R.C.S. Wong, M.L. Ooi / Inorganica Chimica Acta 366 (2011) 350–356
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2.2. Reaction of Cp2Cr2(CO)6 (1) with an equivalent of Woollins’
reagent at ambient temperature
[CpCr(CO)2(SePPh)]2, 691 [Cp2Cr2(CO)3(SePPh)2], 664
[Cp2Cr2(CO)2(SePPh)2], 633 [Cp2Cr2(CO)(SePPh)2)], 589
[Cp2Cr2(CO)2(SePPh)(SeP)], 533 [Cp2Cr2(SePPh)(SeP)],
502 [Cp2Cr2(Se2PPh)(Se)], 451 [Cp2Cr2(CO)(SePPh)], 413
[CpCr(Se2(O)PPh)(O)], 401 [CpCr(Se2(O)PPh)], 385
[CpCr(Se2PPh)], 359 [CpCr(CO)2(SePPh)], 331 [CpCr(CO)(SeP-
Ph)], 303 [CpCr(SePPh)], 273 [CpCrSe2], 228 [CpCrSeP]. Anal.
Calc. for C26H20Cr2O4P2Se2: C, 43.21; H, 2.77; Cr, 14.40; O,
8.86; P, 8.59; Se, 22.16. Found: C, 43.37; H, 2.89; Cr, 14.67;
O, 8.45; P, 8.62; Se, 22.45%.
A
deep green suspension of Cp2Cr2(CO)6 (1) (200 mg,
0.497 mmol) in toluene (ꢂ15 mL) was added WR (264 mg,
0.497 mmol) and the mixture stirred at ambient temperature. A
dark orange brown suspension was obtained after ca. 5 min. The
reaction mixture was allowed to continue stirring for 0.5 h. The
resultant dark orange brown solution was filtered through celite
and the filtrate was concentrated to ca. 3–4 mL before loading onto
a silica gel column (2 cm ꢃ 9 cm) prepared in n-hexane. Elution
gave three fractions:
A deep bluish green ring was remained unmoved on top of the
column.
(i) A dark purplish orange fraction was eluted with n-hexane
(65 mL) which when concentrated to dryness gave fine dark
orange brown crystalline solids of [CpCr(CO)2]2Se (3)
(70 mg, 0.165 mmol, 33.2% yield) [34,35], identified its 1H
NMR in benzene-d6 [d(Cp) 4.36] and TLC against an authen-
tic sample [Rf = 0.64 in 6:3:1 n-hexane/toluene/ether as elu-
ent] together with a trace amount of CpCr(CO)2(SeP(H)Ph)
(4).
(ii) A dark orange brown fraction was eluted with toluene
(48 mL) which when concentrated to dryness gave a dark
brown oily precipitate (189 mg, 60%). Analyses via TLC
showed it consisted of a mixture of [CpCr(CO)2]2Se (3),
trans-[CpCr(CO)2(SePPh)]2 (5) and CpCr(CO)2(SeP(H)Ph) (4)
in ratio of 8:1:1. Attempts to separate the mixture resulted
in failure.
2.4. Reaction of Cp2Cr2(CO)4 (2) with Woollins’ reagent at 60 °C
A
deep green suspension of Cp2Cr2(CO)4 (2) (300 mg,
0.867 mmol) in toluene (ꢂ15 mL) was added WR (461 mg,
0.867 mmol) and stirred at 60 °C for 3 h. The resultant dark brown-
ish green reaction mixture was concentrated to ca. 10 mL left and
was filtered through a sintered-glass funnel to remove a deep
green residue (361 mg). The filtrate was concentrated to ca. 3 mL
left and absorbed onto silica gel (ꢂ1 g). The dark brownish green
slurry was evacuated to dryness under vacuo and chromato-
graphed onto a silica gel column (1.5 cm ꢃ 9 cm) prepared in n-
hexane. Elution under slight pressure gave four fractions:
(i) A greyish brown eluant in n-hexane–toluene (1:2) (45 mL)
when which was concentrated to dryness gave dark brown
crystalline solids of 5 (18 mg, 0.022 mmol, 3% yield).
(iii) An uncharacterized green fraction was eluted with THF
(60 mL) which when concentrated to dryness gave a green
residue (162 mg).
(ii) A dark pinkish purple eluant in n-hexane–toluene (1:1,
15 mL) and when concentrated to dryness, gave dark pinkish
purple crystalline solids of CpCr(CO)2(SeP(H)Ph) (4) (55 mg,
0.152 mmol, 18% yield). Anal. Found: 1H NMR (benzene-d6):
d 4.26 (s, Cp); d 5.72 (s, P–H); d 6.68–7.37 (m, C6H5); 13C
NMR (benzene-d6): d 89.53 (Cp), d 132.71, 132.59, 131.37,
129.67, 129.62 and 129.50 (C6H5), 249.79, 254.22 (CO). 31P
NMR (benzene-d6: proton coupled): d 45.84, 48.26 (d,
A deep bluish green ring was remained unmoved on top of the
column.
