Rhodium(I) Iminophosphine Carbonyl Complexes
Organometallics, Vol. 26, No. 8, 2007 1965
(ESI; m/z): 623 [M+] - CO, 524 [M+] - I. A 13CO-labeled sample
of 1b was prepared by briefly bubbling 13CO through a solution of
H, 4.02; N, 1.55. IR (ν(CO); CH2Cl2): 1717 cm-1. 1H NMR (CD2-
3
Cl2): δ 0.96, 1.13, 1.16, 1.29 (each d, 3H, JHH ) 7.6 Hz, CH-
the compound in CH2Cl2. IR (ν(13CO); CH2Cl2): 1953 cm-1 31P-
.
3
(Me)2), 1.73, 2.55 (each sept, 1H, JHH ) 7.6 Hz, CH(Me)2), 3.28
1
2
{1H} NMR (CD2Cl2): δ 41.3 (d, JRhP ) 169 Hz, JPC ) 12 Hz).
(s, 3H, COMe), 6.93-7.86 (m, 17H, Ar H), 8.17 (d, 3.7 Hz, 1H,
NdCH). 31P{1H} NMR (CD2Cl2): δ 46.5 (d, JRhP ) 135 Hz). MS
(FAB; m/z): 806 [M+] - COMe, 722 [M+] - I, 694 [M+] - CO
- I, 679 [M+] - COMe - I.
13C{1H} NMR δ 190.8 (1JRhC ) 70 Hz, JPC ) 12 Hz).
2
(c) [RhI(CO)(PNAr)] (1c; Ar ) 2,6-iPr2C6H3). A procedure was
employed analogous to that described for 1a using Ph2PC6H4CHd
N(2,6-iPr2C6H3) (82.6 mg, 0.184 mmol) and [RhI(CO)2]2 (50 mg,
0.087 mmol). Yield: 85 mg (69%). Anal. Calcd for C32H32-
INOPRh: C, 54.33; H, 4.56; N, 1.98. Found: C, 54.60; H, 4.48;
(c) [Rh(COMe)I2(PNAr)] (3e; Ar ) 2MeOC6H4). A procedure
analogous to that described above for 3b was employed. Anal. Calcd
for C28H25I2NO2PRh: C, 42.29; H, 3.17; N, 1.76. Found: C, 41.90;
H, 3.41; N, 1.65. IR (ν(CO); CH2Cl2): 1704 cm-1. 1H NMR (CD2-
Cl2): δ 3.30 (s, 3H, COMe), 3.93 (s, 3H, OMe), 6.65-7.85 (m,
18H, Ar H), 8.20 (d, 3 Hz, 1H, NdCH). 31P{1H} NMR (CD2Cl2):
δ 44.7 (d, JRhP ) 135 Hz). MS (FAB; m/z): 752 [M+] - COMe,
625 [M+] - COMe - I. A crystal suitable for study by X-ray
diffraction was obtained by slow diffusion of pentane into a
concentrated chloroform solution of 3e.
1
N, 2.00. IR (ν(CO); CH2Cl2): 1997 cm-1. H NMR (CD2Cl2): δ
0.69 (d, 6H, 6.7 Hz, Me2CH), 1.29 (d, 6H, 6.7 Hz, Me2CH), 2.99
(sept, 2H, 6.7 Hz, Me2CH), 7.0-7.2 (m, 4H, Ar H) 7.42-7.60 (m,
13H, Ar H), 8.00 (d, 2.4 Hz, 1H, NdCH). 31P{1H} NMR (CD2-
Cl2): δ 40.5 (d, JRhP ) 172 Hz). MS (ESI; m/z): 580 [M+] - I.
(d) [RhI(CO)(PNAr)] (1d; Ar ) 2-EtC6H4). A procedure was
employed analogous to that described for 1a, using Ph2PC6H4CHd
N(2-EtC6H4) (221 mg, 0.562 mmol) and [RhI(CO)2]2 (160 mg,
0.280 mmol). Yield: 254 mg (70%). Anal. Calcd for C28H24-
INOPRh: C, 51.64; H, 3.71; N, 2.15. Found: C, 51.66; H, 3.43;
X-ray Structure Determination. Data were collected on a
Bruker Smart CCD area detector with Oxford Cryosystems low-
temperature system using Mo KR radiation (λh ) 0.710 73 Å). The
structure was solved by direct methods and refined by full-matrix
least-squares methods on F2. Hydrogen atoms were placed geo-
metrically and refined with a riding model (including torsional
freedom for methyl groups) and with Uiso constrained to be 1.2
(1.5 for methyl groups) times the Ueq value of the carrier atom.
Complex scattering factors were taken from the program package
SHELXTL.52 Crystallographic data are summarized in Table 3, and
full listings are given in the Supporting Information.
1
N, 1.92. IR (ν(CO); CH2Cl2): 1997 cm-1. H NMR (CD2Cl2):
δ0.75 (t, 3H, CH2Me), 2.57 (q, 2H, CH2Me), 6.80-7.67 (m, 18H,
Ar H), 7.97 (d, 1.8 Hz, 1H, NdCH). 31P{1H} NMR (CD2Cl2): δ
42.4 (d, JRhP ) 162 Hz). MS (FAB; m/z): 623 [M+] - CO, 524
[M+] - I.
