1174 Organometallics, Vol. 19, No. 6, 2000
Flood et al.
7 Hz, P(CH3)3), 1.33 (vt, 18H, N ) 6 Hz, trans-P(CH3)3), 2.62
(s, NH2), 6.70 (d, 2H, J ) 9 Hz), 7.06 (d, 2H). 13C{1H} NMR
17 Hz, cis to OsH). 19F{1H} NMR (C6D6): δ -57.88 (s). Anal.
Calcd for C19H42NF3P4Os: C, 34.81; H, 6.46. Found: C, 35.15;
H, 6.20.
(C6D6): δ 20.71 (d, J PC ) 22 Hz), 23.12 (dvt, J PC ) 2.4, NPC
)
)
4
31 Hz), 28.41 (d, J PC ) 31 Hz), 117.90 (s), 119.73 (d, J PC
L4Os(H)(SC6H5) (8a ). The same procedure as for 7a was
used with 100 mg (0.2 mmol) of 1 and 20 mg (0.18 mmol) of
thiophenol in ca. 3 mL of THF, except that no heating was
necessary. After the sample warmed to room temperature the
31P NMR revealed complete reaction. The pale green, powdery
residue weighed 85 mg, 78%. 1H NMR (C6D6): δ -9.50 (dq,
1H, J PH ) 64, 23 Hz, OsH), 1.27 (d, 9H, J ) 6 Hz, P(CH3)3),
1.30 (d, 9H, J ) 7 Hz, P(CH3)3), 1.43 (vt, 18H, N ) 6 Hz, trans-
P(CH3)3), 6.88 (t, 1H, J ) 7 Hz), 7.20 (t, 2H, J ) 7 Hz), 8.27
(d, 2H, J ) 7 Hz). 13C{1H} NMR (C6D6): δ 22.83 (d, J PC ) 24
Hz), 23.61 (dvt, J PC ) 2.5, NPC ) 35 Hz), 28.58 (dd, J PC ) 27,
1.6), 132.50 (s), 164.52 (d, J PC ) 5.7 Hz). 31P{1H} NMR
(C6D6): δ -35.96 (dd, 2P, J PP ) 19, 16 Hz), -41.89 (dt, 1P,
J PP ) 6, 19 Hz, trans to OsH), -50.74 (dt, 1P, J PP ) 6, 16 Hz,
cis to OsH).
3
L4Os(H)(OC6H4CN) (6e). 6e was prepared using 21 mg
(0.18 mmol) of p-cyanophenol and 100 mg (0.2 mmol) of 1; yield
1
92 mg, 83%. H NMR (C6D6): δ -8.15 (dq, 1H, J PH ) 78, 23
Hz, OsH), 1.13 (m, 36H, P(CH3)3)), 6.87 (d, 2H, J ) 8 Hz), 7.40
(d, 2H). 13C{1H} NMR (C6D6): δ 20.68 (d, J PC ) 21 Hz), 22.95
(dvt, J PC ) 2.7, NPC ) 32 Hz), 27.85 (d, J PC ) 32 Hz), 120.65
(d, 4J ) 2.6), 133.64 (s), C-CN, C-O and CtN not found. 31P-
{1H} NMR (C6D6): δ -36.92 (dd, 2P, J PP ) 19, 17 Hz), -41.75
(dt, 1P, J PP ) 6, 19 Hz, trans to OsH), -49.75 (dt, 1P, J PP ) 6,
17 Hz, cis to OsH).
4
3
2.8 Hz), 119.82 (s), 131.57 (d, J PC ) 3.1), 150.43 (d, J PC
)
10), one C not found (under solvent?). 31P{1H} NMR (C6D6): δ
-49.61 (dd, 2P, J PP ) 18, 13 Hz), -50.86 (dt, 1P, J PP ) 13, 18
Hz, trans to OsH), -53.83 (dt, 1P, J PP ) 13, 18 Hz, cis to OsH).
Anal. Calcd for C19H42SP4Os: C, 35.75; H, 7.00. Found: C,
35.78; H, 6.98.
L4Os(H)(HNC6H5) (7a ). In the glovebox, 100 mg (0.2 mmol)
of 1 (cooled to -20 °C prior to weighing for ease of handling)
and aniline (17 mg, 0.18 mmol) were added to a 9 mm NMR
tube fused to a 14/20 ground-glass joint. Approximately 3 mL
of THF was added, and the tube was removed from the
glovebox, sealed on the vacuum line, and heated in an oil bath
at 110 °C. The reaction, monitored by 31P NMR, was complete
after 60 h. The tube was broken in the glovebox, and the
contents were transferred to a Schlenk flask. Solvent was
removed under vacuum, and the residue was washed with
hexanes (5 × 10 mL) at -78 °C to separate any residual 1.
