Sulfurization of anionic N-heterocyclic dicarbene, [:C{[N(2,6-Pri2C6H3)]2CHCLi}]n (2), with elemental sulfur (in a 1:2 ratio) in Et2O at low temperature gives 3 by inserting two sulfur atoms into the Li–C (i.e., C2 and C4) bonds in polymeric 2. Further reaction of 3 with 2 equiv of elemental sulfur in THF affords 4• via unexpected C–H bond activation, which represents the first anionic dithiolene radical to be structurally characterized in the solid state. Alternatively, 4• may also be synthesized directly by reaction of 1 with sulfur (in a 1:4 ratio) in THF. Reaction of 4• with GeCl2·dioxane gives an anionic germanium(IV)–bis(dithiolene) complex (5). The nature of the bonding in 4• and 5 was probed by experimental and theoretical methods.

Reaction of carbene-stabilized disilicon (1) with Fe(CO)5 gives the 1:1 adduct L:Si=Si[Fe(CO)4 ]:L (L:=C{N(2,6-Pr(i) 2 C6 H3 )CH}2 ) (2) at room temperature. At raised temperature, however, 2 may react with another equivalent of Fe(CO)5 to give L:Si[μ-Fe2 (CO)6 ](μ-CO)Si:L (3) through insertion of both CO and Fe2 (CO)6 into the Si2 core, which represents the first experimental realization of transition metal-carbonyl-mediated cleavage of a Si=Si double bond. The structures and bonding of both 2 and 3 have been investigated by spectroscopic, crystallographic, and computational methods.

While reaction of carbene-stabilized disilicon L:Si═Si:L (L: = C{N(2,6-(i)Pr2C6H3)CH}2) (8) with HCl·NC5H5 results in carbene-stabilized Si2Cl2 (2) and substituted 1H-imidazole (9), combination of the corresponding Fe(CO)4-modified disilicon carbene complex L:Si═Si[Fe(CO)4]:L (6) with pyridine hydrochloride gives a species containing two push-pull-stabilized parent monochlorosilylenes that are bridged by an Fe(CO)3 unit (7). The nature of 7 was further elucidated by spectroscopic, crystallographic, and computational methods. Spectroscopic data suggest that 7 exists as two diastereoisomers.

Reaction of carbene-stabilized diphosphorus, L:P-P:L (5) (L: = :C{N(2,6-Pr(i)2C6H3)CH}2) with pyridine hydrochloride yields [L:(H)P-P:L]Cl (6), a salt containing the HP2(+) cation--the elusive phosphorus analogue of the well known diazonium cation, HN2(+). In addition to reporting the synthesis and structure, the nature of (6) was further probed by DFT computations. Interestingly, carbenes may be employed to deprotonate (6), affording the starting material (5).