Preparation and Reactivity of Mixed-Ligand Ruthenium(II) Hydride Complexes with Phosphites and Polypyridyls

Article abstract of DOI:10.1021/ic034820z

Chloro complexes [RuCl(N-N)P₃]BPh₄ (1-3) [N-N = 2,2′-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5′ -dimethyl-2,2′-bipyridine, 5,5′-Me₂bpy; P = P(OEt) ₃, PPh(OEt)₂ and PPh₂OEt] were prepa

Full text of DOI:10.1021/ic034820z

Inorg. Chem. 2004, 43, 1336−1349
Preparation and Reactivity of Mixed-Ligand Ruthenium(II) Hydride
Complexes with Phosphites and Polypyridyls
,†
Gabriele Albertin,* Stefano Antoniutti,† Alessia Bacchi,‡ Claudia D’Este,† and Giancarlo Pelizzi‡
Dipartimento di Chimica, UniVersita` Ca’ Foscari di Venezia, Dorsoduro 2137,
30123 Venezia, Italy, and Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica,
Chimica Fisica, UniVersita` di Parma, Parco Area delle Scienze, 17/a, 43100 Parma, Italy
Received July 14, 2003
Chloro complexes [RuCl(N-N)P ]BPh4 (1−3) [N-N ) 2,2′-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5′-dimethyl-
3
2,2′-bipyridine, 5,5′-Me2bpy; P ) P(OEt)3, PPh(OEt)2 and PPh2OEt] were prepared by allowing the [RuCl4(N-N)]‚
H O compounds to react with an excess of phosphite in ethanol. The bis(bipyridine) [RuCl(bpy)2{P(OEt)3}]BPh4
2
(7) complex was also prepared by reacting RuCl2(bpy)2‚2H O with phosphite and ethanol. Treatment of the chloro
2
complexes 1−3 and 7 with NaBH yielded the hydride [RuH(N-N)P ]BPh (4−6) and [RuH(bpy)2P]BPh (8) derivatives,
4
3
4
4
which were characterized spectroscopically and by the X-ray crystal structure determination of [RuH(bpy){P(OEt)3}3]-
BPh4 (4a). Protonation reaction of the new hydrides with Brønsted acid was studied and led to dicationic [Ru(η2-
H )(N-N)P ]2+ (9, 10) and [Ru(η2-H )(bpy)2P]2+ (11) dihydrogen derivatives. The presence of the η2-H ligand was
2
3
2
2
indicated by a short T1min value and by the measurements of the JHD in the [Ru](η2-HD) isotopomers. From T
1min
and JHD values the H−H distances of the dihydrogen complexes were also calculated. A series of ruthenium
complexes, [RuL(N-N)P ](BPh4)2 and [RuL(bpy)2P](BPh4)2 (P ) P(OEt)3; L ) H O, CO, 4-CH C H NC, CH CN,
3
2
3
6
4
3
4-CH C H CN, PPh(OEt)2], was prepared by substituting the labile η2-H ligand in the 9, 10, 11 derivatives. The
3
6
4
2
reactions of the new hydrides 4−6 and 8 with both mono- and bis(aryldiazonium) cations were studied and led to
aryldiazene [Ru(C H NdNH)(N-N)P ](BPh4)2 (19, 21), [{Ru(N-N)P }2(µ-4,4′-NHdNC H −C H NdNH)](BPh4)4 (20),
6
5
3
3
6
4
6 4
and [Ru(C H NdNH)(bpy)2P](BPh4)2 (22) derivatives. Also the heteroallenes CO and CS reacted with [RuH-
6
5
2
2
(bpy)2P]BPh4, yielding the formato [Ru{η1-OC(H)dO}(bpy)2P]BPh4 and dithioformato [Ru{η1-SC(H)dS}(bpy)2P]-
BPh4 derivatives.
Introduction
pyridyl ruthenium hydrides are known and include cationic
carbonyls,2 [RuH(bpy)(PPh3)2(CO)]+, neutral3 RuHCl(bpy)-
P2 (P ) PPh3, PCy3), and the bis(2,2′-bipyridine)4 [RuH-
(bpy)2L]+ (L ) CO, PPh3) derivatives. No examples,
however, of ruthenium hydride complexes containing either
the N2P3 donor set or the mixed-ligand phosphite-polypy-
ridyl have been reported. In this paper we describe the
development of a new synthetic route to new ruthenium
hydrides containing both phosphite and polypyridyl as
In the preceding paper of this series1 we have reported
the synthesis and the reactivity of new iron(II) hydride
complexes of the [FeH(N-N)P3]BPh4 (N-N ) 2,2′-bipyridine
and 1,10-phenanthroline; P ) phosphite) type containing
mixed phosphite and polypyridyl as supporting ligands. We
have now extended these studies to ruthenium with the aim
first to test whether similar complexes can be prepared and
then to compare the properties of the complexes through the
two metals, mainly toward the protonation reaction and the
insertion into the M-H bonds. A glance through the literature
shows that, in contrast with iron, some examples of poly-
(2) (a) Sullivan, B. P.; Caspar, J. V.; Johnson, S. R.; Meyer, T. J.
Organometallics 1984, 3, 1241-1251. (b) Luther, T. A.; Heinekey,
D. M. Inorg. Chem. 1998, 37, 127-132. (c) Mullica, D. F.; Farmer,
J. M.; Kautz, J. A.; Gipson, S. L.; Belay, Y. F.; Windmiller, M. S.
Inorg. Chim. Acta 1999, 285, 318-321.
(3) (a) Hallman, P. S.; McGarvey, B. R.; Wilkinson, G. J. Chem. Soc. A
1968, 3143-3150. (b) Heinekey, D. M.; Mellows, H.; Pratum, T. J.
Am. Chem. Soc. 2000, 122, 6498-6499.
(4) Kelly, J. M.; Vos, J. G. J. Chem. Soc., Dalton Trans. 1986, 1045-
1048.
* Author to whom correspondence should be addressed. E-mail: albertin@
unive.it.
† Universita` Ca’ Foscari di Venezia.
‡ Universita` di Parma.
(1) Albertin, G.; Antoniutti, S.; Bortoluzzi, M. Inorg. Chem. 2004, 43,
1328-1335.
1336 Inorganic Chemistry, Vol. 43, No. 4, 2004
10.1021/ic034820z CCC: $27.50 © 2004 American Chemical Society
Published on Web 01/30/2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
at room temperature by treating the solid with ethanol (10 mL)
and enough CH2Cl2 to obtain a saturated solution; yield from 65%
to 80%.
supporting ligands as well as some reactivity, including the
protonation and the insertion reaction of the new hydrides.
These complexes can also be prepared in two steps by reacting
RuCl4(bpy)‚H2O with phosphite to give [RuCl(bpy)P3]BPh4 (1) and
then treating these complexes with an excess of NaBH4 in ethanol.
Anal. Calcd for C52H74BN2O9P3Ru (4a): C, 58.05; H, 6.93; N, 2.60.
Found: C, 57.94; H, 6.99; N, 2.49. ΛM ) 56.6 Ω-1 mol-1 cm2.
Anal. Calcd for C64H74BN2O6P3Ru (4b): C, 65.58; H, 6.36; N, 2.39.
Found: C, 65.46; H, 6.29; N, 2.28. ΛM ) 54.9 Ω-1 mol-1 cm2.
Anal. Calcd for C76H74BN2O3P3Ru (4c): C, 71.98; H, 5.88; N, 2.21.
Found: C, 71.80; H, 5.76; N, 2.15. ΛM ) 57.8 Ω-1 mol-1 cm2.
[RuH(phen)P3]BPh4 (5) [P ) P(OEt)3 (a), PPh(OEt)2 (b),
PPh2OEt (c)]. These complexes were prepared, as red solids,
exactly like the related 2,2′-bipyridine derivatives 4, starting from
the RuCl4(phen)‚H2O precursor; yield from 65% to 75%. Anal.
Calcd for C54H74BN2O9P3Ru (5a): C, 58.96; H, 6.78; N, 2.55.
Found: C, 58.75; H, 6.84; N, 2.68. ΛM ) 51.2 Ω-1 mol-1 cm2.
Anal. Calcd for C66H74BN2O6P3Ru (5b): C, 66.27; H, 6.24; N, 2.34.
Found: C, 66.17; H, 6.16; N, 2.42. ΛM ) 55.3 Ω-1 mol-1 cm2.
Anal. Calcd for C78H74BN2O3P3Ru (5c): C, 72.50; H, 5.77; N, 2.17.
Found: C, 72.65; H, 5.65; N, 2.05. ΛM ) 57.4 Ω-1 mol-1 cm2.
mer-[RuH(5,5′-Me2bpy){P(OEt)3}3]BPh4 (6a-mer) and mer-
and fac-[RuH(5,5′-Me2bpy){P(OEt)3}3]BPh4 (6a). This complex
was prepared following the method used for the related 2,2′-
bipyridine derivative 4 using RuCl4(5,5′-Me2bpy)‚H2O as a precur-
sor. In this case, however, the addition of NaBPh4 to the reaction
mixture caused the separation of the mer isomer 6a-mer as a red-
brown microcrystalline solid in about 45% yield. By cooling to
-25 °C of the mother solution, a further amount of solid separated
out, which resulted to be a mixture of fac and mer isomers (6a)
with yield of about 15%. Anal. Calcd for C54H78BN2O9P3Ru: C,
58.75; H, 7.12; N, 2.54. Found for 6a-mer: C, 58.89; H, 7.15; N,
2.41. ΛM ) 55.7 Ω-1 mol-1 cm2. Found for 6a: C, 58.58; H, 7.24;
N, 2.46. ΛM ) 53.5 Ω-1 mol-1 cm2.
Experimental Section
The general procedures have been previously reported.1 The
RuCl3‚3H2O was a Pressure Chem. (U.S.A.) product, used as
received. p-Tolyl isocyanide was obtained by the method of Ziehn
et al.5
Synthesis of Complexes. The complexes RuCl4(bpy)‚H2O,
RuCl4(phen)‚H2O, RuCl4(5,5′-Me2bpy)‚H2O, and RuCl2(bpy)2‚
2H2O were prepared following the method previously reported.6,7
The spectroscopic data (IR and NMR) of the new complexes are
reported in Tables 1, 2, and 3.
[RuCl(bpy)P3]BPh4 (1) [P ) P(OEt)3 (a), PPh(OEt)2 (b),
PPh2OEt (c)]. An excess of the appropriate phosphite (3.75 mmol)
was added to a solution of RuCl4(bpy)‚H2O (0.30 g, 0.72 mmol)
in 10 mL of ethanol, and the reaction mixture was refluxed for 3
h. After filtration, the solution was concentrated to about 5 mL
and an excess of NaBPh4 (1.5 mmol, 0.513 g) in 3 mL of ethanol
was added. A red-brown solid slowly separated out from the
resulting solution, which was filtered and crystallized from CH2-
Cl2 and ethanol; yield g85%. Anal. Calcd for C52H73BClN2O9P3-
Ru (1a): C, 56.25; H, 6.63; N, 2.52; Cl, 3.19. Found: C, 56.12;
H, 6.74; N, 2.40; Cl, 3.41; ΛM ) 51.7 Ω-1 mol-1 cm2. Anal. Calcd
for C64H73BClN2O6P3Ru (1b): C, 63.71; H, 6.10; N, 2.32; Cl, 2.94.
Found: C, 63.48; H, 6.05; N, 2.25; Cl, 3.13; ΛM ) 55.6 Ω-1 mol-1
cm2. Anal. Calcd for C76H73BClN2O3P3Ru (1c): C, 70.07; H, 5.65;
N, 2.15; Cl, 2.72. Found: C, 70.29; H, 5.52; N, 2.02; Cl, 2.59; ΛM
) 54.8 Ω-1 mol-1 cm2.
