38
J. Berstler et al. / Journal of Organometallic Chemistry 712 (2012) 37e45
(d, 3JHeH ¼ 6.96 Hz, 6H, eCH3), 1.23 (d, 3JHeH ¼ 6.96 Hz, 6H, eCH3).
IR (CH2Cl2): nCO (cmꢀ1) 1997 (m), 1894 (sh), 1881 (vs), 1859 (m).
Anal. Calcd for C26H36CrFeO4P2: C, 53.62; H, 6.23. Found: C, 53.64;
H, 6.12.
2.2.2. [Cr(CO)4(dcpf)]
This compound was prepared using a method identical to that
for the preparation of Cr(CO)4(dippf). Cr(CO)6 (0.1734 g,
0.7880 mmol), dcpf (0.2229 g, 0.3853 mmol) and TMNO (0.0582 g,
0.775 mmol) were used to prepare 0.1278 g (44.7% yield) of the
product which was obtained as a yellow solid. 31P{1H} NMR:
d
(ppm) 49.1 (s). 1H NMR:
d (ppm) 4.28 (AAʹBBʹ, 4H, C5H4), 4.20
(AAʹBBʹ, 4H, C5H4), 2.34 (br, 4H, C6H11), 2.06 (br, 4H, C6H11), 1.86 (m,
20H, C6H11), 1.45 (m, 16H, C6H11). IR (CH2Cl2): nCO (cmꢀ1) 1995 (m),
1891 (sh), 1877 (vs), 1856 (m). Anal. Calcd for C38H52CrFeO4P2: C,
61.46; H, 7.06. Found: C, 61.40; H, 7.24.
Fig. 1. Metal carbonyl compounds of dppf, dippf and dcpf.
of these compounds were examined by spectroelectrochemistry in
order to determine the site of oxidation. Finally, crystal structures
of two dippf compounds and one dcpf compound were determined
and structural parameters from both crystallography and calcula-
tion on bidentate phosphine ligands in a pseudo-octahedral envi-
ronment examined.
2.2.3. [Mo(CO)4(dippf)]
Using Mo(CO)6 (0.1330 g, 0.5038 mmol), dippf (0.1063 g,
0.2541 mmol) and TMNO (0.0374 g, 0.498 mmol), this compound
was prepared in a manner similar to the Cr analog. The compound
was purified using column chromatography with a 1:2 (v/v)
mixture of CH2Cl2/hexanes as the eluent and 0.0638 g (33.3% yield)
of the product was obtained as a yellow solid. 31P{1H} NMR:
41.3 (s). 1H NMR:
C5H4), 2.28 (m, 4H, eCHMe2), 1.33 (d, JHeH ¼ 6.96 Hz, 6H, eCH3),
d
(ppm)
2. Experimental
d
(ppm) 4.33 (AAʹBBʹ, 4H, C5H4), 4.29 (AAʹBBʹ, 4H,
3
2.1. General procedures
3
3
1.29 (d, JHeH ¼ 6.96 Hz, 6H, eCH3), 1.23 (d, JHeH ¼ 6.96 Hz, 6H,
eCH3), 1.19 (d, 3JHeH ¼ 6.96 Hz, 6H, eCH3). IR (CH2Cl2): nCO (cmꢀ1
)
Standard Schlenk techniques under an atmosphere of argonwere
employed in all preparative reactions. A two-column Solv-tek
purification system was used for the purification of methylene
chloride (CH2Cl2), diethyl ether (Et2O), hexanes, and THF under
argon [13]. Chloroform was dried over molecular sieves and
degassed prior to use. Reagents were used without additional
purification unless otherwise noted. The metal carbonyls, M(CO)6
(M ¼ Cr, Mo, W) and M2(CO)10 (M ¼ Mn, Re), ferrocene (FcH), dec-
amethylferrocene (Fc*), dppf, dippf and dcpf were purchased from
Strem. The Cr(CO)6 and FcH were sublimed prior to use. Tetrabuty-
lammonium hexafluorophosphate ([NBu4][PF6]), trimethylamine-
N-oxide (TMNO), and bromine were purchased from Aldrich. The
[NBu4][PF6] was dried at 100 ꢁC under vacuum. The compounds
Mn(CO)5Br [14], Re(CO)5Br [15], [Mn(CO)3Br(dppf)] [16] and
[Re(CO)3Br(dppf)] [16] were prepared according to the literature
procedure. A slurry of silica gel in hexanes was used as the stationary
phase for all column chromatography. 1H (internal TMS reference)
and 31P{1H} (external 85% H3PO4 reference) NMR spectra were
obtained in CDCl3 using a JEOL Eclipse 400 FT-NMR spectrometer. IR
spectra were recorded on a Matteson Satellite FTIR. Elemental
analyses were performed by Quantitative Technologies, Inc.
