Synthesis and reactivity of new ruthenium alkyls and hydrides. Protonation of Cp*Ru(Me2PCH2PMe2)Me and x-ray crystal structure of Cp*2Ru2(μ-Ph2PCH2PPh 2)(AIH5</su

Article abstract of DOI:10.1021/om960703i

Treatment of the pentamethylcyclopentadienylruthenium chloride tetramer [Cp*RuCl]₄ with bis(dimethylphosphino)methane (dmpm) in tetrahydrofuran affords three ruthenium(II) phosphine complexes, Cp*Ru(dmpm)Cl, [Cp*Ru(dmpm)(η¹-dmpm)]Cl,

Full text of DOI:10.1021/om960703i

Organometallics 1997, 16, 2987-2994
2987
Syn th esis a n d Rea ctivity of New Ru th en iu m Alk yls a n d
Hyd r id es. P r oton a tion of Cp *Ru (Me2P CH2P Me2)Me a n d
X-r a y Cr ysta l Str u ctu r e of
Cp *2Ru 2(µ-P h 2P CH2P P h 2)(AlH5)
Wenbin Lin, Scott R. Wilson, and Gregory S. Girolami*
School of Chemical Sciences, University of Illinois at Urbana-Champaign,
505 South Mathews Avenue, Urbana, Illinois 61801
Received August 16, 1996X
Treatment of the pentamethylcyclopentadienylruthenium chloride tetramer [Cp*RuCl]4
with bis(dimethylphosphino)methane (dmpm) in tetrahydrofuran affords three ruthenium(II)
phosphine complexes, Cp*Ru(dmpm)Cl, [Cp*Ru(dmpm)(η1-dmpm)]Cl, and Cp*2Ru2(µ-dmpm)2-
Cl2. Similar treatment of [Cp*RuCl]4 with bis(diphenylphosphino)methane (dppm) in
tetrahydrofuran or diethyl ether affords the dinuclear species Cp*2Ru2(µ-dppm)(µ-Cl)2; in
acetonitrile, this same reaction yields the mononuclear product Cp*Ru(dppm)Cl in high yield.
The mononuclear complexes Cp*Ru(P-P)Cl (where P-P is dmpm or dppm) can be alkylated
with dimethylmagnesium in diethyl ether to give the methyl complexes Cp*Ru(dmpm)Me
and Cp*Ru(dppm)Me. Protonation of these Cp*Ru(P-P)Me complexes with trifluoroacetic
acid results in the rapid reductive elimination of methane and formation of the trifluoro-
acetato complexes Cp*Ru(P-P)(η1-O2CCF3); no ruthenium(IV) hydridomethyl intermediates
could be detected. Treatment of Cp*2Ru2(dppm)2Cl2 with LiAlH4 in diethyl ether yields the
ruthenium aluminohydride complex Cp*2Ru2(µ-dppm)(µ-AlH5), which can be converted to
the ruthenium polyhydride complex Cp*2Ru2(µ-dppm)H6 by treatment with methanol at low
temperatures. The crystal structure of Cp*2Ru2(µ-dppm)(µ-AlH5) shows that the alumino-
hydride unit is bound in a (µ-H)2AlH(µ-H)2 fashion.
In tr od u ction
mediate.13-15,18-20 The intermediacy of a σ complex in
the former mechanism has been suggested by the
observation of proton exchange between the methyl and
hydrido groups prior to the reductive elimination of
methane and by the observation of an inverse kinetic
isotope effect for the elimination of methane from a
transition metal hydridomethyl complex.16,17 Additional
evidence has come from the direct observation of transi-
tion metal methane adducts M(CH4)Ln in low temper-
ature matrix isolation studies21-26 and the detection of
The activation of hydrocarbon C-H bonds and the
functionalization of saturated hydrocarbons by soluble
transition metal complexes have been intensively stud-
ied in the past decade,1-5 and perhaps most notable is
the finding that some organometallic complexes are able
to activate methane.6-15 The activation of alkanes can
occur via two different pathways: oxidative addition to
a coordinately unsaturated metal center via a so-called
σ complex7-12,16,17 and “heterolytic” addition across a
reactive metal-ligand bond via a four-centered inter-
+
cationic transition metal methane adducts M(CH4)Ln
in the gas phase.27,28 Little is known, however, about
X Abstract published in Advance ACS Abstracts, J une 1, 1997.
(1) Bergman, R. G. Science 1982, 223, 902-908.
(2) Shilov, A. E. Activation of Saturated Hydrocarbons by Transition
Metal Complexes; D. Reidel: Boston, 1984.
(3) Crabtree, R. H. Chem. Rev. 1985, 85, 245-269.
(4) Bunel, E.; Burger, B. J .; Bercaw, J . E. J . Am. Chem. Soc. 1988,
110, 976-978.
(5) J ones, W. D.; Feher, F. J . Acc. Chem. Res. 1989, 22, 91-100.
(6) Shilov, A. E.; Shteinman, A. A. Coord. Chem. Rev. 1977, 24, 97-
143.
(16) Bullock, R. M.; Headford, C. E. L.; Hennessy, K. M.; Kegley, S.
E.; Norton, J . R. J . Am. Chem. Soc. 1989, 111, 3897-3908.
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J . Am. Chem. Soc. 1985, 107, 727-729.
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Soc. 1988, 110, 8729-8731.
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P. T.; Chan, A. W. E.; Hoffmann, R. J . Am. Chem. Soc. 1991, 113,
2985-2994.
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J . Am. Chem. Soc. 1988, 110, 7915-7916.
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3544-3546.
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S0276-7333(96)00703-0 CCC: $14.00 © 1997 American Chemical Society

2988 Organometallics, Vol. 16, No. 13, 1997
Lin et al.
the structures of the intermediates generated during
these C-H bond activation processes.
Rea ction of [Cp *Ru Cl]4 w ith d m p m . Three dif-
ferent products have been obtained upon treatment of
[Cp*RuCl]4 with 1 equiv of dmpm in tetrahydrofuran
for 12 h. The reaction produces an orange solution
(which contains two of the products) and an orange
precipitate (which contains the third). The simple 1:1
coordination complex Cp*Ru(dmpm)Cl, 1, can be iso-
lated from the reaction solution as pale orange crystals
in moderate yield by removing the solvent and crystal-
lizing the residue from diethyl ether. Compound 1 can
A potential alternative approach to the synthesis of
σ complexes is the protonation of a transition metal
alkyl compound. If reductive elimination can be slowed
sufficiently and if the metal center is neither too
electron-poor nor too electron-rich, then such protona-
tion reactions may lead to alkyl/hydride products in
which there is some interaction between the alkyl and
hydride ligands. For example, protonation of Cp*Ru-
(PMe3)2Me with HBF4 is known to afford a RuIV complex
[Cp*Ru(PMe3)2Me(H)][BF4],29 but this species adopts a
four-legged piano-stool structure in which the methyl
and hydride ligands are mutually trans. Thus, in this
complex, there are no interactions between the methyl
and hydride groups like those present between the silyl
and hydride ligands in electronically related manganese
complexes of stoichiometry CpMn(CO)L(SiR3)H.30-32
Other Cp*Ru(PR3)2Me complexes are known,29,33-35 but
their reactions with acids have not been studied.
