Structural Diversity of Lithium, Sodium, and Potassium Complexes of N ‐Mesityl‐ P,P ‐diphenylphosphoryl Amide

Metalation of N ‐mesityl‐ P , P ‐diphenylphosphinic amide Ph 2 P(=O)–N(H)Mes ( 1 ) with n ‐butyllithium, sodium amide and potassium hydride yields the corresponding alkali metal N ‐mesityl‐ P , P ‐diphenylphosphoryl amides of lithium ( 2 ), sodium ( 3 ), and potassium ( 4 ). The lithium complex 2 forms a dimer with an eight‐membered (Li–O–P–N) 2 ring. The sodium derivative 3 crystallizes as a dinuclear centrosymmetric complex with a central Na 2 O 2 ring. The potassium congener 4 precipitates as a tetranuclear compound with an inner K 4 O 4 heterocubane cage. In these complexes the phosphoryl amido ligands act as bidentate Lewis bases and form strained four‐membered M –O–P–N rings. Due to this fact, the endocyclic M –O bonds of the M 2 O 2 rings vary within a large range.