Characterization of Five-Coordinate Ruthenium(II) Phosphine Complexes by X-ray Diffraction and Solid-State 31P CP/MAS NMR Studies and Their Reactivity with Sulfoxides and Thioethers

Article abstract of DOI:10.1021/ic960860+

³¹P CP/MAS NMR spectroscopy is examined as a method of characterization for ruthenium(II) phosphine complexes in the solid state, and the results are compared with X-ray crystallographic data determined for RuCl₂(dppb)(PPh₃) (dppb = Ph₂P(CH₂)₄PPh₂), RuBr₂(PPh₃)₃, and the previously determined RuCl₂(PPh₃)₃. Crystals of RuBr₂(PPh₃)₃ (C₅₄H₄₅Br₂P₃Ru) are monoclinic, space group P2_1/a, with a = 12.482(4) ?, b = 20.206(6) ?, c = 17.956(3) ?, β = 90.40(2)°, and Z = 4, and those of RuCl₂(dppb)(PPh₃) (C₄₆H₄₃Cl₂P₃Ru) are also monoclinic, space group P2_1/n, with a = 10.885(2) ?, b = 20.477(1) ?, c = 18.292(2) ?, β = 99.979(9)°, and Z = 4. The structure of RuBr₂(PPh₃)₃ was solved by direct methods, and that of RuCl₂(dppb)(PPh₃) was solved by the Patterson method. The structures were refined by full-matrix least-squares procedures to R = 0.048 and 0.031 (R_w = 0.046 and 0.032) for 5069 and 5925 reflections with I ≥ 3σ(I), respectively. Synthetic routes to RuBr₂(dppb)(PPh₃) and [RuBr(dppb)]₂(μ₂-dppb) are reported. The reactivity of RuCl₂(dppb)(PPh₃) with the neutral two-electron donor ligands (L) dimethyl sulfoxide, tetramethylene sulfoxide, tetrahydrothiophene, and dimethyl sulfide to give [(L)-(dppb)Ru(μ-Cl)₃RuCl(dppb)] is discussed.

Full text of DOI:10.1021/ic960860+

7304
Inorg. Chem. 1996, 35, 7304-7310
Characterization of Five-Coordinate Ruthenium(II) Phosphine Complexes by X-ray
31
Diffraction and Solid-State P CP/MAS NMR Studies and Their Reactivity with Sulfoxides
and Thioethers
Kenneth S. MacFarlane, Ajey M. Joshi, Steven J. Rettig, and Brian R. James*
Department of Chemistry, The University of British Columbia, Vancouver, BC V6T 1Z1, Canada
ReceiVed July 18, 1996X
31P CP/MAS NMR spectroscopy is examined as a method of characterization for ruthenium(II) phosphine complexes
in the solid state, and the results are compared with X-ray crystallographic data determined for RuCl2(dppb)(PPh3)
(dppb ) Ph2P(CH2)4PPh2), RuBr2(PPh3)3, and the previously determined RuCl2(PPh3)3. Crystals of RuBr2(PPh3)3
(C54H45Br2P3Ru) are monoclinic, space group P21/a, with a ) 12.482(4) Å, b ) 20.206(6) Å, c ) 17.956(3) Å,
â ) 90.40(2)°, and Z ) 4, and those of RuCl2(dppb)(PPh3) (C46H43Cl2P3Ru) are also monoclinic, space group
P21/n, with a ) 10.885(2) Å, b ) 20.477(1) Å, c ) 18.292(2) Å, â ) 99.979(9)°, and Z ) 4. The structure of
RuBr2(PPh3)3 was solved by direct methods, and that of RuCl2(dppb)(PPh3) was solved by the Patterson method.
The structures were refined by full-matrix least-squares procedures to R ) 0.048 and 0.031 (Rw ) 0.046 and
0.032) for 5069 and 5925 reflections with I g 3σ(I), respectively. Synthetic routes to RuBr2(dppb)(PPh3) and
[RuBr(dppb)]2(µ2-dppb) are reported. The reactivity of RuCl2(dppb)(PPh3) with the neutral two-electron donor
ligands (L) dimethyl sulfoxide, tetramethylene sulfoxide, tetrahydrothiophene, and dimethyl sulfide to give [(L)-
(dppb)Ru(µ-Cl)3RuCl(dppb)] is discussed.
Introduction
librium dissociation could allow for isolation of [RuBr(dppb)]2-
(µ-Br)2. The geometry of the five-coordinate complex RuCl2-
(dppb)(PPh3) has previously been suggested to be square
pyramidal by low-temperature 31P{1H} NMR spectroscopic
studies.7
Work from this laboratory has investigated the ability of
chlororuthenium complexes containing a single, chelating di-
tertiary phosphine (P-P) per Ru atom to catalyze the hydro-
genation of unsaturated organics, including imines.1 We are
interested in extending these studies to the bromoruthenium
analogs, and therefore the development of synthetic routes to
these species was necessary. The synthetic methodology used
in this laboratory previously to prepare [RuCl(P-P)]2(µ-Cl)2
complexes consisted of the H2 reduction of the mixed-valence,
triply-chloro-bridged complexes [RuCl(P-P)]2(µ-Cl)3 which
were themselves prepared by the reaction of 1 equiv of P-P
ligand with RuCl3(PR3)2(DMA)‚DMA solvate, where DMA )
N,N-dimethylacetamide and R ) Ph or p-tolyl.2 The obvious
entry into the bromoruthenium analogs therefore was from the
known RuBr3(PR3)2 complex.3 Unfortunately, this complex
could not be prepared pure. Dekleva of this laboratory has noted
difficulties in isolating this complex,4 the problems being similar
to those encountered in the preparation of RuCl3(PPh3)2-
(MeOH).5,6 Therefore, another route to the bromo dinuclear
diphosphine complexes was necessary. The complex RuCl2-
(dppb)(PPh3), which is readily prepared from RuCl2(PPh3)3, is
known in solution to be in equilibrium with dinuclear [RuCl-
(dppb)]2(µ-Cl)2 (see eq 1).2,7 Therefore, if the bromo analog
We were also interested in establishing routes from RuCl2-
(dppb)(PPh3) to triply-chloro-bridged diruthenium(II,II) species
as well as investigating the utility of solid-state 31P CP/MAS
NMR spectroscopy for the characterization of the five-coordinate
Ru species; [RuCl(dppb)]2(µ-Cl)2 species are known to react
generally with a ligand L to generate (L)(dppb)Ru(µ-Cl)3RuCl-
(dppb).2 The species with L ) dmso, where dmso implies
S-bonded sulfoxide, has previously been prepared in this
laboratory from cis-RuCl2(dmso)4 and studied by X-ray dif-
fraction and 31P{1H} NMR spectroscopy;2 therefore, the reactiv-
ity of dmso with RuCl2(dppb)(PPh3) was a good starting point
as one of the possible products [(dmso)(dppb)Ru(µ-Cl)3RuCl-
(dppb)] had been characterized previously.
In this paper, we report the results of 31P CP/MAS NMR
spectroscopic studies on RuCl2(PPh3)3 and RuCl2(dppb)(PPh3)
as well as X-ray crystallographic studies of RuBr2(PPh3)3 and
RuCl2(dppb)(PPh3). Details of synthetic chemistry using RuCl2-
(dppb)(PPh3) as a precursor and the characterization of the
products [(L)(dppb)Ru(µ-Cl)3RuCl(dppb)] by solution 31P{1H}
NMR spectroscopy are reported.
