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Formation of heterobimetallic ruthenium-mercury nitrosyl complexes
Polyhedron Vol. 10, No. 10, pp. 101~1017, Printed in Great Britain
1991 0
0277-5387/91 %3.00+.00 1991 Pergamon Press plc
FORMATION OF HETEROBIMETALLIC RUTHENIUMMERCURY NITROSYL COMPLEXES LORETO
BALLESTER-REVENTOS,* ANGEL GUTIERREZ-ALONSO MARIA FELISA PERPINAN-VIELBA
and
Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, 28040-Madrid, Spain (Received
13 June 1990 ; accepted 7 January 199 1)
Abstract-The nitrosyl ruthenium complexes [RuCl(CO)(NO)(PPh,),] and [Ru(NO),(PR,)*] (R = Ph, CH$HJN) react with an excess of mercury salts, HgX,, to give the first nitrosyl ruthenium complexes containing ruthenium-mercury bonds. The reactions take place with substitution of one or more ligands in the parent compound and cis addition of the X and HgX groups.
One of the reactions most extensively used in the synthesis of heterobimetallic transition compounds is the addition of a mercury(I1) compound to an electron-rich metal complex.’ The usual reaction implies an adduct type interaction with formation, in some cases, of the oxidative addition product.* There are very few examples of bimetallic ruthenium-mercury compounds, the majority being adduct type complexes, for example [Ru (&H,), * HgC1,13 and [RuC12(PPh3)3* HgC12].4 Even more scarce are the oxidative addition complexes and only the mononuclear carbonyls [Ru(CF,)
(HgCF3)(CO),(PPh3)215 and VWWW)W)3 (PR,)] are known.6 The unstable derivative [RuCl,(HgCl)(NO) (PPh,),] has also been reported as an unisolated intermediate in the reaction between [RuCl(CO) (NO)(PPh,),] and HgC1,.7 The analogous osmium complex is, however, known.8 We report now the isolation and characterization of the first ruthenium-mercury bimetallic nitrosyls, obtained by oxidative addition of mercury salts to ruthenium nitrosyl derivatives. RESULTS AND DISCUSSION Reactions of[RuCl(CO)(NO)(PPh,),]
The reaction between [RuCl(CO)(NO)(PPh,)J and excess HgIz leads to an orange-brown solid of
* Author to whom correspondence
should be addressed.
formula [RuCl(I)(HgI)(CO)(NO)(PPh,)l (I). The IR spectrum of which (Table 1) shows increases of 43 and 268 cm-’ in the v(C0) and v(N0) bands, respectively, relative to the starting material and indicative of oxidation. This oxidation is not localized over the metal, with a formal oxidation state of +2 in both cases, but over the [RuNO] system which is oxidized from [RuNO]‘, with a bent nitrosyl (NO-) in the starting material,’ to [RuN016, with a linear nitrosyl (NO+) in the reaction product. Using Hg(SCN)2 a similar reaction takes place and together with the addition of the mercuric salt, substitution of the halogen by thiocyanate is also observed, with formation of [Ru(SCN),(HgSCN) (CO)(NO)(PPh,)] (II). Its IR spectrum shows that the carbonyl and nitrosyl bands shift to higher frequencies due to oxidation. There are also two bands at 2100 and 2130 cm-’ due to the v(CN) stretch of two different thiocyanates, which could be those bonded to mercury and ruthenium. The 3’P NMR spectrum in DMSO for this compound shows one single signal at 25.4 ppm with satellites due to the ‘99Hg-31Pcoupling. The coupling constant of 850 Hz is higher than the values reported in the literature,” supporting a tram arrangement of the Hg(SCN) and PPh3 groups in the molecule. As the nitrosyl and carbonyl ligands both have a high tram influence, it is unlikely that these groups are opposite in the molecule and so the stereochemistry for complex II shown in Fig. 1(a) was proposed. The reaction between [RuCl(CO)(NO)(PPh,),]
1013
L. BALLESTER-REVENTOS
1014
et al.
