Formation and Reactivity with tBuCN of a Thorium Phosphinidiide through a Combined Experimental and Computational Analysis

An investigation of the formation of a thorium phosphinidiide reveals that changing from a 2,4,6-iPr3C6H2 (Tipp)-substituted phosphido ligand to a 2,4,6-Me3C6H2 (Mes) ligand forms a similar product, [(C5Me5)2Th]2(P-2,6-CH2C6H2-4-CH3), but via a different sequence of bond activations. The resulting phosphinidiide was reacted with 1 and 2 equiv of tBuCN, leading to mono­(ketimide), [(C5Me5)2Th]2[μ2-P-(2-CH2-6-(NC­(tBu)­(CH2))-4-Me-C6H2)], and bis­(ketimide), [(C5Me5)2Th]2[μ2-P-(2,6-(NC­(tBu)­(CH2))2-4-Me-C6H2)], complexes, respectively, through insertion into the thorium–carbon bonds. An analysis of the Th–P–Th moiety showed a correlation of decreased Th–P–Th bond angle and upfield 31P NMR chemical shift with decreasing Th–P covalent bond character.