14-electron ruthenium(II) hydride, [RuH(CO)(PtBu2Me)2]BAr′4 (Ar′ = 3,5-(C6H3)(CF3)2): synthesis, structure, and reactivity toward alkenes and oxygen ligands

Article abstract of DOI:10.1021/om9910017

Triflate in RuH(OTf)(CO)L₂ (L = P^tBu₂Me) can be abstracted by NaBAr′₄ (Ar′ = C₆H₃-(CF₃)₂) in C₆H₅F to give 14-electron RuH(CO)L₂⁺, which has agostic donation by one ^tBu methyl group from each phosphine. This cation binds CH₂Cl₂ in an η² fashion, and it binds OEt₂ and H₂O in the site trans to CO. It binds ethylene trans to hydride, and additional ethylene is catalytically dimerized to cis- and trans-but-2-ene at -30°C in C₆H₅F/toluene; this dimerization is slower in CH₂Cl₂ solvent. Propylene and H₂C=CHF also bind to RuH-(CO)L₂⁺ trans to hydride, and the latter is converted to ethylene and Ru/F products. Vinyl ethers seem to bind η¹ via ether oxygen more than η² via the CC bond, and trans to CO, and this species then isomerizes to the RuL₂(CO)(η²-CH₂CH₂OR) insertion product at -60°C. In contrast, 2,3-dihydrofuran gives a cyclic oxygen-stabilized carbene complex. A discussion of the results based on DFT (B3PW91) calculations is presented in the following paper.

Full text of DOI:10.1021/om9910017

Organometallics 2000, 19, 2281-2290
2281
A 14-Electr on Ru th en iu m (II) Hyd r id e,
[Ru H(CO)(P tBu 2Me)2]BAr ′4 (Ar ′ ) 3,5-(C6H3)(CF 3)2):
Syn th esis, Str u ctu r e, a n d Rea ctivity tow a r d Alk en es a n d
Oxygen Liga n d s
Dejian Huang,† J ohn C. Bollinger,† W. E. Streib,† Kirsten Folting,†
Victor Young, J r.,§ Odile Eisenstein,‡ and Kenneth G. Caulton*,†
Department of Chemistry and Molecular Structure Center, Indiana University,
Bloomington, Indiana 47405, LSDSMS (UMR 5636), Universite´ de Montpellier 2,
34095 Montpellier Cedex 05, France, and Department of Chemistry, University of Minnesota,
Minneapolis, Minnesota 55455
Received December 17, 1999
Triflate in RuH(OTf)(CO)L2 (L ) PtBu2Me) can be abstracted by NaBAr′4 (Ar′ ) C6H3-
(CF3)2) in C6H5F to give 14-electron RuH(CO)L2+, which has agostic donation by one Bu
t
methyl group from each phosphine. This cation binds CH2Cl2 in an η2 fashion, and it binds
OEt2 and H2O in the site trans to CO. It binds ethylene trans to hydride, and additional
ethylene is catalytically dimerized to cis- and trans-but-2-ene at -30 °C in C6H5F/toluene;
this dimerization is slower in CH2Cl2 solvent. Propylene and H2CdCHF also bind to RuH-
+
(CO)L2 trans to hydride, and the latter is converted to ethylene and Ru/F products. Vinyl
ethers seem to bind η1 via ether oxygen more than η2 via the CC bond, and trans to CO, and
this species then isomerizes to the RuL2(CO)(η2-CH2CH2OR) insertion product at -60 °C.
In contrast, 2,3-dihydrofuran gives a cyclic oxygen-stabilized carbene complex. A discussion
of the results based on DFT (B3PW91) calculations is presented in the following paper.
In tr od u ction
an empty orbital cis to hydride, which is not true of
many 16-electron species MHClL3;3-9 there, the LUMO
is trans to hydride.
We have shown earlier1 that RuHClL2 (L ) PiPr3), a
fragment available from the dimer (RuHClL2)2 present
in hydrocarbon solvents, spontaneously isomerizes donor-
substituted olefins to carbene ligands (eq 1).
We investigate here the influence of changing chloride
to the π-acid ligand CO. We first describe the synthesis
+
and characterization of the necessary RuH(CO)L′2
(L′ ) PtBu2Me).10 The change from PiPr3 to PtBu2Me
RuHClL2 +
H2CdCH(E)
E ) alkoxide, amide
f
(3) Hill, A. F. In Comprehensive Organometallic Chemistry II, Vol.
7; Abel, E. W., Stone, F. G. A., Wilkinson, G., Ed.; Pergamon: New
York, 1995; p 299.
L2ClHRudC(E)(CH3) (1)
(4) (a) Poulton, J . T.; Sigalas, M. P.; Eisenstein, O.; Caulton, K. G.
Inorg. Chem. 1993, 32, 5490. (b) Poulton, J . T.; Folting, K.; Streib, W.
E.; Caulton, K. G.; Inorg. Chem. 1992, 31, 3190. (c) Gusev, D. G.;
Vymenits, A. B.; Bakhmutov, V. I. Inorg. Chem. 1992, 31, 2. (d) Gusev,
D. G.; Kuhlman, R. L.; Renkema, K. B.; Eisenstein, O.; Caulton, K. G.
Inorg. Chem. 1996, 35, 6775. (e), Roper, W. R.; Wright, L. J . J .
Organomet. Chem. 1977, 142, C1.
(5) (a) Maddock, S. M.; Rickard, C. E. F.; Roper, W. R.; Wright, L.
J . Organometallics 1996, 15, 1793. (b) Esteruelas, M. A.; Oro, L. A.;
Valero, C. Organometallics 1995, 14, 3596. (c) Esteruelas, M. A.; Lahoz,
F. J .; On˜ate, E.; Oro, L. A.; Zeier, B. Organometallics 1994, 13, 4258.
(d) Esteruelas, M. A.; Oro, L. A.; Ruiz, N. Organometallics 1994, 13,
1507. (e) Bakhmutov, V. I.; Bertra´n, J .; Esteruelas, M. A.; Lledo´s, A.;
Maseras, F.; Modrego, J .; Oro, L. A.; Sola, E. Chem. Eur. J . 1996, 2,
815.
These reactions are thermodynamically favorable in
part because Ru(II) in a ligand environment devoid of
π-acid ligands is a good π-donor, and the carbene is a
stronger π-acid than the alternative olefin ligand. Es-
sential to a mechanism for reaching this equilibrium
position is the fact that the olefin reagent can coordinate
cis to hydride, where it can insert into the Ru-H bond
(6) (a) Heyn, R. H.; Macgregor, S. A.; Nadasdi, T. T.; Ogasawara,
M.; Eisenstein, O.; Caulton, K. G. Inorg. Chim. Acta 1997, 259, 5. (b)
Gusev, D. G.; Nadasdi, T. T.; Caulton, K. G. Inorg. Chem. 1996, 35,
6772. (c) Ogasawara, M.; Macgregor, S. A.; Streib, W. E.; Folting, K.;
Eisenstein, O.; Caulton, K. G. J . Am. Chem. Soc. 1996, 118, 10189. (d)
Heyn, R. H.; Caulton, K. G. New J . Chem. 1993, 17, 797. (e) Esteruelas,
M. A.; Liu, F.; On˜ate, E. Sola, E.; Zeier, B. Organometallics 1997, 16,
2919. (f) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Sola, E.
J . Am. Chem. Soc. 1996, 118, 89.
and isomerize to the hydrido carbene.2 The 14-electron
configuration of RuHClL2 is thus important in achieving
* Corresponding author. E-mail: caulton@indiana.edu.
† Indiana University.
(7) (a) Hoffman, P. R.; Caulton, K. G. J . Am. Chem. Soc. 1975, 97,
4221. (b) J ung, C. W.; Garrou, P.E.; Hoffman, P. R.; Caulton, K. G.
Inorg. Chem. 1984, 23, 726.
‡ Universite´ de Montpellier 2.
§ University of Minnesota.
(1) Coalter, J . N., III; Spivak, G. J .; Ge´rard, H.; Clot, E.; Davidson,
E. R.; Eisenstein, O.; Caulton, K. G. J . Am. Chem. Soc 1998, 120, 9388.
(2) Coalter, J . N., III; Bollinger, J . C.; Huffman, J . C.; Werner-
Zwanziger, U.; Caulton, K. G.; Davidson, E. R.; Ge´rard, H.; Clot, E.;
Eisenstein, O. New J . Chem. 2000, 24, 9.
(8) Caulton, K. G. New J . Chem. 1994, 18, 25.
(9) (a) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics,
1991, 10, 462. (b) Sanchez Delgado, R. A.; Rosales, M.; Esteruelas, M.
A.; Oro, L. A. J . Mol. Catal. A-Chem. 1995, 96, 231, and references
therein.
10.1021/om9910017 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 05/06/2000

2282 Organometallics, Vol. 19, No. 12, 2000
Huang et al.
Sch em e 1a
a
L ) PtBu2Me.
appears to be necessitated by the fact that, in the
absence of a π-donor chloride to make metastable a 14-
electron configuration, agostic interactions are a viable
substitute. Agostic donation by PtBu2Me is apparently
more potent than by PiPr3. After full characterization
of RuH(CO)L′2+, its reactions with the unconventional
donors CH2Cl2, Et2O, and H2O are reported, followed
by reactivity with olefins without, then with donor
substituents E. It will appear that RuHCl(L) 2 and RuH-
(CO)(L)2+ have noticeably different reactivity with ole-
fins. The following paper will use DFT calculations to
interpret these differences.