2RuCl2(dppb)(PPh3) h [RuCl(dppb)]2(µ-Cl)2 + 2PPh3 (1)
Experimental Section
General Procedures and Materials. Manipulations were carried
out under Ar using standard Schlenk techniques. Reagent grade
solvents (Fisher Scientific) were distilled from CaH2 (CH2Cl2), sodium
(diethyl ether, C6H6 and hexanes), or Mg/I2 (MeOH and EtOH) under
N2. Dibromomethane (Aldrich) was dried over molecular sieves (4
Å) prior to use. Dimethyl sulfoxide (dmso), tetramethylene sulfoxide
(tmso), dimethyl sulfide (dms), and tetrahydrothiophene (tht) were used
as received from Aldrich. 1,4-Bis(diphenylphosphino)butane (dppb)
RuBr2(dppb)(PPh3) could be prepared, a corresponding equi-
X Abstract published in AdVance ACS Abstracts, November 1, 1996.
(1) Fogg, D. E.; James, B. R.; Kilner, M. Inorg. Chim. Acta 1994, 222,
85.
(2) Joshi, A. M.; Thorburn, I. S.; Rettig, S. J.; James, B. R. Inorg. Chim.
Acta 1992, 198, 283.
(3) Stephenson, T. A.; Wilkinson, G. J. Inorg. Nucl. Chem. 1966, 28,
945.
(4) Dekleva, T. W. Ph.D. Thesis, The University of British Columbia,
1983.
(6) Pez, G. P.; Grey, R. A.; Corsi, J. J. Am. Chem. Soc. 1981, 103, 7528.
(7) Jung, C. W.; Garrou, P. E.; Hoffman, P. R.; Caulton, K. G. Inorg.
Chem. 1984, 23, 726.
(5) Ruiz-Ramirez, L.; Stephenson, T. A.; Switkes, E. S. J. Chem. Soc.,
Dalton Trans. 1973, 1770.
S0020-1669(96)00860-9 CCC: $12.00 © 1996 American Chemical Society

Ruthenium(II) Phosphine Complexes
Inorganic Chemistry, Vol. 35, No. 25, 1996 7305
was used as supplied by Aldrich. 1,4-Bis(dicyclohexylphosphino)-
butane (dcypb) was prepared8 by a modified reported procedure from
dicyclohexylphosphine, nBuLi, and 1,4-dibromobutane.9 RuCl2(PPh3)3
(1),3,10 RuBr2(PPh3)3 (2),3,4,11 RuCl2(P(p-tolyl)3)3 (3),4,12,13 and RuCl2-
(dppb)(PPh3) (4)2,7 were prepared according to published procedures.
Solution NMR spectra were recorded on a Varian XL300 spectrometer
(121.42 MHz for 31P{1H}), using residual solvent proton (1H) or external
P(OMe)3 (31P{1H}: δ 141.00 vs external 85% aqueous H3PO4) as the
reference. The 31P{1H} solid-state cross polarization, magic-angle
spinning (CP/MAS) FT-NMR spectra were recorded (with the kind
help of Dr. A. Root formerly of this department) on a Bruker MSL400
or a Bruker CPX200 instrument (161.97 and 80.99 MHz for 31P,
respectively). All 31P chemical shifts (solid state and solution) are
reported with respect to external 85% aqueous H3PO4. The samples
were packed as powders (∼0.2-0.3 g) in Teflon holders of ∼8 mm
i.d. High-resolution, solid-state 31P NMR spectra were obtained, by
combining high-power proton decoupling with 1H-31P cross polariza-
C6H6 (25 mL) for 1 h at rt under Ar. The resulting green solution was
reduced in volume to ∼5 mL, and hexanes (20 mL) was added to
precipitate a mustard solid. The mustard product was collected by
filtration, washed with hexanes (4 × 10 mL), and dried under vacuum.
The diphosphine-bridged complexes (7a,b), occasionally isolated as a
side product in the preparation of RuX2(P-P)(PAr3) species, are
essentially insoluble in most nonaromatic solvents and only sparingly
soluble in aromatic solvents; their insolubility prevented the measure-
ment of NMR spectra. Yield: 0.053 g (61%). UV-vis (C6H6): 364
[2580], 466 [3620], 710 [1170]. Anal. Calcd for C84H84Br4P6Ru2: C,
56.01; H, 4.70; Br, 17.74. Found: C, 56.27; H, 4.58; Br, 17.52.
[(dcypb)Cl2Ru(µ2-(dcypb))RuCl2(dcypb)], 7b. The general pro-
cedure outlined for 7a was followed but using 1 (0.18 g, 0.19 mmol)
and dcypb (0.18 g, 0.40 mmol). Yield of the green solid: 0.13 g (77%).
UV-vis (C6H6): 340 [5080], 384 (sh) [3870], 682 [1940]. Anal. Calcd
for C84H156Cl4P6Ru2: C, 59.49; H, 9.27; Cl, 8.36. Found: C, 59.40;
H, 9.33; Cl, 8.08.
1
tion (CP) (5.5 µs 90° y H pulse, 1 ms contact time, 1 s recycle time)
[(dmso)(dppb)Ru(µ-Cl)3RuCl(dppb)], 8. An excess of dmso (170
µL, 2.3 mmol) was added to a dark-green suspension of 4 (0.18 g,
0.21 mmol) in C6H6 (5 mL). The originally green mixture became
bright orange after refluxing for 1 h under Ar. The solution was cooled
and hexanes (30 mL) added to precipitate a yellow-orange solid, which
was collected on a sintered glass filter, washed with hexanes (5 × 5
mL) to remove PPh3, and dried under vacuum. Yield: 0.12 g (87%).
IR: νSdO 1090 (s, S-bonded dmso). 1H NMR (300 MHz, CDCl3, 20
°C): δ 0.65-2.32 (m, 21H, 15H of CH2 of dppb and 6H of CH3 of
dmso), 3.50 (br m, 1H, CH of CH2 dppb), 6.78 (m, 3H, Ph of dppb),
6.94-7.96 (m, 34H, Ph of dppb), 8.47 (m, 3H, Ph of dppb). 1H NMR
(300 MHz, C6D6, 20 °C): δ 0.50-2.50 (m, 16H, 10H of CH2 of dppb
and 6H of CH3 of dmso), 2.74 (m, 1H, CH of CH2 dppb), 3.29 (m, 3H,
CH2 dppb), 3.51 (m, 2H, CH2 of dppb), 6.67 (t, 4H, Ph of dppb, J )
6.9 Hz), 6.80 (m, 16H, Ph of dppb), 7.34 (t, 3H, Ph of dppb, J )
8.3 Hz), 7.47 (br m, 5H, Ph of dppb), 7.61 (t, 2H, Ph of dppb, J )
6.8 Hz), 7.74 (t, 2H, Ph of dppb, J ) 8.0 Hz), 8.07 (pseudo q, 4H,
Ph of dppb, J ) 8.9 Hz), 8.18 (t, 2H, Ph of dppb, J ) 8.3 Hz),
8.67 (t, 2H, Ph of dppb, J ) 8.0 Hz). UV-vis (C6H6): 378 [3010],
470 (sh) [590]; (CH2Cl2): 376 [2900], 470 (sh) [650]. Anal. Calcd
for C58H62Cl4OP4Ru2S: C, 54.64; H, 4.90. Found: C, 54.45; H, 5.10.
