Inorganic Chemistry
FORUM ARTICLE
was charged with (Et4N)[ReV(O)(apPh)2] (568 mg, 0.616 mmol) and
dissolved in THF (40 mL). Separately, 2,3,4,5,6,6-hexachloro-2,4-cyclo-
hexadien-1-one (222 mg, 0.742 mmol) was dissolved in THF (3 mL)
and added to the [ReV(O)(apPh)2]ꢀ solution, giving an immediate color
change from pale green to dark purple. The reaction mixture was stirred
at 60 °C for 10 days under N2. The mixture was then exposed to air and
the solvent removed in vacuo. The dark residue was taken up in minimal
CH2Cl2 and chromatographed on a silica gel column (230ꢀ400 mesh)
prepared with hexanes. A dark-purple band eluted as the second, major
fraction using 70:30 hexanes/CH2Cl2. Removal of the solvent from the
eluate, followed by dissolution in benzene and lyophilization, afforded
analytically pure ReVI(O)(apPh)(isqPh)(OC6Cl5) (364 mg, 0.345 mmol,
71%) as a purple powder. Single crystals for X-ray diffraction analysis
were grown by the slow evaporation of a saturated CH3CN solution at
8 °C over 2 weeks on a Chromel A (80% Ni and 20% Cr) wire. UVꢀvis
(CH3CN) λmax, nm (ε, Mꢀ1 cmꢀ1): 231 (50 000), 413 (13 300), 523
(17 100), 613 (sh), 894 (3500). MALDI-MS (m/z): 1058 [M]+. FTIR
(ATR, cmꢀ1): 2953 (m), 2923 (m), 2866 (m), 1590 (vw), 1532 (vw),
1479 (m), 1458 (m), 1386 (vs), 1359 (s), 1313 (vw), 1299 (vw), 1252
(m), 1225 (w), 1203 (w),1164 (w), 1135 (w), 1108 (w), 1077 (w), 1027
(w), 989 (s), 934 (s), 924 (s), 894 (w), 880 (w), 864 (w), 830 (vs), 778
(s), 711 (s), 674 (vs), 608 (vw), 553 (s), 426 (m). 1H NMR (300 MHz,
CD2Cl2, δ): 7.7 (td, J = 7 and 2 Hz, NPh: meta, 1H), 7.64 (d, J = 7 Hz,
NPh: ortho, 1H), 7.63 (td, J = 7 and 2 Hz, NPh: meta, 1H), 7.44 (tt, J = 7
Hz, 1 Hz, NPh: para, 1H), 7.32 (t, J = 7 Hz, NPh0: meta, 1H), 7.18 (d, J =
7 Hz, NPh0: ortho, 1H), 7.08 (d, J = 7 Hz, NPh: ortho, 1H), 6.98 (d, J =
2 Hz, ArH, 1H), 6.97 (t, J = 7 Hz, NPh0: meta, 1 H), 6.95 (t, J = 7 Hz,
NPh0: para, 1H), 6.59 (d, J = 2 Hz, ArH, 1H), 6.53 (d, J = 2 Hz, ArH, 1H),
6.51 (d, J = 2 Hz, ArH, 1H), 6.00 (d, J = 7 Hz, NPh0: ortho, 1H), 1.23 (s,
tBu, 9H), 1.19 (s, tBu, 9H), 1.17 (s, tBu, 9H), 0.98 (s, br, tBu, 9H). The
NPh: meta, 1H), 7.45 (d, J = 7 Hz, NPh: ortho, 1H), 7.40 (tt, J = 7 and
1 Hz, NPh: para, 1H), 7.2 (t, J = 7 Hz, NPh0: meta, 2H), 6.97 (tt, J = 7 and
1 Hz, NPh0: ortho, para, 2H), 6.93 (d, J = 2 Hz, ArH, 1H), 6.66 (d, J = 7
Hz, NPh: ortho, 1H), 6.52 (d, J = 2 Hz, ArH, 1H), 6.4 (d, J = 2 Hz, ArH,
1H), 6.29 (br, NPh0: ortho, 1H), 6.26 (d, J = 2.1 Hz, ArH, 1H), 1.48 (s,
tBu Hz, 9H), 1.22 (s, tBu Hz, 9H), 1.20 (s, tBu, 9H), 1.18 (s, tBu, 9 H).
