title: Stabilization of a two-coordinate mononuclear cobalt(0) compound.
abstract: Compound (Me2 -cAAC:)2 Co(0) (2; Me2 -cAAC:=cyclic (alkyl) amino carbene; :C(CH2 )(CMe2 )2 N-2,6-iPr2 C6 H3 ) was synthesized by the reduction of the precursor (Me2 -cAAC:)2 Co(I) Cl (1) with KC8 in THF. The cyclic voltammogram of 1 exhibited one-electron reduction, which suggests that synthesis of a bent 2-metallaallene (2) from 1 should be possible. Compound 2 contains one cobalt atom in the formal oxidation state zero, which is stabilized by two Me2 -cAAC: ligands. Bond lengths from X-ray diffraction are 1.871(2) and 1.877(2) Å with a C-Co-C bond angle of 170.12(8)°. The EPR spectrum of 2 exhibited a broad resonance attributed to the unique quasi-linear structure, which favors near degeneracy and gives rise to very rapid relaxation conditions. The cAACCo bond in 2 can be considered as a typical Dewar-Chatt-Duncanson type of bonding, which in turn retains 2.5 electron pairs on the Co atom as nonbonding electrons.
authors.affiliation: Institut für Anorganische Chemie, Universität Göttingen, Tammannstrasse 4, 37077 Göttingen (Germany).
authors.forename: Kartik Chandra
authors.initials: KC
authors.lastname: Mondal
authors.forename: Sudipta
authors.initials: S
authors.lastname: Roy
authors.forename: Susmita
authors.initials: S
authors.lastname: De
authors.forename: Pattiyil
authors.initials: P
authors.lastname: Parameswaran
authors.forename: Birger
authors.initials: B
authors.lastname: Dittrich
authors.forename: Fabian
authors.initials: F
authors.lastname: Ehret
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kaim
authors.forename: Herbert W
authors.initials: HW
authors.lastname: Roesky
keywords: EPR spectroscopy; carbenes; cobalt; density functional calculations; synthetic methods