In order to promote interactions between the alkyl
and hydride ligands attached to the same metal center,
we have undertaken a study of electron-rich ruthenium
complexes with chelating phosphines that have small
bite angles. Phosphines such as bis(dimethylphos-
phine)methane (dmpm) and bis(diphenylphosphino)-
methane (dppm) cannot span trans positions in a four-
legged piano-stool structure and will constrain the other
two ligands to be mutually cis. This strategy has been
successfully utilized to prepare the stable dihydrogen
complex [CpRu(dppm)(η2-H2)][PF6]; in contrast, the 1,2-
bis(diphenylphosphino)propane complex [CpRu(dppp)-
H2][PF6] is a classical hydride complex in which the two
hydride ligands are mutually trans.36,37 In this paper,
we report preparations of electron-rich ruthenium(II)
alkyls and hydrides and, in particular, our attempts to
prepare cis-hydrido methyl complexes of stoichiometry
[Cp*Ru(P-P)Me(H)]+ (where P-P is dmpm or dppm). We
also report the crystal structure of a ruthenium alumi-
nohydride complex Cp*2Ru2(µ-dppm)(µ-AlH5) and its
conversion to the ruthenium polyhydride Cp*2Ru2(µ-
dppm)H6.
be obtained in better yield by treatment of the cyclooc-
tadiene complex Cp*Ru(COD)Cl with dmpm, and this
is the preferred method of synthesis.42 The piano-stool
1
structure of 1 is clear from the H and 31P{1H} NMR
spectra (see Table 1). The most diagnostic features are
the presence of two resonances for the inequivalent
methylene protons in the backbone of the dmpm ligand
and the two resonances for the PMe2 protons. These
PCH2 and PMe2 groups are diastereotopic since they can
either be distal or proximal to the Cp* ring. These
spectroscopic features are similar to those of the analo-
gous cyclopentadienyl complex CpRu(Cy2PCH2PCy2)Cl
(where Cy is cyclohexyl).43
As mentioned above, the reaction of [Cp*RuCl]4 with
dmpm in tetrahydrofuran affords an orange precipitate.
This precipitate consists of a single compound with the
same empirical formula as 1. 1H and 31P{1H} NMR
spectroscopy establishes that the orange product is the
dmpm-bridged diruthenium complex Cp*2Ru2(µ-dmpm)2-
Cl2, 2. The 1H NMR spectrum of 2 shows that the PCH2
protons are equivalent and appear as a triplet of pseudo-
triplets at δ 2.00, while the PMe2 protons appear as two
virtually-coupled triplets at δ 1.63 and 1.43. The Cp*
resonance is a singlet at δ 1.57. The 31P{1H} NMR
spectrum of 2 shows only a singlet at δ -20.8. The
strong tendency of dmpm ligands to bridge between two
metal centers has been observed in other ruthenium
systems.44
Resu lts a n d Discu ssion
In order to explore the reactivity of seven-coordinate
Cp*Ru complexes that contain phosphines of stoichi-
ometry R2PCH2PR2, it is first necessary to synthesize
suitable Cp*Ru(R2PCH2PR2)Cl starting materials. Ac-
38-41
cordingly, the reactions of [Cp*RuCl]4
with bis-
(dimethylphosphino)methane (dmpm) and bis(diphen-
ylphosphino)methane (dppm) have been investigated.
The third product obtained from the reaction of
[Cp*RuCl]4 with dmpm is ionic and was isolated directly
from the reaction solution by recrystallization from
tetrahydrofuran. The stoichiometry [Cp*Ru(dmpm)(η1-
dmpm)]Cl, 3, is shown most clearly by its 31P{1H} NMR
(29) Bryndza, H. E.; Fong, L. K.; Paciello, R. A.; Tam, W.; Bercaw,
J . E. J . Am. Chem. Soc. 1987, 109, 1444-1456.
(30) Hart-Davis, A. J .; Graham, W. A. G. J . Am. Chem. Soc. 1971,
93, 4388-4393.
(31) Colomer, E.; Corriu, R. J . P.; Vioux, A. Inorg. Chem. 1979, 18,
695-700.
(38) Fagan, P. J .; Ward, M. D.; Caspar, J . V.; Calabrese, J . C.;
Krusic, P. J . J . Am. Chem. Soc. 1988, 110, 2981-2983.
(39) Fagan, P. J .; Ward, M. D.; Calabrese, J . C. J . Am. Chem. Soc.
1989, 111, 1698-1719.
(32) Schubert, U.; Ackermann, K.; Worle, B. J . Am. Chem. Soc. 1982,
104, 7378-7380.
(33) Davies, S. G.; McNally, J . P.; Smallridge, A. J . Adv. Organomet.
Chem. 1990, 30, 1-77.
(40) Fagan, P. J .; Mahony, W. S.; Calabrese, J . C.; Williams, I. D.
Organometallics 1990, 9, 1843-1852.
(34) Bruce, M. I.; Tombins, I. B.; Wong, F. S.; Skelton, B. W.; White,
A. H. J . Chem. Soc., Dalton Trans. 1982, 687-692.
(35) Tilley, T. D.; Grubbs, R. H.; Bercaw, J . E. Organometallics 1984,
3, 274-278.
(41) Lin, W.; Wilson, S. R.; Girolami, G. S. J . Am. Chem. Soc. 1993,
115, 3022-3023.
(42) Luo, L.; Zhu, N.; Zhu, N.-J .; Stevens, E. D.; Nolan, S. P.; Fagan,
P. J . Organometallics 1994, 13, 669-675.
(36) Conroy-Lewis, F. M.; Simpson, S. J . J . Chem. Soc., Chem.
Commun. 1987, 1675-1676.
(37) J ia, G.; Lough, A. J .; Morris, R. H. Organometallics 1992, 11,
161-171.
(43) J oslin, F. L.; Mague, J . T.; Roundhill, D. M. Polyhedron 1991,
10, 1713-1715.
(44) Hartwig, J . F.; Andersen, R. A.; Bergman, R. G. Organometallics
1991, 10, 1710-1719.

