Organometallics
Article
respectively from Na and CaH2. Elemental analyses were performed at
the London Metropolitan University in London, U.K., and
Mikroanalytisches Labor Pascher in Remagen, Germany. Terminal
alkynes were purchased from Aldrich, distilled, degassed via several
freeze−pump−thaw cycles, filtered over activated alumina, and stored
under nitrogen. The supported precatalyst [(SiO)WMe5] (1) and
W methylidyne/methyl species 2 were prepared according to the
literature. GC measurements were performed with an Agilent 7890A
Series instrument (FID detection). Method for GC analyses: column
HP-5; 30 m length × 0.32 mm i.d. × 0.25 μm film thickness; flow rate
1 mL/min (N2); split ratio 50/1; Inlet temperature 250 °C; detector
temperature 250 °C. GC-MS measurements were performed with an
Agilent 7890A Series instrument coupled with an Agilent 5975C Series
instrument. The GC/MS instrument equipped with a capillary column
coated with nonpolar stationary phase HP-5MS was used for
molecular weight determination and identification, which allowed
the separation of hydrocarbons according to their boiling point
differences. The microscope (FEI Titan 80) was operated at an
accelerating voltage of 300 kV, offering a high enough spatial
resolution for atomic high-angle annular dark-field (HAADF) imaging,
which is convenient to discriminate heavy-element atoms such as W.
General Procedure for Alkyne Cyclotrimerization. All
reactions were carried out following the same protocol: a flame-
dried ampule was filled with the catalyst (25 mg, 0.75 μmol, W
loading: 0.55 wt %) in a glovebox, and the terminal alkyne (0.5 mL)
was then added. The ampule was sealed under vacuum, immersed in
an oil bath, and heated to 150 °C. At the end of the reaction, the
ampule was cooled to −78 °C. Then, the mixture was diluted by
addition of the external standard n-pentane and after filtration the
resulting solution was analyzed by GC and GC/MS. For the kinetic
studies on 1-octyne cyclotrimerization, each analysis represents an
independent run.
(m, 2H, Ar), 6.81 (s, 3H, Ar), 2.57−2.53 (m, ArCH2C), 1.60−1.56 (m,
CH2CH2CH3), 1.28 (m, CH2CH2CH3), 0.91−0.89 (m,
CH2CH2CH3). 13C NMR δC (CDCl3, 100 MHz): 142.8, 140.5,
140.3, 137.8, 129.4, 129.1, 126.0, 125.8, 36.1, 35.7, 32.9, 32.5, 32.1,
31.8, 31.6, 30.0, 29.7, 29.6, 29.4, 22.8, 14.2. 7a/7b = 31/69,
determined by GC analysis. MS (EI): m/z 414. HRMS: calcd for
C30H54 (M)+ 414.42200, found (M)+ 414.42053. Anal. Calcd for
C30H54: C, 86.88; H, 13.12. Found: C, 86.81; H, 13.28 (measured
using a mixture of isomers).
1,3,5-Triisopentylbenzene/1,2,4-Triisopentylbenzene (8a/8b). Yel-
low oil. IR (thin film): 2948, 2926, 2860, 1467, 1384, 1365, 1166, 811,
1
3
824, 703 cm−1. H NMR δH (CDCl3, 600 MHz): 7.04 (d, 1H, JHH
=
7.5 Hz, Ar), 6.95−6.93 (m, 2H, Ar), 6.82 (s, 3H, Ar), 2.58−2.54 (m,
ArCH2C), 1.66−1.58 (m, CH2CH2CH3), 1.52−1.43 (m,
CH2CH2CH3), 0.98−0.90 (m, CH2CH2CH3). 13C NMR δC (CDCl3,
150 MHz): 143.1, 140.7, 140.5, 137.9, 129.3, 129.2, 125.8, 41.1, 41.0,
34.0, 33.5, 30.8, 30.3, 28.6, 28.5, 28.0, 22.7. 8a/8b = 32/68,
determined by GC analysis. MS (EI): m/z 288. HRMS: calcd for
C21H36 (M)+ 288.28115, found (M)+, 288.28000. Anal. Calcd for
C21H36: C, 87.42; H, 12.58. Found: C, 87.35; H, 12.45 (measured
using a mixture of isomers).
1,3,5-Tricyclohexylbenzene/1,2,4-Tricyclohexylbenzene (9a/9b).
1
Colorless oil. IR (thin film): 2923, 2847, 1450, 907, 724 cm−1. H
3
NMR δH (CDCl3, 600 MHz): 7.14 (d, 1H, JHH = 8.0 Hz, Ar), 7.0
(app s, 1H, Ar), 7.0−6.99 (m, 1H, Ar), 6.88 (s, 3H, Ar), 2.79−2.74 (m,
ArCHC), 2.46 (app s, ArCHC), 1.90−1.73 (m, CH2), 1.46−1.37 (m,
CH2CH2CH2), 1.29−1.24 (m, CH2). 13C NMR δC (CDCl3, 150
MHz): 147.9, 145.1, 144.6, 142.1, 125.7, 124.6, 124.0, 123.0, 44.9,
44.4, 39.4, 39.1, 34.9, 34.8, 34.7, 34.6, 34.6, 27.4, 27.1, 26.5, 26.4. 9a/
9b = 59/41, determined by GC analysis. MS (EI): m/z 324. HRMS:
calcd for C24H36 (M)+ 324.28115, found: (M)+, 324.28042. Anal.
Calcd for C24H36: C, 88.82; H, 11.18. Found: C, 88.72; H, 11.29
(measured using a mixture of isomers).
1,3,5-Tributylbenzene/1,2,4-Tributylbenzene (3a/3b). Yellow oil.
