Olefin Isomeric Forms in Main
Group 14 Elements
1
Some Isomeric Structures of C2H4
H
H
C
C
H
H
164.7 k cal mol–1
C
CH3
H
65.3 k cal mol–1
H
H
C
H
C
H
0.0 k cal mol–1
G. Trinquier. J. Am. Chem. Soc. 1990, 112, 2130.
Comparison of Energies of M2H 4 (M = Si, Ge, Sn or Pb) Isomers
H
H
H
..
Si
20
22.5
Si
H
H
Pb
H
H
H
Pb
23.9
3.00Å
H
2.40Å
..
Pb
17.5
Pb
H
H
H
2.96Å
H
H
..
Si
10
H
9.8
Si
..
H
H
..
Ge
H
9
Ge
..
H
2.59Å
..
Ge
0
Si
H
H
E kcal mol
–1
Si
2.12Å
Ge
H
H
Sn
Ge
H
H
2.89Å
2.4
H
H
H
H
0
..
Sn
H
H
H
H
2.32Å
9.1
7.0
Sn
H
Ge
H
Sn
2.72Å H
H
..
Sn
H 2.57Å
0
H
2.80Å
H
H
H
H
H
H
Sn
..
0
3.09Å
G. Trinquier. J. Am. Chem. Soc. 1990, 112, 2130; 1991, 113, 144.
..
Pb
H
H
H
3.25Å
Pb
..
0
Known Heavier Element R2EER2 Species Stable Only
if All Four R Groups are Bulky
RR
R
R
E
E
E =Si
Pb
R = C6H2-2,4,6-R3' (R' = Me, Et, Pri, But)
–CH(SiMe3)2, –SiBut3, –Si(SiMe3)3
–C6H2-2,4,6-(CF3)3 and combinations
Lappert, West, Masamune, Sita, Klinkhammer, Weidenbruch, Grützmacher.
If One Substituent (R ) at Each Element is Small, an
Unsymmetric Structure is Sterically Allowed
R
R'
E
E
dimetallene
R'
R
..
E
R
R
E
R'
R'
methylmethylene isomer
(allowed with small groups such as R' = Me)
R ligand must be very large to accomplish this.
e.g., a bulky terphenyl ligand.
Reactions of Sn(Cl)C6H3-2,6-Trip2 with MeLi and t-BuLi
Trip
Trip
Trip
Sn
Cl
Me
MeLi
MeMgBr
Sn
Trip
Me
Sn
1
Trip
MeLi
Trip
Me
Trip
Li
Sn Me
Trip = -C6 H2 -2,4,6-i-Pr3
Trip
Me
Trip
Trip
Sn
Sn
Trip
Trip
Sn
Me
Trip
Me
Trip
t-BuLi
1
Trip
Trip
Trip
Sn
t-Bu
Trip
Trip
Me
Me
Sn
Sn
Trip
MeLi
Li
Trip
Me
Me
Trip
119
Sn NMR 1904
119
Sn NMR δ 257.4, 2856.9 (1 J = 8330 Hz)
B. E. Eichler and P. P. Power. Inorg. Chem., 2000, 39, 5444.
Sn
Sn
Me
Trip
Trip
119
Sn NMR δ 151, -431 (1 J 4040 Hz)
(1J
119
Sn-7Li = 736 Hz)
Structure of 2,6-Trip2H3C6Sn-SnMe2C6H3-2,6-Trip2
Ar
J = 8332 Hz
Sn
Sn
Me
+257.4
+2856.9
Me
Ar
Sn(1)-Sn(2) = 2.8909(2) Å
Sn(1)-C(1) = 2.201(2) Å
Sn(1)-C(73) = 2.164(2) Å
Sn(1)-C(74) = 2.182(3) Å
Sn(2)-C(37) = 2.227(2) Å
C(1)-Sn(1)-Sn(2) = 119.30(6) º
Sn(1)-Sn(2)-C(37) = 101.17(5) º
Eichler, B. E., Power, P. P., Inorg. Chem. 2000, 39, 5444.
Structure of 2,6-Trip2H3C6(Me)(Li)Sn-SnMe2C6H3-2,6-Trip2
Ar
J = 4064 Hz
Sn
Sn(1)-Sn(2) = 2.8508(4) Å
Sn(1)-Li(1) = 2.685(8) Å
Me
+151
Me
Li Me
Sn
-431
Ar
Sn(1)-C(1) = 2.259(4) Å
Sn(1)-C(73) = 2.202(4) Å
Sn(2)-C(37) = 2.229(4) Å
Sn(2)-C(74) = 2.159(4) Å
Sn(2)-C(74) = 2.159(4) Å
C(1)-Sn(1)-Sn(2) = 120.06(9) º
Sn(1)-Sn(2)-C(37) = 110.81(9) º
Eichler, B. E., Power, P. P., Inorg. Chem. 2000, 39, 5444.
t-Bu Co-Ligand Prevents Dimerization
Sn(1)-C(1)
Sn-C(37)
C(1)-Sn-C(37)
Eichler and Power. Inorg. Chem. 2000, 39, 5444.
2.211(2)Å
2.227(2)Å
101.61(8)
Reaction of LiMe with M(Cl)Ar*
(M = Ge, Sn or Pb; Ar* = C6H3-2,6-C6H2-2,4,6-Pr3)2)
2 Ge(Cl)Ar*a + 2 LiMe
Et2O
Ar*
Me
Ge
Ge
Me
Ar*
+ 2 LiCl
Ge–Ge = 2.3173(3)Å
2
Sn(Cl)Ar*b
Pb(Br)Ar*c +
+ 2 LiMe
LiMe
Et2O
Ar*
Et2O
:Pb
..