Table 1. IR spectral data for the compounds obtained (cm- ‘) Compounds
v&N),,,,
V(CN),yanidev(CO) v(NO)
2100s 2130sh 2090s 2110sh 2087m
[RuCl(CN)(HgCN)(CO)(NO)(PPh,)l(III) [RuCl(CO)(NO)(PPh,),.Hg(CN)J(IV)
[WNOWPMJO’) 2240s
2250s
[Ru(SCN),(HgSCN)(NO)(tcep)](VIII)
2250s 2240s [RuCl,(HgPh)(NO)(PPh,)I(XII) [RuCl,(HgPh)(NO)(tcep)](XIII)
2250s
and Hg(CN)2 leads to different compounds depending on the solvent used. When the reaction takes place in dichloromethane-ethanol the complex [RuCl(CN)(Hg CN)(CO)(NO)(PPh,)] (III) is obtained. As is shown in Table 1, the IR spectrum is similar to those of complexes I and II, suggesting a similar structure. There are also two v(CN) stretches corresponding to two different cyanides. The insolubility of this complex and the ready decomposition that occurs in DMSO prevents the attainment of a good NMR spectrum, but as this complex is similar to the thiocyanate complex, a tvans configuration Hg-Ru-P is expected. By assuming a cis disposition of the carbonyl and nitrosyl ligands and according to the proposed mechanism for these reactions (see below), Fig. l(b) is suggested as the most likely stereochemistry for this complex. If the reaction occurs in ethanol a different compound of formula [RuCl(CO)(NO)(PPh,), F;Ph,
rPh3
NCS\I AC0
“\~“/No
NCS+NO
NC/I
i&SCN
(a)
\CO ;IgCN
(b)
Fig. 1. Proposed structures for complexes (a)11 and (b)III.
2110s 2140s 2130s 2150s 2100s 2140sh 21OOs,br
‘@u--Cl)
1968s 2040s
1860s 1873s
321~
1993s
1895s
315w
1935s
1605s 1640s 1605s 1675s 1650s 1880s
280~
1894s 1867s 1870s 1862s 1844s 1869s
320m 270m 325m 320m
(Ru-Cl) (Hg-Cl)
Hg(CN),] (IV) is formed. The IR spectrum shows bands at 1935 cm-‘, v(CO), and 1605 cm-‘, v(NO), very close to those of the parent compound (1925 and 1592 cm-‘, respectively). This suggests a weak interaction between the metals, probably as an adduct complex where the oxidation state of the ruthenium is not sensibly modified, in contrast to the high shift observed in the oxidative addition complex. Complex IV undergoes conversion in solution to the oxidative addition derivative, III. This fact suggests that the adduct is an intermediate in the oxidative addition reaction and the proposed mechanism for this reaction is shown in Scheme 1. The formation of a similar intermediate has been proposed in the reaction of [RuCl,(CO),(PPh,),] with HgPh, to account for the formation of [RuCl(Ph)(CO),(PPh&] as the final product.” The ruthenium-mercury interaction in complex IV is assumed to be via pseudohalogen and chlorine bridges due to the low value of the v(Ru-Cl) stretch, about 40 cm-’ lower than a typical terminal Ru-Cl bond (for example in complex I, Table l), which appears to indicate that the chlorine is acting as a bridge between ruthenium and mercury. Nevertheless, other possible links, like direct bonds between the metals or a single bridge through the cyano group, cannot be excluded, as we have not enough evidence to choose one specific coordination mode.
Ruthenium-mercury
nitrosyl complexes
1015
NO
X
The tetrahedral complex [Ru(NO),(PPh,),] (V) reacts with excess HgX, with substitution of one nitrosyl and one phosphine and oxidation to formal ruthenium(I1) complexes of formula [RuX,(HgX)(NO)(PPh,)]. An exception to this behaviour is the reaction with Hg(SCN), which gives rise to the formation of [Ru(SCN)(HgSCN)2 (NO)(PPh,)] (VII), although this compound has several similarities with the rest of the complexes of the series. The complex [Ru(NO),(tcep)2] (VI) was obtained from B by phosphine substitution. The increase in the v(N0) band can be explained in terms of the lower basicity of tris-2-cyanoethylphosphine relative to triphenylphosphine.