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Ruthenium (II) halide dimethylsulphoxide complexes from hydrogenation reactions
INORG.
NUCL.
CHEM.
LETTERS
Vol. 7, pp. 781-784, 1971.
Persamon Press.
Printed
in
Great
Br/tain.
RUTHENIUM (II) t l A L I D E DIMETHYLSULPHOXIDE COMPLEXES FROM RYDROGENATION REACTIONS
B.R. James,a E. Ochiai a and G.L. Rempel b, aDepartment of Chemistry, University of British Columbia, Vancouver, British Columbia, and bDepartment of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada. (Raceived3 May1971)
Our studies on the catalytic hydrogenation properties of ruthenium halldes in a variety of solvents (I) has led us to the simple preparation of ruthenium (II) halide complexes containing coordinated dlmethylsnlphoxlde, e.g. RuCI2(DMSO) 4.
This compound is air-stable and undergoes only very slow
air-oxidation i n DMSO solutions from which it is isolated; this contrasts with the air-susceptibillty
of most ruthenium (II) complexes, and the DMSO
complexes appear useful as sources of ruthenium (II).
The preparation of a
RuCI3(DMSO) 3 complex has been reported recently (2). 3 g. RuCI3, 3H20 (Johnson Matthey Ltd.) was dissolved in 50 ml DMSO and hydrogen was bubbled through in the absence of air at 80 ° for 20 hr. The yellow crystalline material ~ i c h
deposited out was collected, washed
with benzene and dried under nitrogen (crude yield 3.8 g.). tion was effected from benzene-DMSO solution. CI 14,58%; calculated for RuCI2(C2H6SO)4:
Analysis: C 19.88%, H 4.97%,
C 19.84%, H 4.99%, CI 14.64%.
molar conductance of the compound in DMSO was 0.75 mho cm ing it to be a non-electrolyte c__a__.190@ without melting.
Recrystalllza-
in this medium.
The
-2 -i s at 20 °, show-
Ale compound decomposes at
The electronic spectrum in DMSO (in vaeuo) is:
~max(E), 361 nm (520), 316 nm (360) and 267 nm (1010). The infrared spectrum (KBr and nuJol) shows a strong band with splittlng at 1100-1120 cm
-1
and strong bands at 1023 and 991 cm
781
-1
; medium to
782
RUTHENIUM 01) HALIDE DIMETHYL~IJLPHOXIDE
Vol. 7, No. g
strong bands at 960 and 930 cm-l; and four weak to medium bands at 480, 420, 380 and 345 cm -I.
The band at 1100-1120 cm -I,'. which is higher than VSO
in free DMS0 (1055 cm -I) can be attributed to S coordination the bands in the 930-1023 cm
-i
(3).
Some of
region might correspond to ~SO for oxygen-
bonded DMSO but this region is complicated by the presence of methyl rocking modes~ however, the complexity in the region of the S-O stretch does suggest the coexistence of both S- and O-coordinated species Pd(DMSO)~+almost
llgands.
The cationic
certainly contains mixed sulphur and oxygen
coordination sites (4), and on comparison with the i.r. of that complex we tentatlvely assign the 1023 and 991 cm -I bands to oxygen-bonded DMSO and the 960 and 930 cm -1 to ~CH 3, On comparison with an analogous RuBr2(DMSO) 4 complex (see below)~ the i.r. band at 345 cm -I can probably be assigned to Ru-CI stretching; this appears to be a single band indicating a trans structure for Ehe complex but we have not yet been able to obtain a too well-resolved fau-i.r. spectrum.
The investigation of further details of the structure is in pro-
gress; preparation of the DMSO-d 6 complex will help resolve the ~SO (oxygenbonded) region, Other ruthenium (II) complexes containing DMSO are known.
The
catlonic species [Ru(NH3)5(DMSO)]2+ has sn VSO band at 1042 cm -I and it wa~ suggested that this indicated bonding via the S atom (5); a complex (C6H6) RuCI2(DMSO), possible dimerlc, was stated to have bands at ii00 and I025cm-i(6). The rate Of air oxidation of RuCI2(DMSO) 4 to ruthenium (Ill) in DMSO is in the order of days at room temperature. The compound is fairly inert to / substitution in DMSO and reaction with bromide, thlocyanate or 2,2'-bipyridyl was not observed at an appreciable rate at room temperature.
Aquation occurs
readily in aqueous solution. The amount of hydrogen required for the preparative procedure was measured and showed the overall stoichiometry Ru(lll) + 1/2 H 2 ~
~ Ru(ll) + H +
(7): [i]
RUTHENIUM (H) HALIDE I N M ~ P H O X I D E
Vol. 7, No. 8
783
The hydrogen reduction is quite different to that observed i n dimethylacetamide (DMA) solution where further reduction to ruthenium (I) occurs (8); further, this system has yielded quite different complexes which appear to he protonated species of empirical formulae H[RulIcI3(DMA)] and H[Ru~C13 (DMA)] (9). These species also act as homogeneous hydrogenation catalysts for the reduction of olefinlc substrates (8), while the coordinatively saturated RuCI2(DMSO) 4 is inactive. Reactions such as [i] are of interest in that they must involve hydride intermediates (l)~ the reaction in DMSO shows a first order dependence on ruthenium and an unusual second order in hydrogen, again in contrast to the DMA system (8).