[RuCl(phen)P3]BPh4 (2) [P ) P(OEt)3 (a), PPh(OEt)2 (b),
PPh2OEt (c)]. These complexes were prepared like the related 2,2′-
bipyridine derivatives 1, using RuCl4(phen)‚H2O as a precursor;
yield g75%. Anal. Calcd for C54H73BClN2O9P3Ru (2a): C, 57.17;
H, 6.49; N, 2.47; Cl, 3.13. Found: C, 56.95; H, 6.34; N, 2.32; Cl,
2.95. ΛM ) 55.1 Ω-1 mol-1 cm2. Anal. Calcd for C66H73-
BClN2O6P3Ru (2b): C, 64.42; H, 5.98; N, 2.28; Cl, 2.88. Found:
C, 64.18; H, 5.84; N, 2.20; Cl, 2.63. ΛM ) 57.5 Ω-1 mol-1 cm2.
Anal. Calcd for C78H73BClN2O3P3Ru (2c): C, 70.62; H, 5.55; N,
[RuCl(bpy)2{P(OEt)3}]BPh4 (7a). An excess of triethyl phos-
phite (1.16 mmol, 0.19 mL) was added to a solution of RuCl2-
(bpy)2‚2H2O (0.30 g, 0.58 mmol) in 10 mL of ethanol, and the
reaction mixture was refluxed for 2 h. After filtration, the resulting
solution was concentrated to about half volume and an excess of
NaBPh4 (0.4 g, 1.16 mmol) in 3 mL of ethanol was added. A red-
brown solid slowly separated out, which was filtered and crystallized
from CH2Cl2 and ethanol; yield g75%. Anal. Calcd for C50H51-
BClN4O3PRu: C, 64.28; H, 5.50; N, 6.00; Cl, 3.79. Found: C,
64.04; H, 5.41; N, 5.89; Cl, 3.60. ΛM ) 52.6 Ω-1 mol-1 cm2.
[RuH(bpy)2P]BPh4 (8) [P ) P(OEt)3 (a), PPh(OEt)2 (b),
PPh2OEt (c)]. To a solution of RuCl2(bpy)2‚2H2O (0.5 g, 0.96
mmol) in 15 mL of ethanol was added first an excess of the
appropriate phosphite (1.9 mmol) and then an excess of NaBH4
(0.36 g, 9.6 mmol) in 15 mL of ethanol. The reaction mixture was
refluxed for 30 min, concentrated to about 15 mL, and then filtered.
The addition of an excess of NaBPh4 (0.68 g, 2 mmol) caused the
separation of a red-brown solid, which was filtered and crystallized
from CH2Cl2 and ethanol; yield g85%. Anal. Calcd for C50H52-
BN4O3PRu (8a): C, 66.74; H, 5.82; N, 6.23. Found: C, 66.55; H,
5.88; N, 6.12. ΛM ) 50.8 Ω-1 mol-1 cm2. Anal. Calcd for C54H52-
BN4O2PRu (8b): C, 69.60; H, 5.62; N, 6.01. Found: C, 69.44; H,
5.70; N, 5.88. ΛM ) 55.6 Ω-1 mol-1 cm2. Anal. Calcd for C58H52-
BN4OPRu (8c): C, 72.27; H, 5.44; N, 5.81. Found: C, 72.10; H,
5.37; N, 5.94. ΛM ) 53.1 Ω-1 mol-1 cm2.
2.11; Cl, 2.67. Found: C, 70.45; H, 5.45; N, 2.08; Cl, 2.86. ΛM
)
58.4 Ω-1 mol-1 cm2.
[RuCl(5,5′-Me2bpy){P(OEt)3}3]BPh4 (3a). Also this complex
was prepared following the method used for the related 2,2′-
bipyridine derivative 1a; yield g80%. Anal. Calcd for C54H77-
BClN2O9P3Ru: C, 56.97; H, 6.82; N, 2.46; Cl, 3.11. Found: C,
57.07; H, 6.80; N, 2.32; Cl, 3.01. ΛM ) 55.3 Ω-1 mol-1 cm2.
[RuH(bpy)P3]BPh4 (4) [P ) P(OEt)3 (a), PPh(OEt)2 (b),
PPh2OEt (c)]. To a solution of RuCl4(bpy)‚H2O (0.5 g, about 1.20
mmol) in 10 mL of ethanol was added first an excess of the
appropriate phosphite (6.25 mmol) and then an excess of NaBH4
(0.47 g, 12.5 mmol) in 20 mL of ethanol. The reaction mixture
was stirred at room temperature for 3 h and filtered, and then an
excess of NaBPh4 (0.86 g, 2.5 mmol) in 5 mL of ethanol was added.
The resulting solution was concentrated to about half volume and
then cooled to -25 °C. A red-brown solid separated out, which
was filtered and crystallized from CH2Cl2 and ethanol. Crystals
were obtained by cooling to -25 °C a saturated solution prepared
(5) Appel, R.; Kleinstu¨ck, R.; Ziehn, K.-D. Angew. Chem., Int. Ed. Engl.
1971, 10, 132-132.
(6) (a) Dwyer, F. P.; Goodwin, H. A.; Gyarfas, E. C. Aust. J. Chem. 1963,
62, 42-50. (b) Krause, R. A. Inorg. Chim. Acta 1977, 22, 209-213.
(7) Sullivan, B. P.; Salmon, D. J.; Meyer, T. J. Inorg. Chem. 1978, 17,
3334-3341.
[Ru(η2-H2)(bpy)P3]2+Y2- (9) [P ) P(OEt)3 (a), PPh(OEt)2 (b);
Y2- ) BPh4 and CF3SO3-], [Ru(η2-H2)(bpy)(PPh2OEt)3]2+Y2-
(9c) and [Ru(η2-H2)(phen)(PPh2OEt)3]2+Y2- (10c) (Y2-
)
Inorganic Chemistry, Vol. 43, No. 4, 2004 1337

Albertin et al.
Table 1. Selected IR and NMR Data for Ruthenium Complexes
31P{1H}
NMRb,d
syst (ppm; J, Hz)
31P{1H}
IRa
1H NMRb,c
(ppm; J, Hz)
spin
IRa
1H NMRb,c
(ppm; J, Hz)
spin
NMRb,d
(cm-1
)
assgnt
assgnt
(cm-1
)
assgnt
assgnt
syst (ppm; J, Hz)
[RuCl(bpy){P(OEt)3}3]BPh4 (1a)
[RuH(bpy){PPh2(OEt)}3]BPh4 (4c)
4.27 qnt
3.72 m
1.33 t
CH2
AB2
δ
A 135.4
B 116.6
1965 m
νRuH
3.43 m
3.06 m
0.72 t
CH2
AB2
δ
δ
A 155.9
B 142.0
JAB ) 40.0
δ
CH3
JAB ) 63.2
CH3
0.88 t
0.43 t
[RuCl(bpy){PPh(OEt)2}3]BPh4 (1b)
AB2X spin syst H-
4.13 m
3.74 m
1.45 t
1.09 t
1.00 t
CH2
AB2
δ
δ
A 168.3
B 145.3
(X ) H-)
δX -12.86
CH3
JAB ) 48.0
JAX ) 32
JBX ) 20
[RuH(phen){P(OEt)3}3]BPh4 (5a)
[RuCl(bpy){PPh2(OEt)}3]BPh4 (1c)
1969 m
νRuH
4.16 m
3.67 m
1.43 t
1.37 t
0.90 t
0.87 t
CH2
AB2
A2B
δ
δ
A 151.3
B 140.7
JAB ) 65.0
A 153.7
B 133.1
3.46 qnt
3.20 m
1.05 t
CH2
AB2
δ
A 141.3
B 116.3
δ
CH3
CH3
JAB ) 37.2
δ
δ
0.85 t
[RuCl(phen){P(OEt)3}3]BPh4 (2a)
JAB ) 37.2
4.43 qnt
3.72 m
1.47 t
CH2
AB2
δ
δ
A 136.0
B 116.6
AB2X spin syst H-
(X ) H-)
CH3
JAB ) 64.1
δX -6.73
0.81 t
JAX ) 146
[RuCl(phen){PPh(OEt)2}3]BPh4 (2b)
JBX ) 27
4.25 m
3.69 m
1.54 t
CH2
AB2
δ
δ
A 167.4
B 145.6
A2BX spin syst H-
(X ) H-)
CH3
JAB ) 50.0
δX -13.91
1.02 t
JAX ) 24
[RuCl(phen){PPh2(OEt)}3]BPh4 (2c)
JBX ) 32
3.49 qnt
3.07 m
1.07 t
CH2
AB2
δ
δ
A 141.2
B 116.8
[RuH(phen){PPh(OEt)2}3]BPh4 (5b)
1980 sh
1963 m
νRuH
3.98 qnt
3.81 m
1.35 t
CH2
AB2
δ
δ
A 179.0
B 163.9
CH3
JAB ) 38.3
0.75 t
CH3
JAB ) 46.5
[RuCl(5,5′-Me2bpy){P(OEt)3}3]BPh4 (3a)
0.79 t
A2B
δ
δ
A 176.4
B 157.8
4.35 qnt
3.80 m
2.52 s
2.35 s
1.41 t
CH2
AB2
δ
δ
A 136.2
B 117.1
AB2X spin syst H-
(X ) H-)
JAB ) 26.0
CH3
JAB ) 62.5
δX -6.35
JAX ) 122
CH3 phos
JBX ) 24
0.96 t
A2BX spin syst H-
(X ) H-)
[RuH(bpy){P(OEt)3}3]BPh4 (4a)
1963 w νRuH
1940 w
4.06 m
3.69 m
1.32 t
1.28 t
0.96 t
CH2
AB2
δ
δ
A 150.2
B 140.4
δX -13.55
JAX ) 20
CH3
JAB ) 64.7
JBX ) 30
A2B
δ
δ
A 153.6
B 132.9
[RuH(phen){PPh2(OEt)}3]BPh4 (5c)
1975 s
νRuH
3.44 m
3.07 m
0.65 t
CH2
AB2
δ
δ
A 156.1
B 141.9
AB2X spin syst H-
JAB ) 37.2
(X ) H-)
CH3
JAB ) 40.5
δX -6.92
0.42 t
JAX ) 148
AB2X spin syst H-
JBX ) 27
(X ) H-)
A2BX spin syst H-
(X ) H-)
δX -12.65
JAX ) 30
δX -14.31
JBX ) 20
JAX ) 22
fac- and mer-[RuH(5,5′-Me2bpy){P(OEt)3}3]BPh4 (6a)
JBX ) 34
1970 w, br νRuH
4.07 qnt
3.64 m
2.41 s
2.38 s
2.36 s
1.37 t
1.30 t
1.20 t
0.96 t
CH2
AB2
δ
δ
A 151.1
B 140.7
[RuH(bpy){PPh(OEt)2}3]BPh4 (4b)
1971 m νRuH
4.10 m
3.30 m
1.32 t
1.30 t
1.21 t
0.93 t
CH2
AB2
δ
δ
A 178.0
B 162.9
CH3
JAB ) 65.0
A2B
δ
δ
A 153.9
B 133.4
CH3
JAB ) 48.0
A2B
δ
δ
A 176.0
B 157.6
CH3 phos
JAB ) 36.2
JAB ) 24.9
AB2X spin syst H-
(X ) H-)
AB2X spin syst H-
δX -6.72
(X ) H-)
JAX ) 124
δX -14.34
JBX ) 24
JAX ) 32
