2) {(Na(THF)(3)}(2). 2THF (M = Dy (1), Y (2), Er (3)) or [{(C6H5CH2)(2)C2B10H1 0}M(THF)](2)-[Li(THF)(4)](2) (M = Y (5), Er (6)) in moderate to good yield, respectively. Recrystallization of 3 from a DME solution afforded DME-coor dinated metallacarborane {[(C6H5CH2)(2)C2B10H10]Er(DME)}(2){Na(DME)(2)}(2) (4). 2 and 5 are the first examples of d(0) metallacarboranes incorporating a eta(7)-carboranyl ligand. All of these complexes have been fully charact erized by various spectroscopic date, elemental analyses, and X-ray diffrac tion studies. Molecular orbital calculations indicate that the metal-carbor ane bonding is well delocalized and can be described as the orbital interac tions between the metal's five d orbitals and the cage's five symmetry-adap ted frontier orbitals. It is anticipated that only the d(0)/f(n) transition metal ion with the proper size is capable of being eta(7)-bound to an arac hno-carboranyl ligand.