‘* Complexes VII-XIII show an increase of ca 250 cm-’ in the v(N0) stretch, indicative of a NO+ group in ruthenium(I1) complexes. Complex IX probably contains lattice Hg(CN), and the IR spectrum shows, for the three different M-CN bonds ofthecompound,twobandsat2100and2140cm.-’ Since complex X, containing only Ru-CN and Hg-CN bonds, has only one broad band at 2100 cm-’ which must include both stretches, the extra band in the IR of complex IX may be attributable to the lattice mercury cyanide. The high value of this frequency may indicate that the cyanides of these lattice molecules act as bridges, as in free Hg(CN)2 [v(CN) = 2195 cm-‘]. In the reaction of V with HgCl,, elimination of mercury and formation of [RuCl,(NO)(PPh,),] occurs, whereas complex VI produces [RuCI,(HgCl) (NO)(tcep)] (XI), with v(Ru-Cl) and v(Hg-Cl) at 320 and 270 cm-‘, respectively. In a similar manner, complex V reacts with ClHgPh to give a mixture of [RuCl,(NO)(PPh,),] and [RuCl, (HgPh)(NO)(PPh,)] (XII). Reaction of VI and ClHgPh affords the analogous complex XIII, whose IR spectrum shows only one v(Ru-Cl) band, suggesting a Cl-HgPh break in the addition reaction. The 13CNMR spectrum of XIII shows two signals for the cyanide (119.8 and 120.4 ppm) and for the methylene carbons (23.5 and 22.6, and 11.8
and 9.9 ppm) of the tcep, indicating different CH2CH2CN groups. This fact can be interpreted in terms of a restricted rotation of the phosphine. The phenyl signals appear slightly shifted to lower fields relative to free C1HgPh,13 as expected if HgPh acts as a Lewis acid. The ortho and meta carbons of this phenyl group show coupling to ‘99Hg of similar magnitude to that in the free ClHgPh, supporting the idea of the Cl-HgPh break and the addition of the Cl and HgPh groups to the ruthenium. Finally the “P NMR spectrum of this compound contains a septuplet at 29.6 ppm [‘J(P-H) = 11.5 Hz] with two satellites [*J(Hg-P) = 486 Hz], indicative of a tram Hg-Ru-P arrangement in the molecule. In contrast, the spectrum of XII contains the signal at 26.5 ppm with *J(Hg-P) = 101.8 Hz. This coupling appears to be smaller than those observed for tram dispositions and we cannot determine if mercury and phosphorus are mutually cis or tram in this compound.
EXPERIMENTAL All reactions were carried out under oxygenfree nitrogen. [RuC1(CO)(NO)(PPh3),J7 and [Ru (NOMPPh,M’4were synthesized by the published methods. IR spectra were recorded on KBr pellets using a Perkin-Elmer 1330 spectrophotometer. NMR spectra were recorded with a Bruker WP-8GSY relative to TMS (“C) and 85% [H3P04(3’P). Preparation of[RuCl(I)(HgI)(CO)(NO)(PPh3)]
(I)
A suspension of [RuCl(CO)(NO)(PPh,),] (0.36 g, 0.5 mmol) and Hg12 (0.67 g, 1.5 mmol) in ethanol (30 cm3) was refluxed for 2 h. The brown solution was filtered and the solvent removed in uacuo. The solid was extracted with dicholoromethane. Addition of diethyl ether gave a purple solid in 63% yield. Found: C, 23.9; H, 1.6; N, 1.6. Calc. : C, 25.0; H, 1.7; N, 1.5.
1016
Preparation
L. BALLESTER-REVENTOS of
[Ru(SCN),(HgSCN)(CO)(NO)
@‘WI (11) A mixture of [RuC1(CO)(NO)(PPh,),l] (0.36 g, 0.5 mmol) in dichloromethane (20 cm3) and Hg(SCN), (0.47 g, 1.5 mmol) in ethanol (20 cm-‘) was refluxed for 2 h. The orange-brown precipitate which formed was collected and washed with dichloromethane, ethanol and diethyl ether. Yield 87%. Found:C, 33.1;H, 1.8;N,7.2.Calc.:C,33.2;H, 1.9; N, 7.0.%
Preparation
of
[RuCl(CN)(HgCN)(CO)(NO)
W’hdl (III) To a solution of [RuCl(CO)(NO)(PPh,), (0.36 g, 0.5 mmol) in dichloromethane (15 cm3), a solution of Hg(CN)* (0.38 g, 1.5 mmol) in ethanol (20 cm’) was added and the mixture was stirred for 3 h. The solution, which became orange, was concentrated to 5 cm3 and then 20 cm3 of diethyl ether were added affording III as an orange precipitate. Yield 79%. Found: C, 35.6; H, 2.4; N, 6.0. Calc.: C, 35.5; H, 2.1 ; N, 5.9%.
