Field et al.
cream colored solid after approximately 5 min. The solid was
isolated by filtration and washed with THF to give [RuCl(PPi3)]Cl
(392 mg, 80%). 31P{1H} NMR (162 MHz, ethanol): δ 142.9 (1P,
give a dark yellow solution. The solvent was removed under reduced
pressure, and the resulting dark yellow solid was dissolved in
pentane, filtered, and the solvent removed under reduced pressure
to give Ru(N2)(PPi3) 5 (90 mg, 67%) as a yellow solid. Anal. Found:
C 48.66, H 9.37, N 4.38 C24H54N2P4Ru (MW 595.64) requires C
48.39, H 9.14, N 4.70%. 31P{1H} NMR (162 MHz, benzene-d6): δ
2
q, JP(C)-P(B/P) ) 15.2 Hz, PC); 72.1 (3P, d, PB/P) ppm. HRMS (EI)
m/z: [M]+ 603.1909 (calc. 603.1908). LRMS (ESI+, methanol) m/z:
621 ([RuCl(PPi3)+H2O]+, 100%), 619 ([RuCl(PPi3)+OH]+, 95), 603
([RuCl(PPi3)+H]+, 56), 517 (68).
2
1
161.5 (1P, q, JP(A)-P(E) ) 21.8 Hz, PA); 88.1 (3P, d, PE) ppm. H
{31P} NMR (400 MHz, benzene-d6): δ 2.11 (6H, m, JH-H ) 7.2
3
Sodium tetraphenylborate (60 mg, 180 µmol) was added to a
solution of [RuCl(PPi3)]Cl (104 mg, 163 µmol) in ethanol (ap-
proximately 10 mL) resulting in the immediate formation of a dark
orange precipitate. The precipitate was isolated by filtration and
washed with ethanol to give [RuCl(PPi3)][BPh4] 3·[BPh4] (135 mg,
90%) as a dark orange powder. Crystals suitable for X-ray
diffraction were grown by layering a THF solution of 3·[BPh4]
with pentane. Anal. Found: C 62.29, H 7.97 C48H74BClP4Ru (MW
922.33) requires C 62.51, H 8.09%. 31P{1H} NMR (162 MHz,
Hz, PECH(CH3)2); 1.27 (6H, m, PACH2); 1.28 (18H, d, CH3); 1.16
(6H, m, PECH2); 1.13 (18H, m, CH3) ppm. 13C{1H} NMR (101
MHz, benzene-d6): δ 33.8 (m, PECH(CH3)2); 30.1-29.3 (m,
PACH2CH2); 20.4 (s, PECH(CH3)2); 20.2 (s, PECH(CH3)2) ppm.
IR (fluorolube): 2083 s, ν(Nt N) cm-1
.
Ru(15N2)(PPi3) (15N2-5) (NMR Scale). Ru(N2)(PPi3) 5 (approx
20 mg, 80 µmol) was dissolved in benzene-d6 (0.5 mL) in an NMR
tube fitted with a concentric Teflon tap under dinitrogen. The
solution was frozen with liquid nitrogen, and the headspace
evacuated followed by introduction of 15N2 to the NMR tube. NMR
spectra indicated the successful exchange of the dinitrogen ligand
following thawing of the solution and warming to room temperature.
31P{1H} NMR (202 MHz, benzene-d6): δ 161.8 (1P, ddq, PA, 2JP(A)-N
) 31.4 Hz, 2JP(A)-P(E) ) 21.9 Hz, 3JP(A)-N ) 2.9 Hz); 88.4 (3P, ddd,
PE, 2JP(E)-N ) 5.2 Hz, 3JP(E)-N ) 2.1 Hz) ppm. 15N NMR (50.7 MHz,
benzene-d6) δ -8.9 (1N, Ru-NN); -55.3 (1N, Ru-NN) ppm (by
31P-15N HSQC).