New Ruthenium Alkyls and Hydrides
Ta ble 1. 1H a n d 31P {1H} NMR Da ta for th e Ru th en iu m Com p lexesa ,b
compd, solvent assnmt
1H
Cp*Ru(dmpm)Cl, CD2Cl2 Cp*
Organometallics, Vol. 16, No. 13, 1997 2989
31P
4
1.72 (t, J PH ) 2.2)
-15.0 (s)
1.51 (“t”, J PH + 4J PH ) 8.4)
PMe2
2
2
1.39 (“t”, J PH + 4J PH ) 9.0)
PMe2
3.36 (m)
3.13 (m)
1.57 (br s)
PCH2
PCH2
Cp*
PMe2
PMe2
Cp*2Ru2(µ-dmpm)2Cl2, CD2Cl2
12.2 (s)
2
1.63 (“t”, J PH + 4J PH ) 7.0)
2
1.43 (“t”, J PH + 4J PH ) 5.1)
2.00 (t“t”, J PH ) 14.1,“4J PH” ) 7)
PCH2
Cp*
2
4
Cp*Ru(dmpm)(η1-dmpm)Cl, CD2Cl2
1.80 (d, J PH ) 1.8)
d
2
1.71 (“t”, J PH + 4J PH ) 9.6)
PMe2 (η2)c
PMe2 (η2)
PMe2 (η1)
PMe2 (η0)
PCH2 (η2)
PCH2 (η2)
PCH2 (η1)
Cp*
2
1.50 (“t”, J PH + 4J PH ) 9.6)
2
1.68 (d, J PH ) 7.5)
2
1.16 (d, J PH ) 3.3)
3.80 (m)
3.40 (m)
2
1.89 (d, J PH ) 6.9)
Cp*Ru(dmpm)Me, CD2Cl2
1.76 (s)
-11.7 (s)
2
1.46 (“t”, J PH + 4J PH ) 8.8)
PMe2
PMe2
PCH2
PCH2
Ru-Me
Cp*
PMe2
PMe2
PCH2
Cp*
PMe2
1.09 (“t”, J PH + 4J PH ) 8.8)
3.36 (m)
3.00 (m)
2
3
-0.27 (br t, J PH ) 7.5)
Cp*2Ru2(µ-dmpm)2(η2-O2CCF3)2, CD2Cl2, -40 °C
Cp*Ru(dmpm)(η1-O2CCF3), CD2Cl2, -40 °C
1.68 (s)
-20.8 (s)
-15.8 (s)
2
1.56 (“t”, J PH + 4J PH ) 9.6)
1.47 (“t”, J PH + 4J PH ) 9.0)
2
2
3.38 (t, J PH ) 11.0)
1.64 (s)
1.50 (“t”, J PH + 4J PH ) 7.4)
2
1.31 (“t”, J PH + 4J PH ) 8.4)
PMe2
2
3.51 (m)
3.37 (m)
PCH2
PCH2
Cp*
PPh2
PPh2
4
Cp*Ru(dppm)Cl, CD2Cl2
1.65 (t, J PH ) 2.0)
12.7 (s)
20.0 (s)
12.5 (s)
7.50 (m)
7.36 (m)
7.32 (m)
7.28 (m)
4.89 (m)
4.17 (m)
PPh2
PPh2
PCH2
PCH2
Cp*
o-PPh2
o-PPh2
p, m-PPh2
PCH2
PCH2
Ru-Me
Cp*
4
Cp*Ru(dppm)Me, CD2Cl2
1.84 (t, J PH ) 2.4)
7.46 (m)
7.37 (m)
7.04-7.20 (m)
4.54 (m)
4.11 (m)
3
0.00 (t, J PH ) 7.3)
4
Cp*Ru(dppm)(η1-O2CCF3), CD2Cl2, -50 °C
1.65 (t, J PH ) 2.0)
7.40 (m)
7.39 (m)
7.31 (m)
7.29 (m)
5.62 (m)
5.32 (m)
1.28 (s)
7.48 (m)
7.14 (s)
7.10 (s)
PPh2
PPh2
PPh2
PPh2
PCH2
PCH2
Cp*
o-PPh2
m-PPh2
p-PPh2
PCH2
Cp*
o-PPh2
m-PPh2
p-PPh2
PCH2
Ru(µ-H)Al
Cp*
Cp*2Ru2(µ-dppm)Cl2, CDCl3
35.0 (s)
58.4 (s)
2
3.69 (t, J PH ) 10.2)
Cp*2Ru2(µ-dppm)(AlH5), CD2Cl2
1.48 (s)
7.32 (m)
7.11 (s)
7.09 (s)
2
3.20 (t, J PH ) 10.8)
2
-13.96 (br d, J PH ) 22.8)
Cp*2Ru2(µ-dppm)H6, C6D6
1.71 (s)
64.7 (s)
7.57 (m)
7.09 (br s)
7.01 (br s)
3.51 (t, J PH ) 9.6)
-10.13 (br d, J PH ) 19.2)
o-PPh2
m-PPh2
p-PPh2
PCH2
RuH
2
2
a
b
All chemical shifts are reported in parts per million (ppm), while all coupling constants are in Hertz. All spectra were taken at 25
°C except those specified. c η2, η1, and η0 represent the bidentate dmpm ligand, the coordinated end of the unidentate dmpm ligand, and
d
the dangling end of the unidentate dmpm ligand, respectively. A2BC spin system with δA ) -18.6, δB ) 10.9, δC ) -56.3, J AB ) 39.4,
J BC ) 27.2.
spectrum, which consists of three resonances with
relative intensities of 2:1:1. The two equivalent phos-
phorus nuclei of the bidentate dmpm ligand appear as
a doublet at δ -18.6; the bound end of the η1-dmpm
ligand appears as a doublet of triplets at δ 10.9, while
the dangling end of the η1-dmpm ligand appears as a

2990 Organometallics, Vol. 16, No. 13, 1997
Lin et al.
doublet at δ -56.3. The 1H NMR spectrum is consistent
with this structure: the backbone methylene protons
of the bidentate dmpm ligand appear as two doublets
of triplets at δ 3.80 and 3.40, each of intensity 1, while
the corresponding protons of the unidentate dppm
ligand appear as a doublet of doublets at δ 1.89 of
intensity 2. The PMe2 groups appear as two virtually-
coupled triplets at δ 1.71 and 1.50 for the bidentate
dmpm ligand and as two doublets at δ 1.68 and 1.16
for the η1-dmpm ligand. The Cp* resonance is a doublet
at δ 1.80. The hexachlorodizincate [Zn2Cl62-] salt of 3
can also been prepared in high yield by reduction of
[Cp*RuCl2]2 with zinc in the presence of excess dmpm
in CH2Cl2.
mediacy of species38,48,49 such as [Cp*Ru(MeCN)3]+ or
[Cp*Ru(dppm)(MeCN)]+ that prevent the formation of
the diruthenium compound 5.
Syn th esis of th e Alk ylr u th en iu m (II) Com p lexes
Cp*Ru (dm pm )Me, 6, an d Cp*Ru (dppm )Me, 7. Alkyl-
ruthenium(II) complexes can be obtained in high yield
by treating Cp*Ru(dmpm)Cl with dimethylmagnesium
in diethyl ether. The NMR spectrum of the product
An analogous cyclopentadienyl complex [CpRu-
(dppm)(η1-dppm)]Cl was prepared by Bruce et al. via
substitution of the triphenylphosphine group in [CpRu-
(dppm)(PPh3)]Cl with dppm, but no spectroscopic char-
acterization of this compound was described.45
The formation of the mononuclear monoadduct 1 is
favored if the reactants are stirred for extended periods
in tetrahydrofuran. In contrast, in solvents such as
diethyl ether, the dinuclear complex 2 and the ionic
diadduct 3 are insoluble and only these products can
be isolated. The dimeric complex 2 cannot be converted
into 1 even after being refluxed in tetrahydrofuran for
24 h. Attempts to convert the ionic diadduct 3 into 1
by heating to remove the second molecule of dmpm have
been similarly unsuccessful.
Cp*Ru(dmpm)Me, 6, shows that the PCH2 protons of
the dmpm ligand are inequivalent (they appear as two
doublets of triplets at δ 3.36 and 3.00); the ruthenium-
bound methyl group appears as a triplet at δ -0.27 (3J PH
) 7.5 Hz). The related compound Cp*Ru(dppm)Me, 7,
can be prepared in high yield by treating Cp*Ru(dppm)-
Cl with dimethylmagnesium in diethyl ether.
P r oton a tion of Cp *Ru (d m p m )Me a n d Cp *Ru -
(d p p m )Me. The protonation of the ruthenium methyl
complexes was investigated in order to determine
whether stable alkyl hydride species could be obtained.