Preparation
of [RuCl(CO)(NO)(PPh,),
* Hg(CN),]
(IV) A mixture of [RuC1(CO)(NO)(PPh,),l] (0.36 g, 0.5 mmol) and Hg(CN)* (0.25 g, 1.0 mmol) in ethanol was refluxed for 3 h. During this time the solid changed from green to orange-brown, then was filtered and washed with ethanol, dichloromethane and diethyl ether. Yield 60%. Found : C, 47.8 ; H, 3.2; N, 4.4. Calc.: C, 48.2; H, 3.1 ; N, 4.3%.
Preparation
of [Ru(NO)z(tcep)z] (VI)
A solution of [Ru(NO),(PPh,),] (3.45 g, 5 mmol) and tcep (2.85 g, 15 mmol) in toluene (50 cm3) was refluxed for 2 h. The solution changed from red to orange and a dark orange precipitate appeared. After cooling to room temperature, the solid was filtered, washed with toluene, ethanol and diethyl ether. Yield 77%. Found : C, 39.6 ; H. 4.4 ; N, 20.9. Calc.: C, 39.5; H, 4.4; N, 20.4%.
Preparation
of
[Ru(SCN)(HgSCN),(NO)(PPh,)l
(VII) A suspension of [Ru(NO),(PPh3)z] (0.35 g, 0.5 mmol) and Hg(SCN)* (0.48 g, 1.5 mmol) in ethanol was refluxed for 3 h. The ochre solid was collected, washed with ethanol, toluene and ethanol and
et al.
dried. Yield 84%. Found : C, 26.2 ; H, 1.6 ; N, 5.8. Calc.: C, 26.0; H, 1.6; N, 5.8%. The following complexes were prepared in a similar way using [Ru(NO),(PPh,),] or [Ru(NO),(tcep)2] and a 1: 3 excess of the appropriate mercury salt : [Ru(SCN),(HgSCN)(NO)(tcep)] (VIII) : brown solid ; yield 7 1%. Found : C, 20.4 ; H, 1.8 ; N, 14.0. Calc.: C, 20.6; H, 1.7; N, 14.0%. [Ru(CN),(HgCN)(No)(Pph,) *WdCWI (IX): ochre solid ; yield 69%. Found : C, 29.4 ; H, 1.7 ; N, 9.1. Calc.: C, 29.9; H, 1.6; N, 9.1%. [Ru(CN),(HgCN)(NO)(tcep)] (X) : brown solid ; yield 74%. Found : C, 23.5 ; H, 2.1 ; N, 16.4. Calc. : C, 23.9; H, 2.0; N, 16.3%. [RuCl,(HgCl)(NO)(tcep)] (XI) : yellow-orange solid; yield 58%. Found: C, 17.0; H, 2.0; N, 8.8. Calc.: C, 17.1 ; H, 1.9; N, 8.9%. [RuCl,(HgPh)(NO)(PPh,)1 (XII) : orange-brown solid ; yield 49%. Found : C, 38.9 ; H, 2.7 ; N, 2.2. Calc. : C, 40.4; H, 2.8; N, 2.0%. [RuCl,(HgPh)(NO)(tcep)] (XIII) : orange-brown solid; yield 76%. Found: C, 26.5; H, 2.5; N, 8.4. Calc.: C, 26.8; H, 2.5; N, 8.4%.
Acknowledgement-We thank the Comision Interministerial de Ciencia y Tecnologia (Project PS87-0028) for financial support.
REFERENCES 1. (a) R. W. Johnson, W. R. Muir and D. A. Sweigart, J. Chem. Sot., Chem. Commun. 1970, 643 ; (b) B. Deubzer and H. D. Kaesz, J. Am. Chem. Sot. 1968, 90,3276 ; (c) C. P. Carey, C. R. Cyr, R. L. Anderson and D. F. Marten, J. Am. Chem. Sot. 1975,97,3053. 2. (a) D. J. Cook, J. L. Dawes and R. D. W. Kemmitt, J. Chem. Sot. 1967, 1547 ; (b) I. W. Nowell and D. R. Russell, J. Chem. Sot., Dalton Trans. 1972,2393. 3. W. H. Morrison and D. N. Hendrickson, Znorg. Chem. 1972, 11,2912. 4. M. M. Taqui, S. Shareef, S. Vancheeson and R. A. Levenson, J. Znorg. Nucl. Chem. 1976, 38, 1279. 5. G. R. Clark, S. V. Hoskins and W. R. Roper, J. Organomet. Chem. 1982,234, C9. 6. M. I. Bruce, M. Cooke and M. Green, J. Organomet. Chem. 1968,13,227. 7. K. R. Laing and W. R. Roper, J. Chem. Sot. A 1970, 2149. 8. G. A. Bentley, K. R. Laing, W. R. Roper and J. M. Waters, J. Chem. Sot., Chem. Commun. 1970,998. 9. J. Mason, D. M. P. Mingos, J. Schaefer, D. Sherman and E. 0. Stejskal, J. Chem. Sot., Chem. Commun. 1985,444. 10. (a) M. M. Kubicki, R. Kergoat, J. Y. Le Gall, J. E. Guerchais, J. Douglade and R. Mercier, Aust. J. Chem. 1982, 35, 1543 ; (b) T. A. George and C. D. Turnipseed, Znorg. Chem. 1973,12,394.