2
acetone-d6): δ 144.1 (1P, q, JP(A)-P(B/P) ) 15.4 Hz, PA); 74.0 (3P,
br s, PB/P) ppm. 1H{31P} NMR (400 MHz, acetone-d6): δ 7.38 (8H,
br m, BPhortho); 6.97 (8H, m, BPhmeta); 6.82 (4H, m, BPhpara);
3
2.32 (6H, t, 3JH-H) 7.2 Hz, PCCH2); 2.17 (6H, h, JH-H) 7.3 Hz,
P
B/PCH(CH3)2); 2.17 (6H, m, PB/PCH2); 1.55 (18H, d, CH3); 1.20
(18H, d, CH3) ppm. 13C{1H} NMR (101 MHz, acetone-d6): δ 164.9
(m, BPhipso); 136.8 (s, BPhortho); 125.7 (m, BPhmeta); 122.0 (s,
BPhpara); 30.0 (m, PECH(CH3)2); 26.2 (m, PECH2); 25.9 (d, 1JC-P
30.5 Hz, PACH2); 19.7 (s, CH3); 19.5 (s, CH3) ppm.
)
Synthesis of Fe(N2)(PPi3) (4). Potassium graphite (75 mg, 0.55
mmol) was added to a solution of 2·[BPh4] (230 mg, 0.262 mmol)
in THF (approximately 15 mL). The reaction mixture was stirred
under nitrogen for 24 h. The resulting black suspension was filtered
to give an orange solution. The solvent was removed under reduced
pressure, and the solid residue extracted into pentane (approximately
10 mL). The yellow solution was filtered, and the solvent removed
under reduced pressure to give Fe(N2)(PPi3) 4 as a dark yellow
solid (75 mg, 52%). Crystals suitable for analysis by X-ray
diffraction were precipitated upon cooling of a hot pentane solution
of 4. Anal. Found: C 52.31, H 9.93, N 3.85, C24H54FeN2P4 (MW
550.44) requires C 52.37, H 9.89, N 5.09%. Elemental analysis
performed on crystalline product suggests some loss of weakly
bound dinitrogen ligand upon application of vacuum during
analytical procedure. 31P{1H} NMR (162 MHz, benzene-d6): δ
Synthesis of [Fe(N2)H(PPi3)][BF4] (6·BF4). Fe(N2)(PPi3) 4 (20
mg,
36
µmol)
and
2,6-lutidinium
tetrafluoroborate
(7 mg, 36 µmol) were stirred in THF (approximately 2 mL) under
nitrogen to afford a red solution which turned purple within an
hour. The solution was layered with pentane, and after 24 h the
resulting solid was isolated by filtration to give [Fe(N2)H(PPi3)][BF4]
6·[BF4] as a purple solid (16 mg, 70%). 31P{1H} NMR (121.5 MHz,
2
2
THF-d8): δ 162.0 (1P, dt, JP(C)-P(U) ) 29.8 Hz, JP(C)-P(T) ) 24.4
2
Hz, PC); 88.8 (2P, dd, JP(T)-P(U) ) 11.3 Hz, PT); 78.7 (1P, dt, PU)
ppm. 1H{31P} NMR (400 MHz, THF-d8): δ 2.6-2.4 (8H, m,
PTCH2CH2); 2.57 (2H, m, PTCH); 2.15 (2H, m, PUCH); 2.10-1.80
(4H, m, PUCH2CH2); 1.73 (2H, m, PTCH′);1.50 (6H, d, 3JH-H ) 7
3
Hz, PUCH(CH3)); 1.41 (6H, d, JH-H ) 7 Hz, PTCH(CH3)); 1.34
3
3
(6H, d, JH-H ) 7 Hz, PUCH(CH3)); 1.31 (6H, d, JH-H ) 7 Hz,
PTCH(CH3)); 1.27 (6H, d, 3JH-H ) 7 Hz, PTCH′(CH3)); 1.13 (6H,
2
3
1
175.8 (1P, q, JP(A)-P(E) ) 36.7 Hz, PA); 96.3 (3P, d, PE) ppm.
