Much like chocolate, some of us metallaholics cannot get enough. So WUQXIP proved an irresistible frolic (DOI: 10.1021/om020789h). Let us start with benzene. It can have metals added in two ways, whilst preserving its essential aromaticity.
Making a metal sandwich is of course very well known, ferrocene being the first example where the bonding was identified. Replacing a carbon with a metal is a little more recent, having been suggested by Hoffmann in 1979. This is known as a metallabenzene. The compound below combines both features.

WUQXIP. Click for 3D

ELF basins for WUQXIP. Click for 3D
Tags: Albrecht Salzer, Frank Podewils, Hypervalency, Martin Kaupp, metal, metal delight, metal sandwich, metal-metal bond, metallabenzene, metallocene, three-centre bonding, triple metal bonding delight, Triple metal delight, Trixie Wagner, Ulli Englert, Ulrike Effertz