Organometallics
Article
[Rh(ItBu)η2(C2H4)Cl]2 (5). To a yellow pentane slurry (2 mL) of
[Rh(C2H4)2Cl]2 (15.0 mg, 0.0386 mmol) was added dropwise a
pentane solution (5 mL) of ItBu-free carbene (13.8 mg, 0.0765 mmol).
Continued aggressive stirring led to the precipitation of a pale yellow
solid after 30 min. After stirring for another 2 h, the suspension was
decanted and dried in vacuo. The sample was quickly dissolved in C6D6
and loaded into an NMR tube. 1H NMR demonstrates the quantitative
formation of complex 5. However, compound 5 is unstable, and it
decomposes rapidly with formation of complex 7.
[Rh(PPh3)(SIMes)(C2H4)Cl] (18). A 20 mL vial was charged with
complex 3 (38.0 mg, 0.040) and dissolved in C6H6 (5 mL). Then a
solution of PPh3 (21 mg, 0.080 mmol) in 10 mL of C6H6 was added
dropwise. The resulting yellow-orange solution was stirred for 1 day,
and then the volatiles were removed in vacuo. The yellow residue was
then triturated with cold hexane and collected by filtration. Yield:
48 mg (82%).
3
1H NMR (400 MHz, C6D6): δ 7.72 (t, 5H, ArH, JHH = 8.0 Hz),
7.25 (br, 2H, ArH), 7.09 (d, br, 6H, ArH, 3JHH = 2.1 Hz), 7.07 (d, 6H,
3
1H NMR (C6D6, 400 MHz): δ 7.27 (s, 2H, CH-imidazole), 6.62 (s, 2H,
CH-imidazole), 2.89 (br, 8H, η2-CH2CH2), 2,19 (s, 36H, C(CH3)3).
ArH,, JHH = 6.1 Hz), 6.96 (br, 2H, ArH), 3.75 (m, 4H, NCH2), 2.96
(d, 3H, CH3), 2.55 (d, 3H, CH3), 2.44 (s, 3H, CH3), 2.30 (s, 3H,
CH3), 2.17 (s, 3H, CH3), 2.04 (s, 3H, CH3), 1.82 (4H, η2-CH2
[Rh(ItBu)′(ItBu)((C2H5)Cl]2 (6). A 0.0386 M solution of complex 7
in benzene was left for 2 days at room temperature and resulted in the
formation of a mixture of complexes 6 and 7,45,46 as judged by X-ray
spectroscopy and 1H and 13C{1H} NMR. In addition, significant
amounts of rhodium black precipitated from the solution. Crystals of
complex 6 were grown from C6D6 solution after 2 days. We were able
to isolate 6 in small quantities as single crystals suitable for X-ray
analysis to confirm the structure, but our attempts to obtain solely
complex 6 were hampered due to the unstable nature of the complex.
It is likely that complex 6 is a reactive intermediate for the formation
of 7 and decomposes at room temperature after 2−4 days with
formation of complex 7.45,46
1
CH2). 13C{1H} NMR (125.6 MHz, C6D6): δ 214.91 (d, JRhC = 45.2
2
Hz, JPC = 133.9 Hz, C-carbene), 163.87, 139.25, 137.50, 135.15,
135.90 (d, JPC = 10.9 Hz), 134.50, 134.22, 130.49, 130.17, 129.06,
129.06 (d, JPC = 8.9 Hz), 51.73 (s, N-CH2), 51.40 (s, N-CH2), 41.46
(d, η2-CH2CH2, 1JRhC = 15.32 Hz), 21.33 (s, CH3), 20.80 (s, CH3),
19.03 (s, CH3). 31P{1H} NMR (C6D6, 161.95 MHz, 293 K): δ 39.11
1
(d, JRhP = 111.5 Hz). Anal. Calcd for C41H45N2PRhCl: C 66.99, H
6.17, N 3.81. Found: C 66.38, H 6.29, N 3.94.
[Rh(PPh3)(IMes)(C2H4)Cl] (19). A 20 mL vial was charged with
complex 4 (37.7 mg, 0.040 mmol) and dissolved in C6H6 (5 mL).
Then a solution of PPh3 (21 mg, 0.080 mmol) in 10 mL of C6H6 was
added dropwise. The resulting orange solution was stirred for 1 day,
and then the volatiles were removed in vacuo. The yellow residue was
then triturated with cold hexane and collected by filtration. Yield:
50 mg (85%).
[Rh(PPh3)(SIPr)(C2H4)Cl] (16). A 20 mL vial was charged with
complex 1 (44.0 mg, 0.039 mmol). Then, a solution of PPh3 (21 mg,
0.080 mmol) in 10 mL of C6H6 was added dropwise. The resulting
orange solution was stirred for 1 day, and then the volatiles were
removed in vacuo. The yellow residue was then triturated with cold
hexane and collected by filtration. Yield: 62 mg (81%).
3
1H NMR (400 MHz, C6D6): δ 7.78 (t, 3H, ArH, JHH = 8.0 Hz),
3
7.27 (br, 6H, ArH), 7.10 (d, 6H, ArH, JHH = 7.5 Hz), 7.03 (d, 2H,
ArH), 6.96 (br, 2H, ArH), 6.30 (s, 2H, CHCH), 2.81 (d, 6H, CH3),
1H NMR (CD2Cl2, 600 MHz): δ 7.47 (t, 2H, ArH, 3JHH = 7.7 Hz),
1.50 (br, 4H, CH2CH2), 2.24 (br, 6H, CH3), 2.46 (d, 6H, CH3).
