High-Spin Organocobalt(II) Complexes
Organometallics, Vol. 26, No. 4, 2007 979
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m-(C6H5)B), 9.8 (br, 1 H, p-(C6H5)B), 3.13 (br, 27H, (CH3)3S).
µ
(570), 725 (574). Anal. Calcd for C22H41S3BCo: C, 56.0; H, 8.77.
Found: C, 55.2; H, 8.60.
[PhTttBu]Co(CO)(C(O)Ph) (9). Yield: 45 mg, 81%. H NMR
eff (C6D6) ) 5.1 µB. UV-vis (pentane), λmax (ꢀ, M-1 cm-1): 632
(C6D6): δ 26.9 (br, 2 H, m-(C6H5)), 10.53 (br, 2 H, o-(C6H5)B),
8.45 (br, 2 H, m-(C6H5)B), 7.96 (br, 1 H, p-(C6H5)B), 5.79 (br, 27
H, C(CH3)3S), _13.63 (br, 1 H, p-(C6H5)), _19.9 (br, 2 H, o-(C6H5)).
µeff (C6D6) ) 2.1 µB UV-vis (pentane), λmax (ꢀ, M-1 cm-1): 495
[PhTttBu]Co(Et) (3). Yield: 70 mg (71%). Mp: 108 °C (dec).
1H NMR (C6D6): δ 19.9 (br, 2 H, o-(C6H5)B), 11.2 (br, 2 H,
m-(C6H5)B), 10.3 (br, 1 H, p-C6H5)B), 1.22 (br, 27 H, (CH3)3S),
-9.36 (2 H, br, -CH3). µeff (C6D6) ) 4.1 µB. UV-vis (pentane),
(213), 528 (224), 734 (91). FTIR (pentane): 2002 (νCO), 1709 (νCOR
)
cm-1
.
Synthesis of [PhTttBu]Co(CO)2 (10). Dry CO was passed
through a pentane solution (10 mL) containing 50 mg of the
[PhTttBu]Co(R) complex at room temperature for ∼2 min. An
immediate color change from purple (R ) Bn) or orange (R )
allyl) to brown was apparent. Solvent was removed in vacuo,
yielding a brown solid, [PhTttBu]Co(CO)2. Crystals appropriate for
X-ray diffraction analysis were grown by slow evaporation from a
concentrated pentane solution. Yield: 44 mg, 85%. Mp: 127 °C
λ
max (ꢀ, M-1 cm-1): 609 (443), 740 (830). Anal. Calcd for C23H43S3-
BCo: C, 56.9; H, 8.93. Found: C, 57.0; H, 8.70.
[PhTttBu]Co(Ph) (4). Yield: 68 mg (63%). Mp: 105 °C (dec).
1H NMR (C6D6): δ 40.4 (2 H, br, m-(C6H5)Co), 19.5 (br, 2 H,
o-(C6H5)B), 11.0 (br, 2 H, m-(C6H5)B), 10.2 (br, 1 H, p-(C6H5)B),
3.35 (br, 27 H, (CH3)3S), -20.9 (1 H, br, p-(C6H5)Co), -26.5 (2
H, br, o-(C6H5)Co). µeff (C6D6) ) 4.2 µB. UV-vis (pentane), λmax
(ꢀ, M-1 cm-1): 643 (249), 719 (359), 743 (578). Anal. Calcd for
C27H43S3BCo: C, 60.7; H, 8.12. Found: C, 60.6; H, 7.91.
[PhTttBu]Co(Bn) (5). Yield: 60 mg (55%). Mp: 98 °C. 1H NMR
(C6D6): δ 46.2 (2 H, s, m-(C6H5)), 19.3 (2 H, br, o-(C6H5)B), 11.2
(1 H, s, p-(C6H5)B), 10.3 (2 H, s, m-(C6H5)B), 2.52 (27 H, br,
(CH3)3S), -93.1 (2 H, br, o-(C6H5)), -110.8 (1H, br, p-(C6H5)).
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(dec). H NMR (C6D6): δ 7.68 (2 H, br, o-(C6H5)B), 7.48 (2 H,
br, m-(C6H5)B), 7.29 (1 H, br, p-(C6H5)B), 2.05 (5 H, -CH2), 1.34
(27 H, br, (CH3)3S). 13C NMR (C6D6): δ 206.6 (CO), 132.1 (o-
(C6H5)B), 131.6 (p-(C6H5)B), 125.2 (m-(C6H5)B), 48.1 (CH2), 29.1
((CH3)3S), 14.6 (C(CH3)3). UV-vis (pentane), λmax (ꢀ, M-1 cm-1):
407 (473), 658 (168). FTIR (pentane): 2015, 1949 (νCO) cm-1
.
µ
eff (C6D6) ) 3.8 µB. UV-vis (pentane), λmax (ꢀ, M-1 cm-1): 511
Anal. Calcd for C23H38S3BCoO2: C, 53.9; H, 7.48. Found: C, 55.1;
H, 8.32.
