Organometallics
Article
confirm whether the structures are minima (no imaginary
frequencies) or transition states (only one imaginary frequency).
Solvation effects (toluene, ε = 2.3741) were taken into account by
performing single-point calculations using the SMD model.24 To
obtain better accuracy, single-point energies for the optimized
geometries were recalculated with a larger basis set, which is SDD25
for Ni, Sn, and Ge and 6−311+G(d,p) for other atoms. The final free
energies reported in the article are the large basis set single-point
energies with gas-phase Gibbs free energy correction (at reaction
temperature, see Scheme 9), solvation correction, and dispersion
correction using the DFT-D3(BJ) method developed by Grimme and
co-workers.26
Synthesis of [IBn]2Ni(η2-H2CCHSiMe3) (2c-SiMe3). A sol-
ution of Ni(COD)2 (0.243 g, 0.884 mmol), trimethyl(vinyl)silane
(0.177 g, 1.767 mmol) and IBn (0.270 g, 0.884 mmol) in 10 mL of
pentane was stirred for 30 min. The solution was filtered affording
0.096 g of a dark yellow precipitate (64% yield). 1H NMR (C6D6, 25
°C, 500.129 MHz): δ 0.34 (s, 9H, Si(CH3)3); 1.62 (dd, 1H, vinyl−H,
3JHH = 12.5 Hz, 3JHH = 14.0 Hz); 1.88 (dd, 1H, vinyl−H, 3JHH = 14.0
2
3
2
Hz, JHH = 2.5 Hz); 2.33 (dd, 1H, vinyl−H, JHH = 12.5 Hz, JHH
=
2.5 Hz); 5.08 (d, 2H, CH2−Ph, 2JHH = 15.1 Hz); 5.12 (d, 2H, CH2−
Ph, 2JHH = 15.4 Hz); 5.52 (d, 2H, CH2−Ph, 2JHH = 14.9 Hz); 5.68 (d,
2H, CH2−Ph, 2JHH = 14.4 Hz); 6.18 (s, 2H, HCCH); 6.25 (s, 2H,
HCCH); 6.94−7.04(m, 20H, Ph−H). 13C{1H} NMR (C6D6, 24
°C, 125.76 MHz): δ 1.7 (s, 3C, Si(CH3)3); 30.3 (s, vinyl−C); 31.5 (s,
vinyl−C); 53.8 (s, 2C, CH2−Ph); 54.2 (s, 2C, CH2−Ph); 119.3 (s,
4C, H2CCH2); 127.5 (s, para-Ph−C); 127.5 (s, para-Ph−C); 128.0
(s, ortho-Ph−C); 128.2 (s, ortho-Ph−C); 128.7 (s, meta-Ph−C); 128.7
(s, meta-Ph−C); 138.5 (s, ipso-Ph−C); 138.7 (s, ipso-Ph−C); 205.8
(s, Ni−C); 206.6 (s, Ni−C). 29Si{1H} NMR (C6D6, 27 °C, 59.64
MHz): −6.8 (s, 1Si, SiMe3). Anal. Calcd for C39H44N4NiSi: C, 71.45;
H, 6.77; N, 8.55. Found: C, 71.72; H, 6.76; N, 8.21.
SYNTHESIS, CHARACTERIZATION, AND
REACTIONS
■
Synthesis of [IMes]Ni(η2-H2CCHSiMe3)2 (1b-SiMe3). A
solution of Ni(COD)2 (0.243 g, 0.884 mmol), trimethyl(vinyl)silane
(0.177 g, 1.767 mmol), and IMes (0.270 g, 0.884 mmol) in 10 mL of
pentane was stirred for 30 min. The solution was filtered through
Celite and evaporated in vacuo to afford 0.420 g (85% yield) of a
yellow oil. The product was recrystallized from pentane at −35 °C.
Synthesis of H2CCHGePh3. Vinyl triphenyl germane was
prepared according to a modified procedure that was previously
reported.27 Triphenylgermanium chloride (3.0 g, 8.8 mmol) was
dissolved in 20 mL of THF. Vinylmagnesium chloride in THF (8.3
mL, 13.2 mmol, 1.5 equiv) was added dropwise to solution while
stirring. The reaction was left to stir for 4 h. Degassed water was
added to quench the reaction, after which the solution separated into
two layers. The THF layer was extracted and dried in vacuo to give a
white solid. The solid was dissolved in hot ethanol and filtered while
hot through Celite. The solution was cooled to −40 °C and afforded
1
NMR data is consistent with the C2 symmetric structure. H NMR
(C6D6, 25 °C, 500.13 MHz): δ −0.05 (s, 18H, Si(CH3)3); 2.08 (s,
6H, Ar−CH3); 2.09 (s, 6H, Ar−CH3); 2.11 (s, 6H, Ar−CH3); 2.54
2
3
(dd, 2H, vinyl−H, JHH = 0.6 Hz, JHH = 14.5 Hz); 2.62 (dd, 2H,
3
2
vinyl−H, JHH = 12.7 Hz, JHH = 0.64 Hz); 2.69 (dd, 2H, vinyl−H,
3JHH = 12.7 Hz, JHH = 14.5 Hz); 6.25 (s, 2H, HCCH); 6.70 (m,
3
4
4
2H, Ar−H, JHH < 1.0 Hz); 6.72 (m, 2H, Ar−H, JHH < 1.0 Hz).