The reaction of Cp*Ru(dmpm)Me with trifluoroacetic
acid in CD2Cl2 has been followed by 1H and 31P{1H}
NMR spectroscopy (Figure 1). At -78 °C, the NMR
signals due to 6 disappear immediately upon addition
Rea ction of [Cp *Ru Cl]4 w ith d p p m . Koelle and
co-workers have reported the preparation of Cp*Ru-
(dppm)Cl, 4, in modest yield (15%) by the addition of
dppm to the mixed-valent complex Cp*2Ru2(µ-Cl)3.45,46
We have found that 4 can be prepared in higher yield
1
of HO2CCF3 to the solution. A H NMR spectrum of
the reaction mixture at -78 °C shows resonances due
to a new complex 8, along with a sharp peak at δ 0.20
due to methane (Figure 1b). Compound 8 is tentatively
assigned the formula Cp*2Ru2(µ-dmpm)2(η1-O2CCF3)2,
based on the similarity of its NMR spectrum to that of
the chloro complex Cp*2Ru2(µ-dmpm)2Cl2, 2. The triplet
at δ 3.39 is due to the equivalent protons of the PCH2
units of the bridging dmpm ligands, while the two
virtually-coupled triplets at δ 1.56 and 1.47 can be
assigned to the PMe2 groups. The Cp* resonance
appears as a singlet at δ 1.57. The 31P{1H} NMR
spectrum of 8 consists of a single peak at δ -20.8.
(71%) by stirring a suspension of [Cp*RuCl]4 and dppm
in acetonitrile for 12 h, followed by removal of the
solvent and recrystallization from diethyl ether. The
1H NMR spectrum of 4 contains the diagnostic doublet
of triplets at δ 4.89 and 4.17 due to the two inequivalent
protons of the PCH2 unit.
Interestingly, when [Cp*RuCl]4 is treated with dppm
in diethyl ether or in tetrahydrofuran, dark red crystals
of the dinuclear complex Cp*2Ru2(µ-dppm)Cl2, 5,46,47 are
obtained in essentially quantitative yield. In these
solvents, this product was obtained irrespective of the
phosphine-to-metal ratio employed. The bridging na-
ture of the dppm ligand is shown by the single environ-
ments for the PCH2 protons. It is likely that the
successful synthesis of the mononuclear compound
Cp*Ru(dppm)Cl, 4, in acetonitrile is due to the inter-
When solutions of 8 in CD2Cl2 are allowed to stand
at -70 °C, the signals due to 8 slowly diminish and are
replaced by a new set of signals, which can be assigned
to the mononuclear complex Cp*Ru(dmpm)(η1-O2CCF3),
9. At -40 °C, this conversion goes rapidly to completion
1
(Figure 1c). The H NMR spectrum of 9 contains two
multiplets at δ 3.51 and 3.37 due to the two inequivalent
protons of the PCH2 unit and two virtually-coupled
triplets at δ 1.50 and 1.31 due to the two inequivalent
sets of PMe2 groups. The Cp* resonance appears as a
singlet at δ 1.64. The 31P{1H} NMR spectrum of 9
consists of a singlet at δ -15.8.
When the analogous dppm compound Cp*Ru(dppm)-
Me, 7, is treated with HO2CCF3 at -78 °C in toluene-
d8, the trifluoroacetate complex Cp*Ru(dppm)(η1-O2-
CCF3), 10, is produced instantaneously. No intermediate
(45) Bruce, M. I.; Humphrey, M. G.; Patrick, J . M.; White, A. H.
Aust. J . Chem. 1983, 36, 2065-2072.
(46) Koelle, U.; Kossakowski, J . J . Chem. Soc., Chem. Commun.
1988, 549-551.
(48) Nolan, S. P.; Martin, K. L.; Stevens, E. D.; Fagan, P. J .
Organometallics 1992, 11, 3947-3953.
(49) Ashby, G. S.; Bruce, M. I.; Tomkin, I. B.; Wallis, R. C. Aust. J .
Chem. 1979, 32, 1003-1016.
(47) Koelle, U.; Kossakowski, J . J . Organomet. Chem. 1989, 362,
383-398.

New Ruthenium Alkyls and Hydrides
Organometallics, Vol. 16, No. 13, 1997 2991
F igu r e 2. 1H NMR spectrum (300 MHz) of Cp*2Ru2(µ-
dppm)(µ-AlH5), 11, in CD2Cl2 at 25 °C. The asterisk
indicates the solvent peak.
(Figure 2). Although the X-ray crystallographic results
(see below) show that four of the hydrogen atoms in the
2-
AlH5 group bridge to the ruthenium atoms and one
is terminal on aluminum, we could not identify a
1
separate resonance for the terminal hydride in the H
F igu r e 1. (a) 1H NMR spectrum (300 MHz) of Cp*Ru-
(dmpm)Me in CD2Cl2 at -80 °C; (b) 1H NMR spectrum (300
MHz) after treatment of Cp*Ru(dmpm)Me with HO2CCF3
in CD2Cl2 at -80 °C; (c) same reaction mixture at -40 °C.
NMR spectrum. It is possible that the signals for the
terminal hydrides on aluminum are lost in the base line,
owing to broadening by the quadrupolar aluminum
nucleus.55 Variable-temperature 1H NMR spectroscopy
has shown no evidence of a fluxional process in 11.
The aluminodeuteride isotopolog Cp*2Ru2(µ-dppm)-
(µ-AlD5), 11-d5, has been prepared by the reaction of 5
with excess LiAlD4. The metal deuteride stretches in
analogous to 8 was observed at any temperature. The
1H NMR spectrum of 10 shows two doublets of triplets
at δ 5.62 and 5.32 for the PCH2 unit of the dppm ligand,
in addition to resonances for the phenyl groups and the
Cp* ligand.
11-d5 appear at 1275 and 1255 cm-1
.
X-r a y Sin gle-Cr ysta l Str u ctu r e of 11. A single-
crystal X-ray diffraction study of 11 has been performed
in order to confirm its structure. Crystals of 11, grown
from diethyl ether at -20 °C, crystallize in the mono-
clinic space group P21/c with one molecule in the
asymmetric unit. There is no crystallographic sym-
metry imposed on the molecule, although the idealized
symmetry of the molecules is C2v (Figure 3). Crystal
data are presented in Table 2, and selected bond
distances and angles are collected in Table 3.
For both the dmpm and dppm complexes, protonation
results in the immediate evolution of methane and no
cis-methyl/hydride intermediates could be detected.
When these protonations were carried out with HBF4,
similar results were obtained: methane elimination was
rapid and no cis-methyl/hydride complex could be
observed.
Syn th esis, Str u ctu r e, a n d Rea ctivity of th e Alu -
m in oh yd r id e Com p lex Cp *2Ru 2(µ-d p p m )(µ-AlH5).
There has been recent interest in the structures of
transition metal aluminohydride complexes.50-54 We
find that treatment of Cp*2Ru2(µ-dppm)Cl2, 5, with
LiAlH4 in diethyl ether affords the aluminohydride
complex Cp*2Ru2(µ-dppm)(µ-AlH5), 11. The IR spec-
trum of 11 shows two strong metal hydride stretches
Molecules of 11 consist of two ruthenium centers
2-
bridged by a dppm ligand and an AlH5 unit that is
2-
best written as (µ-H)2AlH(µ-H)2
. Each ruthenium
atom is also η5-bonded to a pentamethylcyclopentadienyl
group. Interestingly, unlike all previously known AlH5
2-
units, which adopt distorted trigonal bipyramidal ge-
1
at 1779 and 1728 cm-1. The H NMR spectrum of 11
2-
ometries,53 the AlH5 unit in 11 exhibits a slightly
at 25 °C shows a doublet at δ -13.96 for the bridging
distorted square pyramidal geometry. The H-Al-H
bond angles between the axial and four basal hydrogen
atoms are almost identical: these bond angles average
at 113(2)° with the largest deviation being 4°. The
terminal hydrogen on aluminum occupies the axial site
of the square pyramid. As expected, the terminal Al-H
bond distance of 1.49(5) Å is much shorter than the
bridging Al-H bond distances of 1.88(2) Å.