Ruthenium-mercury 11. C. F. J. Barnard, J. A. Daniels and R. J. Mawby, J. Chem. Sot., Dalton Trans. 1976,961. 12. W. A. Henderson and C. A. Streuli, J. Am. Chem. Sot. 1960,82, 5791. 13. J. Browning, P. L. Goggin, R. J. Goodfellow, N. W.
nitrosyl complexes
1017
Hurst, L. G. Mallison and M. Murray, J. Chem. Sot., Dalton Trans. 1978, 872. 14. J. J. Levison and S. D. Robinson, 1514.
Chem. Ind. 1969,
1991 0
0277-5387/91 %3.00+.00 1991 Pergamon Press plc
FORMATION OF HETEROBIMETALLIC RUTHENIUMMERCURY NITROSYL COMPLEXES LORETO
BALLESTER-REVENTOS,* ANGEL GUTIERREZ-ALONSO MARIA FELISA PERPINAN-VIELBA
and
Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, 28040-Madrid, Spain (Received
13 June 1990 ; accepted 7 January 199 1)
Abstract-The nitrosyl ruthenium complexes [RuCl(CO)(NO)(PPh,),] and [Ru(NO),(PR,)*] (R = Ph, CH$HJN) react with an excess of mercury salts, HgX,, to give the first nitrosyl ruthenium complexes containing ruthenium-mercury bonds. The reactions take place with substitution of one or more ligands in the parent compound and cis addition of the X and HgX groups.
One of the reactions most extensively used in the synthesis of heterobimetallic transition compounds is the addition of a mercury(I1) compound to an electron-rich metal complex.’ The usual reaction implies an adduct type interaction with formation, in some cases, of the oxidative addition product.* There are very few examples of bimetallic ruthenium-mercury compounds, the majority being adduct type complexes, for example [Ru (&H,), * HgC1,13 and [RuC12(PPh3)3* HgC12].4 Even more scarce are the oxidative addition complexes and only the mononuclear carbonyls [Ru(CF,)
(HgCF3)(CO),(PPh3)215 and VWWW)W)3 (PR,)] are known.6 The unstable derivative [RuCl,(HgCl)(NO) (PPh,),] has also been reported as an unisolated intermediate in the reaction between [RuCl(CO) (NO)(PPh,),] and HgC1,.7 The analogous osmium complex is, however, known.8 We report now the isolation and characterization of the first ruthenium-mercury bimetallic nitrosyls, obtained by oxidative addition of mercury salts to ruthenium nitrosyl derivatives. RESULTS AND DISCUSSION Reactions of[RuCl(CO)(NO)(PPh,),]
The reaction between [RuCl(CO)(NO)(PPh,)J and excess HgIz leads to an orange-brown solid of
* Author to whom correspondence
should be addressed.
formula [RuCl(I)(HgI)(CO)(NO)(PPh,)l (I). The IR spectrum of which (Table 1) shows increases of 43 and 268 cm-’ in the v(C0) and v(N0) bands, respectively, relative to the starting material and indicative of oxidation. This oxidation is not localized over the metal, with a formal oxidation state of +2 in both cases, but over the [RuNO] system which is oxidized from [RuNO]‘, with a bent nitrosyl (NO-) in the starting material,’ to [RuN016, with a linear nitrosyl (NO+) in the reaction product. Using Hg(SCN)2 a similar reaction takes place and together with the addition of the mercuric salt, substitution of the halogen by thiocyanate is also observed, with formation of [Ru(SCN),(HgSCN) (CO)(NO)(PPh,)] (II). Its IR spectrum shows that the carbonyl and nitrosyl bands shift to higher frequencies due to oxidation. There are also two bands at 2100 and 2130 cm-’ due to the v(CN) stretch of two different thiocyanates, which could be those bonded to mercury and ruthenium. The 3’P NMR spectrum in DMSO for this compound shows one single signal at 25.4 ppm with satellites due to the ‘99Hg-31Pcoupling. The coupling constant of 850 Hz is higher than the values reported in the literature,” supporting a tram arrangement of the Hg(SCN) and PPh3 groups in the molecule. As the nitrosyl and carbonyl ligands both have a high tram influence, it is unlikely that these groups are opposite in the molecule and so the stereochemistry for complex II shown in Fig. 1(a) was proposed. The reaction between [RuCl(CO)(NO)(PPh,),]
1013
L. BALLESTER-REVENTOS
1014
et al.