(682), 655 (346), 711 (258), 761 (430). Anal. Calcd for C28H45S3-
BCo: C, 61.4; H, 8.29. Found: C, 59.0; H, 7.52. Samples prepared
in independent syntheses repeatedly tested low in carbon analyses.
[PhTttBu]Co(η3-allyl) (6). Yield: 63 mg (62%). Mp: 94 °C
(dec). 1H NMR (C6D6): δ 10.0 (2 H, br, o-C6H5)B), 8.49 (2H, br,
m-C6H5)B), 7.99 (1 H, br, p-C6H5)B), 1.37 (27 H, br, (CH3)3S).
Synthesis of [PhTttBu]Co(CO) (11). Exposing solutions (pentane
or C6D6) of [PhTttBu]Co(CO)2 to multiple freeze-pump-thaw
cycles resulted in a color change from brown to green. This process
was fully reversible. In situ spectroscopic interrogation of the green
solutions revealed formation of [PhTttBu]Co(CO). 1H NMR
(C6D6): δ 156.3 (6 H, br, (CH2)), 18.4 (s, 2 H, m-(C6H5)B), 10.7
(s, 2 H, o-(C6H5)B), 10.6 (s, 1 H, p-(C6H5)B), FTIR (pentane): 1966
µ
eff (C6D6) ) 2.5 µB. UV-vis (pentane), λmax (ꢀ, M-1 cm-1): 407
(1227), 716 (271). Anal. Calcd for C24H43S3BCo: C, 57.9; H, 8.72.
Found: C, 57.7; H, 8.99.
(νCO) cm-1
.
Synthesis of [PhTttBu]Co(CO)(C(O)R) (R ) Me, Et, Ph). Dry
CO was passed through a pentane solution (10 mL) containing 50
mg of [PhTttBu]Co(R) at room temperature for ∼2 min. An
immediate color change from green to red was apparent. Solvent
was removed in vacuo, yielding a red solid in high yields (80-
90%). Crystals appropriate for X-ray analysis were grown by slow
evaporation of a concentrated pentane solution.
Reaction of [PhTttBu]Co(R) Complexes with NO (R ) Me,
Et, Ph, Bn, allyl); Synthesis of [κ2-PhTttBu]Co(NO)2 (12). Dry
NO was passed through a pentane solution (10 mL) containing 50
mg of the [PhTttBu]Co(R) for ∼2 min. An immediate color change
to brown was apparent. The solvent was removed under reduced
pressure, and the product was extracted with diethyl ether. Crystals
were grown by slow evaporation from a concentrated ethyl ether
[PhTttBu]Co(CO)(C(O)Me) (7). Yield: 50 mg, 90%. Mp: 91
°C (dec). 1H NMR (C6D6): δ 9.07 (2 H, br, o-C6H5)B), 8.10 (1 H,
br, p-C6H5)B), 8.01 (2 H, br, m-C6H5)B), 3.91 (27 H, br, (CH3)3S),
0.99 (3 H, br, (CO)CH3). µeff (C6D6) ) 2.0 µB. UV-vis (pentane),
λmax (ꢀ, M-1 cm-1): 555 (420), 689 (175), 914 (161). FTIR
(pentane): 1997 (νCO), 1686, 1665 (νCOR) cm-1. Anal. Calcd for
C24H41S3O2BCo: C, 54.6; H, 7.83. Found: C, 53.9; H, 7.65.
[PhTttBu]Co(CO)(C(O)Et) (8). Yield: 50 mg, 90%. Mp: 88
solution. Yield: 44 mg, 80%. H NMR (C6D6): δ 7.89 (2 H, br,
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m-(C6H5)B), 7.52 (2 H, br, o-(C6H5)B), 7.15 (1 H, br, p-(C6H5)B),
2.39 (6 H, s, (CH2)), 1.15 (27 H, br, (CH3)3S). FTIR (pentane):
1846, 1789 (νNO) cm-1. Anal. Calcd for C21H38S3N2O2BCo: C,
48.8; H, 7.41; N, 5.43. Found: C, 45.9; H, 7.42; N, 5.70. Samples
prepared in independent syntheses repeatedly tested low in carbon
analyses.
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Acknowledgment. This work was funded by the National
Science Foundation (CHE-0213260).
°C (dec). H NMR (C6D6): δ 8.90 (2 H, br, o-(C6H5)B), 7.81 (2
H, br, m-(C6H5)B), 6.37 (1 H, br, p-(C6H5)B), 3.30 (27 H, br,
C(CH3)3S). µeff (C6D6) ) 1.9 µB. UV-vis (pentane), λmax (ꢀ, M-1
cm-1): 531 (58), 677 (26), 912 (17). FTIR (pentane): 1995 (νCO),
1658 (νCOR) cm-1. Anal. Calcd for C25H43S3BCo: C: 55.4, H, 8.00.
Found: C, 52.1; H, 7.64. Samples prepared in independent
syntheses repeatedly tested low in carbon analyses.
Supporting Information Available: CIF files for all X-ray
structures. This material is available free of charge via the Internet
OM0608253