Heterocyclic substituted methanides as promising alternatives to the ubiquitous nacnac ligandDedicated to Professor Frank T. Edelmann on the occasion of his 60th birthday.Electronic supplementary information (ESI) available: Tables of data collection parameters, bond lengths and angles for compounds 1-9, 2D-NMR spectra of 3, 4 and 8, additional crystal structures of 4, 5 and 7, nine X-ray files in CIF format. CCDC 995110-995118. For ESI and crystallographic data in CIF or other electronic format

• Main Authors: Dauer, David-R, Stalke, Dietmar
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c4dt01008f

A series of group 13 complexes containing deprotonated bisheterocyclomethanes have been prepared and structurally as well as spectroscopically characterised. In the case of the parent neutral homo-disubstituted bisheterocyclomethanes bis-(benzoxazol-2-yl)-methane (abbreviated as (NCOC 6 H 4 ) 2 CH 2 ) ( 1 ) and bis-(benzothiazol-2-yl)-methane (abbreviated as (NCSC 6 H 4 ) 2 CH 2 ) ( 2 ), two interesting ligand systems were investigated with respect to their coordination abilities toward group 13 metals. Upon deprotonation of the acidic methylene bridge in each case a β-diketiminate-like structure is formed, where the negative charge becomes delocalised about the whole ligand framework. There is a mesomeric stabilisation between the carbanionic and the amidic resonance structure. The ligands mentioned above were treated with AlMe 3 , AlMe 2 Cl and GaMe 3 to achieve deprotonation of the backbone and coincidental metal complexation. The resulting complexes [Me 2 Al{(NCOC 6 H 4 ) 2 CH}] ( 3 ), [Me 2 Al{(NCSC 6 H 4 ) 2 CH}] ( 4 ), [ClMeAl{(NCOC 6 H 4 ) 2 CH}] ( 5 ), [ClMeAl{(NCSC 6 H 4 ) 2 CH}] ( 6 ), [Me 2 Ga{(NCOC 6 H 4 ) 2 CH}] ( 7 ), and [Me 2 Ga{(NCSC 6 H 4 ) 2 CH}] ( 8 ) were structurally characterized in the solid state by X-ray single crystal diffraction and in solution by different (heteronuclear) 1D/2D-NMR spectroscopic techniques. Each of those molecules shows a nearly planar arrangement with the group 13 metal cation coordinated by the two ring nitrogen atoms of the conjugated heterocycles. Furthermore, in this work (NCOC 6 H 4 ) 3 C(C 3 H 7 ) ( 9 ) could be isolated, which might turn out to be a promising analogue of the omnipresent trisoxazoline ligands in asymmetric catalysis. A series of group 13 complexes containing deprotonated bisheterocyclomethanes have been prepared as well as structurally and spectroscopically characterised.