3550 Inorganic Chemistry, Vol. 35, No. 12, 1996
Rose et al.
were distilled from their appropriate drying agents.44 Triethylamine
(Aldrich) was distilled from CaH2 and stored under an inert atmosphere.
Pyridine-2-thiol (Aldrich), pyrimidine-2-thiol (Aldrich), chlorotrimeth-
ylsilane (Petrarch), tert-butyldimethylchlorosilane (Petrarch), n-butyl-
lithium (2.5 M solution in hexanes; Aldrich), benzoylhydrazine
(Aldrich), triphenylphosphine (Aldrich), bromine (Aldrich), cyclohexene
(Fisher), toluene (Sure-Seal; Aldrich), and other reagents were used as
received without further purification. Tetrabutylammonium perrhenate
was prepared by mixing aqueous solutions of tetrabutylammonium
bromide and ammonium perrhenate, collecting the precipitated colorless
solid via vacuum filtration on a frit, and recrystallization of the product
from THF/H2O. The reagents 2,39 3,39 [ReOCl3(PPh3)2],45 [Re(N2CO-
(C6H5)Cl2(PPh3)2],46 and tetrabutylammonium hexafluorophosphate
were synthesized by published procedures.47
into a solution of C28H65NO2PReBr4 in CH2Cl2. During the crystal-
lization, one tributylphosphine was lost and replaced with two water
molecules.
Preparation of [Bu4N][ReOBr4(OPPh3)] (6). All steps were
performed open to the atmosphere. To a solution of PPh3 (1.06 g,
4.05 mmol) in 10 mL of CH2Cl2 was added a solution of Br2 (0.205
mL, 4.05 mmol) in 10 mL of CH2Cl2 dropwise via pipet. A water
bath was used to cool the solution during addition. The generated
purple phosphorane solution (Ph3PBr2) was then stirred for 2 h before
being added to a colorless solution of [Bu4N][ReO4] (0.500 g, 4.05
mmol) in 10 mL of CH2Cl2 in the presence of O2 (open air). To the
red-violet reaction mixture was added 100 mL of ether, 100 mL of
pentane, and 0.75 mL of cyclohexene, and a violet solid precipitated
from the reaction mixture. The product was collected via filtration
and air-dried (2.12 g, 2.03 mmol, 51%). Anal. Calcd for C52H66NO2P2-
ReBr4 (mol wt 1303.74): C, 47.86; H, 5.06; N, 1.07. Found: C, 47.61;
H, 5.56; N, 1.37. IR (KBr, cm-1): 2961 (m), 2872 (m), 1458 (s), 1438
(s), 1146 (s), 1120 (s), 1090 (m), 994 (vs), 932 (m), 878 (m), 724 (m),
693 (m), 537 (s). X-ray quality crystals of 6 were prepared by diffusion
of Et2O into a solution of C52H66NO2P2ReBr4 in CH2Cl2. During the
crystallization one triphenylphosphine was lost.
Preparation of [ReO2(C5H5N)4]Cl‚2H2O.51 All steps were per-
formed open to the atmosphere. To a solution of 5 g (19 mmol) of
PPh3 in 30 mL of EtOH was added a solution of 3.5 mL (30 mmol) of
37% HCl containing 1 g (3.73 mmol) of NH4ReO4. The solution was
refluxed in a 50 mL Schlenk flask for 10 min. The color of the solution
changed from milky white to olive. The reaction mixture was cooled
to room temperature and filtered. The precipitate was washed with
two 10 mL portions of EtOH and two 10 mL portions of Et2O to yield
[ReOCl2(OEt)(PPh3)2] in quantitative yield (3 g).
Syntheses. Preparation of Pyridine-2-thiol (1). The yellow
crystalline solid was prepared by the method of Katritzky.48 The crude
product was rotovapped to dryness and Soxhlet-extracted with benzene
until no color was evident in the extract. The extract was rotovapped
to dryness, the solid dissolved in acetone, and the mixture filtered. The
acetone was removed by rotary evaporation, and the resulting solid
was stirred with 125 mL of pentane overnight. The mixture was
filtered, and the solid was dried under vacuum to give pyridine-2-thiol
in 31% yield. IR (KBr pellet, cm-1): 2958 (m), 2876 (m), 1734(w),
1654(w), 1571 (vs), 1491 (m), 1438 (m), 1366 (s), 1257 (m), 1180
(m), 1137 (vs), 982 (m), 742 (s), 486 (s).