1H NMR (253 K, 400 MHz, CD2Cl2, δ): 7.63 (t, J = 7 Hz, NPh: meta,
1H), 7.56 (t, J = 7 Hz, NPh: meta, 1H), 7.44 (d, J = 7 Hz, NPh: ortho,
1H), 7.41 (t, J = 7 Hz, NPh: para, 1H), 7.24 (t, J = 7 Hz, NPh0: meta, 1H),
7.17 (t, J = 7 Hz, NPh0: meta, 1H), 7.01 (d, J = 7 Hz, NPh0: ortho 1H),
6.96 (t, J = 7 Hz, NPh0: para, 1H), 6.92 (d, J = 2 Hz, ArH, 1H), 6.75 (d, J =
7 Hz, NPh: ortho 1H), 6.47 (d, J = 2 Hz, ArH: 1H), 6.40 (d, J = 2 Hz,
ArH, 1H), 6.33 (d, J = 7 Hz, NPh0: ortho, 1H), 6.28 (d, J = 2 Hz, ArH,
1H), 1.44 (s, tBu, 9H), 1.17 (s, tBu, 18H), 1.15 (s, tBu, 9H). Samples for
combustion analysis were prepared by method 3, above, which produces
pentachlorophenol as a byproduct. The reported analysis is for ReVI-
(O)(apPh)(isqPh)Cl 0.5C6H6 0.8C6Cl5OH. The presence of benzene
3
3
in the sample was confirmed by 1H NMR spectroscopy. Anal. Calcd for
47.8H53.8Cl5N2O3.8Re: C, 53.13; H, 5.02; N, 2.59. Found: C, 53.06; H,
C
5.15; N, 2.70.
Synthesis of ReV2(μ-O)2(apPh)2(isqPh)2. Method 1. In a 20 mL
scintillation vial, a solution of ReVI(O)(apPh)(isqPh)Cl (25.6 mg, 0.031
mmol) in CH2Cl2 (5 mL) was added to a solution of bis(benzene)-
chromium [Cr(|6-C6H6)2] (6.3 mg, 0.031 mmol) in CH2Cl2 (5 mL) to
yield a purple solution. The reaction mixture was stirred for 20 min, and
the solvent was removed under vacuum. The resulting purple residue
was extracted into ether and the solvent removed in vacuo to afford
ReV2(μ-O)2(apPh)2(isqPh)2 (19.3 mg, 0.0120 mmol, 79%) as a purple
powder. Recrystallization by the slow evaporation of a concentrated
CH2Cl2 solution afforded single crystals suitable for X-ray diffraction
analysis. Method 2. A 20 dram scintillation vial was charged with
(Et4N)[ReV(O)(apPh)2] (0.327 g, 0.355 mmol) and dissolved in
CH3CN (10 mL) to afford a pale-green solution. The addition of
tris(4-bromophenyl)ammoniumyl tetrafluoroborate [(C6H4Br)3N]-
[BF4] (0.1963 g, 0.345 mmol) in MeCN (5 mL) with vigorous stirring
gave the immediate formation of a dark precipitate. After stirring for
30 min, the solids were collected by vacuum filtration to give ReV2(μ-
O)2(apPh)2(isqPh)2 (0.532 g, 0.335 mmol, 97%) as a dark-purple
powder. Single crystals of ReV2(μ-O)2(apPh)2(isqPh)2 for X-ray diffrac-
tion were grown by vapor diffusion of CH3CN into a concentrated
CH2Cl2. Method 3. A solution of (Et4N)[ReV(O)(apPh)2] (10.7 mg,
0.012 mmol) in CH2Cl2 (5 mL) was added to a solution of ReVI(O)-
(apPh)(isqPh)Cl (8.9 mg, 0.010 mmol) in CH2Cl2 (5 mL), and the
reaction mixture was stirred for 10 min. Removal of the solvent gave a
purple residue that was extracted into ether and dried in vacuo to yield
ReV2(μ-O)2(apPh)2(isqPh)2 (15.2 mg, 0.0096 mmol, 96%) as a dark-
purple powder. Single crystals for study by X-ray diffraction were
obtained by the slow evaporation of a benzene solution. MALDI-MS
(m/z): 1586 [M]+. FTIR (ATR, cmꢀ1): 2953 (s), 2902 (m), 2865 (m),
1589 (m), 1484 (s), 1463 (m), 1391 (m), 1361 (s), 1247 (vs), 1201 (m),
1163 (m), 1024 (m), 994 (s), 928 (m), 888 (s), 861 (s), 832 (s), 765 (s),
708 (vs), 687 (w), 645 (vs), 621 (s), 570 (s), 545 (m), 502 (m), 483 (s),
400 (m). 1H NMR (300 MHz, C6D6, δ): 6.8ꢀ7.0 (m, Ar, 28H), 1.27 (s,
tBu, 36 H), 1.1 (s, tBu, 36H). UVꢀvis (CH2Cl2) λmax, nm(ε, Mꢀ1 cmꢀ1):