L4Os(H)(SC6H4OMe) (8b). The same procedure as for 8a
was used with 100 mg (0.2 mmol) of 1 and 22.4 µL (0.18 mmol)
of p-methoxythiophenol in ca. 3 mL of THF; yield 91 mg, 80%.
1H NMR (C6D6): δ -9.50 (dq, 1H, J PH ) 64, 23 Hz, OsH), 1.26
(d, 9H, J ) 6 Hz, P(CH3)3), 1.31 (d, 9H, J ) 8 Hz, P(CH3)3),
1.40 (vt, 18H, N ) 6 Hz, trans-P(CH3)3), 3.59 (s, OCH3), 7.19
(d, 2H, J ) 7 Hz), 8.10 (d, 2H). 13C{1H} NMR (C6D6): δ 22.27
(d, J PC ) 20 Hz), 22.64 (dvt, J PC ) 2.5, NPC ) 35 Hz), 27.52
(dd, J PC ) 27, 2.8 Hz), 55.95 (s, OCH3), 119.19 (s), 130.52 (d,
3
4J PC ) 3.1), 149.47 (d, J PC ) 10), one C not found (under
1
The bright yellow, powdery residue weighed 89 mg, 84%. H
solvent?). 31P{1H} NMR (C6D6): δ -50.37 (t, 2P, J PP ) 18 Hz),
-51.54 (dt, 1P, J PP ) 12, 18 Hz, trans to OsH), -54.42 (dt,
1P, J PP ) 12, 18 Hz, cis to OsH). Anal. Calcd for C19H42OSP4-
Os: C, 35.95; H, 6.99. Found: C, 35.80; H, 6.83.
NMR (C6D6): δ -8.67 (dq, 1H, J PH ) 74, 23 Hz, OsH), 1.07 (d,
9H, J ) 6 Hz, P(CH3)3), 1.26 (d, 9H, J ) 7 Hz, P(CH3)3), 1.30
(vt, 18H, N ) 6 Hz, trans-P(CH3)3), 2.32 (brd, 1H, J PH ) 6,
NH), 6.57 (d, 1H, J ) 8 Hz), 6.91 (dd, 1H, J ) 8, 3.5 Hz), 7.19
(dd, 1H, J ) 6, 8 Hz), 7.31 (d, 1H, J ) 8 Hz), 7.63 (dd, 1H, J
) 6, 3.5 Hz). 13C{1H} NMR (C6D6): δ 21.80 (d, J PC ) 21 Hz),
23.42 (dvt, J PC ) 2.3, NPC ) 31 Hz), 28.45 (d, J PC ) 29 Hz),
108.15 (s), 115.14 (s), 117.02 (d, 4J PC ) 3.8), 129.12 (s), 129.51
P (CD3)3-P (CH3)3 Exch a n ge Kin etics. A typical phos-
phine exchange experiment was as follows. Approximately 10
mg of L4Os(H)(XC6H4Z) was weighed in the drybox and added
to a 5 mm NMR tube fused to a vacuum valve. Benzene-d6
(0.3 mL) was added to the tube to form a clear solution that
ranged from colorless (phenoxides), to yellow (amides), to pale
green (thiophenoxides). The sample was freeze-pump-thaw
degassed three times, and at least 20 equiv per osmium of L′
(P(CD3)3) was condensed into the tube. Kinetic data were
obtained from 31P NMR spectra using an inverse-gated, proton-
decoupling pulse sequence used to minimize nuclear Over-
hauser enhancements. The average phosphorus T1 value for
these compounds is 10-12 s, so a relaxation delay of 55 s was
used. Integrations against standard materials revealed errors
of less than 5%. Progress of the reaction was monitored either
by continuous data acquisition in the NMR probe at the
designated temperature or by heating the sample in a constant-
temperature bath with periodic measurement of the 31P{1H}
NMR spectra at room temperature. R2 values from the kinetic
plots were usually greater than 0.99.
3
(s), 160.64 (d, J PC ) 6 Hz). 31P{1H} NMR (C6D6): δ -42.15
(dd, 2P, J PP ) 18, 16 Hz), -51.02 (dt, 1P, J PP ) 9, 18 Hz, trans
to OsH), -52.81 (dt, 1P, J PP ) 9, 16 Hz, cis to OsH). Anal.