This compound has been prepared previously from cis-RuCl2(dmso)4.2
The above IR and 31P{1H} NMR spectroscopic data (see Table 5 below)
and magic-angle spinning (MAS) at ∼2.5-4.0 kHz. The solution and
solid-state 31P{1H} NMR data for the complexes are given in the Results
and Discussion section (Tables 3-5). The 1H NMR data are presented
in this Experimental Section for purposes of characterization; the data
are straightforward and are not discussed. The UV-vis spectra were
recorded on a Hewlett Packard 8452A diode array spectrophotometer
and are given as λmax (nm) [ꢀmax (M-1 cm-1)], sh ) shoulder. IR spectra
(Nujol mulls, KBr plates) were recorded (cm-1) on an ATI Mattson
Genesis FTIR spectrometer (s ) strong). Elemental analyses were
performed by Mr. P. Borda of this department.
RuCl2(dppb)(PPh3), 4. Crystals of 4 were isolated as green plates
from a toluene-d8 solution of 4 and 14 equiv of PPh3 after several
months in a N2 glovebox.
RuCl2(dppb)(P(p-tolyl)3), 5. The title complex was prepared in
much the same manner as for the PPh3 analog 4.2 Complex 3 (1.0 g,
0.92 mmol) was dissolved in CH2Cl2 (20 mL), then dppb (0.39 g, 0.92
mmol) was added under a flow of Ar, and the reaction mixture was
stirred at room temperature (rt) for 2 h. The initially orange solution
changed to dark green upon addition of the phosphine. On occasion,
some bridged-phosphine complex, [RuCl2(dppb)]2(µ-dppb), was present.2,7
This insoluble green complex was removed by vacuum filtration (0.08
g, ∼10% of the Ru). The green filtrate was then reduced to ∼5 mL,
and EtOH (40 mL) was added to precipitate the green product, which
was isolated by filtration, washed with EtOH (2 × 10 mL) and hexanes
(3 × 10 mL), and dried under vacuum. Yield: 0.83 g (76%). 1H NMR
(300 MHz, C6D6, 20 °C): δ 1.38 (br m, 4H, PCH2CH2 of dppb), 2.02
(s, 9H, CH3 of p-tolyl), 2.92 (br m, 4H, PCH2 of dppb), 6.65-7.95 (m,
32H, 20H of Ph of dppb and 12H of Ph of P(p-tolyl)3). Anal. Calcd
for C49H49Cl2P3Ru: C, 65.19; H, 5.47; Cl, 7.85. Found: C, 64.91; H,
5.36; Cl, 7.65.
RuBr2(dppb)(PPh3), 6. This bromo analog was prepared in much
the same manner as the chloro derivative 5, the only difference being
that the reaction was performed in CH2Br2. Complex 2 (0.52 g, 0.49
mmol) and dppb (0.20 g, 0.48 mmol) were dissolved in CH2Br2 (10
mL), and the mixture was stirred for 2 h at rt when the originally deep-
red solution gradually changed to yellow-orange. The reaction mixture
was reduced to ∼5 mL and EtOH (40 mL) was added to precipitate
the product. An olive solid was collected, washed with EtOH (2 × 10
mL) and hexanes (2 × 10 mL), and finally dried under vacuum.
Yield: 0.45 g (97%). Anal. Calcd for C46H43Br2P3Ru: C, 58.18; H,
4.56; Br, 16.83. Found: C, 58.04; H, 4.64; Br, 16.76. Crystals of the
starting material RuBr2(PPh3)3 were isolated from the filtrate of the
above preparation as dark-orange prisms.
1
agree with those reported in the literature,2 while the UV-vis and H
NMR data have not been reported before.
[(tmso)(dppb)Ru(µ-Cl)3RuCl(dppb)], 9. The complex was syn-
thesized in the same manner as the dmso analog 8. An excess of tmso
(210 µL, 2.32 mmol) was added to a dark-green suspension of 4 (0.190
g, 0.221 mmol) in C6H6 (5 mL). The originally green mixture became
bright orange after refluxing for 1.5 h under Ar. The solution was
cooled and hexanes (30 mL) added to precipitate a pale-orange solid,
which was collected on a sintered glass filter, washed with hexanes (5
× 5 mL) to remove PPh3, and dried under vacuum. Yield: 0.11 g
(70%). IR: νSdO 1093 (s, S-bonded tmso). 1H NMR (300 MHz,
CDCl3, 20 °C): δ 0.65-3.10 (m, 20H, 12H of CH2 of dppb and 8H of
CH2 of tmso), 3.26 (br m, 3H, CH2 dppb), 3.73 (br m, 1H, CH of CH2
dppb), 6.61 (br m, 3H, Ph of dppb), 7.00-8.12 (m, 35H, Ph of dppb),
8.51 (br m, 2H, Ph of dppb). 1H NMR (300 MHz, C6D6, 20 °C): δ
0.30 (m, 23H, 15H of CH2 of dppb and 8H of CH2 of tmso), 3.82 (br
m, 1H, CH of CH2 dppb), 6.6-8.48 (m, 39H, Ph of dppb), 8.74 (br m,
1H, Ph of dppb). UV-vis (C6H6): 376 [2470], 460 (sh) [830]; (CH2-
Cl2): 374 [2410], 460 (sh) [600]. Anal. Calcd for C60H64Cl4OP4-
Ru2S: C, 55.39; H, 4.96; Cl, 10.90; S, 2.46. Found: C, 55.11; H,
5.20; Cl, 10.71; S, 2.60.
[(dms)(dppb)Ru(µ-Cl)3RuCl(dppb)], 10. An excess of dms (106
µL, 1.44 mmol) was added to a dark-green suspension of 4 (0.17 g,
0.20 mmol) in C6H6 (5 mL). The resulting mixture was stirred at rt
(in a sealed Schlenk tube because of the smell and volatility of dms)
under Ar for 4 h; the syntheses of the other sulfide and sulfoxide analogs
were performed at reflux temperatures under a slow flow of Ar. An
orange-brown product, precipitated by the addition of hexanes (30 mL),
was collected by filtration, washed with hexanes (5 × 5 mL), and dried
under vacuum. Yield: 0.11 g (87%). 1H NMR (300 MHz, CDCl3, 20
°C): δ 0.82-2.75 (m, 20H, 14H of CH2 of dppb and 6H of CH3 of
dms), 3.13 (m, 1H, CH of CH2 dppb), 3.70 (br m, 1H, CH of CH2
[(dppb)Br2Ru(µ2-(dppb))RuBr2(dppb)], 7a. Complex 2 (0.10 g,
0.095 mmol) was stirred with 2 equiv of dppb (0.081 g, 0.19 mmol) in
(8) Chau, D. E. K.-Y. M.Sc. Thesis, The University of British Columbia,
1992.
(9) Priemer, H. Ph.D. Thesis, der Ruhr-Universita¨t Bochum, 1987.
(10) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth. 1970,
12, 237.
(11) Wang, D. K. W. Ph.D. Thesis, The University of British Columbia,
1978.
(12) Knoth, W. H. J. Am. Chem. Soc. 1972, 94, 104.
(13) Armit, P. W.; Sime, W. J.; Stephenson, T. A.; Scott, L. J. Organomet.
Chem. 1978, 161, 391.

