N-heterocyclic germylenes : structural characterisation of some heavy analogues of the ubiquitous N-heterocyclic carbenes

Dodds, Christopher A. and Kennedy, Alan R. and Spicer, Mark D. (2019) N-heterocyclic germylenes : structural characterisation of some heavy analogues of the ubiquitous N-heterocyclic carbenes. Heteroatom Chemistry, 2019. 9178371. ISSN 1042-7163

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    Abstract

    The X-ray crystal structures of three N-heterocyclic germylenes (NHGes) have been elucidated including the previously unknown 1,3-bis(2,6-dimethylphenyl)diazagermol-2-ylidene (1). In addition, the X-ray crystal structures of the previously synthesised 1,3-bis(2,4,6-trimethylphenyl)diazagermol-2-ylidene (2) and 1,3-bis(2,6-diisopropylphenyl)diazagermol-2-ylidene (3) are also reported. The discrete molecular structures of compounds 1 to 3 are comparable, with Ge-N bond lengths in the range 1.835-1.875 Å, while the N-Ge-N bond angles range between 83.6 and 85.2°. Compound 2 was compared to the analogous N-heterocyclic carbene species, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes). The major geometrical difference observed, as expected, was the bond angle around the divalent group 14 atom. The N-Ge-N bond angle was 83.6° for compound 2 versus the N-C-N bond angle of 101.4° for IMes. The Sn equivalent of (1), 1,3-bis(2,6-dimethylphenyl)diazastannol-2-ylidene (4), has also been synthesised and its crystal structure is reported here. In order to test their suitability as ligands, compounds 1 to 3 were reacted with a wide range of transition metal complexes. No NHGes containing metal complexes were observed. In all cases the NHGe either degraded or gave no reaction.

    ORCID iDs

    Dodds, Christopher A. ORCID logoORCID: https://orcid.org/0000-0002-4590-0307, Kennedy, Alan R. ORCID logoORCID: https://orcid.org/0000-0003-3652-6015 and Spicer, Mark D. ORCID logoORCID: https://orcid.org/0000-0002-6000-5677;