Organometallics
Article
ether (1/9) gave a brown fraction yielding, after removal of solvents,
compound 4 as a brown powder (0.008 g, 13%). Elution with
dichloromethane/petroleum ether (1/8) gave a yellow-brown fraction
yielding analogously compound cis-4 as a yellow-brown powder (0.045
g, 75%). Anal. Calcd for C43H47Mo2N2OP: C, 62.17; H, 5.70; N, 3.37.
Found: C, 61.80; H, 5.43; N, 3.13. 1H NMR δ 7.79 [m, 1H, H4(Ph)],
7.59 [t, JHH = 7, 1H, H4(Ph)], 7.47 [false t, JHH = 7, 2H, H3(Ph)],
7.46−7.15 (m, 8H, Ph), 6.99 [t, JHH = 7, 1H, H4(Ph)], 6.43 [false d,
JHH = 7, 2H, H2(Ph)], 5.40, 4.90 (2s, 2 × 5H, Cp), 2.60−0.90 (m,
22H, Cy).
4H, H2,3(Ph)], 7.12 [t, JHH = 7, 1H, H4(Ph)], 6.79 (d, JHP = 2, 1H,
CH), 5.11, 4.65 (2s, 2 × 5H, Cp), 3.54 (s, 3H, OMe), 2.30−0.90 (m,
22H, Cy). 13C{1H} NMR δ 251.6 (d, JCP = 12, MoCO), 233.3 (d, JCP
= 6, MoCO), 177.2 (s, CO2Me), 145.9 [s, C1(Ph)], 137.7 (s, μ-CPh),
128.3, 127.0 [2s, C2,3(Ph)], 126.8 [s, C4(Ph)], 92.1 (d, JCP = 5,
MoCH), 91.2, 88.1 (2s, Cp), 78.4 (d, JCP = 28, μ-CCO2Me), 51.4 (s,
OMe), 51.3 [d, JCP = 14, C1(Cy)], 47.0 [d, JCP = 5, C1(Cy)], 37.8 [s,
C2(Cy)], 36.5 [d, JCP = 6, C2(Cy)], 35.5 [d, JCP = 3, C2(Cy)], 35.2 [d,
JCP = 6, C2(Cy)], 29.6, 29.1 [2d, JCP = 12, C3(Cy)], 28.8 [d, JCP = 8,
C3(Cy)], 28.6 [d, JCP = 12, C3(Cy)], 27.1, 26.9 [2s, C4(Cy)].
Preparation of [Mo2Cp2{μ-κ2:η3-CPhC(CO2Me)C(CO2Me)}(μ-
PCy2)(CO)2] (7b). Neat C2(CO2Me)2 (50 μL, 0.407 mmol) was
added to a solution of compound 1 (0.050 g, 0.075 mmol) in toluene
(10 mL), and the mixture was stirred at 393 K for 7 h to give a brown-
orange solution. The solvent was then removed under vacuum, the
residue extracted with dichloromethane/petroleum ether (1/10), and
the extracts chromatographed through alumina at 288 K. Elution with
dichloromethane/petroleum ether (1/1) gave an orange fraction
yielding, after removal of solvents, compound 7b as an orange
microcrystalline solid (0.040 g, 66%). Anal. Calcd for C37H43Mo2O6P:
C, 55.10; H, 5.37. Found: C, 55.42; H, 5.36. 1H NMR δ 7.20−7.14 (m,
2H, Ph), 7.12−7.06 (m, 3H, Ph), 5.12, 5.07 (2s, 2 × 5H, Cp), 3.61,
3.37 (2s, 2 × 3H, OMe), 2.37 (m, 1H, Cy), 2.40−0.60 (m, 21H, Cy).
13C{1H} NMR (100.61 MHz) δ 248.0 (d, JCP = 11, MoCO), 232.5 (d,
Preparation of [Mo2Cp2{μ-κ1:η2-C(Ph)CH2}(μ-PCy2)(CO)2] (5).
Et2O solution of N2CH2 (2 mL of a 0.07 M solution, 0.14 mmol) was
added to a solution of compound 1 (0.050 g, 0.075 mmol) in
dichloromethane (5 mL), and the mixture was stirred at room
temperature for 5 min. Solvents were then removed under vacuum, the
brown residue extracted with dichloromethane/petroleum ether (1/
10), and the extracts chromatographed through alumina at 288 K.
Elution with dichloromethane/petroleum ether (1/8) gave a greenish
brown fraction yielding, after removal of solvents, compound 5 as a
brown solid (0.045 g, 88%). Attempts to grow single crystals of this
complex were unsuccessful due to its progressive transformation in
solution into a mixture of two isomers not characterized (see text).
