Effect of the Lead(II) Bond Angle on the Reactivity of Diaminoplumbylenes toward Ammonia: From Inertness to Immediate Ammonolysis

Abstract

The reactivity of the N-heterocyclic plumbylenes o-C 6 H 4 (NSiRMe 2 ) 2 Pb (R = Me, t-Bu), nap(NSiRMe 2 ) 2 Pb (nap = naphthalene-1,8-diyl; R = Me, t-Bu), and [Fe{(η 5 -C 5 H 4 )NSit-BuMe 2 } 2 Pb] as well as of the acyclic diaminoplumbylene [(Me 3 Si) 2 N] 2 Pb toward ammonia depends critically on the N− Pb−N bond angle. The five-membered-ring congeners have the smallest angles (ca. 78°) and are inert toward NH 3 . The acyclic and the ferrocene-based congeners exhibit the largest Pb II bond angles (ca. 104 and 99°, respectively) and undergo immediate ammonolysis. The naphthalene-based six-membered-ring congeners have intermediate bond angles (ca. 83°) and show significantly slower ammonolysis, which allowed the isolation of the reactive intermediate [Pb(μ-NH 2 ){nap(NSiMe 3 )(NHSiMe 3 )}] 2 at low temperatures. The plumbylenes of this study which undergo ammonolysis also react readily with aniline.

Reactions of Mesityl Azide with Ferrocene‐Based N‐Heterocyclic Germylenes, Stannylenes and Plumbylenes, Including PPh2‐Functionalised Congeners

“…107.1(2)° [30] . This is in line with previous observations that the 1,1’‐ferrocenylene backbone of N‐heterocyclic carbenes and their heavier analogues [{Fe(η 5 −C 5 H 4 −NR) 2 }E] (E=C–Pb) gives rise to large bond angles at the divalent tetrel atom close to those of corresponding acyclic congeners [27–29,31,32] . The Sn−N bonds of stannylene 16 are longer than the Ge−N bonds of germylene 17 by ca.…”

“…Since plumbylene 15 was inert even under rather forcing conditions (105 °C, toluene) almost identical to those used by Song for o ‐C 6 H 4 (NDipp) 2 Pb ( 3 ; Scheme 1, bottom), we tested three additional diaminoplumbylenes in this context, viz. the acyclic congener [(Me 3 Si) 2 N] 2 Pb [36] as well as our recently reported five‐ and six‐membered N‐heterocyclic plumbylenes o ‐C 6 H 4 (NSiMe 3 ) 2 Pb and nap(NSiMe 3 ) 2 Pb (nap=naphthalene‐1,8‐diyl), [31] all containing Me 3 Si instead of Si t BuMe 2 substituents to decrease steric congestion. However, these compounds proved to be equally inert.…”

“…(18) 18 (E = Sn) [b] 2.035( Chemistry-A European Journal E] (E = C-Pb) gives rise to large bond angles at the divalent tetrel atom close to those of corresponding acyclic congeners. [27][28][29]31,32] The SnÀ N bonds of stannylene 16 are longer than the GeÀ N bonds of germylene 17 by ca. 0.2 Å, which is in accord with the difference of the covalent radii of tin (1.39 Å) and germanium (1.20 Å).…”

“…C 6 D 6 ): δ = 139.3 (d, J = 6.6 Hz, Mes C ipso ), 137.6 (d, J = 5.2 Hz, Mes CCH 3 ), 137.1 (d, J = 5.9 Hz, Mes CCH 3 ), 133.9 (d, J = 9.8 Hz, Ph CH), 133.6 (d, J = 9.3 Hz, Ph CH), 133.5 (d, J = 3.8 Hz, Ar CH), 132.2 (d, J = 2.9 Hz, Ar CH), 132.0 (d, 1 J = 89.8 Hz, Ph C ipso ), 131.5 (d, J = 2.8 Hz, Ar CH), 130.2 (d, J = 3.4 Hz, Ar CH), 130.0 (d, J = 3.1 Hz, Ar CH), 129.8 (d, = 90.8 Hz, Ph C ipso ), 128.0, 127.7 (2 × Ar CH), 119.9 (d, J = 6.6 Hz, cyclopentadienyl C ipso N), 111.6 (cyclopentadienyl C ipso N), 72.4, 70.4 (d, J = 9.8 Hz), 69.9, 68.1 (d, J = 13.6 Hz), 67.8 (d, J = 16.5 Hz), 67.5, 63.8 (7 × cyclopentadienyl CH), 57.0 (d, 1 J = 135.5 Hz, cyclopentadienyl C ipso P), 21.7 (d, J = 1.6 Hz, Mes CH 3 ), 21.1 (d, J = 1.3 Hz, Mes CH 3 ), 20.8 (d, J = 1.5 Hz, Mes CH 3 ), 3.3 ppm (two very closely spaced signals, 2 × SiMe 3 ) 31. P{ 1 H} NMR (202 MHz, C 6 D 6 ): δ = 23.3 ppm.…”

“…H} NMR (101 MHz, C 6 D 6 ): δ = 138.4 (d, J = 4.0 Hz), 138.0 (d, J = 4.7 Hz), 136.7 (d, J = 3.0 Hz), 136.1 (d, J = 4.8 Hz, Mes C ipso ), 133.6 (d, J = 10.2 Hz, Ph m-CH), 133.1 (d, J = 2.8 Hz), 132.8 (d, J = 9.4 Hz, Ph m-CH), 132.6 (d, J = 2.8 Hz), 131.8 (d, J = 2.6 Hz), 131.5 (d, 1 J = 93.8 Hz, Ph C ipso ), 130.3 (d, J = 2.5 Hz), 128.5, 128.4 (2 × Ph o-CH), 125.3 (d, 1 J = 96.1 Hz, Ph C ipso ), 113.5 (d, J = 6.0 Hz, cyclopentadienyl C ipso N), 105.6 (cyclopentadienyl C ipso N), 73.0 (cyclopentadienyl CH), 71.1 (d, J = 9.5 Hz, cyclopentadienyl CH), 70.3 (d, J = 12.6 Hz, cyclopentadienyl CH), 69.9, 69.6 (2 × cyclopentadienyl CH), 68.0 (d, J = 14.3 Hz, cyclopentadienyl CH), 65.8 (cyclopentadienyl CH), 54.7 (d, = 126.6 Hz, cyclopentadienyl C ipso P), 22.2 (d, J = 1.1 Hz, Mes CH 3 ), 21.2 (d, J = 1.3 Hz, Mes CH 3 ), 20.9 (d, J = 1.2 Hz, Mes CH 3 ), 3.9, 3.6 ppm (2 × SiMe 3 ) 31. P{ 1 H} NMR (202 MHz, C 6 D 6 ): δ = 26.0 ppm.…”