Sn
Me
Sn
Ar*
Me
Me
+ 2 LiCl
Sn–Sn = 2.8909(2)Å;
119
Sn NMR, δ = 257.4, 2856.9
117/119
J
Sn–117/119 Sn = 8330 Hz
+ LiBr
Ar*
C–Pb–C = 101.41(4)°;
207
Pb NMR, δ = 7420c
Pb–C = 2.27(1)Å
aStender,
Pu, Power. Organometallics 2001, 20, 1820. bEichler, Power. Inorg. Chem. 2000, 39, 5444. cPu, Twamley, Power. Organometallics 2000, 19, 2874.
Selected Structural Parameters for Digermenes and Related Species
Ge–Ge(Å) Ge-C6H3-Trip2
(Å)
{Ge(Me)C6H3-2,6-Trip2}2 2.3173(3)
Ge-L(Å)a
1.9705(15) 1.9836(17)a
C-Ge-L
Σ°Ge
δ(°)d
111.77(7)
342.89 39.7
342.98 37.9
{Ge(Et)C6H3-2,6-Trip2}2
2.347(3)
1.995(3)
1.913(5)a
106.8(2)
{Ge(Ph)C6H3-2,6-Trip2}2
2.3183(5)
1.997(2)
1.950(3)a
116.08(10) 348.35 33.7
{Ge(Cl)C6H3-2,6-Trip2}2
2.363(2)
1.973(7)
2.209(2)b
118.03(19) 346.59 36.8
{Ge(Cl)C6H3-2,6-Mes2}2
2.443(2)
2.000(6)
2.120(2)b
109.1(2)
2.2026(19)b
101.31(15)
Ge(Cl)C6H3-2,6-Trip2
--
1.989(5)
py·Ge(Cl)C6H3-2,6-Trip2
--
2.0476(12) 2.3021(4)c
332.49 39.0
93.24(3)
2.1403(1)b
aGe-C
bond. bGe-Cl bond. cGe-N bond. dOut of plane angle defined by Ge Ge
δ
.
--
--
290.65
--
Important Spectroscopic and Structural Parameters for
Pb(R)C6H3-2,6-Trip2 Species
Pb-C(Å)
C-Pb-C(°)
207PbNMR(δ)
UV-Vis(nm)
Pb(Me)C6H3-2,6-Trip2
2.272(9), 2.276(15)
101.41(4)
7420
466
Pb(t-Bu)C6H3-2,6-Trip2
2.289(11), 2.329(14)
100.5(5)
7853
576
Pb(Ph)C6H3-2,6-Trip2
2.321(3), 2.264(3)
95.64(11)
6657
460
{Pb(Br)C6H3-2,6-Trip2}2
2.329(11), 2.306(13)
95.4(3)
--
416
--
417
2.79(11)a, 2.80(1)a
py·Pb(Br)C6H3-2,6-Trip2
aPb-Br
2.322(4), 2.7063(6)a
98.0(3)
2.502(4)b
92.39(11)
distance. bPb-N distance.
Pu, Twamley, Power. Organometallics 2000, 19, 2874.
Weak Lead-Lead Bonding Can Be Observed if the Ar
ʹ′ Terphenyl Ligand is Used
Red-green crystals
m.p. 210-214°
Pb-Pb: 3.160(16)Å
Out of plane angle: 39.0°
207Pb NMR: δ 7401.26
Selected bond distances [Å]
and angles [°]:
Pb(1)-C(31) 2.280(6)
Pb(1)-Pb(1A) 3.1601(6)
Pb(1)-C(1) 2.318(6)
C(1)-Pb(1)-C(31) 91.8(2)
Hino, Phillips, Power unpublished work
How to Make Hydrido
Derivatives of Heavy Group 14
Elements Si, Ge, Sn and Pb in
Oxidation State +2.
14
Synthesis of a Diplumbylene
2 Pb(Br)AriPr6 + LiAlH4
Et2O
-78°C
.. ..
AriPr6 Pb---PbAriPr6 +
LiBr + other products
Pb-Pb
= 3.1881(1)Å
Pb-Pb-C = 94.26(4)°
Pu, L.; Twamley, B.; Power, P.P.
J. Am. Chem. Soc. 2000, 122, 3524.
Synthesis of a Distannyne?
2 ClSnAriPr6 + 2 HAlBun2
AriPr6 Sn-SnAriPr6 ?
Sn-Sn = 3.1192(3) Å
Sn-Sn-C = 93.28(5) º
Eichler, B. E., Power, P. P., 1999
Synthesis of Sn(II) Hydride
2 ClSnAriPr6 + 2 HAlBu2
[Sn(H)AriPr6 ]2 + 2 ClAlBu2
Sn1--Sn2 = 3.1192(3) Å
Sn1-H1 = 1.89(3) Å
H(1)
Sn1-H1a = 1.94(3) Å
H1-Sn1-H1a = 71.3 º
H1(A)
1828 1771
Sn1-H1-Sn1a = 108.7 º
NB: IR stretching
frequencies indicate
terminal Sn-H
bonds.
Eichler, B. E., Power, P. P. J. Am. Chem. Soc. 2000, 122, 8785.
A New Synthetic Route to Sn(II) Hydrides [AriPr4Sn(µ-H)]2
[Ar'SnCl]2
LiNMe2
Et2O
- LiCl
H
BH3•THF
Sn
[Ar'Sn(NMe2)]2
- [Me2NBH2]x
Ar'
Ar'
Sn
H
• orange solid
• 85 % yield
• Mp = 181-183 °C
NB: No IR bands near
1800-1900 cm-1
Rivard, Steiner, Fettinger, Guiliani, Augustine and Power, Chem. Commun. 2007, 4919.