Syntheses and Structures of Alkaline Earth Metal Bis(diphenylamides)

Various preparative procedures are employed in order to synthesize alkaline earth metal bis(diphenylamides) such
as (i) metalation of HNPh2 with the alkaline earth metal M, (ii) metalation of HNPh2 with MPh2, (iii) metathesis
reaction of MI2 with KNPh2, (iv) metalation of HNPh2 with PhMI in THF, and (v) metathesis reaction of PhMI with
KNPh2 followed by a dismutation reaction yielding MPh2 and M(NPh2)2. The magnesium compounds [(diox)MgPh2]∞
(1) and (thf)2Mg(NPh2)2 (2) show tetracoordinate metal atoms, whereas in (dme)2Ca(NPh2)2 (3), (thf)4Sr(NPh2)2 (4),
and (thf)4Ba(NPh2)2 (5) the metals are 6-fold coordinated. Additional agostic interactions between an ipso-carbon
of one of the phenyl groups of the amide ligand and the alkaline earth metal atom lead to unsymmetric coordination
of the NPh2 anions with two strongly different M−N−C angles in 3−5.