Table 1. IR spectral data for the compounds obtained (cm- ‘) Compounds
v&N),,,,
V(CN),yanidev(CO) v(NO)
2100s 2130sh 2090s 2110sh 2087m
[RuCl(CN)(HgCN)(CO)(NO)(PPh,)l(III) [RuCl(CO)(NO)(PPh,),.Hg(CN)J(IV)
[WNOWPMJO’) 2240s
2250s
[Ru(SCN),(HgSCN)(NO)(tcep)](VIII)
2250s 2240s [RuCl,(HgPh)(NO)(PPh,)I(XII) [RuCl,(HgPh)(NO)(tcep)](XIII)
2250s
and Hg(CN)2 leads to different compounds depending on the solvent used. When the reaction takes place in dichloromethane-ethanol the complex [RuCl(CN)(Hg CN)(CO)(NO)(PPh,)] (III) is obtained. As is shown in Table 1, the IR spectrum is similar to those of complexes I and II, suggesting a similar structure. There are also two v(CN) stretches corresponding to two different cyanides. The insolubility of this complex and the ready decomposition that occurs in DMSO prevents the attainment of a good NMR spectrum, but as this complex is similar to the thiocyanate complex, a tvans configuration Hg-Ru-P is expected. By assuming a cis disposition of the carbonyl and nitrosyl ligands and according to the proposed mechanism for these reactions (see below), Fig. l(b) is suggested as the most likely stereochemistry for this complex. If the reaction occurs in ethanol a different compound of formula [RuCl(CO)(NO)(PPh,), F;Ph,
rPh3
NCS\I AC0
“\~“/No
NCS+NO
NC/I
i&SCN
(a)
\CO ;IgCN
(b)
Fig. 1. Proposed structures for complexes (a)11 and (b)III.
2110s 2140s 2130s 2150s 2100s 2140sh 21OOs,br
‘@u--Cl)
1968s 2040s
1860s 1873s
321~
1993s
1895s
315w
1935s
1605s 1640s 1605s 1675s 1650s 1880s
280~
1894s 1867s 1870s 1862s 1844s 1869s
320m 270m 325m 320m
(Ru-Cl) (Hg-Cl)
Hg(CN),] (IV) is formed. The IR spectrum shows bands at 1935 cm-‘, v(CO), and 1605 cm-‘, v(NO), very close to those of the parent compound (1925 and 1592 cm-‘, respectively). This suggests a weak interaction between the metals, probably as an adduct complex where the oxidation state of the ruthenium is not sensibly modified, in contrast to the high shift observed in the oxidative addition complex. Complex IV undergoes conversion in solution to the oxidative addition derivative, III. This fact suggests that the adduct is an intermediate in the oxidative addition reaction and the proposed mechanism for this reaction is shown in Scheme 1. The formation of a similar intermediate has been proposed in the reaction of [RuCl,(CO),(PPh,),] with HgPh, to account for the formation of [RuCl(Ph)(CO),(PPh&] as the final product.” The ruthenium-mercury interaction in complex IV is assumed to be via pseudohalogen and chlorine bridges due to the low value of the v(Ru-Cl) stretch, about 40 cm-’ lower than a typical terminal Ru-Cl bond (for example in complex I, Table l), which appears to indicate that the chlorine is acting as a bridge between ruthenium and mercury. Nevertheless, other possible links, like direct bonds between the metals or a single bridge through the cyano group, cannot be excluded, as we have not enough evidence to choose one specific coordination mode.