F igu r e 1. ORTEP diagram of RuH(OTf)(CO)(PtBu2Me)2;
hydrogens are omitted except the one bound to Ru. Selected
bond lengths (Å): Ru1-O2: 2.2088(19), Ru1-C30: 1.803(3),
Ru1P10: 2.394(12), Ru1-P20: 2.3982(13), S3-O2: 1.4723-
(11), S3-O4: 1.4302(27). Angles (°): P20-Ru1-P10: 176.95-
(3), Ru1-P20-C26: 112.17(16), Ru1-P20-C22: 115.17(15),
Ru1-P10-C16: 108.81(14), Ru1-P10-C12: 117.58(11),
C30-Ru1-O2: 173.46(9).
X-ray crystal structure analysis of this complex was
carried out. X-ray quality crystals were grown from a
1
diethyl ether solution at -20 °C. In accord with the H
NMR spectrum, RuH(OTf)(CO)L2 adopts a square-based
pyramidal geometry with the hydride located at the
apical site trans to the empty site (Figure 1). The OTf
ligand is monodentate (the shortest distance of Ru to
nonbonded oxygens of triflate is 3.795 Å), so the Ru is
unsaturated. The correctness of the hydride position on
that side of the RuP2OC plane is supported by the fact
Resu lts
P r ep a r a tion a n d Str u ctu r e of Ru H(OTf)(CO)L2,
1. Reaction of RuHF(CO)L2 (L ) PtBu2Me) with 1 equiv
of Me3SiOTf gives quantitatively RuH(OTf)(CO)L2, 1,
and Me3SiF in methylene chloride, benzene, or diethyl
ether (Scheme 1).11 Taking advantage of the strong Si-F
bond (BDE ) 159 kcal‚mol-1),12 the exothermic reaction
is complete within the time of mixing at room temper-
ature. Although metathesis of AgOTf with metal halide
is a common protocol in the synthesis of transition metal
triflate complexes, it is not a productive method in this
case. Instead, when RuHCl(CO)L2 was treated with
AgOTf in CH2Cl2 or in benzene, the Ag(I) mainly reacts
with phosphine ligand to give [AgL2][OTf].13 The 1H
NMR spectrum of 1 shows a triplet at -25.4 ppm for
the hydride, consistent with the hydride trans to the
vacant site.2,14 Two tBu triplets indicate mutually trans
phosphine ligands with diastereotopic tBu groups. The
CO stretching frequency of 1 appears at 1923 cm-1 and
is much higher than that of RuHF(CO)L2 (1896 cm-1),15
in agreement with weaker donation from the OTf- to
the metal center.16 Since the OTf could coordinate in a
bidentate fashion and make the Ru center saturated,17
t
that no Bu methyls are directed toward it, which is
t
different from the Bu conformation on the other side
of that plane. The shortest distance from Ru to carbon
on a phosphine ligand is 3.30 Å, which is too long for
an agostic interaction. The Ru-O distance (2.2088(19)
Å) is much longer than that of the σ-bound ruthenium
sulfonate complex, cis,trans-Ru(OSO2-p-Tol)2(H2O)(CO)-
(PPh3)2 (2.165(5) and 2.162(6) Å),18 but comparable to
that of Ru-OTf (2.221(3) and 2.233(3) Å) in Ru(OTf)2-
(CO)(Cyttp) (Cyttp ) PhP(CH2CH2CH2PCy2)2).19 The
long Ru-O distance is consistent with low nucleophi-
licity of the OTf ligand.
Syn th esis a n d Str u ctu r e of [Ru H(CO)L2]BAr ′4
a n d its CH2Cl2 Ad d u ct. The weak coordination of OTf
is in agreement with the fact that salt metathesis of 1
with 1 equiv of NaBAr′4 (Ar′ ) 3,5-C6H3(CF3)2) in CH2-
Cl2 at room temperature gives [RuH(CO)(η2-CH2Cl2)-
L2][BAr′4], 2, cleanly in 5 min (Scheme 1). The similar
salt metathesis does not happen between RuHF(CO)L2
(or RuHCl(CO)L2) and NaBAr′4 under the same condi-
tions. Addition of NaBAr′4 to RuHF(CO)L2, or RuHCl-
(CO)L2, in CD2Cl2 only broadens the hydride and the
phosphine resonance peaks, indicating some interac-
tions, presumably between Na+ and the halides. In
contrast, removal of fluoride or chloride from iridium
complexes IrH2F(PtBu2Ph)2 and IrH2Cl(PtBu2Ph)2 by
NaBAr′4 is successful.14 The reaction is also highly
solvent dependent.
(10) Preliminary communication: Huang, D.; Huffman, J . C.; Bol-
linger, J . C.; Eisenstein, O.; Caulton , K. G. J . Am. Chem. Soc. 1997,
119, 7398. Huang, D.; Ge´rard, H.; Clot, E.; Young, V., J r.; Streib, W.
E.; Eisenstein, O.; Caulton, K. G. Organometallics 1999, 18, 5441.
(11) Doherty, N. M.; Critchlow, S. C. J Am. Chem. Soc. 1987, 109,
7906. Hoffman, N. W.; Prokopuk, N.; Robbins, M. J .; J ones, C. M.;
Doherty, N. M. Inorg. Chem. 1991, 30, 4177.
(12) Patai, S., Rappoport, Z., Eds. In Chemistry of Organic Silicon
Compounds; J ohn Wiley & Sons: New York, 1989; Part I, p 385.
(13) Ogasawara, M. Personal communication.
(14) Cooper, A. C.; Clot, E.; Huffman, J . C.; Streib, W. E.; Maseras,
F.; Eisenstein, O.; Caulton, K. G. J . Am. Chem. Soc. 1999, 121, 97.
(15) Poulton J . T.; Sigalas, M. P.; Eisenstein, O. Caulton, K. G. Inorg.
Chem. 1993, 32, 5490.
(18) Harding, P. A.; Robinson, S. D.; Henrick, K. J . Chem. Soc.,
Dalton Trans. 1988, 415.
(16) Lawrance, G. A. Chem. Rev. 1986, 86, 17.
(17) Gudat, D.; Schrott, M.; Bajorat, V.; Nieger, M.; Kotila, S.;
Fleischer, R.; Stalke, D. Chem. Ber. 1996, 129, 337.
(19) Blosser, P. W.; Gallucci, J . C.; Wojcicki, A. Inorg. Chem. 1992,
31, 2376.

A 14-Electron Ru(II) Hydride
Organometallics, Vol. 19, No. 12, 2000 2283
acute (63°), comparable to that of the η2-CH2Cl2 adduct
of Ag(I).22 It is particularly noteworthy that the BAr′4
anion interacts in a pairwise space-filling manner with
the cation: two phenyl rings adopt an atypical rotational
conformation about the B-C(ipso) bond to form a
crevice, into which the CH2Cl2 ligand fits like a knife-
edge. This directs each (acidic) dichloromethane hydro-
gen toward the center of a phenyl ring, to form a
hydrogen bond to the arene π-system.23 The calculated
distance of a CH2Cl2 hydrogen to the center of the Ar′
ring is 2.74 Å. Thus, even in the solid state, an intimate
ion pair is formed, with CH2Cl2 acting as a bridge
between cation and anion. The bridge, however, is weak.
Under dynamic vacuum for 12 h, a solvent-free complex
is obtained. Elemental analysis of the resulting solid is
in agreement with the solvent-free form. Moreover, the
1H NMR spectrum of this solid in CD2Cl2 does not show
a signal for CH2Cl2.24 Accordingly, a much higher CO
stretching frequency (1971 cm-1, Nujol) than that in
CD2Cl2 solution also indicates even less back-donation
from the metal center in the solvent-free form. Two IR
bands at 2722 and 2672 cm-1 are found for the solvent-
free product and are assigned to two agostic C-H bonds
from the phosphines. The agostic interaction may
provide enough stabilization to compensate the energy
cost of losing coordinated CH2Cl2, which is not essential
in the synthesis of the solvent-free complex since the
same complex can also be synthesized independently in
C6H5F (Scheme 1).
F igu r e 2. PLUTO plot of [RuH(η2-CH2Cl2)(CO)(PtBu2Me)2]-
BAr′4; hydrogens are omitted. Selected bond lengths (Å):
Ru-Cl(14): 2.742(10), Ru-P4: 2.339(3), Ru-C2: 1.727(27),
Cl(14)-C(15): 1.756(27), C2-O3: 1.228(26). Bond angles
(deg): P4-Ru-P4A: 177.0(1), P4-Ru-C(2): 86.7(8), P4A-
Ru-C2: 90.6(9), Cl(14)-C(15)-Cl(14A): 109.0(5), Cl(14)-
Ru-Cl(14A): 62.8(8).