Anal. Calcd for C32H39Mo2O2P: C, 56.65; H, 5.79. Found: C, 56.30;
H, 5.45. 1H NMR δ 7.16 [false t, JHH = 7, 2H, H3(Ph)], 7.05 [t, JHH
=
J
CP = 7, CO), 175.4 (s, 2CO2Me), 140.4 [s, C1(Ph)], 128.7, 127.5 [2s,
7, 1H, H4(Ph)], 6.88 [false d, JHH = 7, 2H, H2(Ph)], 5.29 (s, 5H, Cp),
5.13 (d, JHH = 2.2, 1H, CH2), 5.09 (s, 5H, Cp), 5.09 (d, JHH = 2.2, 1H,
CH2), 2.47−2.43 (m, 2H, Cy), 2.35 (m, 1H, Cy), 1.92−1.12 (m, 19H,
Cy). 13C{1H} NMR δ 246.6 (d, JCP = 14, MoCO), 246.5 (d, JCP = 10,
MoCO), 182.0 (s, μ-CPh), 152.0 [s, C1(Ph)], 128.9 [s, C4(Ph)],
128.1, 127.3 [2s, C2,3(Ph)], 90.8, 89.6 (2s, Cp), 68.3 (s, CH2), 49.8 [d,
JCP = 22, C1(Cy)], 41.5 [d, JCP = 16, C1(Cy)], 34.8 [d, JCP = 4,
C2(Cy)], 34.6 [d, JCP = 2, C2(Cy)], 34.3 [d, JCP = 1, C2(Cy)], 34.0 [d,
JCP = 5, C2(Cy)], 28.8 [d, JCP = 12, C3(Cy)], 28.3 [d, JCP = 14,
C3(Cy)], 28.2 [d, JCP = 10, 2C3(Cy)], 26.7, 26.5 [2s, C4(Cy)].
Preparation of [Mo2Cp2{μ-C(Ph)NCH2Ph}(μ-PCy2)(CO)2] (6).
Neat N3CH2Ph (15 μL, 0.12 mmol) was added to a solution of
compound 1 (0.050 g, 0.075 mmol) in dichloromethane (5 mL), and
the mixture was stirred at room temperature for 5 min (Caution:
Benzyl azide is a flammable liquid and forms explosive vapor/air
mixtures). The solvent was then removed under vacuum, the residue
kept under vacuum for 1 h and then extracted with dichloromethane/
petroleum ether (1/10), and the extracts chromatographed through
alumina at 263 K. Elution with dichloromethane/tetrahydrofuran (9/
1) gave a brown fraction yielding, after removal of solvents, compound
6 as a brown microcrystalline solid (0.050 g, 86%). Attempts to grow
single crystals of this complex were unsuccessful due to its progressive
transformation in solution into a mixture of different products not
characterized. Anal. Calcd for C39H46Cl2Mo2NO2P (6·CH2Cl2): C,
C2,3(Ph)], 126.3 [s, C4(Ph)], 112.1 [d, J CP = 4, C(CO2Me)], 101.0 (s,
μ-CPh), 91.2, 89.0 (2s, Cp), 80.0 [d, JCP = 24, μ-C(CO2Me)], 53.3 [d,
JCP = 16, C1(Cy)], 51.7, 51.0 (2s, OMe), 46.7 [d, JCP = 2, C1(Cy)],
38.0 [s, C2(Cy)], 36.3 [d, JCP = 7, C2(Cy)], 35.3, 35.0 [2s, C2(Cy)],
29.5 [d, JCP = 11, C3(Cy)], 28.9 [d, JCP = 10, C3(Cy)], 28.8 [d, JCP
=
12, 2C3(Cy)], 27.0, 26.8 [2s, C4(Cy)].