2-
2
AlH5 group; the J PH coupling constant is 22.8 Hz
(50) Girolami, G. S.; Howard, C. G.; Wilkinson, G.; Dawes, H. M.;
Thornton-Pett, M.; Motevalli, M.; Hursthouse, M. B. J . Chem. Soc.,
Dalton Trans. 1985, 921-929.
(51) Barron, A. R.; Salt, J . E.; Wilkinson, G. J . Chem. Soc., Dalton
Trans. 1986, 1329-1332.
(52) Barron, A. R.; Lyons, D.; Wilkinson, G.; Motevalli, M.; Howes,
A. J .; Hursthouse, M. B. J . Chem. Soc., Dalton Trans. 1986, 279-285.
(53) Barron, A. R.; Wilkinson, G. Polyhedron 1986, 5, 1897-1915.
(54) Barron, A. R.; Wilkinson, G. J . Chem. Soc., Dalton Trans. 1986,
287-289.
(55) Labinger, J . A.; Wong, K. S. J . Organomet. Chem. 1979, 170,
373-384.

2992 Organometallics, Vol. 16, No. 13, 1997
Lin et al.
Ta ble 2. Cr ysta l Da ta for Cp *2Ru 2(µ-d p p m )(AlH5),
11
C45H57P2AlRu2
a ) 17.025(4) Å
b ) 10.063(2) Å
c ) 25.310(10) Å
â ) 105.97(2)°
V ) 4169(4) Å3
Z ) 4
space group: P21/c
T ) -75 °C
λ ) 0.710 73 Å
Fcalcd ) 1.416 g cm-3
µcalcd ) 8.36 cm-1
transm coeff ) 0.821-0.890
RF ) 0.042
mol wt ) 889.02
RwF ) 0.049
Ta ble 3. Selected Bon d Dista n ces a n d An gles for
Cp *2Ru 2(µ-d p p m )(AlH5), 11
Bond Distances (Å)
Ru(1)-P(1)
Ru(1)‚‚‚Al
2.245(2)
2.445(2)
1.55(3)
Ru(2)-C(13)
Ru(2)-C(14)
Ru(2)-C(15)
Ru(2)-H(3)
Ru(2)-H(4)
Al-H(1)
2.234(7)
2.245(7)
2.244(7)
1.55(3)
1.55(3)
1.88(2)
1.88(2)
1.88(2)
1.88(3)
1.49(5)
1.851(6)
1.872(6)
Ru(1)-H(1)
Ru(1)-H(2)
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-C(3)
Ru(1)-C(4)
Ru(1)-C(5)
Ru(2)-P(2)
Ru(2)-Al
1.55(2)
2.223(7)
2.251(8)
2.252(7)
2.230(7)
2.215(7)
2.254(2)
2.464(2)
2.224(7)
2.217(7)
Al-H(2)
Al-H(3)
Al-H(4)
Al-H(5)
F igu r e 3. ORTEP drawing of Cp*2Ru2(µ-dppm)(µ-AlH5),
11. The 35% probability density surfaces are shown, except
for the hydrogen atoms which are represented as arbitrarily-
sized spheres.
P(1)-C
Ru(2)-C(11)
Ru(2)-C(12)
P(2)-C
Bond Angles (deg)
P(1)-Ru(1)-Al
P(2)-Ru(2)-Al
Ru(1)-P(1)-C
98.89(7)
93.78(7)
120.9(2)
121.2(2)
125.3(4)
84(1)
88(1)
97(1)
89(1)
90(1)
Ru(1)-Al-Ru(2)
H(1)-Al-H(2)
H(2)-Al-H(4)
H(3)-Al-H(4)
H(1)-Al-H(3)
H(1)-Al-H(5)
H(2)-Al-H(5)
H(3)-Al-H(5)
H(4)-Al-H(5)
H(1)-Al-H(4)
H(2)-Al-H(3)
134.68(9)
77(1)
84.2(10)
78(1)
The Ru-H distances to the bridging hydride ligands
refined to 1.55 Å. The Ru-Ru distance in 11 is greater
than 4 Å, and thus, the ruthenium atoms are not bonded
to each other. The Ru-P distances of 2.245(2) and
2.254(2) Å are well within the range found for other
ruthenium bis(diphenylphosphino)methane complexes.56
Con ver sion of 11 to th e Ru th en iu m P olyh yd r id e
Cp *2Ru 2(µ-d p p m )H6. Transition metal polyhydride
complexes have been of interest especially since the
recognition in 1983 that such species sometimes contain
nonclassical dihydrogen ligands.57 One of the most
general methods for the synthesis of polyhydride com-
plexes is the addition of LiAlH4 to a metal chloride
complex followed by protolysis.58,59 In certain cases,
such as in the present study, the transition metal
aluminohydride complexes that are intermediates in
such syntheses can be isolated if the protolysis step is
omitted.
Ru(2)-P(2)-C
P(1)-C-P(2)
88(1)
P(1)-Ru(1)-H(1)
P(1)-Ru(1)-H(2)
H(1)-Ru(1)-H(2)
P(2)-Ru(2)-H(3)
P(2)-Ru(2)-H(4)
H(3)-Ru(2)-H(4)
109(2)
117(2)
113(2)
111(2)
140(1)
130(2)
99(1)
Mononuclear ruthenium trihydride complexes of the
general type Cp′Ru(PR3)H3 (where Cp′ is cyclopentadi-
enyl or pentamethylcyclopentadienyl) have been known
for some time and were initially thought to be classical
ruthenium trihydride complexes with trigonal bipyra-
midal structures of C3v symmetry according to NMR and
IR data.58,59 A single-crystal X-ray diffraction study,
however, has shown that Cp*Ru(PPh3)H3 is a classical
ruthenium trihydride that adopts a four-legged piano-
stool structure of Cs symmetry in the solid state.60
Later, Chaudret and co-workers observed unusually
large coupling constants between the hydrides and
proposed that there is an equilibrium between a clas-
sical trihydride and either a hydride/dihydrogen com-
plex or trihydrogen complex.61 Tritium labeling and
theoretical studies by Zilm, Heinekey, and co-workers
have shown that the large coupling constants between
the hydrides are not due to the presence of nonclassical
dihydrogen or trihydrogen ligands but instead are due
to rapid pairwise quantum mechanical hydrogen ex-
change.62 Most likely, 12 adopts a classical structure
with two ruthenium trihydride centers bridged by a
dppm ligand.
Protolysis of 11 with excess methanol in diethyl ether
yields the diruthenium hexahydride complex Cp*2Ru2-
(µ-dppm)H6, 12. The IR spectrum of 12 contains a broad
Cp*2Ru2(µ-dppm)(AlH5) MeOH8
peak at 1980 cm-1 that can be assigned to a Ru-H
stretch. All six hydride ligands are evidently terminal
hydrides; three are bound to each ruthenium atom. At
Exp er im en ta l Section
1
25 °C, the H NMR signal for the hydride ligands in 12
is a doublet at δ -10.2 (2J HP ) 19.2 Hz).
