Mono- and Diaminocarbenes from Chloroiminium and -amidinium Salts:  Synthesis of Metal-Free Bis(dimethylamino)carbene

Bis(trimethylsilyl)mercury cleanly reacts at low temperature with chloroamidinium and -iminium chlorides, generating persistent metal-free cyclic and acyclic diaminocarbenes, as well as transient aryl-, chloro-, and hydrogenoaminocarbenes; with the latter, the corresponding olefin dimers were isolated, whereas with the former, no dimerization processes were observed.