A2BX spin syst H-
(X ) H-)
JBX ) 24
A2BX spin syst H-
(X ) H-)
δX -13.86
JAX ) 20
δX -6.88
JBX ) 30
JAX ) 27
JBX ) 150
1338 Inorganic Chemistry, Vol. 43, No. 4, 2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
Table 1. Continued
31P{1H}
NMRb,d
(ppm; J, Hz)
31P{1H}
NMRb,d
(ppm; J, Hz)
IRa
1H NMRb,c
(ppm; J, Hz)
spin
syst
IRa
1H NMRb,c
assgnt (ppm; J, Hz)
spin
syst
(cm-1
)
assgnt
assgnt
(cm-1
)
assgnt
mer-[RuH(5,5′-Me2bpy){P(OEt)3}3]BPh4 (6a-mer)
[Ru(η2-H2)(bpy)2{PPh(OEt)2}]2+ h (11b)
1969 w νRuH
4.07 qnt
3.63 m
2.38 s
2.36 s
1.30 t
CH2
AB2
δ
A 151.1
B 140.7
4.01 m
1.30 t
CH2
A
159.7
δ
CH3
CH3
JAB ) 65.0
-7.55 br
η2-H2
[Ru(η2-H2)(bpy)2{PPh2(OEt)}]2+ h (11c)
CH3 phos
3.65 m
1.03 t
-7.95 br
CH2
A
138.9 s
0.96 t
CH3
AB2X spin syst H-
η2-H2
(X ) H-)
[Ru(OH2)(bpy){P(OEt)3}3](BPh4)2 (12a)
δX -14.34
4.12 m
3.56 m
2.55 s, br
1.37 t
CH2
AB2
δ
δ
A 129.8
B 128.8
JAB ) 79.6
JAX ) 32
JBX ) 24
OH2
CH3
[RuCl(bpy)2{P(OEt)3}]BPh4 (7a)
3.98 qnt
1.06 t
CH2
CH3
A
127.7 s
153.6 s
0.95 t
[Ru(CH3CN)(bpy){P(OEt)3}3](BPh4)2 (13a)
[RuH(bpy)2{P(OEt)3}]BPh4 (8a)
3.81 qnt
1.12 t
-12.16 d
JPH ) 36
[RuH(bpy)2{PPh(OEt)2}]BPh4 (8b)
4.13 m
3.60 qnt
1.36 t
0.94 t
0.30 s
CH2
A2B
δ
δ
A 129.7
B 125.2
JAB ) 74.9
1881 m νRuH
1895 m νRuH
1917 m νRuH
CH2
CH3
H-
A
CH3
CH3CN
[Ru(bpy)(4-CH3C6H4NC){P(OEt)3}3](BPh4)2 (14a)
3.94 qnt
1.28 t
-12.01 d
JPH ) 32
[RuH(bpy)2{PPh2(OEt)}]BPh4 (8c)
3.69 qnt
1.08 t
CH2
CH3
H-
A
174.1 s
148.1 s
2158 s
νCN
4.17 m
3.63 m
2.34 s
2.30 s
1.38 t
1.36 t
0.99 t
0.97 t
CH2
A2B
δ
A 129.7
B 118.4
δ
CH3
JAB ) 61.2
A2B
δ
δ
A 128.1
B 115.8
CH3 phos
CH2
CH3
H-
A
JAB ) 58.0
-11.93 d
JPH ) 34
[Ru(bpy)(CO){P(OEt)3}3](BPh4)2 (15a)
[Ru(η2-H2)(bpy){P(OEt)3}3]2+ e (9a)
2054 s
νCO
4.18 m
3.57 qnt
1.41 t
CH2
A2B
δ
δ
A 123.2
B 110.0
4.15 m
3.81 m
1.39 t
1.15 t
1.00 t
CH2
AB2
δ
A 130.7
B 129.4
δ
CH3
JAB ) 62.4
CH3
JAB ) 80.0
0.94 t
AB2
δ
δ
A 128.2
B 117.2
[Ru(bpy){PPh(OEt)2}{P(OEt)3}3](BPh4)2 (16a)
4.32 m
4.11 m
3.95 qnt
3.50 m
1.48 t
CH2
AB2C
δ
δ
δ
A 148.7
B 131.2
C 118.3
-9.55 br
η2-H2
JAB ) 55.3
[Ru(η2-H2)(bpy){PPh(OEt)2}3]2+ (9b)
3.97 m
3.82 m
3.49 m
1.43 t
1.40 t
1.21 t
CH2
AB2
δ
A 155.4
B 146.9
JAB ) 50.9
JAC ) -534.5
JAB ) 58.4
δ
CH3
JAB ) 44.4
1.35 m
0.95 m
CH3
A2B
δ
δ
A 162.4
B 161.3
[Ru(CH3CN)(bpy)2{P(OEt)3}](BPh4)2 (17a)
JAB ) 62.7
3.80 qnt
1.66 s
1.01 t
CH2
CH3CN
CH3
A
125.5s
0.96 t
-9.60 br
η2-H2
[Ru(η2-H2)(bpy){PPh2(OEt)}3]2+ f (9c)
[Ru(bpy)(4-CH3C6H4CN)2{P(OEt)3}](BPh4)2 (18a)
3.44 m
3.21 qnt
0.70 t
CH2
AB2
δ
A 140.0
B 129.8
2226 m νCN
3.89 qnt
2.46 s
1.10 t
CH2
CH3
CH3 phos
A
124.6s
δ
CH3
JAB ) 30.5
0.52 t
[Ru(C6H5NdNH)(bpy){P(OEt)3}3](BPh4)2 (19a)
-8.0 br
η2-H2
14.16 s, br
13.70 s, br
4.23 qnt
3.67 m
1.39 t
1.37 t
0.99 t
0.96 t
NH
AB2
δ
δ
A 129.4
B 128.4
[Ru(η2-H2)(phen){PPh2(OEt)}3]2+ f (10c)
3.26 qnt
3.23 m
0.66 t
CH2
AB2
δ
A 140.2
B 130.4
CH2
CH3
JAB ) 69.2
δ
AB2
δ
δ
A 126.9
B 114.2
CH3
JAB ) 30.4
0.54 t
JAB ) 61.0
-7.8 br
η2-H2
[Ru(η2-H2)(bpy)2{P(OEt)3}]2+ g (11a)
3.87 qnt
1.04 t
-7.65 br
CH2
A
125.3 s
CH3
η2-H2
2CF3SO3-). These complexes were prepared in solution by reaction
with CF3SO3H at low temperature. A typical preparation involves
the addition of an excess of CF3SO3H (0.02 mmol, 1.8 µL) to a
solution of the appropriate hydride 4, 5 (0.01 mmol) in 0.5 mL of
CD2Cl2 placed in a 5-mm NMR tube and cooled to -80 °C. The
tube was rapidly transferred into the probe, precooled to -80 °C,
of the NMR spectrometer, and the spectrum was recorded. The
temperature was also increased until 30 °C and the progress of the
reaction detected.
[Ru(η2-H2)(bpy)2P]2+Y2- (11) [P ) P(OEt)3 (a), PPh(OEt)2
(b), PPh2OEt (c); Y2- ) 2CF3SO3-]. These complexes were
prepared at low temperature (-80 °C) in an NMR tube by adding
an excess of CF3SO3H (0.02 mmol, 1.8 µL) to a solution of the
appropriate hydride [RuH(bpy)2P]CF3SO3 (8-CF3SO3) (0.01 mmol)
Inorganic Chemistry, Vol. 43, No. 4, 2004 1339

Albertin et al.
Table 1. Continued
31P{1H}
NMRb,d
(ppm; J, Hz)
31P{1H}
spin
syst (ppm; J, Hz)
IRa
1H NMRb,c
(ppm; J, Hz)
spin
syst
IRa
1H NMRb,c
assgnt (ppm; J, Hz)
NMRb,d
(cm-1
)
assgnt
assgnt
(cm-1
)
assgnt
[Ru(C6H5Nd15NH)(bpy){P(OEt)3}3](BPh4)2i (19a-15N)
[Ru(C6H5NdNH)(phen){PPh(OEt)2}3](BPh4)2 (21b)
AB2XY spin syst
NH
AB2Y
δ
A 126.9
B 114.3
13.85 s, br
13.26 s, br
4.34 m
3.65 m
1.58 t
1.20 t
1.03 t
0.90 t
NH
AB2
δ
A 158.8
B 145.3
(X ) H, Y ) 15N)
δ
δ
δ
X 14.14
JAX ) 4.7
JAB ) 60.7
JAY ) 5.6
JBY ) 4.9
δ
δ
JAB ) 69.2
JAY ) -62.5
JBY ) 4.8
CH2
CH3
JAB ) 46.5
AB2
δ
δ
A 152.0
B 141.1
JBX ) 2.8
JAY ) 5.6
AB2Y
A 129.0
B 128.4
JAB ) 43.0
JBY ) 4.9
JXY ) 67.3
JAB ) 60.7
AB2XY spin syst
(X ) H, Y ) 15N)
[Ru(C6H5NdNH)(bpy)2{P(OEt)3}](BPh4)2 (22a)
14.87 d, br
3.89 qnt
1.13 t
NH
CH2
CH3
A
123.6 s
δ
X 13.69
JAX ) -8.0
JBX ) -2.97
JAY ) -62.5
JBY ) 4.8
JXY ) -63.96
JAB ) 69.2
4.21 m
[Ru(C6H5Nd15NH)(bpy)2{P(OEt)3}](BPh4)2k (22a-15N)
14.89 dt
NH
A
124.1 d
1
J
J
NH ) 65.5
2J N ) 4.7
31P15
15
3
31
PH ) 3.5
3.87 m
1.09 t
CH2
CH3
CH2
CH3
[Ru{η1 -SC(H)dS}(bpy)2{P(OEt)3}]BPh4 (23a)
3.65 m
1.38 t
1242 m δHCS
10.87 s, br
3.84 br
SC(H)d
CH2
A
126.8 s
1.36 t
1.00 t
0.96 t
1.04 br
CH3
[Ru{η1 -SC(H)dS}(bpy)2{PPh(OEt)2}]BPh4 (23b)
1256 m δHCS
10.94 s
3.95 qnt
1.33 t
SC(H)d
CH2
CH3
A
159.1 s
[{Ru(bpy)[P(OEt)3]3}2(µ-4,4′-HNdNC6H4-C6H4NdNH)](BPh4)4 (20a)
14.16 s, br
14.06 s, br
4.20 m
3.64 m
1.35 t
1.01 t
0.96 t
0.92 t
NH
AB2
δ
δ
A 126.3
B 114.1
JAB ) 61.4
A 130.1
B 115.8
[Ru{η1 -OC(H)dO}(bpy)2{P(OEt)3}]BPh4 (24a)
CH2
CH3
1601 s νCO
7.73 s
3.85 qnt
1.04 t
OC(H)d
CH2
CH3
A
128.2 s
AB2
δ
δ
JAB ) 63.0
[Ru{η1-OC(H)dO}(bpy)2{PPh(OEt)2}]BPh4 (24b)
1599 s νCO
7.48 s
4.10 qnt
1.19 t
OC(H)d
CH2
CH3
A
160.9 s
[{Ru(bpy)[P(OEt)3]3}2(µ-4,4′-H15NdNC6H4-C6H4Nd15NH)](BPh4)4j (20a-15N)
14.17 d, br
NH
AB2Y
δ
δ
A 126.7
B 114.2
1
15
J
NH ) 64.5
14.07 d, br
JAB ) 61.4
JAY ) 6.3
JBY ) 5.0
δ
δ
JAB ) 63.0
JAY ) JBY ) e 1
1
15
J
NH ) 63.0
4.21 m
3.65 m
1.36 t
1.01 t
0.96 t
0.93 t
CH2
CH3
AB2Y
A 130.2
B 115.8
a In KBr pellets. b In CD2Cl2 at 25 °C. c Phenyl and polypyridyl proton resonances omitted; for the OC2H5 group of the phosphine JHH ) 7 Hz. d Positive
i
shift downfield from 85% H3PO4. e At 273 K. f At 283 K. g At 203 K. h At 223 K. 15N{1H} NMR, δ (CD2Cl2, 25 °C, positive shift downfield from
j
CH315NO2): AB2Y spin syst (Y ) 15N), δY 0.67, JAY ) 63, JBY ) 4.8; AB2Y spin syst (Y ) 15N), δY -5.07, JAY ) 5.6, JBY ) 4.9 Hz. 15N{1H} NMR,
k
δ: AB2Y spin syst (Y ) 15N), δY -5.97, JAY ) 6.3, JBY ) 5.0 Hz; -18.8 (s, br). 15N{1H} NMR, δ: 0.23 (d, JNP ) 4.7 Hz).