All operations were carried out in a vacuum or under argon.
Solvents were distilled under nitrogen from sodium/benzophe-
(56) Chakravarty, A. R.; Cotton, F. A.; Schwotzer, W. Inorg. Chim.
Acta 1984, 84, 179-185.
(60) Suzuki, H.; Lee, D. H.; Oshima, N.; Moro-oka, Y. Organome-
tallics 1987, 6, 1569-1575.
(57) Kubas, G. J .; Ryan, R. R.; Swanson, B. I.; Vergamini, P. J .;
Wasserman, H. J . J . Am. Chem. Soc. 1984, 106, 451-453.
(58) Davies, S. G.; Moon, S. D.; Simpson, S. J . J . Chem. Soc., Chem.
Commun. 1983, 1278-1279.
(61) Arliguie, T.; Border, C.; Chaudret, B.; Devillers, J .; Poiblanc,
R. Organometallics 1989, 8, 1308-1314.
(62) Zilm, K. W.; Heinekey, D. M.; Millar, J . M.; Payne, N. G.;
Neshyba, S. P.; Duchamp, J . C.; Szczyrba, J . J . Am. Chem. Soc. 1990,
112, 920-929.
(59) Lee, D. H.; Suzuki, H.; Moro-oka, Y. J . Organomet. Chem. 1987,
330, C20-C22.

New Ruthenium Alkyls and Hydrides
Organometallics, Vol. 16, No. 13, 1997 2993
none (pentane, diethyl ether, tetrahydrofuran), sodium (toluene-
d8, benzene-d6), magnesium (methanol), or calcium hydride
(dichloromethane-d2) immediately before use. Bis(dimeth-
ylphosphino)methane (Strem), bis(diphenylphosphino)methane
(Strem), pentamethylcyclopentadiene (Quantum Design), meth-
anol-d4 (Cambridge Isotopes), LiAlH4 (Cerac), LiAlD4 (Cam-
bridge Isotopes), RuCl3‚3H2O (Cerac), and zinc dust (Mallinck-
rodt) were used as received. Trifluoroacetic acid (Aldrich) was
purified by addition of 1% v/v trifluoroacetic anhydride (Ald-
rich) followed by distillation under N2. The compounds
from dichloromethane. Yield: 0.81 g (60%). Anal. Calcd
(found) for C30H58Cl6P4Ru2Zn2: C, 35.3 (36.2); H, 6.37 (6.74);
Cl, 15.6 (16.6); P, 18.2 (16.5); Ru, 14.9 (13.9); Zn, 9.61 (8.00).
The NMR data of 3′ are essentially the same as those of 3.
(P en t a m et h ylcyclop en t a d ien yl)ch lor o[b is(d ip h en yl-
p h osp h in o)m eth a n e]r u th en iu m (II), Cp *Ru (d p p m )Cl, 4.
To a mixture of [Cp*RuCl]4 (0.49 g, 0.45 mmol) and bis-
(diphenylphosphino)methane (0.69 g, 1.80 mmol) was added
acetonitrile (60 mL), and the resulting slurry was stirred for
12 h. An orange solution was obtained, and the solvent was
removed under vacuum. The residue was extracted with
diethyl ether (2 × 80 mL), and the extract was filtered. The
filtrate was concentrated to ca. 130 mL and cooled to -20 °C
to afford orange crystals. Yield: 0.91 g (71%). Anal. Calcd
(found) for C35H37ClP2Ru: C, 64.1 (64.4); H, 5.68 (5.71); Cl,
5.40 (6.13); P, 9.44 (9.11); Ru, 15.4 (13.9). IR (cm-1): 1435
(s), 1302 (vw), 1182 (vw), 1157 (vw), 1094 (m), 1070 (vw), 1025
(m), 1000 (vw), 772 (w), 750 (m), 739 (m), 723 (s), 701 (s), 670
(vw), 652 (vw), 618 (vw), 534 (m), 514 (s), 486 (m), 450 (w).
Bis(p en ta m eth ylcyclop en ta d ien yl)d i(µ-ch lor o)(µ-bis-
(d ip h en ylp h osp h in o)m eth a n e)d ir u th en iu m (II), Cp *2Ru 2-
(µ-d p p m )(µ-Cl)2, 5. To a mixture of [Cp*RuCl]4 (1.70 g, 1.57
mmol) and dppm (1.20 g, 3.13 mmol) was added diethyl ether
(140 mL). The resulting dark red solution was stirred at room
temperature for 2 h and then filtered. The filtrate was
concentrated to ca. 100 mL and cooled to -20 °C to afford dark
red crystals. Yield: 2.37 g (82%). Anal. Calcd (found) for
31,63
38-40
[Cp*RuCl2]2
ture methods.
and [Cp*RuCl]4
were prepared via litera-
IR spectra were recorded on a Perkin-Elmer 599B infrared
spectrometer as Nujol mulls between KBr plates. The 1H
NMR data were obtained on a General Electric QE-300
spectrometer at 300 MHz or on a General Electric NB-300
spectrometer at 300 MHz. The 13C NMR data were obtained
on a General Electric NB-300 spectrometer at 75 MHz or on a
General Electric QE-300 spectrometer at 75 MHz. The 31P-
{1H} NMR data were recorded on a General Electric NB-300
spectrometer at 121 MHz. The 2H NMR data were obtained
on
a General Electric NB-300 spectrometer at 46 MHz.
Chemical shifts are reported in δ units (positive shifts to high
2
frequency) relative to TMS (1H, H, 13C) or 85% H3PO4 (31P).
Microanalyses were performed by the University of Illinois
Microanalytical Laboratory.
(P e n t a m e t h ylcyclop e n t a d ie n yl)ch lor o[b is(d im e t h -
ylp h osp h in o)m eth a n e]r u th en iu m (II), Cp *Ru (d m p m )Cl,
1. To a slurry of [Cp*RuCl]4 (0.593 g, 0.54 mmol) in tetrahy-
drofuran (40 mL) was slowly added a solution of dmpm (0.34
mL, 2.17 mmol) in tetrahydrofuran (40 mL). The solution
turned orange immediately, and an orange precipitate formed
after a few minutes. After the mixture had been stirred at
room temperature for 12 h, the solvent was removed under
vacuum and the residue was extracted with diethyl ether (2
× 80 mL). The extracts were filtered, and the filtrates were
combined, concentrated to ca. 100 mL, and cooled to -20 °C
to afford pale orange crystals. Yield: 0.37 g (63%). Mp:
247.1-248.6 °C. Anal. Calcd (found) for C15H29ClP2Ru: C,
44.2 (44.2); H, 7.11 (7.31); Cl, 8.70 (8.12); P, 15.2 (14.9); Ru,
24.8 (24.6). IR (cm-1): 1411 (m), 1290 (w), 1274 (w), 1151 (vw),
1075 (s), 1023 (m), 948 (s), 928 (vs), 868 (s), 840 (s), 731 (s),
701 (s), 652 (m), 613 (w), 448 (vw).