7306 Inorganic Chemistry, Vol. 35, No. 25, 1996
Table 1. Crystallographic Data
MacFarlane et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) (Esd’s in
Parentheses)
compd
formula
fw
cryst system
space group
a, Å
RuBr2(PPh3)3 (2) RuCl2(dppb)(PPh3) (4)
C54H45Br2P3Ru
1047.75
monoclinic
P21/a
12.482(4)
20.206(6)
17.956(3)
90.40(2)
4528(1)
4
C46H43Cl2P3Ru
860.74
monoclinic
P21/n
10.885(2)
20.477(1)
18.292(2)
99.979(9)
4015.8(6)
4
RuBr2(PPh3)3 (2)
Ru(1)-Br(1)
Ru(1)-Br(2)
Ru(1)-P(1)
2.515(1)
2.526(1)
2.423(2)
Ru(1)-P(2)
Ru(1)-P(3)
P-C
2.389(2)
2.228(2)
1.834(7)-1.857(7)
Br(1)-Ru(1)-Br(2) 155.64(4) C(1)-P(1)-C(13)
106.9(3)
103.0(3)
b, Å
c, Å
Br(1)-Ru(1)-P(1)
Br(1)-Ru(1)-P(2)
Br(1)-Ru(1)-P(3)
Br(2)-Ru(1)-P(1)
Br(2)-Ru(1)-P(2)
Br(2)-Ru(1)-P(3)
P(1)-Ru(1)-P(2)
P(1)-Ru(1)-P(3)
P(2)-Ru(1)-P(3)
Ru(1)-P(1)-C(1)
Ru(1)-P(1)-C(7)
Ru(1)-P(1)-C(13)
C(1)-P(1)-C(7)
82.19(5) C(7)-P(1)-C(13)
84.31(5) Ru(1)-P(2)-C(19) 117.4(2)
110.39(5) Ru(1)-P(2)-C(25) 128.9(3)
93.04(5) Ru(1)-P(2)-C(31) 100.1(2)
91.34(5) C(19)-P(2)-C(25) 101.7(3)
93.96(5) C(19)-P(2)-C(31) 104.7(3)
156.43(7) C(25)-P(2)-C(31) 100.4(3)
101.28(7) Ru(1)-P(3)-C(37) 114.1(2)
101.50(7) Ru(1)-P(3)-C(43) 119.7(2)
â, deg
V, Å3
Z
F
F
calc, g/cm3
1.537
not measured
21
1.424
not measured
21
obsd, g/cm3
T, °C
radiation
λ, Å
Mo
0.710 69
22.59
Cu
1.541 78
57.60
104.4(2)
128.5(2)
115.3(2)
95.4(3)
Ru(1)-P(3)-C(49) 117.2(2)
C(37)-P(3)-C(43) 100.0(3)
C(37)-P(3)-C(49) 101.6(3)
C(43)-P(3)-C(49) 101.5(3)
µ, cm-1
transm factors (relative) 0.73-1.00
0.55-1.00
R(F)a
0.048
0.046
0.031
Rw(F)a
0.032
RuCl2(dppb)(PPh3) (4)
Ru(1)-P(2)
2
a R ) ∑||Fo| - |Fc||/∑|Fo|; Rw ) (∑w(|Fo| - |Fc|)2/∑w|Fo| )1/2
.
Ru(1)-Cl(1)
Ru(1)-Cl(2)
Ru(1)-P(1)
2.3796(8)
2.4047(9)
2.3346(9)
2.2029(9)
2.3786(9)
1.820(4)-1.849(3)
Ru(1)-P(3)
P-C
dppb), 6.65-7.80 (m, 35H, Ph of dppb), 8.04 (t, 2H, Ph of dppb, J )
7.8), 8.33 (m, 3H, Ph of dppb). 1H NMR (300 MHz, C6D6, 20 °C): δ
0.52-2.75 (m, 20H, 14H of CH2 of dppb and 6H of CH3 of dms),
3.35 (br m, 1H, CH of CH2 dppb), 4.12 (br m, 1H, CH of CH2 dppb),
6.68-7.85 (m, 32H, Ph of dppb), 8.15 (m, 4H, Ph of dppb), 8.70 (m,
4H, Ph of dppb). UV-vis (C6H6): 374 [3780], 460 (sh) [730]; (CH2-
Cl2): 372 [3470], 460 (sh) [660]. Anal. Calcd for C58H62Cl4P4Ru2S:
C, 55.33; H, 4.96; Cl, 11.26; S, 2.55. Found: C, 55.48; H, 4.88; Cl,
11.11; S, 2.57.
[(tht)(dppb)Ru(µ-Cl)3RuCl(dppb)], 11. The title product was
synthesized in the same manner as the dmso analog 8. An excess of
tht (180 µL, 2.0 mmol) was added to a dark-green suspension of 4
(0.18 g, 0.21 mmol) in C6H6 (5 mL). The originally green mixture
became bright orange after refluxing for 1 h under Ar. The solution
was cooled and hexanes (30 mL) added to precipitate an orange-brown
solid, which was collected on a sintered glass filter, washed with
hexanes (5 × 5 mL) to remove PPh3, and dried under vacuum. Yield:
0.12 g (90%). 1H NMR (300 MHz, CDCl3, 20 °C): δ 0.85-2.90 (m,
22H, 14H of CH2 of dppb and 8H of CH2 of tht), 3.20 (br m, 1H, CH
of CH2 dppb), 3.69 (br m, 1H, CH of CH2 dppb), 6.78-7.75 (m, 35H,
Ph of dppb), 8.07 (t, 2H, Ph of dppb, J ) 8.8), 8.30 (m, 3H, Ph of
dppb). 1H NMR (300 MHz, C6D6, 20 °C): δ 0.50-2.75 (m, 22H,
14H of CH2 of dppb and 8H of CH2 of tht), 3.39 (br m, 1H, CH of
CH2 dppb), 4.10 (br m, 1H, CH of CH2 dppb), 6.72-7.80 (m, 32H, Ph
of dppb), 8.20 (br m, 4H, Ph of dppb), 8.65 (br m, 4H, Ph of dppb).
UV-vis (C6H6): 374 [3700], 460 (sh) [605]; (CH2Cl2): 372 [3200],
460 (sh) [440]. Anal. Calcd for C60H64Cl4P4Ru2S: C, 56.08; H, 5.02.
Found: C, 56.61; H, 5.13. The slightly high C elemental analysis did
not improve upon reprecipitation of the material.
X-ray Crystallographic Analyses of RuBr2(PPh3)3 (2) and RuCl2-
(dppb)(PPh3) (4). Selected crystallographic data appear in Table 1.
The final unit-cell parameters were obtained by least-squares on the
setting angles for 25 reflections with 2θ ) 22.7-40.3° for 2 and 50.1-
63.6° for 4. The intensities of three standard reflections, measured
every 200 reflections throughout the data collections, remained constant
for both complexes. The data were processed14 and corrected for
Lorentz and polarization effects and absorption (empirical, based on
azimuthal scans).
