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

Abstract

The complexes, Pb(ChAr(Pri4))2 (Ch = O (1), S (2); Ar(Pri4) = C6H3-2,6-(C6H3-2,6-Pr(i)2)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. (207)Pb 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 LiSAr(Me6) with PbBr2 in a 2:1 ratio led not to Pb(SAr(Me6))2, but to a mixture of the monothiolato lead(II) complex, {Pb(Br)(μ-SAr(Me6))}2 (3) and the lithium tristhiolato plumbate, LiPb(SAr(Me6))3 (4). 3 and 4 were isolated and purified by fractional recrystallization, and both were characterized by X-ray crystallography and spectroscopic studies.

An N‐Heterocyclic Boryloxy Ligand Isoelectronic with N‐Heterocyclic Imines: Access to an Acyclic Dioxysilylene and its Heavier Congeners

“…In addition, the Ge−O bond distances (mean: 1.778(2) Å) are significantly shorter than those found in [(2,6‐Dipp 2 C 6 H 3 )O] 2 Ge [mean: 1.827(2) Å], consistent with the stronger π‐donor capabilities predicted for the boryloxy system. Similar trends are seen for 5 and 6 , with Sn–O and Pb–O distances [means: 2.015(2) and 2.131(2) Å] being shorter than in their aryloxy counterparts [means: 2.047(2) and 2.216(8) Å, respectively] ,…”

“…5 is characterized by a 119 Sn{ 1 H} signal at δ Sn =−109.0 ppm, which is downfield shifted from those of [{(Me 3 Si) 2 HC} 2 BO] 2 Sn ( δ =−186 ppm) and [(2,6‐Dipp 2 C 6 H 3 )O] 2 Sn ( δ =−289.7 ppm) . A similar trend is observed for 6 : the 207 Pb{ 1 H} NMR signal (δ Pb =1885 ppm) is shifted downfield compared to those of [{(Me 3 Si) 2 HC} 2 BO] 2 Pb ( δ =1805 ppm) and [(2,6‐Dipp 2 C 6 H 3 )O] 2 Pb ( δ =1070 ppm) …”

“…An approach used to counter this problem exploits aryloxy (ArO − ) ligands featuring bulky ortho substituents, thereby extending steric protection towards the metal center. Thus, monomeric species of the type (ArO) 2 E (E=Ge, Sn, Pb) have been reported by Lappert and by Power using this approach –. That said, further chemistry with these systems typically involves the ArO − unit acting as a leaving group (cf.…”

Dispersion Forces and Counterintuitive Steric Effects in Main Group Molecules: Heavier Group 14 (Si–Pb) Dichalcogenolate Carbene Analogues with Sub-90° Interligand Bond Angles

“…We attribute the lower angular/ substituent dependence to the larger size of lead in comparison to the lighter elements. In the Pb derivatives, the Pb-S bonds lengthen slightly with increasing substituent size and in all cases, 11 the Pb-S distances in plumbylenes 12-14 are longer than the Pb-S distance found in Tokitoh's monothiolato plumbylene, Pb(Tbt)(STbt), (Tbt = C6H2-2,4,6-(CH(SiMe3)2)3) (2.498(10) Å). 36 The C-S bond lengths are very similar to those for the lighter analogues with an almost negligible average decrease of about 0.01 Å upon descending the group.…”

Aminofluoroalkoxide amido and boryloxo lead(ii) complexes

“…17 Yet, beyond β-diketiminates [3][4][5][6][7][8][9][10][11][12][13][14][15] and bulky terphenyls, [18][19][20] the number of ligands suited to the design of heteroleptic low coordinate lead(II) complexes remains limited. [21][22][23][24][25] In particular, the implementation of potentially bidentate alkoxides for the preparation of soluble heteroleptic lead(II) species only includes a handful of examples, 16,24,26 even if homoleptic [Pb(OR)2]n and [Pb(μ2-OR)N(SiMe3)2]2 alkoxides have been known for some time. [27][28][29] We report here on the preparation of a readily available aminofluoroalkoxide that enables the facile synthesis of stable three-coordinate lead(II) complexes, including one of the few Pb II -boryloxides known to date.…”