Table 2. T1min (200 MHz) and JHD NMR Data for Some Dihydrogen and Hydride Complexes and Calculated H-H Distances
rH-H (Å)
no.
compound
T (K)
δ(M-H2)
T1min (ms)
JHD (Hz)
9a
9b
9c
10c
11a
11b
11c
4a
[Ru(η2-H2)(bpy){P(OEt)3}3]2+
[Ru(η2-H2)(bpy){PPh(OEt)2}3]2+
[Ru(η2-H2)(bpy){PPh2(OEt)}3]2+
[Ru(η2-H2)(phen){PPh2(OEt)}3]2+
[Ru(η2-H2)(bpy)2{P(OEt)3}]2+
[Ru(η2-H2)(bpy)2{PPh(OEt)2}]2+
[Ru(η2-H2)(bpy)2{PPh2(OEt)}]2+
[RuH(bpy){P(OEt)3}3]BPh4
203
218
223
217
216
213
218
200
-9.55 br
-9.60 br
-8.0 br
-7.80 br
-7.65 br
-7.55 br
-7.95 br
-6.99 dt
-14.27 dt
4.9
6.1
5.1
5.9
7.0
7.6
7.2
304
233
29.9
30.1
28.9
29.4
32.8
31.2
31.7
0.99a
1.03
1.00
1.02
1.05
1.07
1.06
0.79b
0.81
0.79
0.81
0.83
0.84
0.84
0.94c
0.93
0.95
0.95
0.89
0.92
0.91
a,b The H-H distances were calculated20 from the T1min values for fast rotationb or static regimesa of the H2 ligand. c The H-H distances were calculated
from the JHD values of the HD complexes using the equation2b rH-H ) 1.44-0.0168 (JHD).
in 0.5 mL of CD2Cl2 following the method used for the related
[Ru(η2-H2)(N-N)P3]2+ (9, 10) derivatives.
[RuL(bpy){P(OEt)3}3](BPh4)2 (12-16) [L ) H2O (12a),
CH3CN (13a), 4-CH3C6H4NC (14a), CO (15a), PPh(OEt)2 (16a)].
These complexes were prepared by substituting the η2-H2 molecule
in [Ru(η2-H2)(bpy){P(OEt)3}3]2+ (9a) complex with the appropriate
ligand L, by means the following general method. To a solution of
[RuH(bpy){P(OEt)3}3]BPh4 (0.1 g, 0.093 mmol) in 8 mL of CH2-
1340 Inorganic Chemistry, Vol. 43, No. 4, 2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
Table 3. 13C{1H} NMR Data for Selected Complexes
with ethanol containing an excess of NaBPh4 (0.22 mmol, 75 mg).
A yellow solid slowly separated out from the resulting solution,
which was filtered and crystallized from CH2Cl2 and ethanol; yield
g75%. Anal. Calcd for C76H74B2N5O3PRu (17a): C, 72.50; H, 5.92;
N, 5.56. Found: C, 72.40; H, 5.98; N, 5.45. ΛM ) 121 Ω-1 mol-1
cm2. Anal. Calcd for C82H78B2N5O3PRu (18a): C, 73.76; H, 5.89;
N, 5.25. Found: C, 73.64; H, 5.82; N, 5.30. ΛM ) 124 Ω-1 mol-1
cm2.
13C{1H} NMRa,b (ppm; J, Hz)
assgnt
[Ru(CH3CN)(bpy){P(OEt)3}3](BPh4)2 (13a)
125.4 d
JCP ) 22.0
64.0 t
CN
CH2
63.7 d
16.3 t
CH3
16.0 d
0.60 s
CH3CN
[Ru(C6H5NdNH)(bpy){P(OEt)3}3](BPh4)2 (19a). In a 25-mL
three-necked round-bottomed flask were placed solid samples of
[RuH(bpy)P3]BPh4 (0.10 mmol) and the [C6H5N2]BF4 aryldiazo-
nium salt (0.2 mmol, 0.38 g). The flask was cooled to -196 °C
and CH2Cl2 (8 mL) added. The reaction mixture was brought to
room temperature, stirred for 3 h, and then evaporated to dryness
under reduced pressure. The oil obtained was triturated with ethanol
containing an excess of NaBPh4 (0.18 mmol, 62 mg). An orange
solid separated out from the resulting solution, which was filtered
and crystallized from CH2Cl2 and ethanol; yield g75%. Anal. Calcd
for C82H99B2N4O9P3Ru: C, 65.65; H, 6.65; N, 3.73. Found: C,
65.42; H, 6.77; N, 3.66. ΛM ) 115 Ω-1 mol-1 cm2.
[Ru(bpy)(CO){P(OEt)3}3](BPh4)2 (15a)
190.9 dt
CO
JCP ) 17.0
cis
JCP ) 145
trans
65.6 t
CH2
CH3
64.7 d
16.1 m
[Ru(CH3CN)(bpy)2{P(OEt)3}](BPh4)2 (17a)
127.4 d
JCP ) 16.0
63.1 d
16.3 d
3.5 s
[Ru(η1-SC(H)dS)(bpy)2{P(OEt)3}]BPh4 (23a)
238.6 s
62.6 d
16.2 d
[Ru(η1-OC(H)dO)(bpy)2{P(OEt)3}]BPh4 (24a)
170.6 s
62.1 d
16.3 d
CN
CH2
CH3
CH3CN
[Ru(C6H5Nd15NH)(bpy){P(OEt)3}3](BPh4)2 (19a-15N). This
complex was prepared exactly like the related unlabeled compound
19a, using the labeled [C6H5Nt15N]BF4 aryldiazonium salt; yield
g70%.
SC(H)d
CH2
CH3
[{Ru(bpy)[P(OEt)3]3}2(µ-4,4′-NHdNC6H4-C6H4NdNH)]-
(BPh4)4 (20a). In a 25-mL three-necked round-bottomed flask were
placed solid samples of [RuH(bpy){P(OEt)3}3]BPh4 (4a) (0.1 g,
0.093 mmol) and of the di-diazonium salt [4,4′-N2C6H4-C6H4N2]-
(BF4)2 (18 mg, 0.0465 mmol), the flask was cooled to -196 °C,
and CH2Cl2 (18 mL) was added. The reaction mixture was brought
to room temperature and stirred for about 10 h, and then the solvent
was removed under reduced pressure. The oil obtained was triturated
with ethanol (2 mL) containing an excess of NaBPh4 (0.2 mmol,
68 mg). A yellow solid slowly separated out from the resulting
solution, which was filtered and crystallized from CH2Cl2 and
ethanol; yield g70%. Anal. Calcd for C164H196B4N8O18P6Ru2: C,
OC(H)d
CH2
CH3
[Ru(η1-OC(H)dO)(bpy)2{PPh(OEt)2}]BPh4 (24b)
171.3 s
61.3 d
16.8 d
OC(H)d
CH2
CH3
a In CD2Cl2 at 25 °C. b Phenyl and polypyridyl carbon resonances are
omitted.
Cl2 cooled to -196 °C was added an excess of CF3SO3H (0.36
mmol, 32 µL). The reaction mixture was brought to 0 °C and stirred
for 10 min, and then an excess (1.1 mmol) of the appropriate ligand
molecule L was added. In the case of CO, the reaction mixture
was allowed to stand under a CO atmosphere (1 atm). The resulting
solution was brought to room temperature and stirred for 30 min,
and then the solvent was removed under reduced pressure. The oil
obtained was treated with ethanol (2 mL) containing an excess of
NaBPh4 (0.20 mmol, 68 mg). By stirring the resulting solution, a
yellow or red solid separated out, which was filtered and crystallized
from CH2Cl2 and ethanol; yield between 65% and 80%. Anal. Calcd
for C76H95B2N2O10P3Ru (12a): C, 64.64; H, 6.78; N, 1.98. Found:
C, 64.39; H, 6.74; N, 2.05. ΛM ) 118 Ω-1 mol-1 cm2. Anal. Calcd
for C78H96B2N3O9P3Ru (13a): C, 65.28; H, 6.74; N, 2.93. Found:
C, 65.10; H, 6.84; N, 2.79. ΛM ) 112 Ω-1 mol-1 cm2. Anal. Calcd
for C84H100B2N3O9P3Ru (14a): C, 66.76; H, 6.67; N, 2.78. Found:
C, 66.60; H, 6.72; N, 2.69. ΛM ) 116 Ω-1 mol-1 cm2. Anal. Calcd
for C77H93B2N2O10P3Ru (15a): C, 65.03; H, 6.59; N, 1.97. Found:
C, 64.85; H, 6.58; N, 2.11. ΛM ) 121 Ω-1 mol-1 cm2. Anal. Calcd
for C86H108B2N2O11P4Ru (16a): C, 64.87; H, 6.84; N, 1.76.
Found: C, 64.65; H, 6.94; N, 1.75. ΛM ) 120 Ω-1 mol-1 cm2.
[Ru(RCN)(bpy)2{P(OEt)3}](BPh4)2 (17a, 18a) [R ) CH3 (17),
4-CH3C6H4 (18)]. An excess of HBF4‚Et2O (0.22 mmol, 32 µL)
was added to a solution of [RuH(bpy)2{P(OEt)3}]BPh4 (0.1 g, 0.11
mmol) in 8 mL of CH2Cl2 cooled to -196 °C, and the reaction
mixture, brought to 0 °C, was stirred for 10 min. An excess of the
appropriate nitrile (1.1 mmol) was added and the resulting solution,
brought to room temperature, stirred for 1 h. The solvent was
removed under reduced pressure to give an oil, which was triturated
65.69; H, 6.59; N, 3.74. Found: C, 65.48; H, 6.64; N, 3.67. ΛM
)
248 Ω-1 mol-1 cm2.
[{Ru(bpy)[P(OEt)3]3}2(µ-4,4′-15NHdNC6H4-C6H4Nd15NH)]-
(BPh4)4 (20a-15N). This complex was prepared exactly like the
related unlabeled compound 20a using the [4,4′-15NtNC6H4-
C6H4Nt15N](BF4)2 aryldiazonium salt; yield g65%.
[Ru(C6H5NdNH)(phen){PPh(OEt)2}3](BPh4)2 (21b). This com-
plex was prepared like the related 2,2′-bipyridine derivative 19a
using [RuH(phen){PPh(OEt)2}3]BPh4 (5b) as a precursor; yield
g75%. Anal. Calcd for C96H99B2N4O6P3Ru: C, 71.16; H, 6.16; N,
3.46. Found: C, 71.01; H, 6.27; N, 3.40. ΛM ) 117 Ω-1 mol-1
cm2.
