1,1′-Bis(ortho-carborane) as a κ2 co-ligand

The compounds (dmpe)Ni{κ2-2,2′-[1-(1′-1′,2′-closo-C2B10H10)-1,2-closo-C2B10H10]} (1) and (dppe)Ni{κ2-2,2′-[1-(1′-1′,2′-closo-C2B10H10)-1,2-closo-C2B10H10]} (2) have been synthesised and fully characterised, including crystallographic studies. In all three structures studied (1, 2 and 2·2THF) the metal atom is slightly distorted from square-planar towards tetrahedral (τ4 values [Houser et al., 2007] of 0.30, 0.33 and 0.11, respectively). Consideration of these molecular structures together with those of related species in the literature allows us to tentatively conclude that, in square-planar NiII compounds, the structural trans effect (trans influence) of σ-bonded carborane is greater than that of Cl and sp2 N but less than that of sp2 C and sp3 C.

Graphical abstractTwo compounds are reported in which an approximately square-planar NiII centre is ligated by doubly-deprotonated 1,1′-bis(ortho-carborane) and a chelating diphosphine. The Structural Trans Effect of σ-bonded carborane in this environment is assessed.Figure optionsDownload full-size imageDownload as PowerPoint slide