An N-heterocyclic carbene adduct of diatomic tin, :SnSn:

Reduction of an N-heterocyclic carbene (NHC) adduct of SnCl (2), viz. (IPr) SnCl (2) (IPr =: CN (Dip) C (H) (2) ; Dip = 2, 6-diisopropylphenyl), with a magnesium (I) dimer, has afforded the first NHC complex of a row 5 element in its diatomic form, (IPr) Sn=Sn (IPr) ; a computational analysis of the complex indicates that it comprises a singlet state, doubly bonded tin (0) fragment,: Sn=Sn: , datively bonded by two NHC ligands.