In stronger coordinating solvents such as THF and
diethyl ether, the reaction does not occur even though
NaBAr′4 is soluble in these solvents. It is likely that the
solvation quenches the Lewis acidity of Na+, which can
be the major driving force for the reaction. The orange
complex 2 is highly air sensitive. Moreover, filtration
of the reaction mixture through a Celite pad causes
partial decomposition, and no pure compound can be
isolated after the filtration. To isolate 2, the reaction
solution is therefore centrifuged and the solution de-
canted and layered with pentane in an argon-filled
glovebox. Strict exclusion of air and water is necessary.
Crystals of 2 were obtained after 2 days at -20 °C. The
CO stretching frequency (1951 cm-1) in CD2Cl2 is much
higher than that of 1 (1923 cm-1), in accord with weaker
π-back-donating ability of the metal in the former. The
1H NMR spectrum of 2 at 20 °C in CD2Cl2 shows two
virtual triplets for diastereotopic tBu, one virtual triplet
for PCH3 and a triplet at -19 ppm for the hydride. Also
seen is a single BAr′4 (Ar′ ) 3,5-C6H3(CF3)2) environ-
ment. The lower chemical shift of the hydride compared
to that of 1 (-25 ppm) was the first indication of some
weak ligand trans to the hydride; methylene chloride
is one candidate. However, attempts failed to detect the
coordination of CH2Cl2 by 13C NMR spectroscopy even
at - 95 °C. Therefore, an X-ray crystal structure de-
termination is essential to define the composition and
structure of the product.
A well-formed single crystal of [RuH(CO)L2][BAr′4]‚
2CH2Cl2 grown from CH2Cl2/pentane shows the unit cell
to contain one CH2Cl2 molecule in the lattice, in the
general region of the Ar′ rings, and the other CH2Cl2
donating both chlorines to Ru(II), to complete a six-
coordinate octahedral geometry about the metal (Figure
2). The structural parameters support weak coordina-
tion of CH2Cl2. The Ru/Cl distances are long (2.74 Å),
as in CH2Cl2 adducts of other platinum metals.20 The
C-Cl distance (1.756(27) Å) and angle (109.0(5)°) are
only slightly different from those in free CH2Cl2 (1.772
Å and 111.8°, gas phase).21 The Cl-Ru-Cl angle is quite
An X-ray diffraction study of this CH2Cl2-free mate-
rial (Figure 3), 3, shows no interaction of either the
lattice C6H5F or the BAr′4 anion with the cation. The
RuH(CO)L2+ ion has thus been authentically “isolated”,
although the cation in the crystal is disordered around
a center of symmetry, which limits information on the
quantitative features of the structure. The phosphines
bend toward one another (P-Ru-P ) 166.3(5)°), and
for each phosphine, one tBu group bends inward, toward
Ru (Ru-P-C ) 100.3(5)° and 96.4(5)° compared to
t
119.7(8)° and 116.4(8)° for the second Bu groups). As a
result, there are two short Ru/CH3(tBu) distances (2.74-
(2) and 2.85(2) Å), which speak for the 14-electron RuH-
+
(CO)L2 forming two cis agostic interactions to methyl
C-H bonds. The authentic 14-electron species is thus
too electron deficient to exist without agostic interaction
when L ) PtBu2Me. Removal of the OTf does not cause
a large change of the relative positions of phosphine and
CO. However, since the hydride is not located, further
comparison between RuH(CO)L2+ and its triflate is not
possible.
Rea ctivity of [Ru H(CO)L2]BAr ′4. This highly un-
saturated complex exhibits some interesting reactivity
that is not possible for its less electrophilic five-
coordinated precursor RuH(OTf)(CO)L2.
(A) Dieth yl Eth er . In the presence of ca. 1 equiv of
diethyl ether at -80 °C a 1:1 diethyl ether adduct, 4a ,
is observed when 2 is dissolved in methylene chloride
1
(Scheme 1). The H NMR spectrum of 4a gives a high-
(21) Myers, R. J .; Gwinn, W. D. J . Chem. Phys. 1952, 20, 1420.
(22) Newbound, T. D.; Colsman, M. R.; Miller, M. M.; Wulfsberg, C.
P.; Anderson, O. P.; Strauss, S. H. J . Am. Chem. Soc. 1989, 111, 3762.
(23) Steiner, T.; Starikov, E. B.; Amado, A. M.; Teixeira-Dias, J . J .
C. J . Chem. Soc., Perkin Trans. 2 1995, 1321.
(24) CH2Cl2 in CD2Cl2 is a singlet at 5.34 ppm, different from
CDHCl2, which is a triplet at 5.33 ppm.
(20) (a) The Pt-Cl(CH2Cl) distance is 2.489(4) Å: Butts, M. D.; Scott,
B. L.; Kubas, G. J . J . Am. Chem. Soc. 1996, 118, 11831. (b) The Ir-
Cl(CH2Cl) is 2.462(3) Å; see: Arndtsen, B.; Bergman, R. G. Science
1995, 270, 1970.

2284 Organometallics, Vol. 19, No. 12, 2000
Huang et al.
Sch em e 2
F igu r e 3. ORTEP diagram of [RuH(CO)(PtBu2Me)2]+.
Hydrogens are omitted except the ones on agostic carbons.
Selected bond lengths (Å): Ru1-P2: 2.403(6), Ru1-P2A:
2.332(7), Ru1-C12: 1.69(2), Ru1-C10: 2.85(2), Ru1-
C11A: 2.74(2). Bond angles (deg): P2-Ru1-P2A: 166.3(5),
Ru1-P2A-C8A: 96.4(8), Ru1-P2A-C4A: 116.4(8), Ru1-
P2-C4: 119.7(8), Ru1-P2-C8: 100.3(5). Ru1-C12-
O13: 174(2).
field shifted hydride triplet (-26 ppm, J PH ) 18 Hz) and
two quartets for methylene protons at lower field (3.74,
3.58 ppm) than that of free diethyl ether (3.35 ppm).
The two CH2 peaks are attributed to slow rotation about
the Ru-O bond, and the two ethyls are inequivalent,
with one ethyl above and the other below the basal
plane. The 31P{1H} NMR spectrum of 4a is a singlet at
55 ppm, close to that of 1 (56 ppm). The fact that 4a
can be formed in large excess of CD2Cl2 (solvent) reveals
that diethyl ether is a much better ligand than bidentate
CD2Cl2. At room temperature, the coordinated diethyl
at higher field (3.12 ppm) with integration of four
protons (vs the hydride). One singlet in the 31P{1H}
t
NMR spectrum and two virtual triplets for Bu protons
reveal the two phosphines are mutually trans. At this
temperature, a small amount of butene-1 and butene-2
is observed. When the temperature is raised to -20 °C,
more ethylene is converted to butene-1 and butene-2.
On further warming to 10 °C, all ethylene and butene-1
disappear and only free butene-2 and [RuH(η2-CH2d
CH2)(CO)L2]+ are observed. 1H NMR analysis of the
volatiles shows it to contain cis- and trans-butene-2 with
a 1:3 ratio. If more ethylene (1 atm) is added to the same
tube, dimerization continues. However, the catalyst
decomposes at room temperature after 12 h and the
dimerization ceases. The total turnover number from
the NMR tube experiment is 16 (ethylene per metal).
In CD2Cl2 at -80 °C, a 1:1 adduct is observed with
different chemical shifts of the coordinated C2H4 (3.62
ppm) and the hydride (-2.72 ppm). Moreover, no
ethylene dimer is observed in this solvent until the
temperature rises above 10 °C, at which temperature
butene-2 is formed and the ethylene is completely
consumed. The slower dimerization rate indicates that
competing coordination of CD2Cl2 inhibits the reaction
at lower temperature.
1
ether H NMR peaks coalesce with those of free diethyl
ether, and the hydride signal moves to lower field (-21
ppm) as a broad peak. So does the 31P{1H} NMR peak
(52 ppm). Thus the adduct is in equilibrium with the
methylene chloride adduct, 2, at room temperature.
(B) H2O. If 1 equiv of water is added to a CD2Cl2
solution of 2, an adduct, [RuH(OH2)(CO)L2]BAr′4, 4b,
is formed cleanly (Scheme 1). Spectroscopic evidence for
4b includes a broad singlet (1H NMR) at 3.17 for
coordinated H2O and an upfield triplet for a hydride
(-25 ppm, J PH ) 22.4 Hz). The O-H stretching fre-
quency is located at 3632 and 3550 cm-1, and the CO
stretching frequency (1950 cm-1) is also almost identical
to that of 2. The coordinated water binds stronger than
does methylene chloride and cannot be removed under
vacuum.
(C) Eth ylen e. At -40 °C under 1 atm of ethylene, in
a 4:1 mixture of C6H5F and C6D12, an adduct [RuH(η2-
CH2CH2)(CO)L2]BAr′4, 5, is formed quantitatively,
(Scheme 2). 5 has a hydride triplet at much lower field
(-3.13 ppm) than that of 4a /b, indicating the site trans
to the hydride is occupied. Compared to the free ethyl-
ene (5.40 ppm), the coordinated ethylene protons appear
(D) P r op ylen e. At room temperature, there is no
observable adduct between [RuH(CO)L2]+ and propyl-
1
ene, as the H NMR spectrum of their mixture exhibits
the features of free propylene and unchanged [RuH(CO)-
L2]+ in a C6H5F and C6D12 mixture. At lower temper-
ature (< -50 °C), a 1:1 adduct, [RuH(η2-CH2dCH(Me))-
(CO)L2]+, 6, is formed cleanly, with a hydride signal at
much lower field (-5.0 ppm, a broad apparent triplet)
and an AB pattern 31P{1H} NMR spectrum (chiral

A 14-Electron Ru(II) Hydride
Organometallics, Vol. 19, No. 12, 2000 2285
adduct). These spectral data are in accord with propyl-
ene being coordinated trans to the hydride and with
significant bending of the P-Ru-P axis demonstrated
by the relatively small PP′ coupling constant (165 vs
250 Hz for linear P-Ru-P). No coupling products of
propylene are observed even with heat (80 °C, 2 h),
which causes decomposition of [RuH(CO)L2]+.