Bis(p e n t a m e t h ylcyclop e n t a d ie n yl)d ich lor ob is[b is-
(dim eth ylph osph in o)m eth an e)]dir u th en iu m (II), Cp*2Ru 2-
(µ-d m p m )2Cl2, 2. To a slurry of [Cp*RuCl]4 (2.10 g, 7.75
mmol) in tetrahydrofuran (120 mL) was added a solution of
dmpm (1.20 mL, 7.66 mmol) in tetrahydrofuran (60 mL). The
solution turned orange immediately, and an orange precipitate
began to form. After the mixture had been stirred for 1 h,
the precipitate was collected by filtration. Yield: 1.25 g (40%).
Mp: 242-244 °C. Anal. Calcd (found) for C30H58Cl2P4Ru2: C,
44.2 (44.3); H, 7.11 (7.02); Cl, 8.70 (8.82); P, 15.2 (14.2); Ru,
24.8 (25.2). IR (cm-1): 1300 (w), 1293 (w), 1285 (w), 1137 (vw),
1062 (w), 951 (m), 937 (s), 928 (m), 900 (s), 849 (vw), 797 (m),
723 (s), 677 (w), 618 (m).
C
45H52P2Cl2Ru2: C, 58.3 (58.5); H, 5.61 (5.72); Cl, 7.65 (7.51);
P, 6.69 (6.50); Ru, 21.8 (21.5). IR (cm-1): 2243 (vw), 2211 (vw),
1586 (w), 1572 (w), 1482 (m), 1438 (s), 1308 (vw), 1276 (vw),
1178 (w), 1153 (w), 1091 (s), 1024 (m), 768 (m), 757 (s), 738
(s), 728 (s), 701 (s), 690 (s), 643 (m), 608 (vw), 518 (m), 493 (s),
443 (vw), 430 (vw), 398 (vw).
(P en t a m et h ylcyclop en t a d ien yl)m et h yl[b is(d im et h -
ylp h osp h in o)m eth a n e]r u th en iu m (II), Cp *Ru (d m p m )Me,
6. To a solution of Cp*Ru(dmpm)Cl (0.369 g, 0.91 mmol) in
diethyl ether (60 mL) was added dimethylmagnesium (3.4 mL
of a 0.27 M solution in diethyl ether, 0.91 mmol). The resulting
mixture was stirred at ambient temperature for 24 h to give
a pale yellow solution. The solvent was removed under
vacuum, and the residue was extracted into pentane (80 mL).
The extract was filtered, and the filtrate was concentrated to
ca. 10 mL and cooled to -20 °C to afford pale yellow crystals.
Yield: 0.28 g (80%). Anal. Calcd (found) for C16H32P2Ru: C,
49.6 (49.6); H, 8.34 (8.32); P, 16.0 (15.8); Ru, 26.1 (25.8).
1
13C{1H} NMR (CD2Cl2, 25 °C): δ 88.5 (s, C5Me5), 51.9 (t, J PC
) 19.1 Hz, PCH2), 20.4 (“t”, 1J PC + 3J PC ) 10.2 Hz, PMe2), 14.1
1
3
(t, J PC + J PC ) 11.1 Hz, PMe2), 11.0 (s, C5Me5), -14.6 (br s,
RuMe).
(P en t a m et h ylcyclop en t a d ien yl)m et h yl[b is(d ip h en -
ylp h osp h in o)m eth a n e]r u th en iu m (II), Cp *Ru (d p p m )Me,
7. To a solution of Cp*Ru(dppm)Cl (0.41 g, 0.63 mmol) in
diethyl ether (90 mL) was added dimethylmagnesium (0.78
mL of a 0.81 M solution in diethyl ether, 0.63 mmol). The
resulting mixture was stirred at ambient temperature over-
night to give a yellow slurry. The solvent was removed under
vacuum, and the residue was extracted into toluene (2 × 30
mL). The extract was filtered and concentrated to ca. 25 mL.
Pentane (30 mL) was added to the filtrate, and the resulting
mixture was cooled to -20 °C to afford yellow crystals. Yield:
0.34 g (85%). Anal. Calcd (found) for C36H40P2Ru: C, 68.0
(68.4); H, 6.34 (6.46); P, 9.74 (9.30); Ru, 15.9 (14.0). IR (cm-1):
1585 (vw), 1569 (vw), 1479 (m), 1432 (s), 1377(s), 1303 (vw),
1271 (vw), 1178 (vw), 1155 (vw), 1088 (s), 1024 (m), 998 (vw),
758 (w), 746 (m), 733 (m), 720 (s), 695 (s), 663 (vw), 648 (vw),
613 (vw), 537 (m), 514 (vw).
Bis(p en ta m eth ylcyclop en ta d ien yl)bis(η1-tr iflu or oa c-
e t a t o )b i s [µ-b i s (d i m e t h y l p h o s p h i n o )m e t h a n e ]d i -
r u th en iu m (II), Cp *2Ru 2(µ-d m p m )2(η1-O2CCF 3)2, 8. A so-
lution of Cp*Ru(dmpm)Me (0.029 g, 0.075 mmol) in CD2Cl2
(0.75 mL) was transferred to a NMR tube and cooled to -78
°C. To the NMR tube was added HO2CCF3 (0.007 mL, 0.091
mmol), and the mixture was vigorously shaken to assure
(P e n t a m e t h y lc y c lo p e n t a d ie n y l)b is [b is (d im e t h y l-
p h osp h in o)m eth a n e]r u th en iu m (II) Ch lor id e, [Cp *Ru -
(d m p m )(η1-d m p m )]Cl, 3. This product was isolated as
yellow crystals in low yield by cooling the tetrahydrofuran
filtrate obtained in the above reaction to -20 °C.
(P e n t a m e t h y lc y c lo p e n t a d ie n y l)b is [b is (d im e t h y l-
p h osp h in o)m et h a n e]d ir u t h en iu m (II)
H exa ch lor od i-
zin ca t e, [Cp *R u (d m p m )(η1-d m p m )]2[Zn 2Cl6], 3′. To a
mixture of [Cp*RuCl2]2 (0.61 g, 1.0 mmol) and zinc (0.065 g,
1.0 mmol) in CH2Cl2 (25 mL) was added dmpm (0.80 mL, 5.1
mmol). The reaction mixture was stirred at room temperature
for 24 h, and then it was filtered to give a light orange solution.
The solvent was removed under vacuum to give the product
as yellow powder. The crude product can be recrystallized
(63) Oshima, N.; Suzuki, H.; Moro-oka, Y. Chem. Lett. 1984, 1161-
1164.

2994 Organometallics, Vol. 16, No. 13, 1997
Lin et al.
thorough mixing of the reagents. The NMR tube was kept at
-78 °C for several minutes before it was inserted into the
precooled (-80 °C) NMR probe. 1H and 31P{1H} NMR spectra
show that Cp*Ru(dmpm)Me reacts with HO2CCF3 completely
to give Cp*2Ru2(µ-dmpm)2(η1-O2CCF3)2, which is only stable
below -70 °C.
(P en ta m eth ylcyclop en ta d ien yl)(η1-tr iflu or oa ceta to)-
[bis(dim eth ylph osph in o)m eth an e]r u th en iu m (II), Cp*Ru -
(d m p m )(η1-O2CCF 3), 9. When the above solution of Cp*2Ru2-
(µ-dmpm)2(η1-O2CCF3)2 in CD2Cl2 was kept at -70 °C, it slowly
isomerized to Cp*Ru(dmpm)(η1-O2CCF3). At -40 °C, this
transformation was instantaneous.