We are currently pursuing these mechanistic studies;
a possible interpretation lles in an initial reaction of a dimeric ruthenium (III) with 2 moles of hydrogen, e.g., Rulll 2
+ 2R2
) 2[RuVH 2] ---> 2RulIIH- + 2H+
[2]
RuBr3(Platinum Chemicals) was also reduced by hydrogen in DMSO to yield analogous yellow crystals of RuBr2(DMSO) 4.
The hydrogenation rate
was much faster than for the chloride and this is due in part t e a
competing
hydrogenation of the solvent to dlmethylsulphide catalyzed by the trlbromide. The same reaction is known to be catalyzed by rhodium (III) chloride complexes
(10). Grateful acknowledgement is made to the National Research Council of Canada and to the Universities of British Columbia and Waterloo for support of this research, an4 to Johnson Matthey Limited for the loan of ruthenium.
References l.
B.R. James, Inorg. Chim. Acta Rev., ~, 73 (1970).
2.
J.D. Gilbert, D. Rose and G. Wilkinson, J.Chem. Soc., A, 2765 (1970).
3.
For example, W.Kitch!ng, C.J. Moore and D. Doddrell, Inorg.Cbem.,9,541(1970)
4.
B.B. Wayland and R.F. Schramm, Inorg. Chem., 8, 971 (1969).
784
5,
RUTHENIUM (!I) HAL/DE i ~ M E ~ P H O X I D E
Vol. 7, No. 8
A.D.AIIen,F. Bottomley, R.O.Harris, V.P. Reinsalu and C.V, Senoff, J. Amer. Chem. Soc., 89, 5595 (1967).
6.
I. Ogat~, R.lwata and Y. Ikeda, Tetrahedron Letters, 3011 (1970).
7.
The ruthenium (IV) present in RuCI 3, 3H20 is rapidly converted to ruthenium (III) under these conditions (cf. J.F. Harrod, S. Ciceone and J. Halpern, Can. J. Chem., 39, 1372 (1961).
8.
B.C. Hui and B.R. James, Chem. Commun., 198 (1969).
9.
B.R. James and E. Ochiai, to be published.
i0.
B.R. James, F.T.T. Ng and G.L. Rempel, Can. J. Chem., 47, 4521 (1969).
NUCL.
CHEM.
LETTERS
Vol. 7, pp. 781-784, 1971.
Persamon Press.
Printed
in
Great
Br/tain.
RUTHENIUM (II) t l A L I D E DIMETHYLSULPHOXIDE COMPLEXES FROM RYDROGENATION REACTIONS
B.R. James,a E. Ochiai a and G.L. Rempel b, aDepartment of Chemistry, University of British Columbia, Vancouver, British Columbia, and bDepartment of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada. (Raceived3 May1971)
Our studies on the catalytic hydrogenation properties of ruthenium halldes in a variety of solvents (I) has led us to the simple preparation of ruthenium (II) halide complexes containing coordinated dlmethylsnlphoxlde, e.g. RuCI2(DMSO) 4.
This compound is air-stable and undergoes only very slow
air-oxidation i n DMSO solutions from which it is isolated; this contrasts with the air-susceptibillty
of most ruthenium (II) complexes, and the DMSO
complexes appear useful as sources of ruthenium (II).
The preparation of a
RuCI3(DMSO) 3 complex has been reported recently (2). 3 g. RuCI3, 3H20 (Johnson Matthey Ltd.) was dissolved in 50 ml DMSO and hydrogen was bubbled through in the absence of air at 80 ° for 20 hr. The yellow crystalline material ~ i c h
deposited out was collected, washed
with benzene and dried under nitrogen (crude yield 3.8 g.). tion was effected from benzene-DMSO solution. CI 14,58%; calculated for RuCI2(C2H6SO)4:
Analysis: C 19.88%, H 4.97%,
C 19.84%, H 4.99%, CI 14.64%.
molar conductance of the compound in DMSO was 0.75 mho cm ing it to be a non-electrolyte c__a__.190@ without melting.
Recrystalllza-
in this medium.
The
-2 -i s at 20 °, show-
Ale compound decomposes at
The electronic spectrum in DMSO (in vaeuo) is:
~max(E), 361 nm (520), 316 nm (360) and 267 nm (1010). The infrared spectrum (KBr and nuJol) shows a strong band with splittlng at 1100-1120 cm
-1
and strong bands at 1023 and 991 cm
781
-1
; medium to
782
RUTHENIUM 01) HALIDE DIMETHYL~IJLPHOXIDE
Vol. 7, No. g
strong bands at 960 and 930 cm-l; and four weak to medium bands at 480, 420, 380 and 345 cm -I.