(E) Vin yl F lu or id e. Similar to ethylene and propyl-
ene, excess CH2dCHF also forms, at -60 °C, a 1:1
adduct, [RuH(η2-CH2dCHF)(CO)L2]+, 7, which is also
a chiral complex. The two phosphines are inequivalent,
and the 31P{1H} NMR spectrum shows an AB pattern
with smaller PP coupling constant (140 Hz vs 165 Hz
for the propylene adduct), indicating even more bending
of the P-Ru-P angle. The 19F NMR signal of the
coordinated CH2dCHF has moved strongly upfield
(-150 ppm) compared to that of free vinyl fluoride (-115
ppm). A low-field hydride signal (-3.1 ppm vs -19 for
2) reveals it is trans to the coordinated vinyl fluoride.
Upon warming the solution to room temperature, free
ethylene is formed along with at least seven phosphine-
containing products (Scheme 2). Some of these are
doublets by 31P{1H} NMR, with coupling constants
around 20 Hz, presumably to fluorine on Ru.
F igu r e 4. ORTEP diagram of [Ru(η2-CH2CH2OMe)(CO)-
(PtBu2Me)2]+ All hydrogens are omitted for clarity. Selected
bond distance (Å): Ru1-C2: 1.796(15), Ru1-C4: 2.068(13),
Ru1-O6: 2.226(8), Ru1-P8: 2.409(7), Ru1-P18: 2.411(7).
Bond angles (deg): C2-Ru1-C4; 94.0(7), C2-Ru1-O6:
157.0(13), C4-Ru1-O(6): 63.2(14), C2-Ru1-P(8): 91.4(4),
P8-Ru1-P18: 172.5(3), C5-C4-Ru1; 96.2(9).
(F ) Vin yl Eth er . Addition of 1 equiv of CH2dCH-
(OEt) to [RuH(CO)L2]BAr′4 in fluorobenzene at 25 °C
causes an immediate color change to darker orange.
NMR spectroscopic data reveal clean formation of [Ru-
(CHa2CHb2OCHc CHd3)(CO)L2]BAr′4, 8. The 1H NMR
2
spectrum shows a triplet (3.81 ppm, J HH ) 8 Hz) for Hb
and a quartet (3.14 ppm, J HH ) 7.2 Hz) for Hc. Cor-
respondingly, Ha appears as a triplet of triplets (1.88
ppm, J HH ) J PH ) 8 Hz) and Hd is a triplet (0.85 ppm,
J HH ) 7.2 Hz). In the 13C{1H} NMR spectrum, the CH2-
CH2OCH2CH3 carbons are located at 85.2, 70.4, 13.2
(CHd3), and -0.67(CHa2) ppm, respectively. However,
these data are not decisive about ether oxygen coordina-
tion to Ru. Attempts to grow a single crystal for X-ray
diffraction study failed, as the complex is decomposed
slowly in fluorobenzene/pentane solution even at -40
°C. Methyl vinyl ether reacts similarly to form an
inserted product, [Ru(CH2CH2OMe)(CO)L2]+, 9, which
was crystallized from a fluorobenzene/pentane mixture.
Spectroscopically, it has features similar to those of 8.
Crystal structure determination shows that the oxygen
is coordinated (Figure 4) with a Ru-O(ether) distance
of 2.226(8) Å, longer than that of 1 (2.2088(9) Å). If 9 is
dissolved in diethyl ether, the reverse reaction occurs
to give 4a and free CH2dCH(OMe), which indicates no
strong thermodynamic preference for the substituted
ethyl complex.
(G) Rea ction Mech a n ism of [Ru H(CO)L2]+ w ith
CH2dCH(OEt). To detect any intermediates, this reac-
tion was monitored by low-temperature NMR spectra
in CD2Cl2. Figure 5 depicts the variable-temperature
31P{1H} NMR spectra of the 1:1 mixture of 3 and CH2d
CH(OEt). After 30 min of mixing at -80 °C, one major
product, 11, is formed (Scheme 3), which has an AB
pattern 31P{1H} spectrum (J PP ) 224 Hz). This P/P
coupling is characteristic of little bending of P-Ru-
P, and thus of vinyl ether binding cis to hydride, and
as a σ donor. In the 1H NMR spectrum at the same
temperature, one hydride is detected at very high field
(-28.0 ppm) as an apparent triplet (J PP ) 14 Hz). This
F igu r e 5. Variable-temperature 31P{1H} NMR spectra of
[RuH(CD2Cl2)(CO)L2]BAr′4, 2, plus CH2CH(OEt). Solvent:
CD2Cl2. Peaks are labeled with complex numbers.
indicates the hydride is trans to a vacant site. The R-H
of the vinyl ether is shifted to lower field (7.3 ppm) in
comparison to that (6.5 ppm) of free CH2dCH(OEt). The
â-protons also shifted slightly downfield from that of free
vinyl ether. These spectral data are consistent with
OfRu binding, not a π-adduct through the CdC bond;
the latter would have resulted in high-field shifts of the
vinylic protons. The AB pattern 31P{1H} NMR is likely
due to hindered rotation around the Ru-P axis caused

2286 Organometallics, Vol. 19, No. 12, 2000
Huang et al.
Sch em e 3
as THF and diethyl ether, despite the high solubility of
NaBAr′4 in these solvents. It is likely that the solvent
coordinates the sodium cation and decreases its Lewis
acidity. The insolubility of NaOTf in methylene chloride
or fluorobenzene is another factor promoting reaction.
Qualitatively, the reaction is also highly dependent on
the particle size of NaBAr′4. Very fine powders are much
more effective than larger ones. If the reaction is not
1
complete, the H and 31P NMR spectra give deceptively
simple spectra at room temperature: the spectra show
coalesced peaks of the signals from 1 and 2 (or 3).
Depending on the molar ratio of 1 and 2 (or 3) in the
mixture, the 31P NMR spectrum peak falls between 56
and 49 (in CD2Cl2) or 56-46 (C6H5F). Low-temperature
1H or 31P NMR spectra do however give decoalesced
signals of 1 and 2 (or 3). 2 and 3 can be isolated as
orange crystals by layering the reaction solution with
pentane at -20 °C. Upon separation from the solvent,
2 readily loses CH2Cl2 under vacuum to give 3, which
decomposes slowly under argon at room temperature.
Both compounds are extremely air sensitive, and in
order to isolate pure compound, all the reaction solvents
must be strictly dried and degassed before use and the
manipulations are best carried out in an argon-filled
glovebox to avoid contact with air.
by steric hindrance in the adduct. Hindered rotation is
a fairly common phenomenon in five- or six-coordinated
Ru(PtBu2Me)2 complexes, especially at low tempera-
ture.25 Upon warming to -60 °C, the AB lines broaden,
together with formation of two new compounds, 8 and
12. Further warming to -50 °C for 30 min (Figure 5)
resulted in conversion of the adduct to 8 and 12 (AB
pattern, J PP ) 202 Hz) (Scheme 3). The latter is chiral,
and thus the two phosphines are chemically inequiva-
lent. The structure assigned to 12 is further supported
1
by the H NMR spectrum at the same temperature. A
Str u ctu r e of [Ru H(CO)L2]+. The X-ray crystal
structure of the cation shows that it has two trans
phosphine ligands. Two agostic interactions (discussed
previously)10 are also obvious from the two abnormally
small Ru-P-C(tertiary) angles (96.4° and 100.3° vs
116.4° and 119.7° for those not involved in agostic
interactions), the agostic interactions are cis to each
other, and so the undetermined hydride must be cis to
CO. DFT calculations have been carried out to provide
a geometry of the complex and in particular locating H.10
It has been found that the angle H-Ru-CO is 87° in
the absence of CH2Cl2 and 85° in the presence of
coordinated CH2Cl2. It can thus be assumed that the
structure of RuH(CO)(PtBu2Me)2+, in which two agostic
bonds are present, also has the same overall skeleton.
broad peak is observed at 5.5 ppm for the R-H, and the
most characteristic peaks are the diastereotopic meth-
ylene protons of OCH2Me, which appear at 3.55 and 3.37
ppm as two apparent quintets (J HH ) 8.4 Hz). A singlet
peak at relatively high field (0.4 ppm) is observed for â
CH3 protons. The high-field shift is very likely due to
â-agostic interactions. 12 is a short-lived species; as the
temperature warmed further to -40 °C, it disappears
and 8 is the only observed product.