reported analysis is for ReVI(O)(apPh)(isqPh)(OC6Cl5) C6H6, and the
3
presence of 1 equiv of benzene in the sample was confirmed by 1H NMR
spectroscopy. Anal. Calcd for C53H64Cl5N2O4Re: C, 55.04; H, 5.58; N,
2.42. Found: C, 55.19; H, 5.22; N, 2.40.
Synthesis of ReVI(O)(apPh)(isqPh)Cl. Method 1. The procedure
above for the synthesis of ReVI(O)(apPh)(isqPh)(OC6Cl5) yields ReVI-
(O)(apPh)(isqPh)Cl (62 mg, 0.075 mmol, 12%) as a minor product.
Method 2. A 20 dram scintillation vial was charged with (Et4N)-
[ReV(O)(apPh)2] (25.9 mg, 0.0281 mmol) and dissolved in CH3CN
(5 mL) to afford a pale-green solution. A second 20 dram scintillation
vial was charged with tris(4-bromophenyl)ammoniumyl hexachloroan-
timonate [(C6H4Br)3N][SbCl6] (25.8 mg, 0.0316 mmol) and dissolved
in CH3CN (2 mL). Both solutions were chilled to ꢀ20 °C and
combined to immediately yield a dark-purple solution. The reaction
mixture was stored at ꢀ20 °C for 6 months to deposit purple crystals of
ReVI(O)(apPh)(isqPh)Cl (2.7 mg, 3.26 mmol, 11%) that were used for
X-ray diffraction analysis. Method 3. A 20 dram scintillation vial was
charged with ReVI(O)(apPh)(isqPh)(OC6Cl5) (30.0 mg, 0.0284 mmol)
and dissolved in 1:1 CH2Cl2/CH3CN (10 mL) in air. Excess concen-
trated aqueous HCl (200ꢀ300 μL; 2.48ꢀ3.72 mmol) was added
dropwise, and the reaction mixture was stirred at ambient temperature
for 15 h in air. The reaction mixture was washed with water (3 ꢁ 5 mL)
to remove unreacted HCl, and the organic layer was separated and dried
on MgSO4. Filtration followed by removal of the solvent under reduced
pressure gave purple solids of ReVI(O)(apPh)(isqPh)Cl in quantitative
isolated yield. UVꢀvis (CH2Cl2) λmax, nm (ε, Mꢀ1 cmꢀ1): 295 (sh),
410 (10 500), 515 (12 300), 605 (sh), 920 (1700). MALDI-MS (m/z):
828 [M]+. FTIR (ATR, cmꢀ1): 2958 (m), 2905 (m), 2868 (m), 1588
(m), 1532 (m), 1481 (s), 1451 (m), 1407 (w), 1391 (m), 1362 (s), 1320
(m), 1302 (m), 1264 (s), 1250 (s), 1176 (s), 1111 (w), 1070 (w), 1027
(m), 995 (s), 928 (vs), 915 (vs), 859 (s), 834 (m), 772 (m), 758 (m),
741 (w), 714 (vs), 703 (vs), 671 (m), 652 (m), 643 (s), 616 (s), 555 (m),
541 (m), 503 (m), 474 (w). 1H NMR (293 K, 400 MHz, CD2Cl2, δ):
7.63 (td, J = 7 and 2 Hz, NPh: meta, 1H), 7.54 (td, J = 7 and 2 Hz,
300 (sh), 420 (sh), 480 (33 000), 610 (22 700). Anal. Calcd for C80H100
-
N4O4Re2: C, 60.58; H, 6.35; N, 3.53. Found: C, 60.03; H, 6.35; N, 3.44.
Synthesis of ReV(apPh)(isqPh)Cl2. Method 1. A 50 mL flask with
a Kontes brand high-vacuum PTFE valve was charged with (Et4N)-
[ReV(O)(apPh)2] (0.484 g, 0.524 mmol) and CH2Cl2 (25 mL). The
addition of Me3SiCl (160 μL, 1.26 mmol) afforded a red-orange
solution. The flask was sealed and immersed in a silicone fluid bath at
65 °C for 3 h to yield a clear, maroon solution and then cooled to
ambient temperature. The mixture was exposed to air, and the solvent
was removed under reduced pressure. The residue was taken up in
9875
dx.doi.org/10.1021/ic200923q |Inorg. Chem. 2011, 50, 9864–9878