Synthesis and theoretical studies on rare three-coordinate lead complexes

Abstract

A series of beta-diketiminate lead halide complexes has been synthesised LPbCl (2), LPbBr (3) and LPbI (4) (L = {N(2,6-(i)Pr(2)C(6)H(3))C(Me)}2CH]), which includes a rare example of a three-coordinate lead iodide (4). The chloride and bromide complexes, 2 and 3, are relatively stable in both the solid and solution states, only slowly decomposing to elemental lead over the course of a month in solution, the lead iodide 4 appears to be less stable and decomposes after 3 d in the solid state at ambient temperatures. The lead chloride complex 2 was treated with KN(SiMe3)2 to yield an unusual terminal lead amide complex LPbN(SiMe3)2 (5). Unlike three-coordinate beta-diketiminate transition metal-halide complexes, the ligands are present in a pyramidal arrangement around the lead centre, commonly attributed to the presence of a stereochemically active lone pair. We have investigated the influence of this lone pair on the geometry of the metal halide complexes 2-4, as well as the isostructural germanium and tin complexes (6 and 7, respectively) using DFT calculations. The lone pair in the lead complexes is significantly more diffuse than in the tin and germanium analogues and only a small amount of hybridisation between the 6s and 6p orbitals is observed.

Synthesis and characterization of β-diketiminate germanium(II) and tin(II) bromides

“…This is in contrast to the corresponding bromo derivatives [8]. Independently, Lappert et al and we reported on the b-diketiminate of lead(II) bromo derivative [9,10] [12] with elemental bromine. Herein we outline the preparation and characterization of the monomeric LGeBr (1) and LSnBr (2) [L = HC(CMeNAr) 2 ; Ar = 2,6-iPr 2 C 6 H 3 ] compounds.…”

Reactivity of β-Diketiminato Magnesium Alkyl Complexes: Heterocumulenes and Phosphanes

“…The signals corresponding to the isopropyl group on the N-aryl moiety are broad, indicative of some type of dynamic process occurring in solution, potentially due to hindered rotation of the N-C single bond on the b-diketiminato moiety. [33] A broad signal is visible at d 2.88 ppm, corresponding to the methine proton on the isopropyl groups of the N-aryl moiety. The solid-state structure of 5 is shown in Fig.…”

Heteroleptic lead(II)-halide complexes supported by a bulky iminoanilide ligand

“…No resonance could be detected for 2, perhaps because the complex starts decomposing to unidentifiable species in solution within 3-4 hours, or perhaps owing to strong coupling to iodide (I = 5/2 for 127 I), broadening the resonance that could not be distinguished from the baseline. We note that similarly, the 207 Pb resonance for [{BDI iPr }PbI] has to our knowledge been reported neither in the seminal paper (Chen et al, 2007) nor later. On the other hand, the 207 Pb resonance for 1 was detected at +1317 ppm, i.e.…”

“…All nonhydrogen atoms were refined with anisotropic displacement parameters. (1) and Fulton's directly related [{BDI iPr }PbCl] (Chen et al, 2007). Average values for the two independent components 1a and 1b are given for complex 1.…”