(H) 2,3-Dih yd r ofu r a n . In sharp contrast to the
reaction of acyclic vinyl ethers, the cyclic vinyl ether 2,3-
dihydrofuran reacts with [RuH(CO)L2]+ in C6H5F to give
a carbene complex, 10, in over 90% yield in 1 h at 20 °C
(Scheme 2). The most characteristic feature for the
carbene complex is a low-field peak (302.1 ppm, t,
J PC ) 10 Hz) in proton-coupled 13C NMR spectrum. A
Rea ction s of 3 w ith Eth ylen e. Although there are
two vacant sites of 3, it forms only a 1:1 adduct not only
with diethyl ether but also with ethylene. While the
diethyl ether or H2O adduct has the hydride trans to
the vacant site, the observed ethylene adduct has
coordinated C2H4 trans to the hydride, evidenced by
much lower field hydride chemical shift (-3.1 vs -23
ppm of 3). Coordination site preferences have been
doublet of triplets is also located at 201.5 ppm (2J CH
)
2
35 Hz and J PC ) 7 Hz); the large J CH value reveals
that the hydride is trans to CO, not to the carbene.
Consistently, the 1H NMR spectrum of 10 has a low-
field hydride peak at -1.7 ppm (J PH ) 18 Hz). Moreover,
two triplets are observed at 4.2 and 2.9 ppm for CHa
2
and CHc along with an apparent quintet at 1.5 ppm
2
for Hb (Scheme 2).
2
studied by DFT calculations (see the following paper),
+
and there is very little site preference to RuH(CO)L2
,
Discu ssion
at least for L ) PH3.
Ethylene is catalytically dimerized in fluorobenzene
to give butene-1 and butene-2 at low temperature (-40
°C). Thus two C2 fragments must sometimes be simul-
taneously on Ru. No higher molecular weight oligomers
are detected. Apparently, this Ru(II) does not allow the
polymer chain to grow. In CD2Cl2 the ethylene dimer-
ization reaction does not occur until much higher
temperature (>10 °C). The solvent dependency is most
likely due to competion of CD2Cl2 with ethylene for
binding to Ru. On the basis of the experimental obser-
vation, we propose the formation mechanism of butene
as follows (Scheme 4): First, coordinated ethylene (cis
to hydride) inserts into Ru-H bond to give ethyl
Syn th esis of [Ru H(CO)L2]BAr ′4. Salt metathesis
of RuH(OTf)(CO)L2 with NaBAr′4 occurs smoothly in the
time of mixing in weakly coordinating but polar solvents
such as CH2Cl2 and fluorobenzene to give [RuH(η2-CH2-
Cl2)(CO)L2]BAr′4, 2, and [RuH(CO)L2]BAr′4, 3, respec-
tively. NaBAr′4 has been increasingly used to generate
unsaturated cationic metal complexes or their adducts
with weakly coordinated solvents.26,20a The reaction here
does not go in polar but more coordinating solvents such
(25) Notheis, J . U.; Heyn, R. H.; Caulton, K. G. Inorg. Chim. Acta
1995, 229, 187.
(26) Heinekey, D. M., Radzewich, C. E. Organometallics 1998, 17,
51.

A 14-Electron Ru(II) Hydride
Sch em e 4a
Organometallics, Vol. 19, No. 12, 2000 2287
Sch em e 5
[Ru HClL2] vs [Ru H(CO)L2]+. It has been demon-
strated that 14-electron RuHCl(PiPr3)2 coordinates one
ethyl vinyl ether to give RuHCl(η2-CH2dCH(OEt))-
(PiPr3)2 below -65 °C, and the vinyl ether coordinates
trans to chloride through the CdC bond.1,2 At higher
temperature (> 0 °C) the adduct isomerizes to carbene,
RuHCl(dC(OEt)Me)(PiPr3)2. In this case, the metal
π-basicity controls the thermodynamics of the reaction.1
a
All complexes have +1 charge.
complex. Then a second ethylene inserts to give a
â-agostic butyl complex. â-H elimination leads to a
butene-1 complex of 3. Butene-1 can be replaced by C2H4
or isomerized to butene-2 by insertion and â-H elimina-
tion. An independent experiment shows that 3 catalyzes
isomerization of butene-1 to butene-2 (1:3 cis and trans
mixture) under the same conditions as that of dimer-
ization of C2H4. The selectivity of the final isomerization
product is governed by the relative stability of the free
internal alkene vs the terminal alkene.
Con clu sion
Formally 14-electron [RuH(CO)(PtBu2Me)2]BAr′4 is
synthesized by salt metathesis of RuH(OTf)(CO)L2 and
NaBAr′4 in the noncoordinating but polar solvent fluo-
robenzene. The cation has sawhorse geometry, with two
vacant sites occupied by the C-H bond of phosphine
ligands. The preferred geometry is determined by the
electronic configuration of Ru, which prefers to stay at
a low-spin state, particularly in the presence of the
strong-field ligands hydride and CO. The cationic charge
and the strong π-acid CO significantly weaken the metal
π-basic character but strengthen its σ-acidity. The
reactivity of this complex also testifies to this conclusion.
[RuH(CO)L2]+ only binds CH2Cl2 in η2 fashion but does
not oxidatively add to the C-Cl bond. It does not merely
form a stable adduct with π-acidic ethylene but also
dimerizes it. Selective coordination with vinyl ether
oxygen and the thermodynamics of the subsequent
insertion and isomerization reactions further manifest
the strong Lewis acidity and weakened π-basicity of the
Ru cation. The different coordination geometry of [RuH-
(CO)L2]+ with π-acids and non-π-acidic ligands reveals
that the two low-lying empty orbitals are significantly
different: the site trans to CO prefers a pure donor
ligand, and the site trans to H prefers a π-acidic ligand
(Scheme 5). In this context, it is interesting that vinyl
ethers initially bind through oxygen (and trans to CO)
rather than through the CdC bond. The magnitude of
the site preference is evaluated in the accompanying
paper.
Rea ction w ith Acyclic a n d Cyclic Vin yl Eth er s:
Con tr a stin g Th er m od yn a m ic P r od u cts. Low-tem-
perature NMR spectra (-80 °C) of [RuH(CO)L2]+ with
equimolar ethyl vinyl ether in CD2Cl2 indicates that the
ether coordinates trans to CO through oxygen (11)
(Scheme 3) instead of the CdC bond as in the ethylene
adduct. The metal preference for non π-acidic ligand
(oxygen) further reveals that [RuH(CO)L2]+ is a strong
electrophile and a weak π-base. Insertion occurs at
higher temperature (-60 °C) to give two alkyl products
in comparable rate. One has the OEt group at the
R-carbon and a â-H agostic bond (12) and the other has
OEt at the â-carbon with oxygen coordinated to Ru, 8,
as revealed by the X-ray structure determination. 12 is
converted to 8 on further warming to -40 °C (Scheme
3). The thermodynamics of this reaction are not so
obvious because from 11 to 8 the Ru electron count
remains that same. However, 8 has a four-membered
ring; thus the oxygen may not be coordinated as well
as that in 11. Precisely this inability to predict relative
energies motivated the computational study in the
following paper. Changing the vinyl ether to a cyclic one
could discourage the oxygen chelation due to the ring
constraint. Indeed, 1,2-dihydrofuran reacts with [RuH-
(CO)L2]+ to give carbene 10. The alkyl product, 13, is
not observed.
The results reported here show that, while RuH(CO)-
(PtBu2Me)2 has a π-basicity less than that of RuHCl-
+
(PiPr3)2, as evidenced by its ability to coordinate Lewis
base ligands, it still has the ability to transform selected
vinyl ethers to carbene complexes. However, unlike
RuHCl(PiPr3)2 it also has the ability to isomerize other
vinyl ethers to hydrogenated (â-alkoxyethyl) ligands.
Finally, the regioselectivity for adding Ru-H across the
CdC bond of a vinyl ether is demonstrated to be under
thermodynamic control, since the primary product at
-50 °C is observed to isomerize to the η2-â-methoxyethyl
isomer upon warming. This richly varied behavior

2288 Organometallics, Vol. 19, No. 12, 2000
Ta ble 1. Cr ysta llogr a p h ic Da ta
Huang et al.
1
2
3
9
formula
a, Å
b, Å
C
20H43F3O4P2RuS
C53H58BCl4F24OP2Ru
13.639(1)
13.639(1)
34.558(3)
90.00(0)
90.00(0)
90.00(0)
6429.24
4
C57H60BF25OP2Ru
18.744(3)
17.870(3)
18.608(3)
90.00(0)
95.48(1)
90.00(0)
6204.09
4
C57H62BF24O2P2Ru
8.085(2)
15.004(3)
22.718(5)
90.00(0)
90.81(1)
90.00(0)
2755.58
4
13.622(1)
13.622(1)
34.616(3)
90.00(0)
90.00(0)
90.00(0)
6423(2)
4
c, Å
R, deg
â, deg
ø, deg
V, Å3
Z
fw
599.64
P21/ c
-169
0.71069
1.445
8.034
1482.64
P41212
-170
0.71069
1.532
5.580
0.046
0.044
1408.88
C2/ c
-170
0.71069
1.508
1408.9
P4121′2
-174
space group
temp, °C
λ, Å
0.71069
1.455
Fcalcd g/cm3
µ(Mo KR), cm-1
Ra
4.075
3.918
0.03
0.032
0.079
0.0663
Rw
0.130c
0.1574c
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc |)2/∑w|Fo| ]1/2 where w ) 1/σ2(|Fo|). c On F2.
cal space followed by analysis using the programs DIRAX and
TRACER gave a monoclinic primitive unit cell. After complete
intensity data collection the systematic extinction of 0k0 for
k ) 2n + 1 and of h0l for l ) 2n + 1 uniquely identified the
space group as P21/c. The structure was solved using a
combination of direct methods (MULTAN-78) and Fourier
techniques. The Ru atom position was obtained from the initial
E-map. The remaining non-hydrogen atoms were located in
iterations of least-squares refinement and difference Fourier
calculations. Almost all of the hydrogen atoms were located,
they were initially included in fixed idealized positions, and
later refined with isotropic thermal parameters. Near the
conclusion of the refinement a possible hydride atom H(43)
was introduced. The peak had appeared consistently in several
difference maps. The final R(F) ) 0.031 for the 410 total
variables and using all of the unique data. The largest peak
in the difference map was 0.59 e/Å3 near Ru(1), and the deepest
hole was -0.79 e/Å3. The crystallographic parameters are
listed in Table 1.
