Intramolecularly donor-stabilized silenes: Part 3. Synthesis and structure of 1-[2,6-bis(dimethylaminomethyl)phenyl]-1,2,2-tris(trimethylsilyl)silene

1-[2,6-Bis(dimethylaminomethyl)phenyl]-1,2,2-tris(trimethylsilyl)silene (9) was prepared by treatment of (dichloromethyl)tris(trimethylsilyl)silane (3) with 2,6-bis(dimethylaminomethyl)phenyllithium (molar ratio 1:2). 9 is a crystalline compound, indefinitely stable at room temperature. The X-ray structural analysis of 9 characterized the compound as an intramolecularly amine-stabilized silene with four-coordinate silicon, i.e. only one of the two amine groups of the bis(dimethylaminomethyl)phenyl substituent is coordinated to the electrophilic silicon center (SiN distance 2.035(3) Å). Thus, the silene silicon atom is pyramidalized (sum of angles 348.49°), whereas the configuration at the silene carbon atom is trigonal planar (sum of angles 359.9°). The SiC bond length was found to be 1.759(3) Å. Reaction of 9 with water or methanol led to the addition of these nucleophiles to the SiC bond, producing the silanol 12 and the methoxysilane 13, respectively. The reaction pathway leading to 9 is discussed.