Tetra(amino)methanes: Implications of their structure and reactivity pattern for hypothetical carbon nitride frameworks

Article abstract of DOI:10.1002/cber.19971301206

Because of their possible role as model compounds for the structural units of carbon nitride C₃N₄, the preparation, structural chemistry, and some representative reactions of tetra(amino)methanes have been (re)investigated. In the crystal, C(NMe₂)₄ (1) has a molecular geometry close to D_2d symmetry as proposed by theoretical calculations using state-of-the-art density functional methods. The coordination of the central carbon atom is distorted tetrahedral and the configuration of the nitrogen atoms is strongly pyramidal, as opposed to almost planar in the tetra(amino)silanes. Tetra(pyrrolidinyljmethane has a similar core structure, with all heterocyclic substituents in an envelop conformation flexible in solution. Tetra(piperidinyl)methane is more rigid in solution, owing to a more congested structure, with much higher inversion barriers for the six-membered rings. Hydrolysis of 1 leads to Me₂NH and hexamethylguanidinium hydroxide, and treatment of 1 with HAuCl₄(aq) affords crystalline [C(NMe₂)₃]⁺ AuCl₄^-, the structure of which has also been determined. Compound 1 is a strong nucleophile and can be used as an aminating agent, converting e.g. halosilanes into dimethylaminosilanes, with the guanidinium cation as the leaving group. The experimental results are discussed in the light of recent predictions regarding bulk carbon nitrides. WILEY-VCH Verlag GmbH, 1997.