[Ru(C6H5NdNH)(bpy)2{P(OEt)3}](BPh4)2 (22a). In a 25-mL
three-necked round-bottomed flask were placed solid samples of
the appropriate hydride [RuH(bpy)2P]BPh4 (0.1 mmol) and of the
phenyldiazonium salt [C6H5N2]BF4 (0.2 mmol, 38 mg). The flask
was cooled to -196 °C and CH2Cl2 (5 mL) added. The reaction
mixture was brought to 0 °C with an ice bath, stirred for 1 h, and
then evaporated to dryness under reduced pressure. The oil obtained
was triturated with ethanol (3 mL) containing an excess of NaBPh4
(0.2 mmol, 68 mg). An orange solid slowly separated out from the
resulting solution, which was filtered and crystallized from CH2-
Cl2 and ethanol; yield g75%. Anal. Calcd for C80H77B2N6O3PRu:
C, 72.56; H, 5.86; N, 6.35. Found: C, 72.38; H, 5.94; N, 6.27. ΛM
) 118 Ω-1 mol-1 cm2.
Inorganic Chemistry, Vol. 43, No. 4, 2004 1341

Albertin et al.
[Ru(C6H5Nd15NH)(bpy)2{P(OEt)3}](BPh4)2 (22a-15N). This
compound was prepared exactly like the related unlabeled com-
pound 22a using [C6H5Nt15N]BF4 as a reagent; yield g70%.
[Ru{η1-SC(H)dS}(bpy)2P]BPh4 (23) [P ) P(OEt)3 (a), PPh-
(OEt)2 (b)]. An excess of carbon disulfide (1 mmol, 61 µL) was
added to a solution of the appropriate hydride [RuH(bpy)2P]BPh4
(0.10 mmol) in 8 mL of CH2Cl2 and the reaction mixture stirred
for 2 h. The solvent was removed under reduced pressure to give
an oil, which was triturated with ethanol (3 mL) containing an
excess of NaBPh4 (0.2 mmol, 68 mg). An orange solid separated
out from the resulting solution, which was filtered and crystallized
from CH2Cl2 and ethanol; yield g70%. Anal. Calcd for C51H52-
BN4O3PRuS2 (23a): C, 62.76; H, 5.37; N, 5.74; S, 6.57. Found:
C, 62.59; H, 5.46; N, 5.62; S, 6.40. ΛM ) 54.5 Ω-1 mol-1 cm2.
Anal. Calcd for C55H52BN4O2PRuS2 (23b): C, 65.54; H, 5.20; N,
Table 4. Crystal Data and Structure Refinement for
[RuH(bpy){P(OEt)3}3]BPh4 (4a)
empirical formula
structural formula
C52H73.94BCl0.06N2O9P3Ru
[Ru(C10H8N2){P(OCH2CH3)3}3H0.94Cl0.06]-
B(C6H5)4
1078.51
293(2) K
0.71069 Å
triclinic
P1h
fw
temperature
wavelength
crystal system
space group
unit cell dimensions
a ) 11.415(1) Å
b ) 13.980(1) Å
c ) 17.751(1) Å
R ) 90.832(2)°
â ) 91.227(2)°
γ ) 90.481(2)°
2831.7(4) Å3
2
volume
Z
density (calculated)
absorption coefficient
F(000)
5.56; S, 6.36. Found: C, 65.30; H, 5.27; N, 5.45; S, 6.18. ΛM
)
56.1 Ω-1 mol-1 cm2.
1.265 Mg/m3
0.417 mm-1
1134
[Ru{η1-OC(H)dO}(bpy)2P]BPh4 (24) [P ) P(OEt)3 (a), PPh-
(OEt)2 (b)]. A solution of the appropriate hydride [RuH(bpy)2P]-
BPh4 (0.10 mmol) in 10 mL of CH2Cl2 was stirred at room
temperature under a CO2 atmosphere (1 atm) for 24 h. The solvent
was removed under reduced pressure to give an oil, which was
triturated with ethanol (3 mL) containing an excess of NaBPh4 (0.2
mmol, 68 mg). A yellow solid slowly separated out from the
resulting solution, which was filtered and crystallized from CH2-
Cl2 and ethanol; yield g60%. Anal. Calcd for C51H52BN4O5PRu
(24a): C, 64.90; H, 5.55; N, 5.94, Found: C, 64.75; H, 5.48; N,
5.84. ΛM ) 55.7 Ω-1 mol-1 cm2. Anal. Calcd for C55H52BN4O4-
PRu (24b): C, 67.69; H, 5.37; N, 5.74. Found: C, 67.78; H, 5.30;
N, 5.65. ΛM ) 56.3 Ω-1 mol-1 cm2.
θ range for data collection 1.15-23.26°
index ranges
-12 e h e 12, -15 e k e 15, -19 e l e 19
reflections collected
independent reflections
refinement method
23523
8030 [R(int) ) 0.0280]
full-matrix least-squares on F2
data/restraints/parameters 8030/1/582
GOF on F2
1.129
final R indices [I > 2σ(I)] R1 ) 0.0545, wR2 ) 0.1156
R indices (all data)
largest ∆F max/min
R1 ) 0.0729, wR2 ) 0.1318
0.838/-0.765 e Å-3
calculated positions, with the exception of hydride, which was
located on the Fourier map at about 1.7 Å from the metal, and was
initially refined isotropically. A significant peak appearing in the
difference map suggested consideration of a model of H/Cl
substitution, giving a refined occupancy of about 6% for the
chloride, obtained by restraining similar thermal parameters for the
two anions. The refinement of a full chloride atom gave inconsistent
results. The final model, retaining the restraint on the Ru-H
distance, gave good geometric and thermal parameters for both
anions, and revealed a large prevalence of the hydride anion in the
crystal composition (94%). The final difference map was featureless.
Data collection and refinement results are summarized in Table 4.
Use of the Cambridge Crystallographic Database13 facilities was
made for structure discussion.
Acidity Measurements. The protonation of complexes [RuH-
(N-N)P3]CF3SO3 (4c-CF3SO3, 5c-CF3SO3) and [RuH(bpy)2P]CF3-
SO3 (8-CF3SO3) was studied in CD2Cl2 following the method used
for the related iron derivatives.1 Approximately 2.5 equiv of CF3-
SO3H is required to completely generate the [Ru(η2-H2)(N-N)P3]2+
derivatives. Instead, less than 1.5 equiv of CF3SO3H is required
for the complete formation of the [Ru(η2-H2)(bpy)2P]2+ dicationic
species.
X-ray Crystal Structure Determination of [RuH(bpy)-
{P(OEt)3}3]BPh4 (4a). A large orange prism single crystal was
mounted on a glass fiber, and X-ray diffraction data were collected
on a Bruker-Siemens SMART AXS 1000 equipped with CCD
detector, using graphite monochromated Mo KR radiation (λ )
0.71069 Å). Data collection details: crystal to detector distance )
5.0 cm, 2424 frames collected (complete sphere mode), time per
frame ) 30 s, oscillation ∆ω ) 0.300°. Crystal decay resulted
negligible. Data reduction was performed up to d ) 0.90 Å by the
SAINT package,8 and data were corrected for absorption effects
by the SADABS9 procedure (Tmax ) 1.000, Tmin ) 0.8415). The
phase problem was solved by direct methods10 and refined by full
matrix least squares on all F2,11 implemented in the WinGX
package.12 Anisotropic displacement parameters were refined for
all non-hydrogen atoms, while hydrogen atoms were introduced in
Scheme 1a
a
N-N ) bpy (1, 4); phen (2, 5); 5,5′-(Me)2bpy (3, 6); P ) P(OEt)3 (a);
PPh(OEt)2 (b); PPh2OEt (c).
Results and Discussion
Preparation of Hydride Complexes. The synthesis of
mixed-ligand hydride complexes [RuH(bpy)P3]BPh4 and
[RuH(phen)P3)]BPh4 was achieved by reacting RuCl4(N-N)‚
H2O species first with an excess of phosphite and then of
NaBH4, as shown in Scheme 1.
The reaction proceeds to give first the chloro complex
[RuCl(N-N)P3]+ (1-3) intermediates, which can be isolated
(8) SAINT: SAX, Area Detector Integration; Siemens Analytical instru-
ments Inc., Madison, WI, Bruker AXS Copyright 1997-1999.
(9) Sheldrick, G. SADABS: Siemens Area Detector Absorption Correction
Software; University of Go¨ttingen: Go¨ttingen, Germany, 1996.
(10) Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo,
C.; Guagliardi, A.; Moliterni, A. G.; Polidori, G.; Spagna R. Sir97:
A New Program For SolVing And Refining Crystal Structures; Istituto
di Ricerca per lo Sviluppo di Metodologie Cristallografiche CNR:
Bari, Italy, 1997.
(11) Sheldrick, G. Shelxl97. Program for structure refinement; University
of Go¨ttingen: Go¨ttingen, Germany, 1997.
(12) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837-838.
(13) Allen, F. H.; Kennard, O.; Taylor, R. Acc. Chem. Res. 1983, 16, 146-
153.
1342 Inorganic Chemistry, Vol. 43, No. 4, 2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
Scheme 2a
Chart 1
a
P ) P(OEt)3 (a); PPh(OEt)2 (b); PPh2OEt (c).
while only one singlet is observed for the monophosphite
complex 8. These data, however, do not give any conclusive
information on the geometry of the chloro derivatives.
as BPh4 salts and characterized, and then the further reaction
of this intermediate with NaBH4 affords the final [ReH(N-
N)P3]+ (4-6) derivatives. The hydrides can also be prepared
in one pot by reacting the RuCl4(N-N)‚H2O compounds with
an excess of both phosphite and NaBH4 in ethanol.
Bis(2,2′-bipyridine) hydride complexes [RuH(bpy)2P]BPh4
(8) were also prepared by allowing the RuCl2(bpy)2‚2H2O
complex to react first with an excess of phosphite and then
with NaBH4, as shown in Scheme 2.
1
The H and 31P NMR spectra of the hydride cations
containing the PPh2OEt ligand [RuH(N-N)(PPh2OEt)3]+ (4c,
5c) are strictly comparable with those of the related iron
complexes and suggest the presence in solution of a mer
geometry I (Chart 1).
The 1H NMR spectra of the related P(OEt)3 and PPh(OEt)2
[RuH(N-N)P3]+ (4a, 4b, 5a, 5b) complexes, instead, show
two sets of signals in the hydride region. Each of these
appears as a doublet of triplets due to the coupling of H-
with the phosphorus nuclei, and they were easily simulated
using an AB2X (X ) H) model (Table 1).The two coupling
constants JPH of the two multiplets show different values,
and, whereas in the multiplet near -7 ppm the two JPH have
comparable values of 20-30 Hz, in those at -14 ppm one
constant (120-150 Hz) is far greater than the other (20-30
Hz), suggesting that one phosphite is in a trans geometry
with respect to the hydride ligand. These results may be
interpreted on the basis of the presence of two isomers, in
one of which the hydride ligand is in a mutually cis position
with all the phosphites, while in the other the hydride is trans
with respect to one phosphite and cis with respect to the
other two. The 31P{1H} NMR spectra confirm the hypothesis
of the two isomers, showing two AB2 multiplets which can
be simulated with the parameters reported in Table 1. On
the basis of these data we propose the two geometries, mer
I and fac II, for the two isomers (Chart 1). Spectroscopic
data also indicated that the mer isomer is present in major
amounts (between 70% and 80%), but the attempts to
separate the two isomers in pure form by fractional crystal-
lization failed. Only in one case the mer isomer of [RuH-
(5,5′-Me2bpy){P(OEt)3}3]BPh4 (6a-mer) was obtained in
pure form, while in the other cases only mixtures enriched
in one isomer were always obtained.
Instead, suitable crystals for the X-ray crystal structure
determination of the mer isomer of the [RuH(bpy){P(OEt)3}3]-
BPh4 (4a) complex were separated by Pasteur method, and
the crystal structure is shown in Figure 1, which also reports
the atom numbering. Table 5 lists the most relevant geometric
parameters of the ruthenium coordination.
