Structure, properties and comparison of C,N-chelated and amido-stabilized plumbylenes

Abstract

The molecular structure of {2-[(CH3)2NCH2]C6H4}2Pb (1) in the solid state was determined by X-ray diffraction techniques on a single crystalline material. Bulky amido ligand stabilized complexes [(i-C3H7)2C6H3]NHLi (2) and [(i-C3H7)2C6H3N(Me3Si)]2Pb (3) were synthesized and characterized both in the solid state and solution by 1H, 13C, 15N and 207Pb NMR and XRD techniques. The structure of both C,N-chelated and bulky amido plumbylenes is compared.

Reactivity of di-n-butyl-dicyclopentadienylzirconium towards amido stabilized stannylenes

“…The tin-tin bond length (2.804(4) Å) compares well to standard Sn-Sn bond distances of 2.78 Å in Me 6 Sn 2 , as found in the vapour phase by GED (gas electron diffraction), and of 2.763(2) Å in Ph 6 Sn 2 [8]. On the other hand, the Sn-Sn bond distance of 4.2364 Å in the complex of Piers [1] and of 3.5567 Å in 4 [6] indicates very weak contacts in both complexes, if any. The coordination sphere of the zirconium and tin atoms is essentially tetrahedral, with the two Cp rings and the two oxygen atoms for the zirconium atom, and an oxygen atom, the nitrogen atom from the amidic ligand, the n-butyl carbon atom and the second tin atom for each of the tin atoms.…”

“…Because of its thermal instability, even at 20°C, compound 9 could not be isolated and identified. The reaction course differs from the one reported by Piers et al who used the bulky CH[(SiMe 3 )] 2 ligand [1] as well as the C,N chelating ligand for ensuring the stabilization of stannylene 1 [6]. In the case of the stannylene stabilized by the amido ligand 7, we observed migration of the n-butyl group from zirconium to tin, followed by elimination of one of the amido ligands and complexation with one half equivalent of dicyclopentadienylzirconium, providing compound 9.…”

“…Recently, we have described oxidation products of 4 [6]. A sixmembered oxa-zircona cyclic complex was obtained from the zirconocene moiety, while the eight-membered oxa-stanna cyclic complex raised from the stannylene moiety bearing its ligands.…”

“…For example, Piers and coworkers have studied the reactivity of Lappert's stannylene towards zirconocene derivatives [1]. We have recently reported analogous reactivity and products of C,N-chelated stannylene (1) [2] and plumbylene (2) [3,4] toward the zirconocene derivative known as Negishi reagent [5] (Scheme 1), where the product is the trinuclear carbene-like complex 4 in the case of 1 and a zirconium complex formed by a C-H activation with C-C coupling containing two five-membered cycles in the case of plumbylene 2 [6]. Different products of transmetallation (6) with ligand transfer from plumbylene to zirconocene can be isolated when only one instead of two equivalents of n-butyllithium is used for in situ generated zirconocene [7].…”

Coordination Chemistry of Disilylated Germylenes with Group 4 Metallocenes

“…In addition to our recently reported stannylene and plumbylene compounds 25 also a few other zirconocene stannylene complexes, 26−28 two recently reported examples of titanocene silylene complexes, 29,30 and an example of a silylene hafnocene complex 31 are known.…”