(P en ta m eth ylcyclop en ta d ien yl)(η1-tr iflu or oa ceta to)-
[bis(diph en ylph osph in o)m eth an e]r u th en iu m (II), Cp*Ru -
(d p p m )(η1-O2CCF 3), 10. A solution of Cp*Ru(dppm)Me (0.03
g, 0.048 mmol) in CD2Cl2 (0.75 mL) was transferred to a NMR
tube and cooled to -78 °C. To the NMR tube was added HO2-
CCF3 (0.01 mL, 0.13 mmol), and the mixture was vigorously
shaken to assure thorough mixing of the reagents. The NMR
tube was kept at -78 °C for several minutes before it was
inserted into the precooled (-80 °C) NMR probe. 1H and
31P{1H} NMR spectra showed that Cp*Ru(dppm)Me reacts
with HO2CCF3 completely to give Cp*Ru(dppm)(η1-O2CCF3)
at -78 °C.
Bis(p en t a m et h ylcyclop en t a d ien yl)(µ-η2,η2-p en t a h y-
d r id oa lu m in a to)[µ-bis(d ip h en ylp h osp h in o)m eth a n e]d i-
r u th en iu m (II), Cp *2Ru 2(µ-d p p m )(AlH5), 11. To a mixture
of Cp*2Ru2(µ-dppm)Cl2 (1.06 g, 1.14 mmol) and LiAlH4 (0.31
g, 8.17 mmol) was added diethyl ether (140 mL). The mixture
was stirred at ambient temperature for 4 h and then allowed
to settle for 30 min. The mixture was filtered, and the pale
yellow filtrate was concentrated to ca. 35 mL and cooled to
-20 °C to afford yellow crystals. Yield: 0.89 g (88%). Anal.
Calcd (found) for C45H57AlP2Ru2: C, 60.8 (60.6); H, 6.46 (6.55);
Al, 3.03 (2.77). IR (cm-1): 1779 (s), 1728 (s), 1586 (vw), 1439
(w), 1355 (vw), 1307 (vw), 1262 (vw), 1185 (vw), 1156 (vw),
1092 (s), 1069 (w), 1028 (m), 798 (vw), 782 (m), 739 (s), 703
(s), 695 (s), 661 (m), 641 (m).
glass fibers using Paratone-N oil (Exxon) and were im-
mediately cooled to -75 °C in a nitrogen stream on the
diffractometer. Standard peak search and indexing procedures
gave rough cell dimensions, and the diffraction symmetry was
verified by examination of the axial photographs. Least-
squares refinement using 25 reflections yielded the cell dimen-
sions given in Table 2.
Data were collected in one quadrant of reciprocal space
(-h,+k,(l). Systematic absences for 0k0 (k * 2n) and h0l (l
* 2n) were consistent only with the space group P21/c. The
measured intensities were reduced to structure factor ampli-
tudes and their esd’s by correction for background, scan speed,
and Lorentz and polarization effects. While corrections for
crystal decay were unnecessary, absorption corrections were
applied; the maximum and minimum transmission factors
were 0.890 and 0.821, respectively. Systematically absent
reflections were deleted, and symmetry equivalent reflections
were averaged to yield the set of unique data. Only those data
with I > 2.58 σ(I) were used in the least-squares refinement.
The structure was solved by direct methods (SHELXS-86)
and difference Fourier syntheses. The positions of the ruthe-
nium and phosphorus atoms were deduced from an E-map.
Subsequent least-squares refinement and difference Fourier
syntheses revealed the positions of the remaining non-
hydrogen atoms. Hydrogen atoms H(1)-H(5) surfaced in late
difference Fourier maps; owing to high correlations between
hydride positional parameters and metal atom variables,
however, chemically similar metal-hydrogen bond lengths
were constrained to be equal in length. The remaining
hydrogen atoms were included in the refinement as fixed
contributors in “idealized” positions with C-H ) 0.96 Å. The
quantity minimized by the least-squares program was ∑w(|Fo|
- |Fc|)2, where w ) 1.23/(σ(Fo)2 + (pFo)2). The analytical
approximations to the scattering factors were used, and all
structure factors were corrected for both the real and imagi-
nary components of anomalous dispersion. In the final cycle
of the least-squares refinement, all non-hydrogen atoms were
independently refined with anisotropic thermal coefficients
and common isotropic thermal parameters were refined for
four hydrogen atom groups representing aliphatic and aro-
matic hydrogens and bridging and terminal metal hydrides.
Successful convergence was indicated by the maximum shift/
error of 0.051 in the last cycle. Final refinement parameters
are given in Table 2. The largest peaks in the final difference
Fourier map were in the vicinity of the ruthenium atoms. A
final analysis of the variance between observed and calculated
structure factors showed a slight dependence on sin θ.
Bis(p en t a m et h ylcyclop en t a d ien yl)(µ-η2,η2-p en t a d eu -
ter ioa lu m in a to)[µ-bis(d ip h en ylp h osp h in o)m eth a n e]d i-
r u th en iu m (II), Cp *2Ru 2(µ-d p p m )(AlD5), 11-d 5. This com-
pound was prepared as for compound 11 except that LiAlD4
was used and the reaction mixture was stirred at room
temperature for 48 h to ensure completion of the reaction. IR
(cm-1): 1275 (s), 1255 (s), 1185 (vw), 1156 (vw), 1092 (m), 1068
(vw), 1029 (w), 782 (m), 763 (s), 739 (s), 698 (s), 646 (m), 515
(m), 496 (s).
Ack n ow led gm en t. We thank the Exxon Educa-
tional Foundation for support of this research and
Teresa Prussak-Wieckowska for assistance with the
X-ray structure determination. W.L. thanks the De-
partment of Chemistry at the University of Illinois for
a fellowship.
Bis(p en ta m eth ylcyclop en ta d ien yl)h exa h yd r id o[µ-bis-
(d ip h en ylp h osp h in o)eth a n e]r u th en iu m (II), Cp *2Ru 2(µ-
d p p m )H6, 12. To a solution of Cp*2Ru2(µ-dppm)(AlH5) (0.147
g, 0.166 mmol) in diethyl ether (30 mL) at -78 °C was added
methanol (1.5 mL). The solution turned purplish-red after it
had been warmed to ambient temperature and stirred for 1.5
h. The solvent was removed under vacuum, and the residue
was extracted into pentane (60 mL). The extract was filtered,
and the filtrate was concentrated to ca. 10 mL and cooled to
-20 °C to afford light maroon crystals. Yield: 0.06 g (42%).
IR (cm-1): 3089 (w), 3078 (w), 1980 (br, s), 1481 (s), 1436 (s),
1358 (w), 1184 (vw), 1155 (vw), 1095 (s), 1088 (m), 1067 (w),
1027 (w), 790 (s), 761 (s), 748 (m), 724 (vs), 705 (m), 692 (s),
650 (w), 520 (m), 510 (m), 500 (m), 450 (br, m).
Su p p or tin g In for m a tion Ava ila ble: Tables of full crys-
tallographic details, atomic coordinates including calculated
hydrogen atom coordinates, and full bond distances and angles
for 11 (11 pages). Ordering information is given on any
current masthead page.
OM960703I
(64) For a description of the crystallographic methods and programs
employed, see: J ensen, J . A.; Wilson, S. R.; Girolami, G. S. J . Am.
Chem. Soc. 1988, 110, 4977-4982.
Cr ysta llogr a p h ic Stu d ies.64 Single crystals of Cp*2Ru2-
(µ-dppm)(µ-AlH5) 11, grown from pentane, were mounted on