13C{1H} NMR (C6D6, 23 °C, 75.47 MHz): δ 1.13 (s, 6C, Si(CH3)3);
18.4 (s, 2C, Ar−CH3); 18.6 (s, 2C, Ar−CH3); 21.0 (s, 2C, Ar−CH3);
51.1 (s, vinyl−C); 53.0 (s, vinyl−C); 126.0 (s, H2CH2); 129.3 (s,
meta-Ph−C); 129.5 (s, meta-Ph−C); 135.5 (s, ortho-Ph−C); 135.7 (s,
ortho-Ph−C); 137.8 (s, para-Ph−C); 138.3 (s, ipso-Ph−C−N); 203.8
(s, Ni−C). 29Si{1H} NMR (C6D6, 27 °C, 59.64 MHz): −5.0 (s, 2Si,
SiMe3). Repeated elemental analyses gave variable but consistently
low values for C, possibly due to Ni-carbide formation; this was also
observed in previous work with 1a-SiMe3 and 1d-SiMe3.
1
1.5 g of white crystals (50% yield). H NMR (C6D6, 25 °C, 500.13
2
3
MHz): δ 5.78 (dd, 1H, vinyl−CH, J = 3.0 Hz, J = 20.0 Hz); 6.14
(dd, 1H, vinyl−CH, 2J = 3.0 Hz, 3J = 13.5 Hz); 6.65 (dd, vinyl−CH,
2
3J = 13.5 Hz, J = 20.0 Hz); 7.13 (second order m, 9H, ortho- and
para-H); 7.55 (m, 6H, para-H). 13C{1H} NMR (C6D6, 25 °C, 125.76
MHz): δ 128.6 (s, ortho-Ph−C); 129.2 (s, para-Ph−C); 134.4 (s,
CHCH2); 134.7 (s, CHCH2); 135.4 (s, meta-Ph−C); 136.5 (s,
ipso-Ph−C).
Synthesis of (IPr)Ni(η2-CH2CHGePh3)2 (1a-GePh3). A
solution ofNi(COD)2 (0.062 g, 0.023 mmol), IPr (0.088 g, 0.023
mmol), and triphenyl(vinyl) germane (0.150 g, 0.046 mmol) in 10
mL of pentane was stirred for 30 min. The solution was filtered
Synthesis of [IBn]Ni(η2-H2CCHSiMe3)2 (1c-SiMe3). Ni-
(COD)2 (0.243 g, 0.884 mmol) was dissolved in 5 mL of toluene.
The solution was charged with 10 equiv of trimethyl(vinyl)silane
(0.177 g, 1.767 mmol) and stirred for 1 h to ensure all Ni(COD)2 had
dissolved. A solution of IBn (0.270 g, 0.884 mmol) in toluene was
added dropwise to the reaction mixture at −40 °C and stirred for 30
min. The solution was filtered through Celite, and volatiles were
removed in vacuo affording 0.262 g of a thick yellow oil (87% yield).
1
affording 0.160 g of a yellow solid. (64% yield). H NMR (C6D6, 25
3
°C, 500.133 MHz): δ 0.52 (d, 6H, CH(CH3)2, JHH = 6.8 Hz); 0.84
3
3
(d, 6H, CH(CH3)2, JHH = 6.8 Hz); 1.05 (d, 6H, CH(CH3)2, JHH
=
3
6.8 Hz); 1.48 (d, 6H, CH(CH3)2, JHH = 6.8 Hz); 2.89 (septet, 2H,
CH(CH3)2, JHH = 6.8 Hz); 2.93 (d, 2H, vinyl−H, JHH = 14.5 Hz);
3.00 (d, 2H, vinyl−H, 3JHH = 12.3 Hz); 3.12 (septet, 2H, CH(CH3)2,
3
3
1
Major isomer: H NMR (C6D6, 25 °C, 300.129 MHz): δ 0.18 (s,
3JHH = 6.8 Hz); 3.19 (dd, 2H, vinyl−H, JHH = 12.3 Hz, JHH = 14.5
Hz); 6.64 (s, 2H, CHCH); 7.00−7.05 (m, 14H, 2,6-Ph−H, 4-
(2,6-iPr2Ph)−H); 7.06−7.1 (m, 10H 4-Ar−H, 3,5-(2,6-iPr2Ph)−H);
7.2−7.3 (m, 12H 3,5-Ar−H). 13C{1H} NMR (C6D6, 23 °C, 75.47
MHz): δ 21.0 (s, isopropyl−(CH3)2); 22.1 (s, isopropyl−(CH3)2);
25.8 (s, isopropyl−(CH3)2); 26.6 (s, isopropyl−(CH3)2); 28.4 (s,
isopropyl−CH); 28.7 (s, isopropyl−CH); 51.0 (s, vinyl−C); 57.3 (s,
vinyl−C); 123.6 (s,CHCH); 124.2 (s, meta-(2,6-iPr2Ph)−C); 124.5
(s, 4-(2,6-iPr2Ph)−C); 129.6 (s, para-Ph−C); 135.9 (s, ortho, meta−
Ph−C);137.4 (s, ipso-Ph−C−N); 139.8 (s, ipso-Ph−C); 146.0 (s,
ortho-(2,6-iPr2)Ph−C); 146.1 (s, ortho-(2,6-iPr2)Ph−C); 204.0. (s,
Ni−C). Anal. Calcd For C67H72Ge2N2Ni: C, 72.55; H, 6.54; N, 2.53.
