Ever increasing demand for green and sustainable chemical processes has set up a drive to replace transition metals with earth-abundant, nontoxic, and environmentally benign alternatives. In this regard, the alkaline earth metal complexes have attracted significant attention. Herein, we have used a β-diketiminato ligand with methyl-pyridine side arm to synthesize magnesium (1) and calcium (2) compounds. The constitutions of 1 and 2 have been confirmed by single crystal X-ray studies, which show that the magnesium and calcium atom in 1 and 2 possesses octahedral geometry. Subsequently, we have used them as catalysts (1 mol %) for hydroboration of a wide range of aldehydes using pinacolborane (HBpin) at room temperature. The strategy has further been extended to ketones with 2 mol % catalyst loading. DFT calculations have been performed to understand the mechanism.

The NHC•borane chemistry has been majorly restricted to imidazol-2-ylidene classes of carbenes. In our previous communication, we have reported the synthesis of 6-SIDipp•BH3 [6-SIDipp = 1,3-di(2,6-diisopropylphenyl) tetrahydropyrimidine-2-ylidene] and its electrophilic...

Organocalcium compounds have been reported as efficient catalysts for various transformations, for cases in which one of the substrates contained an E-H (E=B, N, Si, P) bond. Here, we look at the possibility of employing an organocalcium compound for a transformation in which none of the precursors has a polar E-H bond. This study demonstrates the utilization of a well-defined amidinatocalcium iodide, [PhC(NiPr) CaI] (1) for cyanosilylation of a variety of aldehydes and ketones with Me SiCN under ambient conditions without the need of any co-catalyst. The reaction mechanism involves a weak adduct formation between 1 and Me SiCN leading to the activation of the Si-C bond, which subsequently undergoes σ-bond metathesis with a C=O moiety. Such a mechanistic pathway is unprecedented in alkaline earth metal chemistry. Experimental and computational studies support the mechanism.