(e) [RhI(CO)(PNAr)] (1e; Ar ) 2-MeOC6H4). A procedure was
employed analogous to that described for 1a, using Ph2PC6H4CHd
N(2-MeOC6H4) (69 mg, 0.175 mmol) and [RhI(CO)2]2 (50.4 mg,
0.088 mmol). Yield: 38 mg (33%). Anal. Calcd for C27H22INO2-
PRh: C, 49.64; H, 3.39; N, 2.14. Found: C, 49.44; H, 3.41; N,
1.95. IR (ν(CO); CH2Cl2): 1995 cm-1. 1H NMR (CD2Cl2): δ 3.76
(s, 3H, OMe), 6.82-7.60 (m, 18H, Ar H), 7.99 (d, 2.1 Hz, 1H,
NdCH). 31P{1H} NMR (CD2Cl2): δ 44.5 (d, JRhP ) 171 Hz).
MS (FAB; m/z): 625 [M+] - CO, 526 [M+] - I, 498 [M+] -
CO - I.
Kinetic Experiments. Samples for kinetic runs were prepared
by placing the required amount of freshly distilled iodomethane in
a 5 cm3 graduated flask, which was then filled up to the mark with
CH2Cl2. A portion of this solution was used to record a background
spectrum. Another portion (typically 500 µL) was added to the solid
Rh complex (typically 5-8 µmol) in a sample vial to give a reaction
solution containing 10-15 mM [Rh]. A portion of the reaction
solution was quickly transferred to the IR cell, and the kinetic
experiment was started. Pseudo-first-order conditions were em-
ployed, with a least a 10-fold excess of MeI, relative to the metal
complex. The IR cell (0.5 mm path length, CaF2 windows) was
maintained at constant temperature throughout the kinetic run by a
thermostated jacket. Spectra were scanned in the metal carbonyl
ν(CO) region (2200-1600 cm-1) and saved at regular time intervals
under computer control. After the kinetic run, absorbance versus
time data for the appropriate ν(CO) frequencies were extracted and
analyzed off-line using Kaleidagraph curve-fitting software. The
decays of the bands of 1a-g were all well fitted by exponential
curves with correlation coefficients g0.999, to give pseudo-first-
order rate constants. Each kinetic run was repeated at least twice
to check reproducibility, the kobs values being averaged values with
component measurements deviating from each other by e5%.
(f) [RhI(CO)(PNAr)] (1f; Ar ) 4-MeOC6H4). A procedure was
employed analogous to that described for 1a, using Ph2PC6H4CHd
N(4-MeOC6H4) (84 mg, 0.21 mmol) and [RhI(CO)2]2 (54 mg, 0.09
mmol). Yield: 101 mg (82%). Anal. Calcd for C27H22INO2PRh:
C, 49.64; H, 3.39; N, 2.14. Found: C, 49.46; H, 3.28; N, 2.11. IR
1
(ν(CO); CH2Cl2): 1997 cm-1. H NMR (CDCl3): δ 3.79 (s, 3H,
OMe), 6.78 (m, 4H, Ar H), 7.52 (m, 14H, Ar H), 7.97 (bs, 1H,
NdCH). 31P{1H} NMR (CDCl3): δ 46.8 (d, JRhP ) 168 Hz).
(g) [RhI(CO)(PNAr)] (1g; Ar ) 3,5-(CF3)2C6H3). A procedure
was employed analogous to that described for 1a, using Ph2PC6H4-
CHdN(3,5-(CF3)2C6H3) (93.4 mg, 0.19 mmol) and [RhI(CO)2]2
(45.2 mg, 0.08 mmol). Yield: 102 mg (85%). Satisfactory elemental
analysis was not obtained for this compound, despite clean
spectroscopic data, presumably due to air sensitivity. IR (ν(CO);
1
CH2Cl2): 2002 cm-1. H NMR (CDCl3): δ 6.90-7.01 (m, 1H,
C6H2(CF3)2-H), 7.38-7.66 (m, 16H, Ar H), 7.92 (bs, 1H, Nd
CH). 31P{1H} NMR (CDCl3): δ 46.1 (d, JRhP ) 165 Hz). MS
(FAB; m/z): 759 [M+], 731 [M+] - CO, 632 [M+] - I, 604 [M+]
- CO - I.
Acknowledgment. We thank the EPSRC and BP Chemicals
Ltd. for funding this research (studentship to J.M.W.) and Dr.
Glenn Sunley for helpful discussions.
Synthesis of Rh(III) Complexes. (a) [Rh(COMe)I2(PNAr)] (3b;
Ar ) 2,6-Me2C6H3). Complex 1b (15 mg) was dissolved in THF
(5 cm3), and iodomethane (2 cm3) was added. After the mixture
was stirred for 1 h, the volatiles were removed in vacuo to yield a
dark orange solid. Anal. Calcd for C29H27I2NOPRh: C, 43.91; H,
3.43; N, 1.77. Found: C, 44.25; H, 3.73; N, 1.58. IR (ν(CO); CH2-
Supporting Information Available: Tables giving kinetic data
and CIF files giving crystallographic data. This material is available
1
Cl2): 1716 cm-1. H NMR (CDCl3): δ2.10 (s, 6H, Me), 3.55 (s,
3H, COMe), 6.78-7.64 (m, 17H, Ar H), 8.15 (d, 2.7 Hz, 1H, Nd
CH). 31P{1H} NMR (CDCl3): δ 46.9 (d, JRhP ) 131 Hz). MS (FAB;
m/z): 623 [M+] - COMe - I.
(b) [Rh(COMe)I2(PNAr)] (3c; Ar ) 2,6-iPr2C6H3). A procedure
analogous to that described above for 3b was employed. Anal. Calcd
for C33H35I2NOPRh: C, 46s.67; H, 4.15; N, 1.65. Found: C, 46.57;
OM070019B
(52) Sheldrick, G. M. SHELXTL, an Integrated System for Solving and
Refining Crystal Structures from Diffraction Data, Revision 5.1; Bruker
AXS Ltd., Madison, WI.