The structure of 2 was solved by direct methods, and that of 4 was
solved by the Patterson method. All non-hydrogen atoms of both
structures were refined with anisotropic thermal parameters. Hydrogen
atoms were fixed in calculated positions (C-H ) 0.99 Å for 2 and
0.98 Å for 4, BH ) 1.2Bbonded atom). A secondary extinction correction
(Zachariasen type, isotropic) was applied for 2, the final value of the
extinction coefficient being 1.3(1) × 10-7. No extinction correction
was necessary for 4. Neutral atom scattering factors for all atoms15
and anomalous dispersion corrections for the non-hydrogen atoms16
Cl(1)-Ru(1)-Cl(2) 158.75(3) Ru(1)-P(2)-C(4)
112.8(1)
Cl(1)-Ru(1)-P(1)
Cl(1)-Ru(1)-P(2)
Cl(1)-Ru(1)-P(3)
Cl(2)-Ru(1)-P(1)
Cl(2)-Ru(1)-P(2)
Cl(2)-Ru(1)-P(3)
P(1)-Ru(1)-P(2)
P(1)-Ru(1)-P(3)
P(2)-Ru(1)-P(3)
Ru(1)-P(1)-C(1)
Ru(1)-P(1)-C(5)
Ru(1)-P(1)-C(11)
C(1)-P(1)-C(5)
C(1)-P(1)-C(11)
C(5)-P(1)-C(11)
88.61(3) Ru(1)-P(2)-C(17) 118.2(1)
109.76(3) Ru(1)-P(2)-C(23) 119.7(1)
85.82(3) C(4)-P(2)-C(17)
87.06(3) C(4)-P(2)-C(23)
99.9(2)
102.6(2)
91.42(3) C(17)-P(2)-C(23) 100.7(2)
91.87(3) Ru(1)-P(3)-C(29) 105.3(1)
97.01(3) Ru(1)-P(3)-C(35) 125.0(1)
161.78(3) Ru(1)-P(3)-C(41) 115.4(1)
101.20(3) C(29)-P(3)-C(35)
99.3(2)
119.7(1)
101.3(1)
124.1(1)
103.9(2)
101.6(2)
103.3(2)
C(29)-P(3)-C(41) 104.6(2)
C(35)-P(3)-C(41) 104.4(1)
P(1)-C(1)-C(2)
C(1)-C(2)-C(3)
C(2)-C(3)-C(4)
P(2)-C(4)-C(3)
115.1(3)
115.4(3)
116.6(3)
114.6(2)
were taken from the International Tables for X-Ray Crystallography.
Selected bond lengths and bond angles appear in Table 2. A complete
table of atomic coordinates and equivalent isotropic thermal parameters,
crystallographic data, hydrogen atom parameters, anisotropic thermal
parameters, bond lengths, bond angles, torsion angles, intermolecular
contacts, and least-squares planes for both structures are included as
Supporting Information.
Results and Discussion
Earlier attempts to grow X-ray diffraction quality crystals of
RuCl2(dppb)(PPh3) (4) were unsuccessful. Therefore, a com-
parative solid-state 31P NMR spectroscopic study of 4 and
RuCl2(PPh3)3 (1) was undertaken in the hope of determining
the solid-state structure of 4. Complex 1 was chosen for
comparison as the structure had previously been elucidated by
X-ray studies.17 Eventually X-ray quality crystals of 4 were
grown, as were crystals of RuBr2(PPh3)3 (2), and diffraction
studies of the two complexes allowed comparison with the solid-
state structure of 1 and the evaluation of solid-state NMR (31P
CP/MAS) as a method for solid-state structural characterization.
Molecular Structures. The molecular structure of 2 (Figure
1) is crystallographically isomorphous to that determined
previously by La Placa and Ibers17 for the chloro analog RuCl2-
(PPh3)3 (1). The geometry of 2 at the Ru is distorted square
(15) International Tables for X-ray Crystallography; Kynoch Press: Bir-
mingham, England, 1974; Vol. IV, pp 99-102.
(16) International Tables for X-ray Crystallography; Kluwer Academic
Publishers: Boston, MA, 1992; Vol. C, pp 200-206.
(14) teXsan: Crystal Structure Analysis Package (1985, 1992), Molecular
Structure Corp., The Woodlands, TX.
(17) La Placa, S. J.; Ibers, J. A. Inorg. Chem. 1965, 4, 778.

Ruthenium(II) Phosphine Complexes
Inorganic Chemistry, Vol. 35, No. 25, 1996 7307
Figure 2. ORTEP plot RuCl2(dppb)(PPh3) (4). Thermal ellipsoids for
non-hydrogen atoms are drawn at 33% probability (some of the phenyl
carbons have been omitted for clarity).
ligands with dppb; this is reflected in the Ru-P-C(ipso) angles
being somewhat less extreme in 4 compared with those in 2
(see Table 2).
Figure 1. ORTEP plot of RuBr2(PPh3)3 (2). Thermal ellipsoids for
non-hydrogen atoms are drawn at 33% probability.
Other five-coordinate Ru(II) phosphine complexes that
have been characterized by X-ray crystallography include
RuCl2(PMA)(P(p-tolyl)3)18 and RuCl2(isoPFA)(PPh3)19 which
both contain P-N chelates (PMA ) o-(diphenylphosphino)-
N,N-dimethylaniline and isoPFA ) 1-[R,R-dimethylethyl]-2-
(diisopropylphosphino)ferrocene). Interestingly, the latter com-
plex has an ortho-H of a PPh3 ligand blocking the sixth
coordination site of an octahedron while the former complex
does not. RuCl2(PMA)(P(p-tolyl)3) is known to coordinate a
range of small molecules including O2, CO, H2O, H2S, SO2,
and MeOH.18
The mixed-phosphine complexes RuCl2(dppb)(P(p-tolyl)3)
(5), RuBr2(dppb)(PPh3) (6), and the previously reported RuCl2-
((R)-binap)(PPh3)2,20 are all believed to have the same geometry
around Ru as in 4, on the basis of low-temperature 31P{1H}
NMR spectroscopic studies (Table 3).
pyramidal, with the sixth coordination site blocked by an
ortho-H (H(5)) of a PPh3 ligand. The Ru(1)-H(5) distance,
2.68 Å, compares with the 2.59 Å observed for the metal-
ortho-H distance in 1.17
The geometry of 4 is essentially identical to that of 1 and 2
(Figure 2). The Ru(1)-H(29) distance is 2.69 Å, essentially
identical to the corresponding distance observed in 2. The metal
centers of 2 and 4 are best described as being near the center
of gravity of a distorted square pyramid composed of trans P
atoms and trans Cl atoms in the base, with a third P atom at
the apex. The main differences in the structures of 1, 2, and 4
are probably due to the chelating dppb ligand in 4. For example,
the P-Ru-P angle for the dppb chelate in 4 is 97.01°, while
the corresponding P-Ru-P angles in 1 and 2 are 101.1 and
101.50°, respectively.
The Ru metal center in each of 1, 2, and 4 is found above
the mean plane created by the two halides and two basal
phosphorus atoms, the Ru atom being observed 0.456,17 0.518,
and 0.404 Å above the basal plane, respectively. In all three
complexes, the apical Ru-P distances (2.20-2.23 Å) are shorter
than the basal Ru-P distances (2.34-2.42 Å). Also, the Ru-P
distances of the phosphine groups involved in the agostic
hydrogen interaction (i.e., the ortho-H of a phenyl group) are
longer than the other basal Ru-P bond lengths.