2.3. Reaction of excess Cp2Cr2(CO)6 (1) with Woollins’ Reagent at
ambient temperature
A
deep green suspension of Cp2Cr2(CO)6 (1) (101 mg,
J = 387.6 Hz). IR: m(CO) at 1954.93vs, 1942.23vs, 1871.60vs,
0.251 mmol) in toluene (ꢂ10 mL) was added in 0.125 equivalent
of WR (16 mg, 0.031 mmol). The color of the reaction mixture
changed to orange brown immediately. The reaction mixture was
stirred at ambient temperature. After 1 h, no more color change
was observed and the resultant dark orange brown reaction mix-
ture was filtered through a sintered-glass funnel. The filtrate was
concentrated to ca. 3 mL and loaded onto a silica gel column pre-
pared in n-hexane (1.5 cm ꢃ 11.5 cm). Three fractions were eluted:
1853.25sh, and 1847.43sh cmꢁ1 and other peaks at
1159.72m, 1110.70m, 1093.53m, 1067.03m, 1055.44m,
1014.44m, 921.75m, 912.90m, 846.61m, 823.99m,
748.56m, 727.74w, 706.84vw, 690.43m, 685.54m,
639.48m, 590.79m, 550.25 m cmꢁ1 (nujol). HR-MS ESI+
(m/z): (52Cr, 80Se): 362.2380 [CpCr(CO)2(SeP(H)Ph)], 723
[Cp2Cr2(CO)4(SePPh)2], 695 [Cp2Cr2(CO)3(SePPh)2], 666
[Cp2Cr2(CO)2(SePPh)2], 633 [Cp2Cr2(CO)(SePPh)2], 451
[Cp2Cr2(CO)(SePPh)],
[CpCr(SePPh)(O)],
413
362
[CpCr(Se(O)PPh)(O)],
[CpCr(CO)2(SeP(H)Ph)],
401
331
(i) A dark orange brown fraction with n-hexane (10 mL) which
upon evaporation to dryness gave a black crystalline solid 3
(62 mg, 0.146 mmol, 58.2% yield).
(ii) A dirty green fraction was eluted with n-hexane/toluene
mixture (4: 1) (18 mL) which upon evaporation to dryness
gave green crystalline solids of unreacted Cp2Cr2(CO)6 (1)
(17 mg, 0.042 mmol, 16.7% recovery).
(iii) A greyish brown fraction was eluted with toluene (36 mL)
which upon evaporation to dryness gave the dark brown
crystalline solids of trans-[CpCr(CO)2(SePPh)]2 (5) (45 mg,
0.062 mmol, 24.7% yield). Anal. Found: 1H NMR (benzene-
d6): d 4.01 (s, Cp); d 7.02–7.72 (m, C6H5). 13CNMR (ben-
zene-d6): d 90.4 (Cp), d 126.02, 128.89, 129.65, 130.56,
[CpCr(CO)(SePPh)], 303 [CpCr(SePPh)], 273 [CpCrSe2]. Anal.
Calc. for C13H10CrO2PSe: C, 43.09; H, 2.76; Cr, 14.36; O,
8.84; P, 8.56; Se, 22.10. Found: C, 43.37; H, 2.58; Cr, 14.39;
O, 8.68; P, 8.47; Se, 22.54%.
(iii) A dark green eluant in ether (9 mL) which when concen-
trated to dryness gave dark brownish green crystalline solids
of Cp2Cr2(Se2P(O)Ph)2 (6) (14 mg, 0.018 mmol, 2% yield).
Anal. Found: 1H NMR (toluene-d8): d 5.04 (s, Cp); d 6.82–
7.08 (m, C6H5). 13C NMR (benzene-d6): d 126.02 (Cp), d
129.67, 130.56, 132.46, 138.20 and 138.63 (C6H5); 31P NMR
(benzene-d6): d ꢁ123.34. I.R:
m at 1157.67w, 1106.17m,
1084.11m, 1058.96m, 1026.21m, 998.64m, 815.55m,
138.23 and 138.65 (C6H5), d 249.79, 254.22 (CO). IR:
m
(CO)
741.12w, 728.43sh, 686.71w cmꢁ1 (nujol). HR-MS ESI+ (m/
at 1962.47vs, 1951.77vs, 1899.03vs cmꢁ1; other peaks at
1086.72m, 1063.01m, 1016.07m, 860.22vw, 844.94vw,
828.13w, 803.69w, 741.04w, 690.62w, 664.64vw cmꢁ1
z):
[CpCr(Se2(O)PPh)(O)],
(
52Cr, 80Se): 801.5744 [Cp2Cr2(Se2P(O)Ph)2], 413
401
[CpCr(Se2P(O)Ph)],
385
[CpCr(Se2PPh)], 303 [CpCr(Se2P)], 273 [CpCrSe2]. Anal. Calc.
for C20H20Cr2O2P2Se4: C, 29.93; H, 2.49; Cr, 12.97; O, 3.99;
(nujol). HR-MS ESI+ (m/z):
(
52Cr, 80Se): 722.4748