[R u H(η2-CH2Cl2)(CO)(P t Bu 2Me)2][BAr ′4], 2. RuH(OTf)-
(CO)(PtBu2Me)2 (200 mg, 0.33 mmol) was mixed with NaBAr′4
(300 mg, 0.34 mmol) in an test tube (10 mL, with a Teflon-
lined screw cap). To the mixture was added CH2Cl2 (5 mL).
After shaking for 5 min, the orange solution was centrifuged
and decanted to a Schlenk tube and layered with pentane. The
solution was kept at -20 °C for one week to form large orange
crystals. The crystals were filtered, washed with pentane, and
dried briefly. 1H NMR (CD2Cl2, 20 °C): 7.7(s, 8H, BAr′4-), 7.50
(br s, 4H, BAr′4-), 5.34 (s, CH2Cl2), 1.54 (vt, N ) 4.8 Hz, 6H,
PCH3), 1.30 (vt, N ) 14.4 Hz, 18H, PtBu), 1.13(vt, N ) 13.2
Hz, 18H, PtBu), -19.4 (br t, J PH ) 17 Hz, 1H, Ru-H). 31P{1H}
NMR (CD2Cl2, 20 °C): 49 (s). 19F NMR (CD2Cl2, 20 °C): -62.0
(s). IR (CD2Cl2, cm-1): ν(CO) ) 1951.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion of [Ru H(η2-
CH2Cl2)(CO)(P tBu 2Me)2]BAr ′4, 2. The X-ray quality crystals
were grown from methylene chloride and pentane at -20 °C.
The crystals were highly air-sensitive, readily lost solvent, and
decomposed upon warming to room temperature. A large
clump of crystals was pipetted under nitrogen to a watch glass
cooled with dry ice. A small, nearly equidimensional fragment
was cleaved from a larger crystal while still under the solvent
and affixed to the end of a glass fiber using silicone grease.
The sample was then rapidly transferred to the goniostat,
where it was cooled to -170 °C for characterization and data
collection. A systematic search of a limited hemisphere of
reciprocal space located a set of diffraction maxima with
systematic absences and symmetry corresponding to a tet-
ragonal space group. Subsequent solution and refinement
confirmed P41212 to be the proper choice. The data were
collected using a standard moving-crystal-moving-detector
toward olefins will be interpreted by DFT calculations
as due to a subtle interplay of ligands at the metal and
the substituent on the olefin.
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions and manipulations
were conducted using standard Schlenk and glovebox tech-
niques. Solvents were dried and distilled under argon and
stored in airtight solvent bulbs with Teflon closures. All NMR
solvents were dried, vacuum-transferred, and stored in an
1
argon-filled glovebox. H, 31P, and 13C NMR were recorded on
a Varian Gem XL300 or Unity I400 spectrometer. Chemical
shifts are referenced to solvent peaks (1H, 13C) and external
H3PO4 (31P). Infrared spectra were recorded on a Nicolet 510P
FT-IR spectrometer. Elemental analyses were conducted on
the Perkin-Elmer 2400 CHNS/O analyzer at the Department
of Chemistry, Indiana University. RuHCl(CO)L227 and RuHF-
15
(CO)L2 were synthesized by a literature method. NaBAr′4 is
prepared following Brookhart and co-workers’ procedure.28
Other chemicals are commercially available and used as
received or degassed before use. Compounds for which com-
bustion analyses are not shown are either thermolabile,
transient intermediates, or closely related to analogous spe-
cies.1,2,10
Ru H(OTf)(CO)(P tBu 2Me)2, 1. RuHF(CO)L2 (2.0 g, 4.3
mmol) was dissolved in dry diethyl ether (30 mL). To the
solution, Me3SiOTf (0.83 mL, 43 mmol) was slowly added via
a syringe. An exothermic reaction occurred immediately. In
the case of fast addition, reflux of the solvent is observed. The
solution color changed to bright yellow. After the addition (5
min), the solution was stirred for 10 min and the volatiles were
removed in vacuo. The residue was recrystallized from diethyl
ether (-40 °C) to yield yellow needles, 2.2 g (92%). Anal. Calcd
for C20H43F3O4P2RuS: C, 40.06; H, 7.23. Found: C, 40.40; H,
6.95. 1H NMR (C6D6, 20 °C): 1.48 (vt, N ) 5.1 Hz, PCH3), 1.13
(vt, N ) 13 Hz, 18H, PC(CH3)3), 1.00 (vt, N ) 13 Hz, 18H,
PC(CH3)3), -24.7 (t, J PH ) 19 Hz, 1H, Ru-H). 31P{1H} NMR
(C6D6, 25 °C): 56.4 (s). 19F NMR (C6D6, 25 °C): -76.6 (CF3-
SO3). IR (C6D6, cm-1): ν(CO) ) 1923.
Cr ysta l Str u ctu r e Deter m in a tion of 1. Crystals were
grown from diethyl ether at -20 °C. A suitable crystal was
mounted in a nitrogen atmosphere glovebag using silicone
grease. The crystal was then transferred to the goniostat,
where it was cooled to -169 °C for characterization and data
collection. An automated search of selected regions of recipro-
(27) Gill, D. F.; Shaw, B. L. Inorg. Chim. Acta 1979, 32, 19. Huang,
D.; Folting, K.; Caulton, K. G. Inorg. Chem. 1996, 35, 7035.
(28) Brookhart, M.; Grant, B.; Volpe, J . Organometallics 1992, 11,
3920.

A 14-Electron Ru(II) Hydride
Organometallics, Vol. 19, No. 12, 2000 2289
technique with fixed backgrounds at each extreme of the scan.
Data were corrected for Lorentz and polarization effects, and
equivalent reflections were averaged. The structure was
readily solved by direct methods (SHEXTL-PC) and Fourier
techniques. All non-hydrogen atoms were refined anisotropi-
cally in the full-matrix least-squares. It was immediately
obvious that the CO ligand was disordered. When the oc-
cupancies of the C and O atoms were allowed to vary, they
converged rapidly to 50%, indicating one CO in two alternate
cis positions. A final difference Fourier was featureless, the
largest peaks, located at the F sites, being 0.8 e/A3. The
crystallographic data are listed in Table 1.
hydride. A final difference Fourier map was featureless, with
the largest peak having an intensity of 0.49 e/Å3 and residing
near the ruthenium atom. The crystallographic data are
collected in Table 1.
[Ru H(OEt2)(CO)(P tBu 2Me)2]BAr ′4. [RuH(CO)L2]BAr′4 (20
mg, 1.4 × 10-2 mmol) was dissolved in CD2Cl2 (0.5 mL). To
1
the solution was added diethyl ether (1.4 µL). H NMR (400
MHz, -80 °C): -26.0 (t, J PH ) 18 Hz, Ru-H), 1.18 (br, PtBu),
1.25 (br, PtBu), 3.58 (q, J HH ) 5.2 Hz, 2H, OCH2), 3.75(q, J )
5.6 Hz, 2H, OCH2), 7.55 (s, 4H, para-H of Ar′), 7.77 (s, 8H,
ortho-H of Ar′). 31P{1H} NMR (162 MHz, -80 °C): 55.0 (s).
Upon warming to 20 °C, the phosphine peak shifted to 51.2
ppm, and the hydride peak moves to -21.3 ppm as a broad
line. The methylene proton peaks for coordinated OEt2 coalesce
with those of free (excess) OEt2 to one quartet at 3.48 ppm.
[Ru H(OH2)(CO)(P tBu 2Me)2]BAr ′4. This orange complex
was first synthesized when the NaBAr′4 is not sufficiently
dried,29 and then by conscious addition of stoichiometric water.