Of note is the Ru-P(1)-C(1) (the ipso carbon of the phenyl
group involved in the agostic interaction) bond angle in 2 of
104.4° which is significantly smaller than the other Ru-P-
C(ipso) angles (which range from 114-129°) with the exception
of that involving one of the phenyl rings attached to the other
basal P-atom on the “open side” of the molecule (Ru-P(2)-
C(31) ) 100.1°). This is also observed in 4 where the Ru-
P-C(ipso) angles on the open side of the complex are 105.3°
for the phenyl group (C(29)) involved in the agostic interac-
tion and 101.3° for a phenyl group (C(5)) on the other basal
P(1) atom. These smaller ipso angles are thought to result from
the mutual interaction of the phenyl groups, this being reflected
in the larger Ru-P-C(ipso) angles of 128.5 and 128.9° in 2
for C(7) and C(25), respectively: the phenyl groups seem to
be effectively “pushed back” from the apex of the square
pyramid toward the open side of the complex. The geometry
of 4 is somewhat less sterically demanding than in 2 as the
number of phenyl groups is decreased by replacing two PPh3
The observed ABX pattern is consistent with the structure
determined by X-ray crystallography and 31P CP/MAS NMR
spectroscopy for 4. The spectra are consistent with two cis-
and one trans-phosphorus-phosphorus interactions, the trans
2JPP coupling constants being much greater in magnitude than
2
cis JPP coupling constants.22
The dynamic process observed in the room temperature 31P-
{1H} NMR spectrum of 5 (and the other mixed-phosphine
complexes) (Table 3) is due to intramolecular exchange of the
dppb (or binap)2,20,23 nuclei on the NMR time scale as observed
for 4 by Jung et al.7 The rate of PPh3 dissociation is too slow
to be responsible for the fluxional process observed at room
temperature (the line width of the PPh3 was essentially invariant
over the temperature range -66 to +20 °C).
31P CP/MAS NMR Spectroscopy. The 31P CP/MAS NMR
spectra of RuCl2(PPh3)3 (1) and RuCl2(dppb)(PPh3) (4) both
show the isotropic peaks as well as peaks at integral values of
the spinning frequency (i.e., spinning sidebands). Figures 3 and
(18) Mudalige, D. C.; Rettig, S. J.; James, B. R.; Cullen, W. R. J. Chem.
Soc., Chem. Commun. 1993, 830.
(19) Hampton, C. R. S. M.; Butler, I. R.; Cullen, W. R.; James, B. R.;
Charland, J.-P.; Simpson, J. Inorg. Chem. 1992, 31, 5509.
(20) Mezzetti, A.; Costella, L.; Del Zotto, A.; Rigo, P.; Consiglio, G. Gazz.
Chim. Ital. 1993, 123, 155.
(21) Hoffman, P. R.; Caulton, K. G. J. Am. Chem. Soc. 1975, 97, 4221.
(22) Dixon, K. R. In Multinuclear NMR; Mason, J., Ed.; Plenum: New
York, 1987; Chapter 13.
(23) Joshi, A. M. Ph.D. Thesis, The University of British Columbia, 1990.

7308 Inorganic Chemistry, Vol. 35, No. 25, 1996
MacFarlane et al.
Table 3. 31P{1H} NMR Data for RuCl2(PPh3)3 and RuX2(dppb)(PAr3) Complexes
complex
RuCl2(PPh3)3 (1)a
solvent
CD2Cl2
temp (°C)
-97
chem shift, δ
2JPP, Hz
2JAX ) 30.5
δA ) 75.7
δX ) 24.1
δA ) 25.7
δA ) 26.7
δA ) 28.4
δB ) 36.2
δX ) 86.1
δA ) 26.3
δB ) 35.2
δX ) 83.2
δA ) 25.5
δA ) 24.5
δA ) 25.9
δB ) 36.6
δX ) 83.9
δA ) 24.7
δB ) 34.9
δX ) 84.4
δA ) 27.6
δA ) 27.3
δA ) 29.3
δB ) 37.5
δX ) 86.8
RuCl2(dppb)(PPh3) (4)
RuCl2(dppb)(P(p-tolyl)3) (5)
RuBr2(dppb)(PPh3) (6)
C6D6
C7D8
C7D8
20
20
-70
140b
142b
2JAX ) unresolved
2JBX ) -37.7
2JAB ) 297.5
2JAX ) -22.6
2JBX ) -37.5
2JAB ) 302.4
141b
c
CH2Cl2
-75
C6D6
CD2Cl2
CD2Cl2
20
20
-66
141b
2JAX ) unresolved
2JBX ) -35.7
2JAB ) 303.2
2JAX ) unresolved
2JBX ) -35.9
2JAB ) 303.7
135b
CDCl3
-58
C6D6
CD2Cl2
CD2Cl2
20
20
-66
145b
2JAX ) unresolved
2JBX ) -35.8
2JAB ) 300.4
a Data taken from ref 21. b Tripletlike pattern; J value indicates line spacing. The δB of the AB2 pattern observed at 20 °C appears as a very
broad resonance between 50-60 in all cases. c Data taken from ref 7.
The two mutually trans basal PPh3 ligands in 1 are equivalent
in solution even at -97 °C as evidenced by the AX2 pattern
simulated in Figure 3a. However, in the solid state the two
basal P-atoms are inequivalent as evidenced by both the ABX
pattern observed in the 31P CP/MAS (TOSS) NMR spectrum
(Figure 3b) and the X-ray diffraction study performed by La
Placa and Ibers,17 one of the basal PPh3 ligands showing a weak
interaction between the Ru center and an ortho-phenyl hydrogen;
2
the JAB scalar coupling is 333 Hz for the trans-disposed
phosphines.
The move of the solid-state chemical shifts to higher field
relative to the solution values implies increased shielding in
the solid state, particularly for the resonance at 16.9 ppm
designated as δA. Such chemical shift differences between the
solid-state CP/MAS and solution NMR data have been observed
for other compounds, including tertiary phosphines and their
transition metal complexes.25-32 Differences of e 5-6 ppm are
common, and the compounds are still considered to possess
similar structures in solution and in the solid state, at least
qualitatively.25-32 Larger chemical shift differences are often
considered a manifestation of major structural differences.26 The
highest-field signal observed at δ 16.9 in the 31P CP/MAS NMR
spectrum of 1 is attributed to the basal PPh3 with a longer Ru-P
bond (2.412 Å17). The other upfield resonance of 1 at δ 22.8
corresponds to the basal P atom that is not involved in the ortho-
phenyl hydrogen-Ru interaction (the Ru-P bond length is
(24) Dixon, W. T.; Schaefer, J.; Sefcik, M. D.; Stejskal, E. O.; McKay, R.
A. J. Magn. Reson. 1982, 49, 341.
(25) Diesveld, G. E.; Menger, E. M.; Edzes, H. T.; Veeman, W. S. J. Am.
Chem. Soc. 1980, 102, 7935.
(26) Maciel, G. E.; O’Donnel, D. J.; Greaves, R. AdV. Chem. Ser. 1982,
196, 389.
Figure 3. (a) Simulated solution NMR spectrum of RuCl2(PPh3)3 (1)
obtained using the literature data,21 with the expansion shown inset.
(b) 80.99 MHz 31P CP/MAS NMR (TOSS) spectrum of 1.
(27) Bemi, L.; Clark, H. C.; Davies, J. A.; Fyfe, C. A.; Wasylishen, R. E.
J. Am. Chem. Soc. 1982, 104, 438.
(28) Bemi, L.; Clark, H. C.; Davies, J. A.; Drexler, D.; Fyfe, C. A.;
Wasylishen, R. E. J. Organomet.Chem. 1982, 224, C5.
(29) Clark, H. C.; Davies, J. A.; Fyfe, C. A.; Hayes, P. J.; Wasylishen, R.
E. Organometallics 1983, 2, 177.
(30) Fyfe, C. A.; Clark, H. C.; Davies, J. A.; Hayes, P. J.; Wasylishen, R.
E. J. Am. Chem. Soc. 1983, 105, 6577.
(31) Kroto, H. W.; Klein, S. I.; Meidine, M. F.; Nixon, J. F.; Harris, R.