The band at 1100-1120 cm -I,'. which is higher than VSO
in free DMS0 (1055 cm -I) can be attributed to S coordination the bands in the 930-1023 cm
-i
(3).
Some of
region might correspond to ~SO for oxygen-
bonded DMSO but this region is complicated by the presence of methyl rocking modes~ however, the complexity in the region of the S-O stretch does suggest the coexistence of both S- and O-coordinated species Pd(DMSO)~+almost
llgands.
The cationic
certainly contains mixed sulphur and oxygen
coordination sites (4), and on comparison with the i.r. of that complex we tentatlvely assign the 1023 and 991 cm -I bands to oxygen-bonded DMSO and the 960 and 930 cm -1 to ~CH 3, On comparison with an analogous RuBr2(DMSO) 4 complex (see below)~ the i.r. band at 345 cm -I can probably be assigned to Ru-CI stretching; this appears to be a single band indicating a trans structure for Ehe complex but we have not yet been able to obtain a too well-resolved fau-i.r. spectrum.
The investigation of further details of the structure is in pro-
gress; preparation of the DMSO-d 6 complex will help resolve the ~SO (oxygenbonded) region, Other ruthenium (II) complexes containing DMSO are known.
The
catlonic species [Ru(NH3)5(DMSO)]2+ has sn VSO band at 1042 cm -I and it wa~ suggested that this indicated bonding via the S atom (5); a complex (C6H6) RuCI2(DMSO), possible dimerlc, was stated to have bands at ii00 and I025cm-i(6). The rate Of air oxidation of RuCI2(DMSO) 4 to ruthenium (Ill) in DMSO is in the order of days at room temperature. The compound is fairly inert to / substitution in DMSO and reaction with bromide, thlocyanate or 2,2'-bipyridyl was not observed at an appreciable rate at room temperature.
Aquation occurs
readily in aqueous solution. The amount of hydrogen required for the preparative procedure was measured and showed the overall stoichiometry Ru(lll) + 1/2 H 2 ~
~ Ru(ll) + H +
(7): [i]
RUTHENIUM (H) HALIDE I N M ~ P H O X I D E
Vol. 7, No. 8
783
The hydrogen reduction is quite different to that observed i n dimethylacetamide (DMA) solution where further reduction to ruthenium (I) occurs (8); further, this system has yielded quite different complexes which appear to he protonated species of empirical formulae H[RulIcI3(DMA)] and H[Ru~C13 (DMA)] (9). These species also act as homogeneous hydrogenation catalysts for the reduction of olefinlc substrates (8), while the coordinatively saturated RuCI2(DMSO) 4 is inactive. Reactions such as [i] are of interest in that they must involve hydride intermediates (l)~ the reaction in DMSO shows a first order dependence on ruthenium and an unusual second order in hydrogen, again in contrast to the DMA system (8).
We are currently pursuing these mechanistic studies;
a possible interpretation lles in an initial reaction of a dimeric ruthenium (III) with 2 moles of hydrogen, e.g., Rulll 2
+ 2R2
) 2[RuVH 2] ---> 2RulIIH- + 2H+
[2]
RuBr3(Platinum Chemicals) was also reduced by hydrogen in DMSO to yield analogous yellow crystals of RuBr2(DMSO) 4.
The hydrogenation rate
was much faster than for the chloride and this is due in part t e a
competing
hydrogenation of the solvent to dlmethylsulphide catalyzed by the trlbromide. The same reaction is known to be catalyzed by rhodium (III) chloride complexes
(10). Grateful acknowledgement is made to the National Research Council of Canada and to the Universities of British Columbia and Waterloo for support of this research, an4 to Johnson Matthey Limited for the loan of ruthenium.
References l.
B.R. James, Inorg. Chim. Acta Rev., ~, 73 (1970).
2.
J.D. Gilbert, D. Rose and G. Wilkinson, J.Chem. Soc., A, 2765 (1970).
3.
For example, W.Kitch!ng, C.J. Moore and D. Doddrell, Inorg.Cbem.,9,541(1970)
4.
B.B. Wayland and R.F. Schramm, Inorg. Chem., 8, 971 (1969).
784
5,
RUTHENIUM (!I) HAL/DE i ~ M E ~ P H O X I D E
Vol. 7, No. 8
A.D.AIIen,F. Bottomley, R.O.Harris, V.P. Reinsalu and C.V, Senoff, J. Amer. Chem. Soc., 89, 5595 (1967).
6.
I. Ogat~, R.lwata and Y. Ikeda, Tetrahedron Letters, 3011 (1970).
7.
The ruthenium (IV) present in RuCI 3, 3H20 is rapidly converted to ruthenium (III) under these conditions (cf. J.F. Harrod, S. Ciceone and J. Halpern, Can. J. Chem., 39, 1372 (1961).
8.
B.C. Hui and B.R. James, Chem. Commun., 198 (1969).
9.
B.R. James and E. Ochiai, to be published.
i0.
B.R. James, F.T.T. Ng and G.L. Rempel, Can. J. Chem., 47, 4521 (1969).