The metal coordination is octahedral, and the hydride
ligand is trans to one bipyridyl nitrogen, resulting in a mer
geometry for the complex. As reported in the Experimental
Section, the hydride is partially substituted by a chloride
anion in the solid state (H:Cl ≈ 94:6), hence the final Ru-H
distance is biased by the restraints applied in the refinement
and we are not considering it in this discussion. Nevertheless,
we can investigate the effect of hydride coordination on the
bipyridyl ligand, by comparing the different local bonding
The intermediate chloro complex [RuCl(bpy)2P]BPh4 (7)
can also be isolated in this case, and their further reaction
with NaBH4 allows the final hydride compounds (8) to be
obtained.
Extensive studies on the reaction of RuCl4(N-N)‚H2O with
phosphite and NaBH4 showed that the monohydride cations
[RuH(N-N)P3]+ (4, 5, 6) were the only hydride species
formed in the reaction, and that the change of the experi-
mental conditions and of the ratio between the reagents only
gave a lowering in the yields of 4, 5, or 6 due to the formation
of decomposition products. Neutral hydride species such as
RuH2(N-N)P2 and RuHCl(N-N)P2 were not obtained, and
even the attempts to synthesize hydride complexes containing
exclusively nitrogen-donor ligands such as RuH2(N-N)2 or
RuHCl(N-N)2, failed. We also tested the reaction of RuCl4-
(N-N)‚H2O with phosphines such as PPh3 or Ph2PCH2CH2-
PPh2 in the presence of NaBH4, but no hydride was obtained
under any attempted condition. It seems, therefore, that the
synthesis of hydride species can only be obtained with
phosphites using RuCl4(N-N)‚H2O as a precursor and that
the cationic monohydrides [RuH(N-N)P3]+ (4-6), containing
the N2P3 donor atoms set, are the only stable species formed
in the reaction. It can also be noted that the known2-4 mixed-
ligand hydride complexes of ruthenium with polypyridyl are
of the RuHCl(bpy)(PPh3)2, [RuH(bpy)(CO)P2]+ (P ) PPh3,
PCy3), and [RuH(bpy)2L]+ (L ) CO, PPh3) type and were
obtained by substituting phosphine ligands with bpy in
RuHCl(PPh3)3 or RuHCl(CO)P3 precursors.
Good analytical data were obtained for both chloro (1, 2,
3, 7) and hydrido (4, 5, 6, 8) complexes which are orange
or red-brown solids stable in air and in a solution of polar
organic solvents, in which they behave as 1:1 electrolytes.14
The IR and NMR data (Table 1) support the proposed
formulation, which is further confirmed by an X-ray analysis
of the [RuH(bpy){P(OEt)3}3]BPh4 (4a) complex (see below).
The 1H NMR spectra of the chloro complex [RuCl(N-N)-
P3]+ (4-6) and [RuCl(bpy)2P]+ (8) cations show the
characteristic signals of the phosphite and the nitrogenous
(bpy and phen) ligands. The 31P{1H} NMR spectra, further-
more, appear as AB2 multiplets for the tris(phosphite) 4-6,
(14) Geary, W. J. Coord. Chem. ReV. 1971, 7, 81-122.
Inorganic Chemistry, Vol. 43, No. 4, 2004 1343

Albertin et al.
Chart 2
found in 4a (2.176 and 2.225 Å for [RuH(bpy)2(CO)]+ and
[RuH(dmbpy)(CO)2(NCS)]+, respectively).
As concerns the phosphite ligands, the Ru-P3 bond is
remarkably shorter (2.222(1) Å) than the Ru-P1 (2.291(1)
Å) and Ru-P2 (2.279(2) Å) ones, which are trans each other,
and which are closer to the average found for Ru-P(OEt)3
bond lengths (2.30 Å). The shortening of the Ru-P1 distance
could be favored by the lower steric hindrance exerted by
the bpy and the hydride ligands in the equatorial plane, due
to the small radius of H- and to the tight bite angle of bpy
(N1-Ru-N2 ) 76.6(1)°), which allows more room for the
phosphite ligand (P3-Ru-N2 ) 100.1(1)°).
Figure 1. Perspective view of the molecular structure of mer-[RuH(bpy)-
{P(OEt)3}3]+ (4a+). Ethoxy groups are omitted for clarity. The H/Cl
substitutional disorder is not shown. Thermal ellipsoids are at the 50% level.
Table 5. Selected Bond Lengths [Å] and Angles [deg] for
[RuH(bpy){P(OEt)3}3]BPh4 (4a)
Monophosphite [RuH(bpy)2P]BPh4 (8) hydride complexes
were obtained only with the 2,2′-bipyridine ligand, and their
1H and 31P NMR spectra suggest, in contrast to the related
iron complexes, a cis geometry of type III (Chart 2) for these
derivatives. The value of 32-36 Hz found for the JHP of the
hydride ligand, in fact, indicates a mutually cis position of
the hydride and phosphite ligands by comparison with the
values of the related 4, 5, and 6 derivatives.
Protonation Reactions. Hydride complexes [RuH(N-N)-
P3)Y (4, 5) (Y ) BPh4, CF3SO3) react with the Brønsted
acids CF3SO3H or HBF4 to give the dihydrogen derivatives
[Ru(η2-H2)(N-N)P3]2+ (9, 10) as shown in eq 1. The reaction
Ru-N1
Ru-N2
Ru-P3
Ru-P2
2.151(3)
2.178(4)
2.222(1)
2.280(2)
Ru-P1
2.291(1)
2.42(3)
1.67(4)
2.42(3)
Ru-Cl
Ru-H
Ru-Cl (6%)
N1-Ru-N2
N1-Ru-P3
N2-Ru-P3
N1-Ru-P2
N2-Ru-P2
P3-Ru-P2
N1-Ru-P1
N2-Ru-P1
76.6(1)
P3-Ru-P1
P2-Ru-P1
P1-Ru-H
P2-Ru-H
P3-Ru-H
H-Ru- N1
H-Ru- N2
94.43(5)
164.07(6)
84(1)
80(2)
95(2)
176.6(1)
100.1(1)
90.0(1)
98.3(1)
91.24(6)
85.2(1)
95.3(1)
89(2)
165(2)
geometry of the two nitrogen donors, N1 trans to P3 (Ru-
N1 ) 2.151(3) Å), and N2 trans to H (Ru-N2 ) 2.178(4)
Å).
excess CF SO H8
(1)
3
3
[RuH(N-N)P3]+
[Ru(η2-H2)(N-N)P3]2+
9, 10
or HBF4
4, 5
As for the Ru-N1 bond, this is the first structural
determination of a ruthenium complex containing a phosphite
ligand trans to a bipyridyl; we note that the bond length is
only slightly longer than the average Ru-N distance found
for bipyridyl nitrogens trans to a generic P donor (2.12 Å).
The larger value of Ru-N2 (trans to hydride) compared to
Ru-N1 could be due to electronic effects, but also to steric
reasons: N2 is cis to the bulky phosphite at P3, whereas N1
is adjacent to the small hydride ion, and can get closer to
the metal. To elucidate the role of the electronic effects we
carried out a search in the Cambridge Structural Database
(version 5.24, November 2002), which has shown that only
four other ruthenium hydride bipyridyl complexes15-18 are
structurally known, one of these being a Ru4 cluster with
bridging H-,16 and one containing the 6,6′-dimethyl-2,2′-
bipyridine ligand (dmbpy).17 Focusing on the mononuclear
complexes, only two of these are mer isomers,15,17 and the
Ru-N bonds trans to the hydride are comparable to those
N-N ) bpy (4, 9), phen (5, 10); P ) P(OEt)3 (a);
PPh(OEt)2 (b); PPh2OEt (c) (1)
was studied in an NMR tube at temperatures varying between
-80 and +20 °C and showed that, in the case of the [RuH-
(N-N)(PPh2OEt)]+ (4c, 5c) complexes, the addition of the
triflic acid CF3SO3H caused the disappearance of the hydride
1
resonances in the H NMR spectra and the appearance of
one broad signal (half-height width of about 180 Hz at -80
°C) at -8.0 to -7.8 ppm respectively, attributed to the η2-
H2 ligand. Measurements of T1min (Table 2) on this signal
gave values of 5.1 (9c) and 5.9 (10c) ms, in agreement19
with the proposed formulation. The spectra of the isotopo-
mers [Ru(η2-HD)(N-N)P3]2+ derivatives appear as a triplet
of doublets from which a JHD value of 28.9 (9c) and 29.4
Hz (10c) was measured, which further confirms the formation
of the dihydrogen derivatives. Furthermore, the split of each
peak of the triplet is attributable to the coupling with the
phosphorus nuclei of a phosphite, with JPH of about 9 Hz
(15) Haasnoot, J. G.; Hinrichs, W.; Weir, O.; Vos, J. G. Inorg. Chem. 1986,
25, 4140-4143.
(16) Nijhoff, J.; Bakker, M. J.; Hartl, F.; Freeman, G.; Ingham, S. L.;
Johnson, B. F. G. J. Chem. Soc., Dalton Trans. 1998, 2625-2634.
(17) Homanen, P.; Haukka, M.; Pakkanen, T. A.; Pursiainen, J.; Laitinen,
R. H. Organometallics 1996, 15, 4081-4084.
(18) Haukka, M.; Hirva, P.; Luukkanen, S.; Kallinen, M.; Ahlgre´n, M.;
Pakkanen, T. A. Inorg. Chem. 1999, 38, 3182-3189.
(19) (a) Hamilton, D. G.; Crabtree, R. H. J. Am. Chem. Soc. 1988, 110,
4126-4136. (b) Bautista, M. T.; Earl, K. A.; Maltby, P. A.; Morris,
R. H.; Schweitzer, C. T.; Sella, A. J. Am. Chem. Soc. 1988, 110, 7031-
7036. (c) Desrosiers, P. J.; Cai, L.; Lin, Z.; Richards, R.; Halpern, J.
J. Am. Chem. Soc. 1991, 113, 4173-4184.
1344 Inorganic Chemistry, Vol. 43, No. 4, 2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
Chart 3
Scheme 3
for 9c and 11 Hz for 10c, suggesting that the H2 should be
in a mutually trans position with one phosphite ligand.
Finally, taking into account that the 31P{1H} NMR spectra
of 9c and 10c appear as an AB2 multiplet, a fac geometry
IV (Chart 3) can be proposed for the observable η2-H2
derivatives.
model. These values are also strictly comparable with those
calculated from JHD of the ruthenium complexes and seem
to indicate that the H-H distances (from JHD) in mixed-
ligand [M(η2-H2)(N-N)P3]2+ complexes are not influenced
by the nature of the central metal. A comparable value of
0.92 Å for rH-H was in fact calculated for the 2,2′-bipyridine
[Ru(η2-H2)(PPh3)2(bpy)(CO)]2+ derivative.2b
Variable temperature NMR studies also indicated that the
dihydrogen complexes are rather stable and the loss of
hydrogen begins over 5-10 °C. However, as for the related
iron complexes, no solid sample was isolated.
The protonation reaction of the related PPh(OEt)2 and
P(OEt)3 [RuH(N-N)P3]+ (4a, 5a, 4b, 5b) derivatives contain-
1
ing both the mer and fac isomers was also studied. The H
NMR spectra, in fact, showed that the addition of the triflic
1
acid caused the disappearance of both the H multiplet at
-7 and at -14 ppm of the hydrides of the two isomers.
