Stable Plumbylene Dichalcogenolate Monomers with Large Differences in Their Interligand Angles and the Synthesis and Characterization of a Monothiolato Pb(II) Bromide and Lithium Trithiolato Plumbate

The complexes, Pb­(ChArPri4)2 (Ch = O (1), S (2); ArPri4 = C6H3-2,6-(C6H3-2,6-Pri2)2)
were synthesized by alcoholysis and salt metathesis routes and represent
the first fully characterized monomeric, two-coordinate, lead dichalcogenolates
in the solid state. Structural studies showed that the S–Pb–S
angle (77.21(4)°) is about 22° narrower than the corresponding
O–Pb–O angle. 207Pb NMR and electronic spectroscopy
show that the separation between the highest occupied molecular orbital
(HOMO) and the lowest unoccupied molecular orbital (LUMO) decreases
from the bisaryloxo plumbylene to the bisthiolato derivative. Reaction
of LiSArMe6 with PbBr2 in a 2:1 ratio
led not to Pb­(SArMe6)2, but to a
mixture of the monothiolato lead­(II) complex, {Pb­(Br)­(μ-SArMe6)}2 (3) and the lithium
tristhiolato plumbate, LiPb­(SArMe6)3 (4). 3 and 4 were isolated
and purified by fractional recrystallization, and both were characterized
by X-ray crystallography and spectroscopic studies.