Synthesis and Characterization of a Quasi‐One‐Coordinate Lead Cation

Abstract

Demethylierung von [PbMe(2,6‐Trip2C6H3)] (Trip=2,4,6‐iPr3C6H2) mit Tris(perfluorphenyl)boran in Toluol ergibt [Pb(2,6‐Trip2‐C6H3)(η2‐MeC6H5)][BMe(C6F5)3] (siehe Struktur). Das Bleizentrum ist durch eine Einfachbindung mit dem 2,6‐Trip2C6H3‐Liganden verknüpft und wird durch ein Toluolmolekül schwach solvatisiert.

Weak Arene Stabilization of Bulky Amido‐Germanium(II) and Tin(II) Monocations

“…Perhaps the lowest-coordinate Group 14 cation so far reported is 5, in which the bulky terphenyl ligated Pb center has only a weak h 2 -interaction with a molecule of toluene (closest Pb À C toluene distance: 2.832 (10) ). [13] Accordingly, this was described as a quasi-one-coordinate cation, a view that was supported by spectroscopic and crystallographic data.…”

“…Most revealing are their 13 C{ 1 H} NMR spectra which exhibit twelve aryl resonances, thus indicating that there are no arene-metal interactions that persist long enough to be observed on the NMR timescale. When the solutions were cooled to À70 8C (close to the solubility limits of the compounds), the 13 C{ 1 H} NMR spectra partially resolved, and sixteen broad aryl signals were observed.…”

“…Relevant bond lengths [] and angles [8] for 7: Ge1-N1 1.8153(18), Si1-N1 1.7715(19), N1-C1 1.448(3), Ge1-C28 2.642(2), Ge1-C33 2.661(2), Ge1-C15 3.013(2), Ge1-C20 3.116(2); C1-N1-Si1 121.80(14), C1-N1-Ge1 116.00(14), Si1-N1-Ge1 122.12(10). Relevant bond lengths [] and angles[8] for 6: Sn1-N1 2.0413(18), Si1-N1 1.7460(19), N1-C1 1.437(3), Sn1-C28 2.821(2), Sn1-C33 2.827(2), Sn1-C15 3.034(2), Sn1-C20 3.083(2); C1-N1-Si1 122.03(14), C1-N1-Sn1 115.67(13), Si1-N1-Sn1 122.29(10).…”

Weak Arene Stabilization of Bulky Amido‐Germanium(II) and Tin(II) Monocations

“…Perhaps the lowest-coordinate Group 14 cation so far reported is 5, in which the bulky terphenyl ligated Pb center has only a weak h 2 -interaction with a molecule of toluene (closest Pb À C toluene distance: 2.832(10) ). [13] Accordingly, this was described as a quasi-one-coordinate cation, a view that was supported by spectroscopic and crystallographic data.…”

“…While these contacts are closer than the shortest C phenyl ···E distances in the neutral species, LSnCl (3.110(3) ) and LGeCl (3.074(3) ), [14a] they are comparable to the shortest Pb···C toluene separation (2.832(10) ) in 5. [13] Given the markedly larger covalent and dicationic radii for lead (1.54 /1.32 ) relative to those of tin (1.40 /0.93 ) and germanium (1.22 /0.90 ), [17] and the fact that 5 is viewed as quasi-one-coordinate, it is reasonable to describe the Group 14 metal centers of 6 and 7 as having similar, if not lower, degrees of coordination than that of 5 in the solid state. This is also borne out by the fact that the h 2 -C···E distances in 6 and 7 are of the same order as h 6 -C···E distances in much higher coordination number arene complexes, for example, 2, [5] and considerably longer than h 5 -C···E interactions in cyclopentadienyl complexes, for example, 1.…”