K.; Packer, K. J.; Reams, P. J. Organomet. Chem. 1985, 280, 281.
(32) Komoroski, R. A.; Magistro, A. J.; Nicholas, P. P. Inorg. Chem. 1986,
25, 3917.
4 show simulated solution 31P, and 31P CP/MAS (TOSS ) TOtal
Suppression of Sidebands)24 NMR spectra of 1 and 4, respec-
tively. Table 3 lists the low-temperature 31P{1H} NMR solution
data used for the simulations illustrated in Figures 3 and 4, as
well as for 5 and 6; Table 4 lists the 31P CP/MAS NMR data
for 1 and 4.

Ruthenium(II) Phosphine Complexes
Inorganic Chemistry, Vol. 35, No. 25, 1996 7309
Å for the PPh3 systems). The difference of 52.7 ppm between
the apical and the averaged basal phosphorus chemical shifts
in the 31P CP/MAS NMR spectrum is close to the 51.6 ppm
difference observed in the solution spectrum.
The solid-state 31P CP/MAS (TOSS) NMR spectrum of RuCl2-
(dppb)(PPh3) (4) exhibits an ABX pattern similar to that
observed in the low-temperature solution NMR spectrum (see
Figure 4). The solid-state chemical shifts correspond well with
the solution parameters (Tables 3 and 4). The shift of ∼3-4
ppm in the CP/MAS NMR resonances toward lower field
relative to the solution values indicates reduced shielding of
the P nuclei in the solid state, opposite to the behavior observed
for RuCl2(PPh3)3; see above (Tables 3 and 4). The high field
2
AB quartet centered at δ 34.8 with a JAB scalar coupling 320
Hz again indicates trans-disposed inequivalent phosphines. This
320 Hz value is somewhat greater than the corresponding
solution phase coupling of 302.4 Hz, suggesting the presence
of additional constraints and interactions in the solid state which
may not exist, or are averaged out, in solution. The downfield
signal at δ 86.3 is assigned to an apical P atom and, because of
the forced cis configuration of the chelating dppb ligand, the
apical phosphine must be part of the diphosphine. Again, the
2
2
cis P-Ru-P couplings, JAX and JBX, cannot be seen in the
CP/MAS NMR spectrum because their magnitudes are much
smaller than the typical line widths encountered in solid-state
NMR spectra (ω1/2 ∼ 50-100 Hz).
The resonances at 30.4 (δA) and 39.2 (δB) are assigned to
the PPh3 ligand and the basal -PPh2 part of the dppb chelate,
respectively, on the basis of the results of a nonquaternary
suppression (NQS) experiment,35 in which only the peaks due
to P atoms attached to a nonquaternary carbon are suppressed
(presumably because of relatively fast relaxation of the P nucleus
by the protons on the nonquaternary carbon). The NQS
spectrum in Figure 4 shows considerable loss of intensity for
the resonances at δ 86.3 and 39.2, the signals which are due to
P nuclei attached to a nonquaternary carbon (i.e., the alkyl chain
of dppb). The unaffected resonance at δ 30.4 is therefore
assigned to the PPh3 ligand containing three P-phenyl (quater-
nary carbon) linkages. The similarities between the solution
and the solid-state NMR data for RuCl2(dppb)(PPh3) suggest
very similar solution (at least at low temperature) and solid-
state structures.
Figure 4. (a) Simulated solution NMR spectrum of RuCl2(dppb)(PPh3)
(4) obtained using the literature data,7 with the expansion shown inset.
(b) 80.99 MHz 31P CP/MAS NMR (TOSS) spectrum of 4. (c) Spectrum
as in (b) but showing nonquaternary suppression (NQS) with a dipolar
dephasing of 303 µs.
Table 4. Solid-State 31P CP/MAS NMR Spectral Data for
RuCl2(PPh3)3 (1) and RuCl2(dppb)(PPh3) (4)
1
Recently, J(101,99Ru,31P) coupling in 31P CP/MAS spectra
chem shift, δ
of Ru/phosphorus-containing complexes has been observed with
1J(99Ru,31P) values ranging from 100 to 174 Hz for the Ru-
phosphine and -phosphido interactions.36 No P-Ru coupling
was observed in the 31P CP/MAS NMR spectrum in the present
study, although the downfield signal in Figure 4b does show
an approximate six-line satellite as expected for coupling to a
nucleus of spin I ) 5/2 (i.e., 101,99Ru); however, closer inspection
suggests that the lines are due to incomplete suppression of
spinning sidebands which coincidentally at this spinning rate
(3.5 kHz) superimpose on the downfield signal.
Reactivity of RuCl2(dppb)(PPh3) and the Preparation of
(P-P)Cl2Ru(µ2-P-P)RuCl2(P-P) Complexes. The reactivity
of the five-coordinate mixed-phosphine complexes with neutral
two-electron donor ligands was investigated in attempts to isolate
Ru(II) complexes containing a single dppb ligand per Ru. It is
desirable to remove the PPh3 ligand from the Ru(II) complexes
for their potential use as hydrogenation catalysts, because work
from this laboratory on imine hydrogenation has shown RuCl2-
(P-P)(PPh3) species to be relatively poor catalysts compared
complex
(assgnt) (2JPP, Hz)
RuCl2(PPh3)3 (1)
(ABX pattern)
RuCl2(dppb)(PPh3) (4) 30.4 (PA)
(ABX pattern)
16.9 (PA)
22.8 (PB)
72.5 (PX)
86.3 (Px)
(2JAB ) 333)
39.2 (PB)
(2JAB ) 320)
2.374 Å17). These assignments are based on an established
empirical linear correlation between the crystallographically
determined Ru-P distances in a series of Ru(II)-PPh3 com-
plexes and the corresponding 31P chemical shifts observed in
solution, the chemical shifts becoming more high field with
increasing Ru-P bond lengths.33 This trend in 31P chemical
shift with Ru-P bond length has also been observed for Ru-
(II)-dppb complexes.34 Of note, the negative slope (-2.91 ×
10-3 Å ppm-1) for the graph of Ru-P bond length versus 31P
chemical shift for the Ru(II)-dppb complexes34 is identical to
that of the plot for the PPh3 systems;33 however, the intercepts
are somewhat different (2.423 Å for the dppb systems and 2.465
(33) Jessop, P. G.; Rettig, S. J.; Lee, C.-L.; James, B. R. Inorg. Chem.
1991, 30, 4617.
(35) Opella, S. J.; Frey, M. H. J. Am. Chem. Soc. 1979, 101, 5854.
(36) Eichele, K.; Wasylishen, R. E.; Corrigan, J. F.; Doherty, S.; Sun, Y.;
Carty, A. J. Inorg. Chem. 1993, 32, 121.
(34) MacFarlane, K. S. Ph.D. Thesis, The University of British Columbia,
1995.

7310 Inorganic Chemistry, Vol. 35, No. 25, 1996
MacFarlane et al.