Found: C, 72.52; H, 6.76; N, 2.37.
3
3
18H, Si(CH3)3); 2.52 (broad multiplet, 2H, vinyl−H); 2.78 (d, 2H,
vinyl−H, 3JHH = 15.48 Hz); 2.92 (d, 2H, vinyl−H, 3JHH = 12.25 Hz);
4.77 (d, 2H, CH2−Ph, 2JHH = 15.05 Hz); 4.97 (d, 2H, CH2−Ph, 2JHH
= 16.23 Hz); 6.23 (s, 2H, H2CCH2); 6.98 (m, 8H, 2,6−Ph−H);
7.00 (m, 12H, 3,4,5−Ph−H). 13C{1H} NMR (C6D6, 23 °C, 75.47
MHz): δ 1.2 (s, 6C, Si(CH3)3); 49.9 (fluctional s, vinyl−C); 53.1
(fluctional s, vinyl−C); 53.9 (s, 2C, CH2−Ph); 120.9 (s, H2CCH2);
128.9 (s, meta-Ph−C); 137.4 (s, ipso-Ph−C); ortho- and para-Ph−C
are obscured by solvent C6D6 peak P204.4 (s, Ni−C). 29Si{1H} NMR
1
(C6D6, 27 °C, 59.64 MHz): −4.1 (s, 2Si, SiMe3). Minor isomer: H
NMR (C6D6, 25 °C, 300.129 MHz): δ 0.15 (s, 18H, Si(CH3)3); 2.26
3
3
(dd, 2H, vinyl−H, JHH = 12.5 Hz, JHH = 15.9 Hz); 2.78 (d, 2H,
vinyl−H, 3JHH = 15.9 Hz, 2JHH = 1.0 Hz); 2.92 (d, 2H, vinyl−H, 3JHH
= 12.5 Hz, JHH = 1.0 Hz); 4.83 (fluctional s, 2H, CH2−Ph, JHH
2
2
Synthesis of (iPr3P)Ni(η2-CH2CHGePh3)2. Ni(COD)2 (0.209
g, 0.76 mmol, 1 equiv) was dissolved in 10 mL of toluene.
Triisopropylphosphine (0.120 g, 0.76 mmol, 1 equiv) and triphenyl-
(vinyl)germane (0.500 g, 1.51 mmol, 2 equiv) were added, and the
solution was stirred for 1 h. The yellow solution was evaporated in
vacuo leaving a red/yellow solid. Extraction into pentane,
crystallization at −40 °C, and filtration gave 0.601 g of yellow solid
(89% yield). 1H NMR (C6D6, 25 °C, 500.133 MHz): δ 0.56 (dd, 9H,
CH3CHP, 3JHH = 7.25 Hz, 3JHP = 12.2 Hz); 0.83 (dd, 9H, CH3CHP,
=
2
16.2 Hz); 5.00 (fluctional s, 2H, CH2−Ph, JHH = 7.3 Hz); 6.21
(fluctional s, 2H, H2CCH2); 6.95 (m, 8H, 2,6−Ph−H); 7.04 (m,
12H, 3,4,5−Ph−H). 13C{1H} NMR (C6D6, 23 °C, 75.47 MHz): δ 0.9
(s, 6C, Si(CH3)3); 51.3 (s, vinyl−C); 52.2 (s, vinyl−C); 53.7 (s, 1C,
CH2−Ph); 54.4 (s, 1C, CH2−Ph); 120.8 (s, H2C = CH2); 121.2 (s,
H2C = CH2); 128.9 (s, meta-Ph−C); 137.6 (s, ipso-Ph−C); ortho and
para Ph−C are obscured by solvent C6D6 peak. 203.9 (s, Ni−C).
29Si{1H} NMR (C6D6, 27 °C, 59.64 MHz): −4.3 (s, 2Si, SiMe3).
L
Organometallics XXXX, XXX, XXX−XXX