Ruthenium-mercury
nitrosyl complexes
1015
NO
X
The tetrahedral complex [Ru(NO),(PPh,),] (V) reacts with excess HgX, with substitution of one nitrosyl and one phosphine and oxidation to formal ruthenium(I1) complexes of formula [RuX,(HgX)(NO)(PPh,)]. An exception to this behaviour is the reaction with Hg(SCN), which gives rise to the formation of [Ru(SCN)(HgSCN)2 (NO)(PPh,)] (VII), although this compound has several similarities with the rest of the complexes of the series. The complex [Ru(NO),(tcep)2] (VI) was obtained from B by phosphine substitution. The increase in the v(N0) band can be explained in terms of the lower basicity of tris-2-cyanoethylphosphine relative to triphenylphosphine.‘* Complexes VII-XIII show an increase of ca 250 cm-’ in the v(N0) stretch, indicative of a NO+ group in ruthenium(I1) complexes. Complex IX probably contains lattice Hg(CN), and the IR spectrum shows, for the three different M-CN bonds ofthecompound,twobandsat2100and2140cm.-’ Since complex X, containing only Ru-CN and Hg-CN bonds, has only one broad band at 2100 cm-’ which must include both stretches, the extra band in the IR of complex IX may be attributable to the lattice mercury cyanide. The high value of this frequency may indicate that the cyanides of these lattice molecules act as bridges, as in free Hg(CN)2 [v(CN) = 2195 cm-‘]. In the reaction of V with HgCl,, elimination of mercury and formation of [RuCl,(NO)(PPh,),] occurs, whereas complex VI produces [RuCI,(HgCl) (NO)(tcep)] (XI), with v(Ru-Cl) and v(Hg-Cl) at 320 and 270 cm-‘, respectively. In a similar manner, complex V reacts with ClHgPh to give a mixture of [RuCl,(NO)(PPh,),] and [RuCl, (HgPh)(NO)(PPh,)] (XII). Reaction of VI and ClHgPh affords the analogous complex XIII, whose IR spectrum shows only one v(Ru-Cl) band, suggesting a Cl-HgPh break in the addition reaction. The 13CNMR spectrum of XIII shows two signals for the cyanide (119.8 and 120.4 ppm) and for the methylene carbons (23.5 and 22.6, and 11.8
and 9.9 ppm) of the tcep, indicating different CH2CH2CN groups. This fact can be interpreted in terms of a restricted rotation of the phosphine. The phenyl signals appear slightly shifted to lower fields relative to free C1HgPh,13 as expected if HgPh acts as a Lewis acid. The ortho and meta carbons of this phenyl group show coupling to ‘99Hg of similar magnitude to that in the free ClHgPh, supporting the idea of the Cl-HgPh break and the addition of the Cl and HgPh groups to the ruthenium. Finally the “P NMR spectrum of this compound contains a septuplet at 29.6 ppm [‘J(P-H) = 11.5 Hz] with two satellites [*J(Hg-P) = 486 Hz], indicative of a tram Hg-Ru-P arrangement in the molecule. In contrast, the spectrum of XII contains the signal at 26.5 ppm with *J(Hg-P) = 101.8 Hz. This coupling appears to be smaller than those observed for tram dispositions and we cannot determine if mercury and phosphorus are mutually cis or tram in this compound.
EXPERIMENTAL All reactions were carried out under oxygenfree nitrogen. [RuC1(CO)(NO)(PPh3),J7 and [Ru (NOMPPh,M’4were synthesized by the published methods. IR spectra were recorded on KBr pellets using a Perkin-Elmer 1330 spectrophotometer. NMR spectra were recorded with a Bruker WP-8GSY relative to TMS (“C) and 85% [H3P04(3’P). Preparation of[RuCl(I)(HgI)(CO)(NO)(PPh3)]
(I)
A suspension of [RuCl(CO)(NO)(PPh,),] (0.36 g, 0.5 mmol) and Hg12 (0.67 g, 1.5 mmol) in ethanol (30 cm3) was refluxed for 2 h. The brown solution was filtered and the solvent removed in uacuo. The solid was extracted with dicholoromethane. Addition of diethyl ether gave a purple solid in 63% yield. Found: C, 23.9; H, 1.6; N, 1.6. Calc. : C, 25.0; H, 1.7; N, 1.5.