Preparation of 3-(Trimethylsilyl)pyridine-2-thiol (2). The yellow
crystalline solid was prepared by the method of Block.49 After
sublimation, the crude product (102.4% yield) was washed with acetone
and pentane, and crystals were grown by diffusion of pentane into a
CH2Cl2 solution of the ligand. Recrystallized yield: 40%. IR (KBr
pellet, cm-1): 2940 (s), 2854 (s), 1604 (s), 1572 (s), 1309 (vs), 1236
(s), 1203 (m), 1150 (vs), 1122 (s), 1064 (m), 1041 (s), 851 (vs), 749
(vs), 622 (m), 512 (w), 475 (m).
To a gray-green solution of [ReOCl2(OEt)(PPh3)2] (1 g, 1.19 mmol)
in 25 mL of EtOH was added dropwise 5 mL (62 mmol) of pyridine.
The solution was refluxed for 2 h, whereupon the volume was reduced
under vacuum to 10 mL. The product was recrystallized from EtOH/
Et2O, collected by filtration, and dried in the air to give [ReO2(C5H5N)4]-
Cl‚ 2H2O (0.7 g, 95% yield). IR (KBr, cm-1): 3382 (s), 3063 (m),
1604 (m), 1477 (m), 1447 (s), 1345 (m), 1209 (m), 1150 (w), 1068
(m), 820 (s), 778 (s), 704 (s), 468 (w).
Preparation of 3,6-Bis(tert-butyldimethylsilyl)pyridine-2-thiol (3).
The yellow crystalline solid was prepared by the method of Block.50
The crude product was quenched with H2O and neutralized with HCl.
The mixture was rotary-evaporated to dryness, dissolved in CH2Cl2,
and then extracted with water. The aqueous layers were extracted with
CH2Cl2, and the CH2Cl2 extracts were combined and dried over MgSO4.
The solution was filtered, and the filtrate was rotary-evaporated to
dryness. The desired product was then sublimed from the crude reaction
mixture. The sublimed product was further purified by washing with
hexanes, to give 6.4 g of pure product (63% yield). IR (KBr pellet,
cm-1): 2940 (w), 2849 (w), 1565 (m), 1468 (m), 1289 (s), 1259 (s),
1160 (m), 1141 (s), 1098 (s), 1033 (m), 804 (s), 677 (m), 581 (w), 500
(w).
Preparation of [ReO(η2-2-SC5H4N)2(η1-2-SC5H4N)] (7). To a
solution of 5 (0.250 g, 0.25 mmol) in 15 mL of THF at 0 °C was
added a solution of 1 (0.107 g, 0.96 mmol) and Et3N (0.097 g, 0.96
mmol) in 5 mL of THF dropwise via syringe. Upon addition, the
reaction mixture changed in color from violet to dark green, with a
colorless solid (Et3NHBr) precipitating from the reaction mixture. After
being stirred for 2 h, the reaction mixture was filtered to remove the
precipitated triethylamine hydrobromide and the filtrate evaporated to
dryness. Recrystallization of the crude product from CH2Cl2/ether
afforded dark green blocks of 7 (0.070 g, 0.13 mmol, 55%). Anal.
Calcd for C15H12N3OReS3 (mol wt 532.70): C, 33.82; H, 2.27; N, 7.89.
Found: C, 34.40; H, 2.44; N, 8.94. IR (KBr, cm-1): 3044 (w), 1584
(vs), 1568 (sh), 1554 (m), 1439 (s), 1414 (s), 1264 (s), 1142 (w), 1120
(w) 1039 (w), 962 (m), 954 (sh), 803 (w), 761 (vs), 736 (w), 647 (w),
484 (w). 1H NMR (CDCl3, 293 K): all resonances are coalesced into
the baseline. UV-vis (λmax, nm (ꢀ, M-1 cm-1) in CH2Cl2): 242 (1.06
× 104), 285 (1.04 × 104), 365 (6.3 × 103), 650 (90).