Preparation of cis-[Mo2Cp2{μ-κ2:η3-CPhC(CO2Me)C(CO2Me)}-
(μ-PCy2)(CO)2] (cis-7b). A solution of compound 7b (0.050 g, 0.062
mmol) in tetrahydrofuran (5 mL) was irradiated with visible−UV light
for 20 min at 288 K to give a yellow solution. Workup as described for
7b yielded compound cis-7b as an orange microcrystalline solid (0.042
g, 84%). Anal. Calcd for C37H43Mo2O6P: C, 55.10; H, 5.37. Found: C,
49.82; H, 5.12. 1H NMR δ 7.26−7.15 [m, 3H, H3,4(Ph)], 6.85 [false d,
JHH = 8, 2H, H2(Ph)], 5.15 (s, 10H, Cp), 3.45, 3.42 (2s, 2 × 3H,
OMe), 1.90−1.10 (m, 22H, Cy). 13C{1H} NMR (100.61 MHz) δ
236.1 (d, J CP = 10, 2MoCO), 177.8 (d, JCP = 3, CO2Me), 177.5 (s, CO
2Me), 137.9 [s, C1(Ph)], 128.3, 127.9 [2s, C2,3(Ph)], 127.4 [s,
C4(Ph)], 126.0 [d, J
= 4, C(CO2Me)], 99.5 (s, μ-CPh), 89.3 (s,
CP
2Cp), 63.7 [d, JCP = 30, μ-C(CO 2Me)], 51.6, 51.5 (2s, OMe), 49.3 [d,
JCP = 16, C1(Cy)], 45.0 [d, JCP = 8, C1(Cy)], 35.5 [d, JCP = 3, C2(Cy)],
34.8 [d, JCP = 4, C2(Cy)], 28.8, 28.5 [2d, J = 10, C3(Cy)], 26.6 [s,
CP
2C4(Cy)].
Computational Details. All DFT computations were carried out
using the Gaussian09 package,33 in which the hybrid method B3LYP
was used with the Becke three-parameter exchange functional34 and
the Lee−Yang−Parr correlation functional.35 An accurate numerical
integration grid (99 590) was used for all the calculations via the
keyword Int = Ultrafine. Effective core potentials and their associated
double-ζ LANL2DZ basis set were used for the metal atoms.36 The
light elements (P, O, C, and H) were described with the 6-31G*
basis.37 Geometry optimizations were performed under no symmetry
restrictions, and frequency analyses were performed for all the
stationary points to ensure that minimum structures with no imaginary
frequencies were achieved. NMR shielding contributions and coupling
constants were calculated using the gauge-including atomic orbitals
(GIAO) method,38 in combination with the LANL2DZ basis set for
the Mo atoms and the 6-311+G(2d,p) basis set for the remaining
atoms.39
1
54.82; H, 5.43; N, 1.64. Found: C, 54.44; H, 5.53; N, 1.81. H NMR
(400.13 MHz, 253 K) δ 7.39−7.35 (m, 3H, Ph), 7.30−7.24 (m, 6H,
Ph), 7.02 [tt, JHH = 7, 1.5, 1H, H4(Ph)], 5.10, 5.04 (2s, 2 × 5H, Cp),
4.92, 4.81 (2d, JHH = 13, 2 × 1H, NCH2), 2.18−1.05 (m, 22H, Cy).
13C{1H} NMR (100.61 MHz, 253 K) δ 257.9 (d, JCP = 11, MoCO),
244.7 (d, JCP = 7, MoCO), 189.9 (d, JCP = 23, μ-CPh), 158.5, 136.4
[2s, 2C1(Ph)], 129.4, 129.0, 128.4, 127.3, 126.7, 124.6 (6s, Ph), 92.7,
91.8 (2s, Cp), 70.0 (s, NCH2), 54.4 [d, JCP = 12, C1(Cy)], 50.0 [s,
C1(Cy)], 36.9 [d, JCP = 6, C2(Cy)], 35.4, 35.1 [2d, JCP = 4, C2(Cy)],
34.7 [d, JCP = 6, C2(Cy)], 29.3 [d, JCP = 11, C3(Cy)], 29.1, 28.6, 28.5
[3d, JCP = 10, C3(Cy)], 26.9, 26.6 [2s, C4(Cy)].
Preparation of [Mo2Cp2{μ-κ2:η3-CPhCHC(CO2Me)}(μ-PCy2)-
(CO)2] (7a). Neat methyl propiolate (40 μL, 0.45 mmol) was added
to a solution of compound 1 (0.050 g, 0.075 mmol) in toluene (10
mL), and the mixture was stirred at 333 K for 2 h to give an orange
solution. The solvent was then removed under vacuum, the residue
extracted with dichloromethane/petroleum ether (1/10), and the
extracts chromatographed through alumina at 288 K. Elution with
dichloromethane/petroleum ether (1/4) gave an orange fraction
yielding, after removal of the solvents, compound 7a as an orange
microcrystalline solid (0.041 g, 73%). Anal. Calcd for C35H41Mo2O4P:
C, 56.16; H, 5.52. Found: C, 56.46; H, 5.71. 1H NMR δ 7.34−7.25 [m,
ASSOCIATED CONTENT
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* Supporting Information
The Supporting Information is available free of charge on the
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Organometallics 2016, 35, 3498−3506