Stable lead(ii) boroxides

Abstract

The first examples of lead(ii) boroxides, [Pb(OB{CH(SiMe3)2}2)2] (1) and [{N^C}PbOB{CH(SiMe3)2}2] (5; N^C = 2-Me2NCH2C6H4), were prepared via simple protocols. These structurally characterised compounds are stable and, unlike lead(ii) alkoxides and siloxides, do not trigger uncontrolled formation of lead(ii) oxoclusters.

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

“…These reactions afford the target metallylenes [(HCDippN) 2 BO] 2 E in good yield [ 4 : E=Ge (86 %), 5 : E=Sn (88 %), 6 : E=Pb (78 %); Scheme ]. 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)…”

Aminofluoroalkoxide amido and boryloxo lead(ii) complexes

“…16 We have also shown that [Pb II ]boryloxides could be obtained as the two-coordinate [Pb(OB{CH(SiMe3)2}2)2] or as the three-coordinate [{2-Me2NCH2C6H4}PbOB{CH(SiMe3)2}2] bearing a bidentate organoligand. 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.…”

“…Complex 3, a colourless solid that melts at 128 °C and decomposes irreversibly at 150 °C, is a rare example of stable lead(II) boryloxide. 17 It exhibits good solubility in most common organic solvents, including hydrocarbons. Colourless single crystals suitable for X-ray diffraction analysis were grown from a concentrated petroleum ether solution stored at -43 °C.…”

“…36 The Pb-Oboryloxide interatomic distance in 3 (2.128(2) Å) lies between that in the three-coordinate [{2-Me2NCH2C6H}PbOB{CH(SiMe3)2}2] and the two-coordinate [Pb(OB{CH(SiMe3)2}2)2] (2.1874(19) Å and 2.067(6)-2.089(5) Å, respectively). 17 The geometry about the boron atom is trigonal planar (Σθ(B2) = 360.0°). The relatively narrow B2-O1-Pb1 angle of 132.90(2)° suggests only a small p-contribution to the O1-Pb1 bonds.…”

“…On the whole, complex 3 is an unusual example of threecoordinate lead(II) compounds, and is one of the three cases of known Pb-boryloxide. 17 The complex is stable in the solid state and shows minor formation of homoleptic species upon ligand scrambling in solution (see above). Its stability is seen as the expression of the chelating bidentate ligand {RO F } -, but also of the steric protection, and hence the kinetic stability, imparted by the very bulky boryloxide {(Me3Si)2CH}2BO -.…”