Table 5. 31P{1H} NMR Data (121.42 MHz, 20 °C) for the
Dinuclear Complexes [(L)(dppb)Ru(µ-Cl)3RuCl(dppb)]
8-11 in high yield. This route to 8 is cleaner than the original
route from cis-RuCl2(dmso)4, which required removal of the
side products, [RuCl(dppb)]2(µ-Cl)2 and Ru2Cl4(dppb)3, before
isolation of the product;2 the S-bonded dmso, indicated by the
complex
dmso, Me2SOa
(8)
solvent
CDCl3
chem shift, δ
2JPP, Hz
δA ) 54.2, δB ) 51.2
δC ) 42.2, δD ) 29.5
δA ) 53.9, δB ) 52.9
δC ) 42.5, δD ) 33.7
δA ) 54.7, δB ) 50.8
δC ) 43.4, δD ) 26.3
δA ) 55.1, δB ) 52.2
δC ) 44.2, δD ) 29.1
δA,B ) 51.3b
42.8
30.2
43.8
29.6
41.1
27.8
42.8
29.0
ν
SO value, was confirmed by an X-ray study.2 Complex 8 was
C6D6
not formed by reacting Ru2Cl4(dppb)3 with excess dmso.
The Ru2Cl4(dppb)2(L) species, where L ) dmso, tmso, dms,
or tht, have structure I as evidenced by 31P{1H} NMR
tmso, C4H8SO
(9)
CDCl3
C6D6
L ) dms, Me2S
(10)
CDCl3
C6D6
δC ) 48.2, δD ) 46.0
δA ) 52.5, δB ) 51.8
δC ) 48.6, δD ) 46.2
δA ) 51.9, δB ) 51.2
δC ) 49.1, δD ) 46.7
δA,B ) 52.3a
35.6
44.1
35.3
43.2
36.1
tht, C4H8S
(11)
CDCl3
C6D6
spectroscopy (Table 5). Each of the complexes 8-11 shows
spectra consisting of two independent AB patterns of equal
integral intensity as observed previously for other triply-chloro-
bridged diruthenium complexes.2 Of the two AB quartet
patterns, the relatively downfield pattern is insensitive to the
δC ) 49.5, δD ) 47.1
36.1
a The chemical shifts differ slightly from those given in the literature2
because of the differences in the methods of referencing. b Indicates
unresolved AB pattern.
2
nature of ligand L (δAB ) 52 ( 2, JAB ) 43 ( 2 Hz) and is
therefore assigned as shown to the (µ-Cl)3RuCl(P-P) portion
of the molecule; the other set of signals varies with the nature
of L (δCD ) 26-49, 2JCD ) 28-36 Hz) and is attributed to the
L(P-P)Ru fragment. Occasionally, one of the two AB quar-
tets (the δAB end) is not resolved in a certain solvent and
appears as a broad singlet, as for 10 in CDCl3 and 11 in C6D6,
the spectra showing strong second-order effects (see Table 5).
The greater difference in the chemical shift between the two
halves of the AB pattern in C6D6 (10) or CDCl3 (11) may
prevent averaging of the signals. It is worth noting that the
spectra of complexes 10 and 11 are resolved in “opposite”
solvents. The second-order effects have been previously
observed for Ru2Cl4(dppb)2(PhCN) in CD2Cl2; if the solution
of the nitrile complex is cooled to -40 °C, the singlet observed
in the 31P{1H} NMR spectrum at rt begins to resolve into a
tight AB pattern.40
with Ru2Cl4(P-P)2 complexes.1 Recall that, in solution, the
mixed-phosphine complexes RuCl2(P-P)(PPh3) are in equilib-
rium with the dinuclear Ru2Cl4(P-P)2 species (see eq 1).
Occasionally, in the preparation of 4 or 5, a bridged-phosphine
side product (dppb)Cl2Ru(µ2-dppb)RuCl2(dppb) is isolated.2,7
This species can be prepared in good yields by addition of 2
equiv of dppb to RuCl2(PPh3)3 (1).37 Although the phosphine-
bridged, bromo-analog (dppb)Br2Ru(µ2-dppb)RuBr2(dppb) was
not observed as a side product in the preparation of 6, it was
isolated in this work by the addition of 2 equiv of dppb to 2.
The complex 7a has properties similar to those of the previously
reported chloro analog,37 being essentially insoluble in most
nonaromatic solvents and only sparingly soluble in aromatic
solvents. Also prepared by the same method is (dcypb)Cl2Ru-
(µ2-dcypb)RuCl2(dcypb) (7b). The mixed-phosphine complex
RuCl2(dcypb)(PPh3) has been observed in solution [-70 °C,
CD2Cl2, δA ) 17.1, δB ) 24.1, δX ) 88.0; 2JAB ) 303.7, 2JAX
The IR spectrum of 9 shows νSdO at 1093 cm-1 indicating
that the coordinated tmso is S-bonded as previously confirmed
for 8 by X-ray crystallography.2
2
and JBX are unresolved] but has not yet been isolated as it is
Conclusions. This study has demonstrated the utility of 31
P
very soluble in most common organic solvents. Despite the
insolubility of the bridged-phosphine complexes, they still can
be useful as starting materials (e.g., for synthesis of RuCl2-
(dppb)(py)2 (py ) pyridine)38). The corresponding bridged (R)-
binap (2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) analog could
not be prepared by addition of 2 equiv of the diphosphine to
RuCl2(PPh3)3 as used to prepare 7a,b. The binap ligand is
presumably too rigid to effectively bridge two metals.
Work from this laboratory has previously reported on the
preparation from RuCl2(dppb)(PPh3) of the complexes Ru2Cl4-
(dppb)2(L), where L ) CO,2 NEt3,2 MeCN,39 and PhCH2NH2,40
while Ru2Cl4(dppb)2(dmso) (8) was prepared from cis-
RuCl2(dmso)4.2 Other dinuclear Ru2Cl4(dppb)2(L) species (L
) η2-H2, N2, and Me2CO) were prepared directly from the air-
sensitive dimer [RuCl(dppb)]2(µ-Cl)2.2
CP/MAS NMR spectroscopy in determining the geometry and
structure of Ru(II) phosphine complexes, and the solid-state
structure suggested by 31P CP/MAS NMR was confirmed by
X-ray crystallography in the case of RuCl2(dppb)(PPh3). 31P
CP/MAS NMR spectroscopy offers an obvious advantage over
solution 31P NMR spectroscopy where the spectra can sometimes
be complicated by exchange processes. The utility of the
complex RuCl2(dppb)(PPh3) as a precursor for the preparation
of [(L)(dppb)Ru(µ-Cl)3RuCl(dppb)] species is further estab-
lished.
Acknowledgment. We thank the Natural Sciences and
Engineering Research Council of Canada for financial support,
Johnson Matthey Ltd. and Colonial Metals Inc. for the generous
loan of RuCl3‚xH2O, and Dr. A. Root for experimental assistance
in performing the solid-state 31P CP/MAS NMR spectroscopic
experiments.
The reactions of dmso, tmso, dms, and tht with 4 have now
been found to give the corresponding Ru2Cl4(dppb)2(L) species
Supporting Information Available: Tables of atomic coordinates
and equivalent isotropic thermal parameters, hydrogen atom parameters,
anisotropic thermal parameters, complete bond lengths and angles, and
torsion angles for the structures of 2 and 4 (40 pages). Ordering
information is given on any current masthead page.
(37) (a) Bressan, M.; Rigo, P. Inorg. Chem. 1975, 14, 2286. (b) James,
B. R.; McMillan, R. S.; Morris, R. H.; Wang, D. K. W. AdV. Chem.
Ser. 1978, 167, 123.
(38) Batista, A. A.; Queiroz, S. L.; Oliva, G.; Gambardella, M. T. do. P.;
Santos, R. H. A. Personal communication.
(39) Fogg, D. E.; James, B. R. Inorg. Chem., submitted for publication.
(40) Fogg, D. E.; James, B. R. Inorg. Chem. 1995, 34, 2557.
IC960860+