2010 (m), 1890 (vs). Anal. Calcd for C26H36FeMoO4P2∙1.5 CH2Cl2: C,
43.82; H, 5.22. Found: C, 43.87; H, 4.91.
2.2.4. [Mo(CO)4(dcpf)]
The compound was prepared using a procedure similar to that of
the Cr analog. Column chromatography was performed using a 1:2
(v/v) mixture of CH2Cl2/hexanes as the eluent. Mo(CO)6 (0.1330 g,
0.5038 mmol), dcpf (0.1458 g, 0.2520 mmol) and TMNO (0.0372 g,
0.496 mmol) were used to prepared 0.0574 g (29.0% yield) of the
product as a yellow solid. 31P{1H} NMR:
d
(ppm) 33.6 (s). 1H NMR:
d
(ppm) 4.30 (AAʹBBʹ, 4H, C5H4), 4.15 (AAʹBBʹ, 4H, C5H4), 2.23 (br, 4H,
C6H11), 1.88 (br, 4H, C6H11), 1.69 (m, 20H, C6H11),1.21 (m, 16H, C6H11).
IR (CH2Cl2): nCO (cmꢀ1) 2009 (m), 1887 (vs). Anal. Calcd for
C38H52FeMoO4P2∙0.1 CH2Cl2 : C, 57.56; H, 6.62. Found: C, 57.47; H,
6.68.
2.2.5. [W(CO)4(dippf)]
The compound was prepared using the same procedure as was
employed for the Cr analog. W(CO)6 (0.1690 g, 0.4802 mmol), dippf
(0.1065 g, 0.2546 mmol) and TMNO (0.0375 g, 0.4993 mmol) were
used in the synthesis. The product was purified by column chro-
matography using a 1:2 (v/v) mixture of CH2Cl2/hexanes to elute
the product. The product was obtained as a yellow solid (0.0602 g,
2.2. Preparation of compounds
2.2.1. [Cr(CO)4(dippf)]
35.9% yield). 31P{1H} NMR:
d d (ppm) 4.33
(ppm) 25.8 (s). 1H NMR:
Cr(CO)6 (0.1713 g, 0.7784 mmol) and dippf (0.1618 g,
0.3868 mmol) were placed in a flask, degassed, and dissolved in
a mixture of 5 ml of CH2Cl2 and 12 ml of THF. TMNO (0.0585 g,
0.779 mmol) was added and the reaction was allowed to stir
overnight. The solution was filtered via cannula and solvent was
removed in vacuo. The product was purified using column chro-
matography. Unreacted dippf was removed by eluting with
hexanes. The product was the second orange band eluted from the
column using Et2O. Solvent was removed in vacuo and 0.0951 g
(42.2% yield) of the product was obtained as a yellow solid. 31P{1H}
(AAʹBBʹ, 4H, C5H4), 4.26 (AAʹBBʹ, 4H, C5H4), 2.34 (m, 4H, eCHMe2),
3
3
1.33 (d, JHeH ¼ 6.96 Hz, 6H, eCH3), 1.30 (d, JHeH ¼ 6.96 Hz, 6H,
eCH3), 1.23 (d, 3JHeH ¼ 6.96 Hz, 6H, eCH3), 1.19 (d, 3JHeH ¼ 6.96 Hz,
6H, eCH3). IR (CH2Cl2): nCO (cmꢀ1) 2006 (m), 1879 (vs). Anal. Calcd
for C26H36FeO4P2W: C, 43.73; H, 5.08. Found: C, 43.95; H, 4.74.
2.2.6. [W(CO)4(dcpf)]
The compound was prepared using a procedure similar to that of
the Cr analog. Column chromatography was performed using a 1:5
(v/v) mixture of Et2O/hexanes as the eluent. The product was
obtained as a yellow solid (0.1197 g, 34.8% yield) from W(CO)6
(0.2743 g, 0.7795 mmol), dcpf (0.2266 g, 0.3916 mmol) and TMNO
NMR:
d d (ppm) 4.31 (AAʹBBʹ, 4H, C5H4),
(ppm) 55.8 (s). 1H NMR:
4.29 (AAʹBBʹ, 4H, C5H4), 2.40 (m, 4H, eCHMe2), 1.40 (d,
3JHeH ¼ 6.96 Hz, 6H, eCH3), 1.37 (d, 3JHeH ¼ 6.96 Hz, 6H, eCH3), 1.26
(0.0565 g, 0.752 mmol). 31P{1H} NMR:
d
(ppm) 17.6 (s). 1H NMR: