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Metalation of N‐mesityl‐P,P‐diphenylphosphinic amide with nBuLi in toluene yields tetranuclear lithium N‐mesityl‐P,P‐diphenylphosphinimidate ([Ph2P(OLi)=N−Mes]4, 1). Metalation of Ph2P(O)−N(H)Mes with a mixture of dibutylmagnesium and butyllithium in DME leads to formation of dinuclear [Ph2P{OLi(dme)}=N−Mes]2 (2). Excess of Ph2P(O)−N(H)Mes gives dinuclear [Li(O−PPh2=N−Mes){Ph2P(=O)−N(H)−Mes}]2 (3) with three‐coordinate alkali ions. The metathetical approach via reaction of 1 with anhydrous magnesium bromide in ethereal solution yields [{(thf)LiBr}2{(thf)Li(O−PPh2=NMes)(Et2O)Li(O−PPh2=NMes)}] (4). Heterobimetallic Li/Mg compounds are not accessible by these protocols. Reactions of 1 with DME, with excess of Ph2P(O)−N(H)Mes or with LiBr allows the straightforward conversion to compounds 2, 3 and 4. [ABSTRACT FROM AUTHOR]

Metalation of N -mesityl- P , P -diphenylphosphinic amide Ph 2 P(O)-NHMes (HL, I ) with MgBu 2 and Ae{N(SiMe 3 ) 2 } 2 (Ae = Ca, Sr, and Ba) yields alkaline-earth metal complexes with the compositions of [(thf) n Ae(L·HL) 2 ] [Ae/n = Mg/0 ( II ), Ca/2 ( III )] as well as of [Sr 2 L 3 (L·HL)(HL)] ( 1 ), [Ba 2 L 3 (L·HL)(HL)] ( 2 ), [Ba 3 L 6 ] ( 3 ), and [(thf) 2 Ba 3 L 6 ] ( 4 ). In III , 1 , 2 , and 3 , the alkaline-earth metal atoms are in severely distorted octahedral environments, and the structural distortions are partially caused by the small O-Ae-N bite angles of the chelating Ph 2 P(O)-NMes anions. The substructures (L·HL) contain N-H···N hydrogen bridges, stabilizing the arrangement of the ligands in complexes II , III , 1 , and 2 . In the trinuclear barium complex [Ba(μ-L) 3 Ba(μ-L) 3 Ba] ( 3 ), a rigid adjustment of the anionic L bases leads to a C 3 -symmetric molecule in the crystalline state with bridging oxygen atoms. Due to the small O-Ba-N bite angles of the chelating anions, vacant coordination sites are available at the outer barium centers. Coordination of thf bases in these gaps yields the complex [(thf)Ba(μ-L) 3 Ba(μ-L) 3 Ba(thf)] ( 4 ). However, THF is unable to deaggregate the trinuclear complexes into smaller barium-containing moieties. Increasing the radius of the alkaline-earth metals and increasing the nuclearity of these compounds lead to decreasing solubility in common organic solvents. NMR studies verify that the molecular structures of these alkaline-earth metal complexes are maintained in ethereal solvents and toluene., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)