3
7.36 (br, 4H, ArH), 7.28 (br, 9H, ArH), 7.25 (t, 6H, JHH = 6.8 Hz
1
13C{1H} NMR (100.6 MHz, C6D6): δ 187.57 (d, JRhC = 47.5 Hz,
ArH), 3.96 (br, 2H, NCH2), 3.89 (br, 2H, NCH2), 3.82 (septet, 3JHH
=
2JPC = 141.9 Hz, C-carbene), 138.64, 138.35, 135.95 (d, JPC = 11.0 Hz),
135.21, 134.58, 134.29, 130.16, 129.31, 128.68, 127.65 (d, JPC = 9.0
Hz), 41.37 (d, η2-CH2CH2, 1JRhC = 15.3 Hz), 21.34 (s, CH3), 20.60
(s, CH3), 18.87 (s, CH3). 31P{1H} NMR (C6D6, 161.95 MHz, 293 K):
6.6 Hz, 2H, CH), 3.48 (septet, 3JHH = 6.7 Hz, 2H, CH), 1.68 (br, 4H,
η2-CH2CH2), 1.52 (d, 6H, CH3, 3JHH = 6.08 Hz), 1.38 (d, 6H, CH3,
3
3JHH = 6.6 Hz), 1.28 (d, 6H, CH3, JHH = 6.5 Hz), 1.22 (d, 6H, CH3,
3JHH = 6.80 Hz). 13C{1H} NMR (100.6 MHz, C6D6): δ 215.71 (d,
1JRhC = 44.6 Hz, 2JPC = 132.91 Hz, C-carbene), 149.44, 147.02, 135.68
(d, JPC = 10.71), 134.06, 133.70, 129.06, 127.60 (d, JPC = 8.83), 125.26,
123.92, 54.38 (s, N-CH2), 54.33 (s, N-CH2), 41.38 (d, η2-CH2CH2,
1JRhC = 15.4 Hz), 30.57 (s, CH), 29.44 (s, CH), 27.11 (s, CH3), 26.88
(s, CH3), 24.90 (s, CH3), 23.95 (s, CH3). 1P{1H} NMR (C6D6, 161.95
1
δ 40.48 (d, JRhP = 116.3 Hz). MS m/e for C41H43N2PRhCl: calcd
732.1907, found 732.2189. Anal. Calcd for C41H43N2PRhCl: C 67.17,
H 5.91, N 3.82. Found: C 67.34, H 6.01, N 3.67.
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S
1
MHz, 293 K): δ 37.75 (d, JRhP = 111.6 Hz). MS m/e for
C47H57N2PRhCl: calcd 818.3003, found 818.2978. Anal. Calcd for
C47H57N2RhCl·1.1H2O: C 67.27, H 7.11, N 3.34. Found: C 67.04,
H 7.03, N 3.64.
[Rh(PPh3)(IPr)(C2H4)Cl] (17). During the review process of the
manuscript, an alternate procedure for the preparation of complex 17
was reported.72 A 20 mL vial was charged with complex 2 (44.0 mg,
0.040 mmol). A solution of PPh3 (21 mg, 0.080 mmol) in 10 mL of
C6H6 was then added dropwise. The resulting orange solution was
stirred for 1 day, and then the volatiles were removed in vacuo. The
yellow residue was then triturated with cold hexane and collected by
filtration. Yield: 57 mg (87%).
AUTHOR INFORMATION
Corresponding Author
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ACKNOWLEDGMENTS
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The Natural Sciences and Engineering Council of Canada
(NSERC) and the Canada Foundation for Innovation (CFI)
are thanked for funding of this work. Johnson Matthey is
thanked for a generous gift of Rh complexes. E.C.K. thanks
Queen’s University for a Queen’s Graduate Scholarship and the
government of Ontario for an Ontario Graduate Scholarship.
1H NMR (600 MHz, CH2Cl2): δ 7.57 (t, 2H, ArH, 3JHH = 7.7 Hz),
7.42 (br, 4H), 7.35 (br d, 6H), 7.29 (d, 3H, ArH, 3JHH = 7.0 Hz), 7.18
3
(d, 6H, ArH, JHH = 3.4 Hz), 7.06 (br, 4H, CHCH), 3.54 (septet,
3
3JHH = 5.7 Hz, 4H, CH), 3.10 (septet, JHH = 5.6 Hz, 4H, CH), 1.67
3
(br, 8H, η2-CH2CH2), 1.47 (d, 6H, CH3, JHH = 5.2 Hz), 1.33 (d,
3
3
6H, CH3, JHH = 5.3 Hz), 1.17 (d, 6H, CH3, JHH = 5.5 Hz), 1.07 (d,
6H, CH3, 3JHH = 5.6 Hz). 31P{1H} NMR (C6D6, 161.95 MHz, 293 K):
REFERENCES
■
δ 40.12 (d, JRhP = 116.9 Hz). 13C{1H} NMR (100.6 MHz, C6D6): δ
1
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1
2
188.89 (d, JRhC = 47.5 Hz, JPC = 141.4 Hz, C-carbene), 148.57,
146.13, 137.48, 135.92 (d, JPC = 10.8 Hz), 134.34, 133.89, 129.95,
129.23, 127.71 (d, JPC = 9.0 Hz), 124.85, 124.33 (CHCH), 123.52,
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41.35 (d, η2-CH2CH2, JRhC = 15.3 Hz), 29.31 (s, CH), 29.04 (s,
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1
CH), 26.52 (s, CH3), 26.43 (s, CH3), 23.69 (s, CH3), 23.06 (s, CH3).
MS m/e for C47H55N2PRhCl: calcd 816.2847, found 816.3390. Anal.
Calcd for C47H55N2PRhCl: C 69.07, H 6.78, N 3.43. Found: C 69.18,
H 7.01, N 3.13.
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dx.doi.org/10.1021/om200710y|Organometallics 2011, 30, 6423−6432