Calcd for C18H43NP4Os: C, 36.79; H, 7.38. Found: C, 36.59;
H, 7.25.
L4Os(H)(HNC6H4OMe) (7b). The same procedure as for
7a was used with 100 mg (0.2 mmol) of 1 and 22 mg (0.18
mmol) of p-methoxyaniline in ca. 3 mL of THF at 110 °C for
80 h; yield 93.4 mg, 84%. 1H NMR (C6D6): δ -8.33 (dq, 1H,
J PH ) 75, 23 Hz, OsH), 1.09 (d, 9H, J ) 6 Hz, P(CH3)3), 1.28
(d, 9H, J ) 7 Hz, P(CH3)3), 1.33 (vt, 18H, N ) 6 Hz, trans-
P(CH3)3), 1.87 (brd, 1H, 7 Hz, NH), 3.61 (s, OCH3), 6.49 (brs,
1H), 6.95 (brs, 1H), 7.08 (brs, 1H), 7.21 (brs, 1H). 13C{1H} NMR
(C6D6): δ 21.81 (d, J PC ) 22 Hz), 23.40 (dvt, J PC ) 3.6, NPC
)
34 Hz), 28.57 (d, J PC ) 29 Hz), 55.27 (OCH3), 114.56 (s), 115.01
(s), 116.20 (s), 120.94 (s), 141.54 (s), 152.81 (s). 31P{1H} NMR
(C6D6): δ -41.51 (dd, 2P, J PP ) 18, 16 Hz), -50.34 (dt, 1P,
J PP ) 9, 18 Hz, trans to OsH), -52.38 (dt, 1P, J PP ) 9, 16 Hz,
cis to OsH). Anal. Calcd for C19H45ONP4Os: C, 36.95; H, 7.34.
Found: C, 37.21; H, 7.35.
Kin etic Mod elin g of L/L′ Exch a n ge. The Weigert pro-
gram17 was used to iteratively calculate time/concentration
curves for particular exchange schemes. For example, the
model for the exchange of L4Os(H)(NHCHOMe) given in the
results section interconverts 16 isotopic substitutional isomers
of 9 (including enantiomers), 16 of 12, and 10 of 13, using 89
equations and 5 distinct rate constants, some multiplied by
statistical factors. The concentration numbers for the isoto-
pomers of 9 were converted to phosphorus integral values, and
the rate constants kL , kL , and kL were calculated. For the
L4Os(H)(HNC6H4CF 3) (7c). The same procedure as for 7a
was used with 100 mg (0.2 mmol) of 1 and 22.8 µL (0.18 mmol)
of p-trifluoromethylaniline in ca. 3 mL of THF at 110 °C for
40 h; yield 100 mg, 85%. 1H NMR (C6D6): δ -8.61 (dq, 1H,
J PH ) 75, 23 Hz, OsH), 1.01 (d, 9H, J ) 6 Hz, P(CH3)3), 1.19
(vt, 18H, N ) 6 Hz, trans-P(CH3)3), 1.20 (d, 9H, J ) 7 Hz,
P(CH3)3), 2.96 (brd, 1H, 6 Hz, NH), 6.27 (d, 1H, J ) 9 Hz),
7.20 (d, 1H, J ) 8 Hz), 7.37 (d, 1H, J ) 8 Hz), 7.62 (d, 1H, J
) 9 Hz). 13C{1H} NMR (C6D6): δ 21.64 (d, J PC ) 22 Hz), 23.34
(dvt, J PC ) 3.2, NPC ) 31 Hz), 28.07 (d, J PC ) 29 Hz), 107.88
L
a
b
c
rate constants kion ) a4 × 10-4, kassoc ) 1 × 106, kL′ ) 1 × 104,
k-L ) 1 × 10-3, and kisom ) 1 × 108, calculated rates were kL
L
a
a
) 1.99 × 10-6 and kL ) kL ) 7.11 × 10-7; that is, LaLa/Lb/Lc
b
c
) 1:0.36:0.36.
1
(q, J CF ) 31 Hz, CF3), 113.99 (s), 114.3 (s), 116.06 (s), 126.13
Ack n ow led gm en t. This work was supported by the
National Science Foundation.
3
3
(d, J PC ) 2.5 Hz), 126.93 (d, J PC ) 3.8 Hz), 163.22 (brs). 31P-
{1H} NMR (C6D6): δ -41.77 (dd, 2P, J PP ) 18, 17 Hz), -50.45
(dt, 1P, J PP ) 9, 18 Hz, trans to OsH), -51.72 (dt, 1P, J PP ) 9,
OM990850R