Preparation of [Bu4N][ReOBr4(H2O)]‚2H2O (5). All steps were
performed open to the atmosphere. To a solution of PBun (2.842 g,
3
14.05 mmol) in 20 mL of CH2Cl2 was added a solution of Br2 (2.269
g, 14.20 mmol) in 20 mL of CH2Cl2 dropwise via pipet. The generated
purple phosphorane solution (Bun PBr2) was then added to a colorless
3
solution of [Bu4N][ReO4] (2.000 g, 4.06 mmol) in 20 mL of CH2Cl2
in the presence of O2 (open air). The red-violet reaction mixture was
stirred 45 min after complete addition of the phosphorane. After 45
min, 100 mL of ether, 3 mL of cyclohexene, and 100 mL of pentane
were added to the reaction mixture and a violet solid precipitated from
the reaction mixture. The product was collected via vacuum filtration
on a frit, washed with ether, and air-dried (3.0 g, 3.1 mmol, 75%).
Anal. Calcd for C28H65NO2PReBr4 (mol wt 983.77): C, 34.15; H, 6.60;
N, 1.42. Found: C, 34.53; H, 6.46; N, 1.51. IR (KBr, cm-1): 2961
(s), 2872 (m), 1466 (s), 1381 (w), 1226 (w), 993 (vs), 808 (w), 738
(w). X-ray quality crystals of 5 were prepared by diffusion of Et2O
Preparation of [ReO(η2-2-SC5H3N-3-SiMe3)2(η1-2-SC5H3N-3-
SiMe3)] (8). Compound 5 (0.250 g, 0.25 mmol), 2 (0.176 g, 0.96
mmol), and Et3N (0.096 g, 0.96 mmol) were mixed in 20 mL of THF
as described for 7. Recrystallization of the crude product from a
concentrated solution of hexanes at -20 °C afforded 8 as a green
microcrystalline solid (0.059 g, 0.079 mmol, 33%). Anal. Calcd for
C24H36N3OReS3Si3 (mol. wt. 749.24): C, 38.47; H, 4.84; N, 5.61.
Found: C, 38.38; H, 4.10; N, 5.74. IR (KBr, cm-1): 2959 (m), 1560
(m), 1539 (w), 1368 (vs), 1249 (m), 1080 (w), 1022 (w), 966 (m), 841
(vs), 801 (w), 760 (w). 1H NMR (CD2Cl2, 243 K): δ 8.68 (bd, 1H),
8.56 (bd, 1H), 7.80 (m, 2H), 7.65 (d, 1H), 7.26 (dd, J ) 6.8 Hz, 1.3
Hz, 1H), 7.07 (m, 2H), 6.37 (t, J ) 6.3 Hz, 1H), 0.44 (s, 9H), 0.33 (s,
9H), 0.20 (s, 9H).
(44) Perrin, D. D.; Armarego, W. L. F.; Perrin, D. R. Purification of
Laboratory Chemicals; Pergamon Press: London, 1980.
(45) Parshall, G. W. Inorg. Synth. 1977, 17, 100.
(46) Chatt, J.; Dilworth, J. R.; Leigh, G. J.; Gupta, V. D. J. Chem. Soc. A
1971, 2631.
Preparation of [ReO(OH)(η2-SC5H2N-3,6-(SiMe2But)2)2] (9). Com-
pound 5 (0.250 g, 0.25 mmol), 3 (0.326 g, 0.96 mmol), and Et3N (0.097
(47) Ferguson, J. A. Interface 1970, 6 (2), 1.
(48) Jones, R. A.; Katritzky, A. R. J. Chem. Soc. 1958, 3610.
(49) Block, E.; Gernon, M.; Kang, H.; Zubieta, J. Angew. Chem., Int. Ed.
Engl. 1988, 27, 1342-1344.
(50) Block, E.; Gernon, M.; Kang, H.; Ofari-Okai, G.; Zubieta, J. Inorg.
Chem. 1991, 30, 1736.
(51) Chang, L.; Rall, J.; Tisato, F.; Deutsch, E.; Heeg, M. J. Inorg. Chim.
Acta 1993, 205, 35-41.
Rose, David J.