The crystallization procedure is the same as that of [RuH(CO)-
[Ru H(CO)(P tBu 2Me)2]BAr ′4, 3. Crystals of 2 were pumped
in vacuo for 12 h to give solvent-free powder, 3. Alternatively,
this complex is obtained following the same procedure as in
the synthesis of [RuH(η2-CH2Cl2)(CO)(PtBu2Me)2]BAr′4 using
C6H5F as solvent. Yield: 40%. Anal. Calcd for C51H55BF24OP2-
Ru: C, 46.57; H, 4.22. Found: C, 46.15, H, 4.33. IR (Nujol,
cm-1): 2722, 2672 (agostic ν(C-H)), 1971 (ν(CO)). 1H NMR
(C6D5F, 300 MHz, 20 °C): 8.24 (br s, 8H, Ar′), 7.62 (br s, 4H,
Ar′), 1.09 (vt, N ) 5.2 Hz, 6H, PCH3), 0.91 (vt, N ) 14 Hz,
1
(PtBu2Me)2]BAr′4. H NMR (400 MHz, CD2Cl2, 20 °C): δ 7.72
(s, 8H, ortho H of Ar′), 7.55 (s, 4H, para H of Ar′), 3.17 (s, 2H,
OH2), 1.35 (vt, N ) 6.8 Hz, 6H, PCH3), 1.28 (vt, N ) 14.4 Hz,
18 H, tBu), 1.25 (vt, N ) 15 Hz, 18 H, tBu), -25.1 (t, J ) 22.4,
Ru-H). 31P{1H} NMR (162 MHz, 20 °C): δ 51.3 (s). IR (CD2-
Cl2, cm-1): 3632 (ν(OH)), 3550 (ν(OH)), 1950 (ν(CO)).
18H, PtBu), 0.88 (vt, N ) 13 Hz, 18H, PtBu), -23.0 (t, J PH
20 Hz, Ru-H). 31P{1H} NMR (121 MHz, 20 °C): 46.6 (s).
)
Str u ctu r e Deter m in a tion of [Ru H(CO)(P tBu 2Me)2]-
BAr ′4, 3. X-ray quality crystals were grown from fluorobenzene
and pentane at -20 °C. A small, single crystal was selected
from the bulk sample and affixed to the tip of a glass fiber
with the use of silicone grease. The mounted sample was then
transferred to the goniostat and cooled to -165 °C for
characterization and data collection. The sample was handled
under nitrogen atmosphere at dry ice temperature to prevent
decomposition and solvent loss. A systematic search of a
limited hemisphere of reciprocal space located a set of data
with monoclinic symmetry and systematic absences that
correspond to the centrosymmetric space group C2/c or the
noncentrosymmetric space group Cc. Subsequent solution and
successful refinement of the structure suggest the centrosym-
metric choice. Data were collected by the moving-crystal-
moving-detector technique with fixed background counts at
each extreme of the scan. Data were corrected for Lorentz and
polarization effects. The structure was solved by direct meth-
ods (SHELXTL) and Fourier techniques. Hydrogen atoms were
placed in calculated positions and refined with the use of a
riding model. All non-hydrogen atoms were refined anisotro-
pically except for the carbon atoms of the disordered phosphine
ligands. The distinction between centric/acentric space groups
deserves some comment. In the final model in C2/c, the entire
cation is disordered about a center of symmetry, with the Ru
atom only about 0.3 Å away from it. This could be interpreted
as an indication that the chosen space group symmetry is too
high. However, refinement in the acentric space group pro-
duces a model in which the anion and solvent molecules
contain near precise, but noncrystallographic (in Cc), 2-fold
axes; the anisotropic thermal parameters behave poorly, and
correlation is problematic. In the centric model, the anion and
C6H5F solvent molecules each contain a crystallographic 2-fold
axis; anisotropic thermal parameters refine well, except for
the carbon atoms in the disordered phosphine ligands, and
there are no significant correlation problems. Difficulty with
anisotropic thermal parameters in the disordered cation can
be attributed to near-overlap of the two components of the
disorder. Even in the seemingly ordered Cc model, a large
disparity in the Ru-P bond lengths suggests a disorder of the
ruthenium. Also, the phosphine carbon atoms in the Cc model
were much more difficult to locate and refine than were the
other carbon atoms in the structure. The cation disorder thus
seems to carry over into the acentric model, and there is no
advantage to selecting Cc as the space group. While the
presence of a hydride can neither be confirmed nor denied
based on the X-ray results, there is an open space in the
ruthenium atom coordination sphere, cis to the CO, for the
Isom er iza tion of Bu ten e-1 by [Ru H(CO)L2]BAr ′4. [RuH-
(CO)L2]BAr′4 (10 mg, 7.6 × 10-3 mmol) was dissolved in C6H5F
(0.5 mL). The solution was degassed before butene-1 (1 atm)
was added. After mixing for 5 min at room temperature, 1H
NMR analysis of the mixture shows no butene-1 but butene-
1
2, with a cis:trans ratio of 1:3. H NMR of butene-2: 1.57 (d,
J ) 5.4 Hz, CH3 cis-butene-2), 1.586 (m, CH3 of trans-butene-
2), 5.41 (m, 1H, CHdCH of trans-butene-2), 5.48 (m, CHdCH
of cis-butene-2).
Reaction of [Ru H(CO)L2]BAr ′4 with Eth ylen e in C6H5F.
In an NMR tube [RuH(CO)(PtBu2Me)2]BAr′4 (10 mg, 7.6 × 10-3
mmol) was dissolved in a 4:1 mixture of C6H5F and C6D12 (for
lock purposes). The orange solution was degassed and the tube
charged with C2H4 (1 atm) and mixed under low temperature.
The tube was transferred to a precooled NMR probe for
measurements. At -40 °C, [RuH(η2-C2H4)(CO)(PtBu2Me)2]+ is
formed cleanly along with a small amount of butene-1 and
1
butene-2 (cis:trans ) 1:3). H NMR of butene-1: 5.90 (m, 1H,
1
CHd), 5.03 (dm, J HH ) 17.7 Hz, H, CH2d), 4.96 (dm, J HH
)
9.9 Hz, 1H, CH2d), 2.01 (apparent quintet, J HH ) 6.9 Hz, CH2-
Me), 0.96 (t, J ) 6.9 Hz, CH3). NMR evidence for [RuH(η2-
C2H4)(CO)(PtBu2Me)2]+: 31P{1H} NMR (121 MHz): 48.9 (s).
1H NMR (300 MHz): 5.4 (s, free C2H4), 3.12 (br s, 4H, C2H4
coordinated), 1.18 (vt, N ) 4.7 Hz, 6H, PCH3), 0.924 (vt, N )
13.8 Hz, 18H, PC(CH3)3), 0.798 (vt, N ) 14 Hz, 18H, PC(CH3)3),
-3.13 (vt, J ) 22 Hz, 1H, Ru-H). Upon warming to -20 °C,
the coordinated and free C2H4 peak broadens and more
butene-1 and butene-2 are formed. Further warming to 10 °C
converts all free C2H4 and butene-1 to butene-2, while the
ethylene adduct remains. The final molar ratio of converted
C2H4 and metal complex is 8:1. If the tube is refilled with C2H4
(1 atm) and stirred at room temperature overnight, more
butene-2 is formed. The turnover number (number of con-
sumed C2H4 per metal complex) increases to ca. 16. However,
the catalyst decomposes after 12 h at 20 °C.
Rea ction of [Ru H(CO)(P tBu 2Me)2]+ w ith Eth ylen e in
CD2Cl2. The same procedure as above was followed in CD2-
Cl2 to afford [RuH(η2-C2H4)(CD2Cl2)(CO)(PtBu2Me)2]BAr′4. 1H
NMR (-50 °C, 300 MHz): 5.40 (s, free C2H4), 3.62 (br, 4H,
coordinated C2H4), 1.77 (vt, N ) 6.3 Hz, 6H, PCH3), 1.36 (vt,
N ) 15 Hz, 18H, PC(CH3)3), 0.79 (vt, N ) 13.5 Hz, 18H, PC-
(CH3)3), -2.72 (t, J PH ) 20 Hz, Ru-H). No butene-2 is observed
at this temperature. Upon warming up to 20 °C, coordinated
(29) NaBAr′4 hydrate is heated at 150 °C under vacuum for 1 day
to obtain absolutely dry NaBAr′4.

2290 Organometallics, Vol. 19, No. 12, 2000
Huang et al.
and free C2H4 are coalesced to one broad peak at 5.1 ppm and
butene-2 is detected.
13.8 Hz, 18H, PtBu), 0.925 (vt, N ) 4.8 Hz, 6H, PCH3), 0.825
(t, J HH ) 7.2 Hz, 3H, CH3), 0.763 (vt, N ) 12.8 Hz, 18H, PtBu).
13C{1H} NMR (100 MHz, C6D5F, 20 °C): 205.4 (t, J PC ) 29
Hz, Ru-CO), 85.2 (s, CH2O), 71.0 (s, OCH2), 37.9 (vt, N ) 19
Hz, PCMe3), 36.7 (vt, N ) 18 Hz, PCMe3), 29.2 (s, PC(CH3)3),
29.0 (s, PC(CH3)3), 13.2 (s, OCH2CH3), 3.4 (vt, N ) 17 Hz,
PCH3), -0.7 (t, J PC ) 5.5 Hz, Ru-CH2). 31P{1H} NMR (162
MHz, 20 °C): 42.2 (s).
Rea ction of [Ru H(CO)L2]+ w ith P r op ylen e. The same
procedure was followed as in the reaction with C2H4 in
fluorobenzene/C6D12.
31P{1H} NMR (-40 °C): 54 (d, J PP ) 165
Hz), 45 (d, J PP ) 165 Hz). 1H NMR (-50 °C): -5.0 ppm (vt,
J PH ) 20 Hz, Ru-H).