However, only one broad signal between -9 and -10 ppm
attributable to the η2-H2 ligand was observed, while two new
AB2 multiplets appeared in the 31P{1H} NMR spectra
concurrent with the disappearance of those of the hydride
precursors, in agreement with the reaction of both the isomers
of the hydrides giving η2-H2 derivatives. The presence of
only one η2-H2 signal observed between -80 and +10 °C
may be explained, either by a partial overlapping of the
signals of the two η2-H2 isomers formed, or by the large
broadness of the signal of the isomer present in minor
amount. The loss of dihydrogen even at -80 °C cannot be
excluded. In every case the formation of at least one η2-H2
complex was observed, which was confirmed both by T1min
measurements on this broad signal and by determination of
the JHD values of the related [Ru(η2-HD)(N-N)P3]2+ isotopo-
mers (Table 2). The presence of the coupling between the
η2-HD and one phosphite ligand (JPH about 9-10 Hz) also
suggests a fac-type geometry IV for the η2-H2 derivatives.
From the JHD values the H-H distances were calculated,2b
and they are reported in Table 2. Values between 0.93 and
0.95 Å were observed for the tris(phosphite) [Ru(η2-H2)(N-
N)P3]2+ (9, 10) derivatives. The H-H bond length in the H2
ligand can also be calculated20 by the T1min values. The results
for the ruthenium complexes are reported in Table 2 for both
a slow and a fast rotation model and, unexpectedly,21 do not
result comparable with those calculated from the JHD values.
In fact, a H-H distance of 0.93-0.95 Å from the JHD values,
which is intermediate between the two possible values of
0.99-1.03 Å (slow rotation) and 0.79-0.81 Å (fast rotation)
for the H-H bond length calculated for the T1min values, has
been calculated.
Monophosphite complexes [RuH(bpy)2P]Y (8) (Y ) BPh4,
CF3SO3) also react with Brønsted acid in CH2Cl2 solution
to give the dihydrogen [Ru(η2-H2)(bpy)2P]2+ (11) cations
(Scheme 3), which are stable in solution until 5-10 °C, but
lose H2 if attempts of separation in a solid state are made.
Measurements of T1min (7.2-7.6 ms) and JHD (31.2-32.8
Hz) values (Table 2) strongly support the formulation of 11
as dihydrogen derivatives. The observed value for 2JPH of
HD
about 7-8 Hz also suggests a mutually trans position of the
phosphine and the dihydrogen ligands as in type-V geometry.
Furthermore, the H-H distances of the dihydrogen ligand
were also calculated both from the JHD and the T1min values
and are reported in Table 2. Bond H-H lengths of 0.89-
0.92 Å were calculated from JHD for [Ru(η2-H2)(bpy)2P]2+
(11) derivatives and were slightly shorter than the values of
the related [Ru(η2-H2)(N-N)P3]2+ (9, 10) cations. In the
monophosphites 11, however, the H-H distances deduced
from JHD could not be correlated with those deduced from
T1min values, using either a fast rotation model or with those
using a slow rotation one, the calculated H-H distance being
an intermediate value between the two.
Studies on the protonation of the hydride complexes 4, 5,
and 8 reveal that the tris(phosphite) [Ru(η2-H2)(N-N)P3]2+
(9, 10) cations are, as expected, more acidic than the
monophosphite [Ru(η2-H2)(bpy)2P]2+ (11) derivatives. In
fact, approximately 2.5 equiv of CF3SO3H is required for
the complete protonation of [RuH(N-N)P3]+, while less than
1.5 equiv is required for the monophosphite [RuH(bpy)2P]+
hydride cations.
A qualitative comparison between the acidity of the
ruthenium [Ru(η2-H2)(N-N)(PPh2OEt)3]2+ (9, 10) cations and
the related [Fe(η2-H2)(N-N)(PPh2OEt)3]2+ derivatives1 can
also be made, and shows that the ruthenium complexes 9,
10 are slightly more acidic than the related iron compounds.
However, although more acidic than those of iron, the
ruthenium complexes 9, 10 are the least acidic among the
known dicationic derivatives,22 whose complete formation
from the [RuH(N-N)P3]+ precursors requires less than 2.5
equiv of CF3SO3H. The bis(bipyridine) [Ru(η2-H2)(bpy)2P]2+
In the related iron complexes1 [Fe(η2-H2)(N-N)P3]2+ values
for the H-H distances of 0.92-0.94 Å were deduced for
the JHD values, which showed a good agreement with the
distances calculated by the T1 method using a static rotation
(20) Earl, K. A.; Jia, G.; Maltby, P. A.; Morris, R. H. J. Am. Chem. Soc.
1991, 113, 3027-3039.
(21) Gusev, D. G.; Kuhlman, R. L.; Renkema, K. B.; Eisenstein, O.;
Caulton, K. G. Inorg. Chem. 1996, 35, 6775-6783.
Inorganic Chemistry, Vol. 43, No. 4, 2004 1345

Albertin et al.
Scheme 4a
Chart 4
a
P ) P(OEt)3; P1 ) PPh(OEt)2; R1 ) 4-CH3C6H4.
Scheme 5a
The IR spectrum of the nitrile complex 13a does not show
any absorption attributable to the νCN probably due to its
1
low intensity.24 The H and 13C NMR spectra, however,
a
R ) CH3 (17), 4-CH3C6H4 (18); P ) P(OEt)3.
confirm the presence of the CH3CN ligand showing a singlet
at 0.30 ppm of the methyl group in the proton spectrum,
while a singlet at 0.60 ppm and a doublet at 125.4 ppm (JCP
) 22 Hz) appear in the 13C{1H} NMR spectrum (Table 3)
and were attributed to the CH3 and the CN carbon atoms of
the acetonitrile ligands, respectively. The HMQC and HMBC
experiments confirm the attributions, showing the correlation
between the methyl proton signal at 0.30 ppm with the 13C
signals at 0.60 ppm (HMQC) and at 125.4 (HMBC) of the
CH3CN ligand. Furthermore, the presence of a doublet for
the CN carbon resonance with JCP of 22 Hz suggests that
the nitrile ligand should be in a trans position with one
phosphorus nucleus of the phosphite ligands. Taking into
account that the 31P spectrum appears as an A2B multiplet,
a fac geometry (VI) can be reasonably proposed for the nitrile
complex 13a.
The isocyanide derivative 14a was obtained as a mixture
of two isomers, probably with a mer (VII) and fac (VIII)
geometry (Chart 4). The 31P{1H} NMR spectrum, in fact,
shows two A2B multiplets, while two singlets of the methyl
substituent of the 4-CH3C6H4NC ligand were observed in
the proton spectra. The presence of the isocyanide was
confirmed by the IR spectrum, which shows the νCN bond
as a strong, slightly broad absorption at 2158 cm-1.
One strong νCO band at 2054 cm-1 was observed in the
IR spectrum of the carbonyl complex 15a, whose 13C
spectrum (Table 3) shows the resonance of the carbonyl
carbon atom as a doublet of triplets [A2BY (Y ) 13C)
multiplet] at 190.9 ppm, with values for the two JCP of 17.0
and 245 Hz. The different values for the two JCP suggest
that the carbonyl ligand should be in a mutually trans position
with one phosphite and cis with the other two. The 31P{1H}
NMR spectrum of the carbonyl complex 15a appears as an
A2B multiplet, and therefore a fac geometry of the type IX
(Chart 4) can be proposed.
(11) derivatives are also, indeed, less acidic than the known
dicationic dihydrogen complexes, thus highlighting that the
presence of nitrogen-donor ligands such as bpy and phen
can delocalize the positive charge of the complexes making
the η2-H2 ligand relatively less acidic.
Substitution Reactions. Studies on the dihydrogen com-
plexes 9, 10, 11 show that the η2-H2 ligand is labile and can
be easily substituted by several molecules allowing new
ruthenium complexes to be prepared. Some examples are
reported in Schemes 4 and 5. With molecules such as H2O
and phosphite, however, the deprotonation to give the [RuH-
(bpy)P3]+ precursor can be predominant on the substitution
of the η2-H2 ligand. The preparation of the complexes,
therefore, must first involve the loss of H2 to give, probably,
the [Ru(κ1-OSO2CF3)(bpy)P3]+ intermediate which, by sub-
stitution of the triflate, yields the final complexes.
At first, the aquo complex 12a was obtained in an attempt
to isolate the η2-H2 complex in the solid state, due to the
presence of traces of H2O in the solvent. It was also prepared
as a yellow solid by adding an excess of H2O to a solution
of the η2-H2 complex in CH2Cl2. Nitrile, isonitrile, carbonyl,
and mixed-phosphite derivatives 13-16 were also prepared
and are yellow or red-orange solids stable in air and in a
solution of polar organic solvents, diamagnetic and 1:2
electrolyte.14 Analytical and spectroscopic data (Table 1)
support the proposed formulation.
The presence of H2O as a ligand in [Ru(OH2)(bpy)P3]-
(BPh4)2 is confirmed by the 1H NMR spectrum, which shows
a slightly broad singlet at 2.55 ppm attributed23 to the H2O
protons. In the spectra the signals of the phosphite and the
bpy ligands are also present, while the 31P{1H} NMR spectra
appear as an AB2 multiplet. Unfortunately, these data do not
allow us to distinguish between a mer or fac geometry.
The 13C{1H} NMR spectrum of [Ru(CH3CN)(bpy)2-
{P(OEt)3}](BPh4)2 (17a) shows one singlet at 3.5 ppm and
one doublet at 127.4 ppm (JCP ) 16 Hz) attributed to the
methyl and CN carbon atoms, respectively, of the CH3CN
(22) (a) Schlaf, M.; Lough, A. J.; Maltby, P. A.; Morris, R. H. Organo-
metallics 1996, 15, 2270-2278. (b) Rocchini, E.; Mezzetti, A.;
Ru¨egger, H.; Burckhardt, U.; Gramlich, V.; Del Zotto, A.; Martinuzzi,
P.; Rigo, P. Inorg. Chem. 1997, 36, 711-720. (c) Forde, C. E.; Landau,
S. E.; Morris, R. H. J. Chem. Soc., Dalton Trans. 1997, 1663-1664.
(d) Landau, S. E.; Morris R. H.; Lough, A. J. Inorg. Chem. 1999, 38,
6060-6068. (e) Smith, K. T.; Tilset, M.; Kuhlman, R.; Caulton, K.
G. J. Am. Chem. Soc. 1995, 117, 9473-9480.
(24) The low intensity or even absence of νCN in acetonitrile complexes is
a feature that has already been observed: Rouschias, G.; Wilkinson,
G. J. Chem. Soc. A 1967, 993-1000.
(23) Albertin, G.; Antoniutti, S.; Bacchi, A.; Boato, M.; Pelizzi, G. J. Chem.
Soc., Dalton Trans. 2002, 3313-3320.
1346 Inorganic Chemistry, Vol. 43, No. 4, 2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
Chart 5
Chart 6
Scheme 6
whereas no reaction was observed with CO, alkenes, and
terminal alkynes.
The reaction with mono- and bis(aryldiazonium) cations
proceeds with both [RuH(N-N)P3]+ and [RuH(bpy)2P]+
complexes yielding mononuclear 19, 21, 22 and binuclear
20 aryldiazene derivatives.
Carbon disulfide and carbon dioxide also react with all
the hydrides 4-8, but only with the bis(bipyridine) deriva-
tives [RuH(bpy)2P]+ (8) were the thioformato 23 and formato
24 complexes prepared in pure form. With the tris(phosphite)
[RuH(N-N)P3]+ (4-6) cations, instead, the reaction with CS2
is very slow at room temperature, while CO2 does not react.
The use of reflux conditions, however, causes some decom-
position, which prevents the separation of pure samples of
the thioformato derivative. It can also be noted that only the
hydrides with P(OEt)3 and PPh(OEt)2 undergo a fast insertion
reaction which allows the isolation of the final products,
while the related PPh2OEt hydride derivative reacts so slowly
as to prevent the separation of the product in pure form.
