Synthesis and structures of the transition metal(II) β-diketiminates [ML2] (M = Mn, Fe, Ni, Cu, Pd), [ML2′] (M = Ni, Cu) and [M(η3-C3H5)L] (M = Ni, Pd); L or L′ = [{N(SiMe3 or H)C(Ph)}2CH]

Abstract A series of crystalline late transition metal β-diketiminates 1 – 10 , using the ligand [{N(SiMe 3 )C(Ph)} 2 CH] − (≡ L − ) or [{N(H)C(Ph)} 2 CH] − (≡ L′ − ) is reported. The homoleptic pseudo-tetrahedral crystalline complexes [M(L) 2 ] [M = Mn ( 1 ), Fe ( 2 ), Ni ( 3 ), Cu ( 5 ) were prepared from [Li(L)] 2 and the appropriate anhydrous MCl 2 in thf. The planar metal analogues [M(L′) 2 ] [M = Ni ( 4 ), Cu ( 6 )] were obtained for 4 from NiCl 2 and [Li(L)] 2 in thf followed by chromatography on hydrated alumina, or for 6 from hydrated CuSO 4 and either [Li(L)] 2 or H(L). The precursor for [Pd(L) 2 ] ( 7 ) and [{Pd(L)(μ-Cl)} 2 ] ( 8 ) was [Pd(cod)Cl 2 ] (one or two molar equivalents), while the allyl complexes [Pd(η 3 -C 3 H 5 )(L)] ( 9 ) or [Ni(η 3 -C 3 H 5 )(L)] ( 10 ) were prepared from [{Pd(η 3 -C 3 H 5 )(μ-Cl)} 2 ] or [{Ni(η 3 -C 3 H 5 )(μ-Br)} 2 ], respectively. Whereas in each of the crystalline complexes 1 – 6 the MNCCCN rings are planar, in the centrosymmetric 7 and in 9 they are boat-shaped. The compounds 1 , 2 , 3 , 5 and 6 (unlike 4 , 7 , 8 and 9 ) are paramagnetic; the magnetic moment in CDCl 3 corresponds approximately to a low-spin complex for 1 and a high-spin complex for 2 . The molecular structures of the crystalline compounds (X-ray data) 2 , 3 , 4 , 5 , 6 , 7 and 9 are presented. Quantum chemical calculations (B3LYP) on the Ni( 3 ) and Pd( 7 ) complexes correlated well with the experimental structures, although the calculated Gibbs free energy for both tetrahedral and square-planar geometries showed the latter configuration more stable than the former by ca. 60 (Ni) and 100 (Pd) kJ mol −1 over a range of temperatures.