Insertion reactions of beta-diketiminate-stabilised calcium amides with 1,3-dialkylcarbodiimides.

A series of heteroleptic beta-diketiminate-stabilised calcium amides of the form [{ArNC(Me)CHC(Me)NAr}Ca{NR1R2}(THF)] (Ar = 2,6-diisopropylphenyl; R1 = H, R2 = Ar; R1 = H, R2 = CH2CH2OMe; R1 = R2 = Ph) react with 1,3-dialkylcarbodiimides, R3NCNR3 (R3 = Cy, iPr), to yield the corresponding insertion products [{ArNC(Me)CHC(Me)NAr}Ca{(R3N)2CNR1R2}(THF)] at room temperature in hydrocarbon solutions. These latter compounds contain both beta-diketiminate and guanidinate ligands bound to calcium. Solid-state data are consistent with the guanidinate ligands adopting a number of binding modes including 2 through 3 coordination, with varying degrees of delocalisation of the non-bound guanidinate nitrogen lone-pair across the -framework of the ligand. DFT computational studies have been conducted to address these variations in coordination behaviour.