Synthesis and Crystal Structures of Sodium and Calcium ­Complexes with the LigandN-(2,6-Dimethylphenyl)diphenylphosphinic Amide

Synthesis and Oligonuclear Structures of Strontium and Barium Complexes with Protonated and Deprotonated N-Mesityl-P,P-diphenylphosphinic Amide Ligands

Metalation of N-mesityl-P,P-diphenylphosphinic amide Ph₂P(O)-NHMes (HL, I) with MgBu₂ and Ae{N(SiMe₃)₂}₂ (Ae = Ca, Sr, and Ba) yields alkaline-earth metal complexes with the compositions of [(thf)_nAe(L·HL)₂] [Ae/n = Mg/0 (II), Ca/2 (III)] as well as of [Sr₂L₃(L·HL)(HL)] (1), [Ba₂L₃(L·HL)(HL)] (2), [Ba₃L₆] (3), and [(thf)₂Ba₃L₆] (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 Ph₂P(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)₃Ba(μ-L)₃Ba] (3), a rigid adjustment of the anionic L bases leads to a C₃-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)₃Ba(μ-L)₃Ba(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.

Recent progress in the application of group 1, 2 & 13 metal complexes as catalysts for the ring opening polymerization of cyclic esters

This review focuses on recent developments concerned with the use of well-defined main group complexes as (pre-)catalysts for the ROP of cyclic esters to give aliphatic polyesters; factors influencing catalytic activity, selectivity and polymer properties are all discussed.

N-(3,5-Dimethylphenyl)-P,P-diphenylphosphinic amide

In the title compound, C20H20NOP, the P atom, with a distorted tetrahedral geometry, is attached to an O atom, two phenyl groups, and a 3,5-dimethylaniline group. The N—P—C [102.29 (12) and 108.97 (12)°] and C—P—C [107.14 (12)°] bond angles are all smaller than the ideal 109.5° tetrahedral bond angle, whereas the O—P—C [113.07 (12) and 110.62 (12)°] and O—P—N [114.24 (13)°] angles are all larger than 109.5°. A weak intramolecular C—H...O hydrogen bond helps to establish the molecular conformation. In the crystal, the molecules are linked by N—H...O hydrogen bonds, generating [001] chains.

Synthesis, crystal structures and magnetic properties of six coordination compounds constructed with pyridine iminomethyl–TEMPO radicals and [M(hfac)2] (M = CuII and MnII)

We describe the crystal structures and magnetic properties of six coordination metal-(R-Py-iminomethyl-TEMPO) radical compounds.

Imidazol-2-ylidene-N′-phenylureate ligands in alkali and alkaline earth metal coordination spheres – heterocubane core to polymeric structural motif formation

Synthetic and structural details of imidazol-2-ylidene-N′-phenylureate ligand supported two potassium complexes with a hetero-cubane K₄O₄ core and a polymeric structure, along with a mixed metal Ca–K complex are presented.

Synthesis, crystal structures and magnetic behaviour of four coordination compounds constructed with a phosphinic amide-TEMPO radical and [M(hfac)2] (M = Cu(II), Co(II) and Mn(II))

In the present work we describe the synthesis, crystal structures and magnetic properties of four coordination compounds obtained by assembling a new phosphinic amide containing the TEMPO moiety, 1-piperidinyloxy-4-[(diphenylphosphinyl)amino]-2,2,6,6-tetramethyl radical (dppnTEMPO), with [M(hfac)2] building blocks (M = Cu(II), Co(II), Mn(II)). The crystal structures of the coordination compounds revealed the usefulness of the functionalized radical to provide discrete or extended architectures. In the copper compound () the ligand is coordinated through the oxygen atom of the NP[double bond, length as m-dash]O linkage to the metal, which exists in a square pyramidal or octahedral geometry. For the cobalt and manganese complexes (), both the phosphinic amide and the nitroxide oxygen atoms are involved in the coordination to the metal leading to one dimensional systems. In the cobalt complex () an interesting spin topology in the zig-zag chain was obtained due to the oxygen atom of the phosphinic amide group being μ2 coordinated to two cobalt(ii) ions. The magnetic behaviour of the coordination compounds shows overall antiferromagnetic interactions involving the metal ion and the organic radical. DFT calculations were performed in order to assign the main path for the magnetic interactions.