Good analytical data were obtained for the new complexes
19-24, which are yellow or orange solids stable in the air
and in solution of polar organic solvents, in which they
behave as 1:1 (23, 24), 2:1 (19, 21, 22), or 4:1 (20)
electrolytes.14 Infrared and NMR (1H, 31P, 13C, 15N) data
(Tables 1 and 3) support the proposed formulation, and a
Scheme 7a
a
P ) P(OEt)3 (a), PPh(OEt)2 (b).
ligand. The HMQC and HMBC experiments confirm these
attributions showing a correlation between the methyl proton
signal at 1.66 ppm and the carbon signals at 3.5 (HMQC)
and 127.4 ppm (HMBC), respectively. Furthermore, the
presence of a doublet for the CN carbon resonance with JCP
of 16 Hz suggests a mutually trans position of the nitrile
and the phosphine ligand as in type-X geometry (Chart 5).
Insertion Reactions: Preparation of Aryldiazene and
Formato Derivatives. Insertion reactions into the Ru-H
bond of the new mixed-ligand hydride complexes 4, 5, 6, 8
were studied extensively with several unsaturated molecules,
and the results are summarized in Schemes 6 and 7.
1
geometry in solution was also established. The 31P and H
NMR spectra of the [Ru(PhNdNH)(N-N)P3]2+ complexes
19, 21 indicate the presence of two isomers, as had been
observed in the hydride 4-5 precursors. Furthermore, a
comparison of the spectroscopic data (Table 1) with those
of the related iron complexes1 suggests that their geometries
should be of the fac- and mer-types of Chart 6.
The NMR spectra of the binuclear complex 20a show two
NH signals in the proton spectra, two AB2 multiplets in the
31P, and also two AB2Y (Y ) 15N) multiplets present in the
15N spectra of the 15N-labeled 20a-15N derivative. These data
may suggest, in this case as well, the presence of the two
isomers. However, because the complex is binuclear, a total
of four isomers (two of which are equivalent) should be
formed, of the type shown in Chart 7.
+
Aryldiazonium cation (ArN2 ) and heteroallenes (CS2 and
CO2) quickly react with the ruthenium hydride to give
aryldiazene,25,26 thioformato, and formato27 derivatives,
(25) For aryldiazene complexes see: (a) Sutton, D. Chem. ReV. 1993, 93,
995-1022. (b) Kisch, H.; Holzmeier, P. AdV. Organomet. Chem. 1992,
34, 67-109. (c) Zollinger, H. Diazo Chemistry II; VCH: Weinheim,
Germany, 1995.
(26) Albertin, G.; Antoniutti, S.; Bacchi, A.; Ballico, G. B.; Bordignon,
E.; Pelizzi, G.; Ranieri, M.; Ugo, P. Inorg. Chem. 2000, 39, 3265-
3279 and references therein.
(27) (a) Aresta, M.; Quaranta, E.; Tommasi, I. New J. Chem. 1994, 18,
133-142. (b) Pandey, K. K. Coord. Chem. ReV. 1995, 140, 37-114.
(c) Leitner, W. Coord. Chem. ReV. 1996, 153, 257-284. (d) Yin, X.;
Moss, J. R. Coord. Chem. ReV. 1999, 181, 27-59. (e) Field, L. D.;
Lawrenz, E. T.; Shaw, W. J.; Turner, P. Inorg. Chem. 2000, 39, 5632-
5638. (f) Field, L. D.; Shaw, W. J.; Turner, P. Organometallics 2001,
20, 3491-3499. (g) Gandhi, T.; Nethaji, M.; Jagirdar, B. R. Inorg.
Chem. 2003, 42, 667-669.
1
The H NMR spectra of the monophosphite [Ru(PhNd
NH)(bpy)2P](BPh4)2 (22) show only one NH signal, which
is split into a doublet in the 15N-labeled complex 22a-15N,
of 65.5 Hz, in agreement28 with the proposed
15NH
with J
formulation. Furthermore, the 31P spectra show only one
singlet suggesting the presence of only one isomer. Finally,
the 15N NMR spectra of 22a-15N appear as a doublet due to
(28) (a) Laing, K. R.; Robinson, S. D.; Uttley, M. F. J. Chem. Soc., Dalton
Trans. 1973, 2713-2722. (b) Carrol, J. A.; Sutton, D.; Xiaoheng, Z.
J. Organomet. Chem. 1983, 244, 73-86.
Inorganic Chemistry, Vol. 43, No. 4, 2004 1347

Albertin et al.
Chart 7
Chart 9
band at 1242-1256 cm-1. Furthermore, the absence of a
measurable coupling constant between the CH proton of SC-
(H)S ligand and the phosphorus nucleus of the phosphite
suggests a mutually cis position of the thioformato and the
phosphite as in a type-XII geometry (Chart 9). Finally, the
thioformate ligand should act as monodentate in our ruthe-
nium complexes 23, a heptacoordinate Ru(II) species being
rather improbable.
The IR spectra of the formato complexes [Ru{η1-OC(H)d
O}(bpy)2P]BPh4 (24) show a strong absorption at 1601-
1599 cm-1 attributed to νasymCO of the η1-formato ligand.
2
Other η1-formato complexes show νasymCO bands in the
2
1603-1667 cm-1 range,31 whereas η2-formates generally
show νasymCO bands32 between 1554 and 1585 cm-1.
2
The 13C spectra confirm the presence of the OC(H)O
ligand showing one singlet at 170.6 ppm (24a) and at 171.3
(24b) due to the formato carbon atom. The 1H NMR spectra
do not allow us to clearly assign the formyl CH resonance,
due to the superimposing with the phenyl proton signals.
However, a HMQC experiment clearly shows the correla-
tion between one singlet at 7.73 (24a) and at 7.48 (24b) ppm
in the proton NMR spectra and the singlet due to the 13C
formyl carbon resonance at 170-171 ppm, in agreement with
the presence of the formato ligand. The absence of a
measurable coupling constant between the CH proton of OC-
(H)dO and the phosphorus nucleus of the phosphite may
suggest a mutually cis position of the formato with the
phosphite as in type-XIII geometry (Chart 9) in this case as
well.
Chart 8
the coupling with the phosphorus nucleus. The value of JNP
of 4.7 Hz also suggests, by comparison with the values of
the related 19a-15N and 20a-15N compounds, a mutually cis
position of the diazene and the phosphite ligand, as in a type-
XI geometry (Chart 8).
Aryldiazene complexes of ruthenium are known25 and are
generally stabilized25a,29 by phosphine and/or carbonyl as
supporting ligands. The preparation of our derivatives 19-
22 shows how bipyridine or phenanthroline in the mixed-
ligand fragments Ru(N-N)P3 and Ru(bpy)2P are also able to
stabilize this class of “diazo” derivatives.
The 1H NMR spectra of the thioformato [Ru{η1-SC(H)d
S}(bpy)P]BPh4 (23) show a singlet at 10.87-10.94 ppm
attributed30 to the CH proton of the SC(H)S ligand. In the
13C spectra of 23a the carbon signal of this ligand appears
as a singlet at 238.6 ppm, and the attribution is confirmed
by a HMQC experiment, which shows the correlation be-
tween this signal at 238.6 ppm and those in the proton NMR
spectra at 10.87 ppm, in agreement with the presence of the
thioformato ligand. The IR spectra also confirm the presence
of the SC(H)S ligand showing the δHCS as a medium-intensity
Formato complexes obtained by insertion of CO2 into the
metal-hydride bond are of interest as an important chemical
step in functionalizing this molecule,27 and the preparation
of [Ru{η1-OC(H)dO}(bpy)2P]BPh4 complexes constitutes
a new example for the ruthenium central metal with nitrogen
donor and phosphite as supporting ligands.
(30) (a) Darensbourg, D. J.; Rokicki, A. Organometallics 1982, 1, 1685-
1693. (b) Jia, G.; Meek, D. W. Inorg. Chem. 1991, 30, 1953-1955.
(c) Bianchini, C.; Ghilardi, C. A.; Meli, A.; Midollini, S.; Orlandini,
A. Inorg. Chem. 1985, 24, 932-939. (d) Robinson, S. D.; Sahajpal,
A. Inorg. Chem. 1977, 16, 2718-2722. (e) Albertin, G.; Antoniutti,
S.; Del Ministro, E.; Bordignon, E. J. Chem. Soc., Dalton Trans. 1994,
1769-1775.
(31) (a) Nietlispach, D.; Veghini, D.; Berke, H. HelV. Chim. Acta 1994,
77, 2197-2208. (b) Whittlesey, M. K.; Perutz, R. W.; Moore, M. H.
Organometallics 1996, 15, 5166-5169. (c) Antinolo, A.; Fajardo, M.;
Garcia-Yuste, S.; del Hierro, I.; Otero, A.; Elkrami, S.; Mourad, Y.;
Mugnier, Y. J. Chem. Soc., Dalton Trans. 1995, 3409-3414. (d) Scott,
M. J.; Goddard, C. A.; Holm, R. H. Inorg. Chem. 1996, 35, 2558-
2567. (e) Fong, L. K.; Fox, J. R.; Cooper, N. J. Organometallics 1987,
6, 223-231.
(29) (a) Albertin, G.; Antoniutti, S.; Pelizzi, G.; Vitali, F.; Bordignon, E.
Inorg. Chem. 1988, 27, 829-835. (b) Haymore, B. L.; Ibers, J. A. J.
Am. Chem. Soc. 1975, 97, 5369-5379. (c) Albertin, G.; Antoniutti,
S.; Bacchi, A.; Bordignon, E.; Pelizzi, G.; Ugo, P. Inorg. Chem. 1996,
35, 6245-6253.
(32) (a) Bradley, M. G.; Roberts, D. A.; Geoffroy, G. L. J. Am. Chem.
Soc. 1988, 103, 379-384. (b) Kolomnikov, I. S.; Gusev, A. I.;
Aleksandrov, G. G.; Lobeeva, T. S.; Struchkov, Y. T.; Vol’pin, M. E.
J. Organomet. Chem. 1973, 59, 349-351.
1348 Inorganic Chemistry, Vol. 43, No. 4, 2004

Mixed-Ligand Ruthenium(II) Hydride Complexes
Conclusions
lene, to give formato [Ru{η1-OC(H)dO}(bpy)2P]BPh4 and
dithioformato [Ru{η1-SC(H)dS}(bpy)2P]BPh4 derivatives.
In this paper the synthesis of a new series of mixed-ligand
hydride complexes of ruthenium(II) with phosphite and
polypyridine of the type [RuH(N-N)P3]BPh4 and [RuH-
(bpy)2P]BPh4 is described. Among the properties shown by
these complexes, we can highlight the easy protonation with
Brønsted acid to give dicationic dihydrogen [Ru(η2-H2)(N-
N)P3]2+ and [Ru(η2-H2)(N-N)P32+ derivatives. Acidity studies
of these η2-H2 complexes were also carried out and compared
with other dicationic dihydrogen derivatives. The Ru-H
bond of the mixed-ligand hydride can undergo insertion of
both aryldiazonium cation, to give aryldiazene, and heteroal-
Acknowledgment. The financial support of MIUR (Rome),
PRIN 2002, is gratefully acknowledged. We thank Daniela
Baldan for technical assistance.
Supporting Information Available: Crystallographic data in
CIF format. Experimental details and spectroscopic data (IR, NMR)
of compounds 4c-CF3SO3, 5c-CF3SO3, and 8-CF3SO3. This mater-
ial is available free of charge via the Internet at http://pubs.acs.org.
IC034820Z
Inorganic Chemistry, Vol. 43, No. 4, 2004 1349