Rea ction of [Ru H(CO)L2]+ w ith Vin yl F lu or id e. The
1
Low -Tem p er a tu r e Rea ction of [Ru H(CO)L2]BAr ′4 w ith
CH2dCH(OEt). [RuH(CO)(PtBu2Me)2]BAr′4 (26 mg, 0.02 mmol)
was dissolved in CD2Cl2 (0.5 mL) in an NMR tube with a Teflon
screw cap. To the cold (-80 °C) wall of the tube was added
CH2dCH(OEt) (2.0 µL, 0.02 mmol); this was mixed thoroughly
with the cold CD2Cl2 solution before the tube was transported
to the -80 °C NMR probe for observation. After 30 min, most
of the [RuH(CO)(PtBu2Me)2]BAr′4 was consumed to give [RuH-
(O(Et)(C2H3))(CO)(PtBu2Me)2]BAr′4. 13P{1H} NMR (162 MHz):
procedure was that of the reaction with C2H4. H NMR (300
MHz, -60 °C): -3.1 (dd, J PH ) 16 Hz, J PH ) 23 Hz, Ru-H).
31P{1H} NMR (121 MHz, -60 °C): 53.2 (d, J PP ) 140 Hz), 49.8
(d, J PP ) 140 Hz). The AB pattern peaks coalesce to a singlet
at 52.1 ppm upon warming (-30 °C). As the temperature rises
to -10 °C, the peak disappears and five 31P signals appear.
19F NMR (282 MHz, -60 °C): -150.8 (br s); this peak also
broadens and disappears as the temperature rises.
[Ru (η2-CH2CH2OCH3)(CO)(P tBu 2Me)2]BAr ′4. To [RuH-
(CO)L2]BAr′4 (200 mg, 152 mmol) dissolved in C6H5F (5 mL)
was added excess methyl vinyl ether, and the mixture was
stirred for 5 min. The volatiles were evaporated, and the
residue was recrystallized in C6H5F layered with pentane.
Yield: 190 mg (92%). 1H NMR (C6H5F:C6D12 ) 10:1, 20 °C,
400 MHz): 4.09 (t, J HH ) 7.7 Hz, 2H, CH2O), 3.04 (s, 3H,
OCH3), 2.07 (tt, J HH ) J PH ) 7.7 Hz, Ru-CH2), 1.13 (vt, N )
13.7 Hz, 18H, PC(CH3)3), 1.09 (vt, N ) 5.0 Hz, 6H, PCH3), 0.90
(vt, N ) 13.0 Hz, 18H, PC(CH3)3). 31P{1H} NMR (162 MHz):
45.0 (s). 13C{1H} NMR (100 MHz): 205.4 (t, J PC ) 15 Hz, Ru-
CO), 89.6 (s, CH2O), 60.6 (s, OCH3), 38.0 (vt, N ) 18 PC(CH3)3),
36.6 (vt, N ) 18 PC(CH3)3), 29.3 and 29.0 (s, PC(CH3)3), 2.9
(vt, N ) 17.4 Hz, PCH3), -1.18 (t, J PC ) 5.5 Hz, Ru-CH2). IR
(C6H5F): 1939 cm-1 (ν(CO)).
1
46.6 (d, J PP ) 224 Hz), 48.6 (d, J PP ) 224 Hz). H NMR (400
MHz); -28.0 (t, J PH ) 14 Hz, Ru-H), 7.32 (d, J HH ) 11 Hz,
CHOEt), 4.3, 3.70 (m, CH2dCHO), 3.92 (br, OCH2). As the
temperature is warmed to -60 °C, two new products formed.
They are [Ru(η2-CH2CH2OEt)(CO)L2]BAr′4 and [Ru(CH(OEt)-
(Me))(CO)L2]BAr′4 with integration of about 1:1. Spectroscopic
data for the latter: 31P{1H} NMR (162 MHz, -70 °C): 44.9
1
(d, J PP ) 202 Hz), 44.0 (d, J PP ) 202 Hz). H NMR (-70 °C,
400 MHz): 5.5 (m, Ru-CH(OEt), 3.55, 3.37 (apparent quintet,
J HH ) 8 Hz, diastereotopic OCH2Me), 0.36 (s, â-agostic CH-
(OEt)CH3). Upon warming to -40 °C, only [Ru(η2-CH2CH2-
OEt)(CO)L2]BAr′4 is detected.
Rea ction of [Ru H(CO)L2]BAr ′4 w ith 2,3-Dih yd r ofu r a n .
RuH(OTf)(CO)(PtBu2Me)2 (100 mg, 0.16 mmol) and NaBAr′4
(150 mg, 0.17 mmol) were mixed in C6H5F (1 mL) and
vigorously stirred for 5 min. The solution was then centrifuged,
and the liquid was transferred to an NMR tube. To the solution
was syringed 2,3-dihydrofuran (10 mL, 0.17 mmol) to yield a
bright yellow solution. After 1 h of mixing, the reaction is
Str u ctu r e Deter m in a tion of [Ru (η2-CH2CH2OMe)(CO)-
(P tBu 2Me)2]BAr ′4, 9. The single crystals were grown from a
solvent mixture of fluorobenzene and pentane at -20 °C. A
medium-sized crystal was chosen from the bulk sample and
affixed to the tip of a glass fiber with the use of silicone grease
under nitrogen atmosphere. The mounted sample was then
transferred, under a stream of dry nitrogen, to the goniostat;
at the goniostat the crystal was inserted directly into the
instrument’s cryogenic stream and cooled to -174 °C for
characterization and data collection. A systematic search of a
limited hemisphere of reciprocal space located a set of data
with tetragonal symmetry and with systematic absences
uniquely characteristic of space group P41212. Subsequent
solution and refinement confirmed this space group choice.
Data were collected by the moving-crystal-moving-detector
technique with fixed background counts at each extreme of
the scan. Data were corrected for Lorentz and polarization
effects, and equivalent data were averaged. The structure was
solved by direct methods (SHELXTL) and Fourier techniques.
All hydrogen atoms were placed in calculated positions and
refined with the use of a riding model. All non-hydrogen atoms
except those representing the partially resolved solvent mol-
ecule were refined anisotropically. The structure solution and
refinement were complicated by the fact that the entire cation
is disordered about a 2-fold rotation axis. Even the ruthenium
is slightly off axis. Especially problematic is that the disorder
causes the images of the two phosphine ligands to be convo-
luted together. Successful refinement of the cation required
that geometric restraints be applied to the phosphine ligands
to influence them toward geometric consistency both internally
and between the two ligands and also that thermal parameter
restraints be applied to the atoms of those ligands. A final
difference electron density map was featureless, with the
largest peak having an intensity of 0.83 e/Å3. The crystal-
lographic data are collected in Table 1.
complete to give 10 in 90% yield based on 31P{1H} NMR
1
integration. H NMR (400 MHz, -10 °C): -1.71 (t, J PH ) 20
Hz, 1H, Ru-H), 0.87 (vt, N ) 13.7, 18H, PC(CH3)3), 0.94 (vt,
N ) 13.8, 18H, PC(CH3)3), 1.30 (vt, N ) 5 Hz, 6H, PCH3), 1.50
(apparent quintet, J ) 8 Hz, 2H, Hb), 2.84 (t, J HH ) 8 Hz, 2H,
Hc), 4.0 (t, J HH ) 8 Hz, 2H, Ha), 7.75 (s, 4H, para-H of Ar′),
8.32 (s, 8H, ortho-H of Ar′). 31P{1H} NMR (162 Hz, -10 °C):
57.2 (s). 13C{1H} NMR (-10 °C): 302 (t, J PC ) 7 Hz, RudC),
201.5 (dt, J CH ) 35 Hz, from 1H coupled 13C spectrum, J PC
)
8 Hz), 82.7, 57.4, 23.6 (s, CH2 of furan ring), 37.3 (vt, N ) 21
Hz, PCMe3), 36.8 (vt, N ) 20 Hz, PCMe3), 28.3 (s, PC(CH3)3),
27.9 (s, PC(CH3)3, 10.2 (vt, N ) 24.4 Hz, PCH3). After the NMR
measurement, the solution was transferred to a test tube and
layered with pentane for 24 h to give yellow crystals, which
were filtered, washed with pentane, and dried to yield 120 mg
(54%) product.
Ack n ow led gm en t. This work was supported by the
National Science Foundation, the Universite´ of Mont-
pellier 2, and the French CNRS.
Su p p or t in g In for m a t ion Ava ila b le: Full crystallo-
graphic details, positional and thermal parameters, and
distances and angles for 1, 2, 3, and 9. This material is
available free of charge via the Internet at http://pubs.acs.org.
[Ru (η2-CH2CH2OC2H5)(CO)(P tBu 2Me)2]BAr ′4. The same
procedure as above was followed except using 1 equiv of CH2d
CH(OEt). 1H NMR (C6D5F, 20 °C, 400 MHz): 3.81 (t, 2H,
J HH ) 8 Hz, CH2OEt), 3.14 (q, J HH ) 7.2 Hz, 2H, OCH2Me),
1.88 (tt, J HH ) 8 Hz, J PH ) 8 Hz, 2H, Ru-CH2), 1.00 (vt, N )
OM9910017