1016
Preparation
L. BALLESTER-REVENTOS of
[Ru(SCN),(HgSCN)(CO)(NO)
@‘WI (11) A mixture of [RuC1(CO)(NO)(PPh,),l] (0.36 g, 0.5 mmol) in dichloromethane (20 cm3) and Hg(SCN), (0.47 g, 1.5 mmol) in ethanol (20 cm-‘) was refluxed for 2 h. The orange-brown precipitate which formed was collected and washed with dichloromethane, ethanol and diethyl ether. Yield 87%. Found:C, 33.1;H, 1.8;N,7.2.Calc.:C,33.2;H, 1.9; N, 7.0.%
Preparation
of
[RuCl(CN)(HgCN)(CO)(NO)
W’hdl (III) To a solution of [RuCl(CO)(NO)(PPh,), (0.36 g, 0.5 mmol) in dichloromethane (15 cm3), a solution of Hg(CN)* (0.38 g, 1.5 mmol) in ethanol (20 cm’) was added and the mixture was stirred for 3 h. The solution, which became orange, was concentrated to 5 cm3 and then 20 cm3 of diethyl ether were added affording III as an orange precipitate. Yield 79%. Found: C, 35.6; H, 2.4; N, 6.0. Calc.: C, 35.5; H, 2.1 ; N, 5.9%.
Preparation
of [RuCl(CO)(NO)(PPh,),
* Hg(CN),]
(IV) A mixture of [RuC1(CO)(NO)(PPh,),l] (0.36 g, 0.5 mmol) and Hg(CN)* (0.25 g, 1.0 mmol) in ethanol was refluxed for 3 h. During this time the solid changed from green to orange-brown, then was filtered and washed with ethanol, dichloromethane and diethyl ether. Yield 60%. Found : C, 47.8 ; H, 3.2; N, 4.4. Calc.: C, 48.2; H, 3.1 ; N, 4.3%.
Preparation
of [Ru(NO)z(tcep)z] (VI)
A solution of [Ru(NO),(PPh,),] (3.45 g, 5 mmol) and tcep (2.85 g, 15 mmol) in toluene (50 cm3) was refluxed for 2 h. The solution changed from red to orange and a dark orange precipitate appeared. After cooling to room temperature, the solid was filtered, washed with toluene, ethanol and diethyl ether. Yield 77%. Found : C, 39.6 ; H. 4.4 ; N, 20.9. Calc.: C, 39.5; H, 4.4; N, 20.4%.
Preparation
of
[Ru(SCN)(HgSCN),(NO)(PPh,)l
(VII) A suspension of [Ru(NO),(PPh3)z] (0.35 g, 0.5 mmol) and Hg(SCN)* (0.48 g, 1.5 mmol) in ethanol was refluxed for 3 h. The ochre solid was collected, washed with ethanol, toluene and ethanol and
et al.
dried. Yield 84%. Found : C, 26.2 ; H, 1.6 ; N, 5.8. Calc.: C, 26.0; H, 1.6; N, 5.8%. The following complexes were prepared in a similar way using [Ru(NO),(PPh,),] or [Ru(NO),(tcep)2] and a 1: 3 excess of the appropriate mercury salt : [Ru(SCN),(HgSCN)(NO)(tcep)] (VIII) : brown solid ; yield 7 1%. Found : C, 20.4 ; H, 1.8 ; N, 14.0. Calc.: C, 20.6; H, 1.7; N, 14.0%. [Ru(CN),(HgCN)(No)(Pph,) *WdCWI (IX): ochre solid ; yield 69%. Found : C, 29.4 ; H, 1.7 ; N, 9.1. Calc.: C, 29.9; H, 1.6; N, 9.1%. [Ru(CN),(HgCN)(NO)(tcep)] (X) : brown solid ; yield 74%. Found : C, 23.5 ; H, 2.1 ; N, 16.4. Calc. : C, 23.9; H, 2.0; N, 16.3%. [RuCl,(HgCl)(NO)(tcep)] (XI) : yellow-orange solid; yield 58%. Found: C, 17.0; H, 2.0; N, 8.8. Calc.: C, 17.1 ; H, 1.9; N, 8.9%. [RuCl,(HgPh)(NO)(PPh,)1 (XII) : orange-brown solid ; yield 49%. Found : C, 38.9 ; H, 2.7 ; N, 2.2. Calc. : C, 40.4; H, 2.8; N, 2.0%. [RuCl,(HgPh)(NO)(tcep)] (XIII) : orange-brown solid; yield 76%. Found: C, 26.5; H, 2.5; N, 8.4. Calc.: C, 26.8; H, 2.5; N, 8.4%.
Acknowledgement-We thank the Comision Interministerial de Ciencia y Tecnologia (Project PS87-0028) for financial support.
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nitrosyl complexes
1017
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Chem. Ind. 1969,