Synthesis, Structure, and Bonding of d⁰/fⁿ Metallacarboranes Incorporating the η⁷-Carboranyl Ligand

Abstract

Treatment of 1,2-(C 6 H 5 CH 2 ) 2 -1,2-C 2 B 10 H 10 with excess Na or Li metal in THF followed by reaction with MCl 3 in the presence of excess alkali metal gave novel 13-vertex closo-metallacarboranes 5), Er ( 6)) in moderate to good yield, respectively. Recrystallization of 3 from a DME solution afforded DME-coordinated metallacarborane {[(C 6 H 5 CH 2 ) 2 C 2 B 10 H 10 ]Er(DME)} 2 {Na(DME) 2 } 2 (4). 2 and 5 are the first examples of d 0 metallacarboranes incorporating a η 7 -carboranyl ligand. All of these complexes have been fully characterized by various spectroscopic date, elemental analyses, and X-ray diffraction studies. Molecular orbital calculations indicate that the metal-carborane bonding is well delocalized and can be described as the orbital interactions between the metal's five d orbitals and the cage's five symmetryadapted frontier orbitals. It is anticipated that only the d 0 /f n transition metal ion with the proper size is capable of being η 7 -bound to an arachno-carboranyl ligand.

Synthesis and Structural Chemistry of Non-Cyclopentadienyl Organolanthanide Complexes

“…Recrystallization of the Er complex from DME affords DME-solvated {[(C 6 H 5 CH 2 ) 2 C 2 B 10 H 10 ]Er(DME)} 2 {Na(DME) 2 } 2 (115). 195 The synthesis of a full-sandwich η 7 -C 2 B 10 -lanthanacarborane was achieved by use of the carboranefluorene ligand [Me 2 Si(C 13 H 8 )(C 2 B 10 H 11 )]Li(OEt) 2 (116) made from Li 2 [C 2 B 10 H 10 ] and Me 2 Si(C 13 H 9 )Cl. Reaction of equimolar amounts of 116, YbCl 3 , Na metal, and Me 3 NHCl in THF results in formation of {{[η 7 -Me 2 Si(C 13 H 9 )(C 2 B 10 H 11 )] 2 Yb III } 2 Yb II }{Na 8 -(THF) 20 } (117).…”

Unexpected Intramolecular Oxidative Addition: Novel Synthetic Route to High-Valent Group 4 Metallacarboranes Bearing a η6- or η7-Carboranyl Ligand

“…9 The 13-vertex closo-metallacarboranes of the type [η 6 -(C 6 H 5 CH 2 ) 2 C 2 B 10 H 10 ]MCl(THF) x are believed to serve as intermediates which accept two more electrons from Na metal to form the final product. 9 This methodology is, however, not suitable for the preparation of the highvalent group 4 metallacarboranes, since M(IV) can be reduced to M(II) in the presence of group 1 metals or [nido-R 2 C 2 B 10 H 10 ] 2-ions. 4,10 Therefore, a new method is definitely desirable.…”

New class of metallacarboranes incorporating the η7-carboranyl ligand

“…Interaction between o-carborane and excess alkali metal in tetrahydrofuran (THF) followed by treatment with AnCl 4 gave {[(η 7 -C 2 B 10 H 12 )(η 6 -C 2 B 10 H 12 )An][M 2 (THF) 5 ]} 2 [M = Na, K; An = Th (1), U (2)]. 2 has been subjected to an X-ray diffraction study.…”

“…Each asymmetrical unit contains two [η 5 :η 7 -Me 2 C(C 5 H 4 )(C 2 B 10 H 11 )]Er 2-structural motifs that are connected by three Na atoms through several B-H-Na 2e-3c bonds (Fig. 3).…”

“…The asymmetrical units are then linked to each other via B-H-Er bonds to form an infinitive polymeric chain. An X-ray analysis reveals that 5 is a centrosymmetric tetranuclear lanthanacarborane cluster with two {[η 5 :η 7 -Me 2 C(C 5 H 4 )(C 2 B 10 H 11 )]Er 2 (µ-Cl)(THF) 3 } units that are connected by two sets of three B-H-Er 2e-3c bonds (Fig. 4).…”