IR (thin film): 2961, 2922, 2856, 1460, 1375, 821, 703 cm−1. 1H NMR
Computational Details. All DFT static calculations were
performed at the GGA level with the Gaussian09 set of programs
using the BP86 functional of Becke and Perdew.23 The electronic
configuration of the molecular systems was described with the
standard split-valence basis set with a polarization function of Ahlrichs
and co-workers for H, C, Si, and O (SVP keyword in Gaussian).24 For
W, we used the small-core, quasi-relativistic Stuttgart/Dresden
effective core potential, with an associated valence basis set contracted
(standard SDD keywords in Gaussian 09).25 A cluster of Si2O4H4W
units was chosen, and no symmetry constraints were imposed in any
case. The stationary points were identified exactly by the curvature of
the potential-energy surface at these points corresponding to the
eigenvalues of the Hessian. All reported transition states possess
exactly one negative Hessian eigenvalue, while all other stationary
points exhibit exclusively positive eigenvalues. It should be noted that
the entropic contribution calculated in the gas phase (p = 1 atm) is
likely exaggerated in dissociative steps.26 All thermochemical analyses
were performed at p = 1354 atm, as suggested by Martin et al.27
The reported energies have been optimized via single-point
calculations on the BP86 geometries (ΔG° at 150 °C) with triple-ζ
valence plus polarization (TZVP keyword in Gaussian) using the M06
functional; however, solvent effects were estimated with the polarizable
continuous solvation model PCM using DCM as solvent.28
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δH (CDCl3, 600 MHz): 7.05 (d, 1H, JHH = 7.5 Hz, Ar), 6.95−6.93
(m, 2H, Ar), 6.82 (s, 3H, Ar), 2.59−2.53 (m, ArCH2C), 1.59−1.54
(m, CH2CH2CH3), 1.41−1.34 (m, CH2CH2CH3), 0.97−0.91 (m,
CH2CH2CH3). 13C NMR δC (CDCl3, 150 MHz): 142.8, 140.4, 140.2,
137.8, 129.4, 129.1, 126.0, 125.8, 35.8, 35.4, 33.9, 33.7, 32.6, 32.1, 23.0,
22.6, 14.1. MS (EI): m/z 246. 3a/3b = 29/71, determined by GC
analysis. HRMS: calcd for C18H30 (M)+ 246.23420, found (M)+
246.23360. Anal. Calcd for C18H30: C, 87.73; H, 12.27. Found: C,
87.60; H, 12.16 (measured using a mixture of isomers).
1,3,5-Tripentylbenzene/1,2,4-Tripentylbenzene (5a/5b). Yellow
oil.21 IR (thin film): 2951, 2923, 2853, 1454, 1376, 824, 726, 703
1
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cm−1. H NMR δH (CDCl3, 400 MHz): 7.05 (d, 1H, JHH = 7.5 Hz,
Ar), 6.95−6.93 (m, 2H, Ar), 6.82 (s, 3H, Ar), 2.59−2.53 (m,
ArCH2C), 1.62−1.56 (m, CH2CH2CH3), 1.37−1.32 (m,
CH2CH2CH3), 0.92−0.88 (m, CH2CH2CH3). 13C NMR δC (CDCl3,
100 MHz): 142.8, 140.5, 140.3, 137.8, 129.4, 129.1, 126.0, 125.8, 36.1,
35.7, 32.9, 32.4, 32.2, 31.8, 31.4, 31.2, 22.7, 14.2. 5a/5b = 31/69,
determined by GC analysis. MS (EI): m/z 288. HRMS: calcd for
C21H36 (M)+ 288.28115, found (M)+, 288.28008. Anal. Calcd for
C21H36: C, 87.42; H, 12.58. Found: C, 87.47; H, 12.38 (measured
using a mixture of isomers).
1,3,5-Trihexylbenzene/1,2,4-Trihexylbenzene (6a/6b). Yellow
oil.21 IR (thin film): 2948, 2917, 2847, 1451, 1375, 824, 719 cm−1.
3
1H NMR δH (CDCl3, 600 MHz): 7.05 (d, 1H, JHH = 7.5 Hz, Ar),
ASSOCIATED CONTENT
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6.95−6.93 (m, 2H, Ar), 6.81 (s, 3H, Ar), 2.60−2.54 (m, ArCH2C),
1.62−1.55 (m, CH2CH2CH3), 1.38−1.32 (m, CH2CH2CH3), 0.91−
0.89 (m, CH2CH2CH3). 13C NMR δC (CDCl3, 150 MHz): 142.8,
140.5, 140.3, 137.8, 129.4, 129.1, 126.0, 125.8, 36.1, 35.7, 32.9, 32.5,
31.9, 31.7, 31.5, 29.7, 29.3, 22.8, 14.2. 6a/6b = 30/70, determined by
GC analysis. MS (EI): m/z 330. HRMS: calcd for C24H42 (M)+
330.32810, found (M)+ 330.32683. Anal. Calcd for C24H42: C, 87.19;
H, 12.81. Found: C, 87.29; H, 12.88 (measured using a mixture of
isomers).
S
* Supporting Information
Figures and tables giving IR, NMR, and other characterization
data and calculation details. This material is available free of
AUTHOR INFORMATION
■
1,3,5-Trioctylbenzene/1,2,4-Trioctylbenzene (7a/7b). Yellow oil.22
IR (thin film): 2951, 2917, 2844, 1454, 1378, 817, 716 cm−1. 1H NMR
Corresponding Authors
3
δH (CDCl3, 400 MHz): 7.05 (d, 1H, JHH = 7.5 Hz, Ar), 6.95−6.93
E
Organometallics XXXX, XXX, XXX−XXX