CO reduction by calcium and ytterbium hydride complexes with a bulky monodentate carbazolyl ligand.

The bulky monodentate carbazolyl ligand 1,8-bis(3,5-di tert butylphenyl)-3,6-di tert butylcarbazole ( dtbp Cbz) was employed in the synthesis of monomeric heteroleptic amido carbazolyl complexes of Ca and Yb. For both central metal atoms, dimeric hydride complexes [( dtbp Cbz)Ca(benzene)H] 2 , [( dtbp Cbz)Ca(THF)H] 2 , [( dtbp Cbz)Yb(benzene)H] 2 and [( dtbp Cbz)Yb(THF)H] 2 were obtained, which show remarkably poor solubility in organic solvents. The characteristic hydride 1 H NMR resonance of [( dtbp Cbz)Ca(benzene)H] 2 was observed at 2.07 ppm, and for the first time, characteristic vibrational modes of the Ca 2 H 2 and Yb 2 H 2 moiety are discussed. Despite their poor solubility, the hydride complexes could be reacted with CO to yield the corresponding ethenediolate complexes.