Palladium and platinum complexes of a benzannulated N-heterocyclic plumbylene with an unusual bonding mode.

Reaction of the N,N'-diisobutyl-substituted benzannulated N-heterocyclic plumbylene (NHPb) 1 with [Pd(PPh(3))(4)] and [Pt(PPh(3))(4)] gave the complexes [M(NHPb)(PPh(3))(3)] (M = Pd [2], Pt [3]). X-ray diffraction studies of both complexes showed an angle of ~125° between the plumbylene plane and the transition-metal-Pb axis, indicating coordination of the transition metal to the empty π orbital of the plumbylene Pb atom. The experimentally determined metric parameters of complexes [2] and [3] are discussed on the basis of DFT calculations.

Low coordinate lanthanide(II) complexes supported by bulky guanidinato and amidinato ligands.

The preparation of a series of homoleptic, four-coordinate lanthanide(ii) complexes, [Ln(Priso)(2)] (Ln = Sm, Eu or Yb) incorporating the bulky guanidinate ligand Priso(-) ([(ArN)(2)CNPr(i)(2)](-), Ar = 2,6-diisopropylphenyl) is described. X-ray crystallography shows the complexes to be isostructural and to exhibit coordination geometries midway between tetrahedral and planar. Comparisons between the geometries of the complexes and those of the bulkier systems, [Ln(Giso)(2)] (Giso(-) = [(ArN)(2)CNCy(2)](-), Cy = cyclohexyl) are discussed.

Syntheses and molecular structures of some saturated N-heterocyclic plumbylenes.

Cyclic diamino plumbylenes derived from saturated heterocycles are obtained from deprotonation of diamines and subsequent reaction with PbCl(2), or by reaction of a suitable diamine with Pb[N(SiMe(3))(2)](2). Single crystal X-ray studies have been used to probe the solid state structures of a range of these complexes and have shown the fine balance between monomer and dimer formation which is related to the bulk of the organic group attached to the nitrogen atoms. Dimerisation is also shown to effect structural changes within the core of the heterocyclic plumbylene.

Homoleptic lanthanide(II)-bis(guanidinate) complexes, [Ln(Giso)(2)] (Giso = [(ArN)(2)CN(C(6)H(11))(2)](-), Ar = C(6)H(3)Pr(i)(2)-2,6): planar 4-coordinate (Ln = Sm or Eu) vs distorted tetrahedral (Ln = Yb) geometries.

The first homoleptic lanthanide(II)-guanidinate complexes have been prepared and shown to have differing coordination geometries (including unprecedented examples of planar 4-coordination) that depend on the size of the lanthanide metal.