d, JH-H ) 7 Hz, PTCH′(CH3)); -14.53 (1H, s, Fe-H) ppm. H
NMR (400 MHz, THF-d8, high field): δ -14.53 (1H, ddt, Fe-H,
1H{31P} NMR (400 MHz, benzene-d6):
δ 2.29 (6H, m,
2
2
PECH(CH3)2); 1.35 (6H, m, PACH2); 1.28 (18H, m, CH3); 1.25
(18H, m, CH3); 1.10 (6H, m, PECH2) ppm. 13C{1H} NMR (101
MHz, benzene-d6): δ 34.3 (m, CH3); 29.0 (m, PECH2); 28.8 (m,
PACH2); 20.5 (d, 1JC-P ) 11 Hz, PECH(CH3)2) ppm. IR (fluorolube):
ν 1985 s (Nt N) cm-1. LRMS (ESI+, methanol) m/z: 523
([Fe(PPi3)+H]+, 100%), 522 (81).
2JH-P(T) ) 67.2 Hz, JH-P(C) ) 51.7 Hz, JH-P(U) ) 24.4 Hz) ppm.
IR (fluorolube): 2095 s, ν(Nt N) cm-1
.
[Fe(15N2)H(PPi3)][BF4] ([15N2-6][BF4]) (NMR Scale). An NMR
sample of 6·[BF4] was prepared by addition of 2,6-lutidinium
tetrafluoroborate (16 mg, 82 µmol) to a solution of Fe(N2)(PPi3)
(4) (44 mg, 80 µmol) in THF-d8 (0.5 mL) in an NMR tube fitted
with a concentric Teflon tap under dinitrogen. The resulting solution
of 6·[BF4] was frozen in liquid nitrogen, and the headspace was
evacuated followed by introduction of 15N2 to the NMR tube. NMR
spectra indicated the successful exchange of the dinitrogen ligand
Fe(15N2)(PPi3) (15N2-4) (NMR Scale). Fe(N2)(PPi3) 4 (ap-
proximately 20 mg, 80 µmol) was dissolved in benzene-d6 (0.5
mL) in an NMR tube fitted with a concentric Teflon valve under
dinitrogen. The solution was frozen in liquid nitrogen, and the
headspace was evacuated followed by introduction of 15N2 to the
NMR tube. NMR spectra indicated the successful exchange of the
dinitrogen ligand following thawing of the solution and warming
to room temperature. 31P{1H} NMR (202 MHz, benzene-d6): δ
175.6 (1P, dq 2JP(A)-(E) ) 36.7 Hz, 2JP(A)-N ) 9.7 Hz, PA,); 96.1 (3P,
d, PE) ppm. 15N NMR (50.7 MHz, benzene-d6) δ 18.1 (1N,
Fe-NN); -18.0 (1N, Fe-N) ppm.
following thawing of the solution and warming to room temperature.
2
31P{1H} NMR (162 MHz, THF-da): δ 161.9 (1P, m, JP(C)-P(U)
)
2
2
30 Hz, JP(C)-P(T) ) 24 Hz, PC); 88.6 (2P, m, JP(T)-P(U) ) 11 Hz,
PT); 78.5 (1P, m, PU) ppm. 15N{1H} NMR (40.6 MHz, THF-da) δ
-19.5 (1N, Fe-NN); -51.5 (1N, Fe-N) ppm. 1H NMR (400 MHz,
2
THF-d8, high field): δ -14.5 (1H, ddt, Fe-H, JH-P(T) ) 67 Hz,
2
2JH-P(C) ) 52 Hz, JH-P(U) ) 24 Hz) ppm.
Synthesis of Ru(N2)(PPi3) (5). Potassium graphite (109 mg, 0.81
mmol) was added to a suspension of [RuCl(PPi3)]Cl 3·Cl (144 mg,
0.226 mmol) in THF (approximately 15 mL). The reaction mixture
was stirred under nitrogen for 18 h after which it was filtered to
Synthesis of [Ru(N2)H(PPi3)][BF4] (7·[BF4]). 2,6-Lutidinium
tetrafluoroborate (17 mg, 100 µmol) was added to a solution of
Ru(N2)(PPi3) 5 (60 mg, 100 µmol) in THF (approximately 15 mL).
The solution turned green for several minutes before reverting to
2252 Inorganic Chemistry, Vol. 48, No. 5, 2009