3010
Inorg. Chem. 1994, 33, 3010-3013
Synthesis, Structure, Reactivity, and Solution Behavior of Bis{dicarbonyl[hydridotris(1,2,4triazoly1) boratolruthenium(I)](RwRu) Kom-Bei Shiu' and Wei-Ning Cuo Department of Chemistry, National Cheng Kung University, Tainan, Taiwan 70101, ROC
Shie-Ming Peng and Ming-Chu Cheng Department of Chemistry, National Taiwan University, Taipei, Taiwan 10764, ROC Received October 14, I993 Metal-metal-bonded dinuclear compounds, especially those Figure 1. ORTEPdrawingofcomplex [R~~~~-HB(tz)~)(CO)z12.(1) (50% probability ellipsoids). with multiple bonds,' are potential building blocks for metallic clusters.2 Though scission of the u, T , and 6 bonds usually occurs when the dimers react with ?r-acids such as CO or i~ocyanides,~ the metal-metal bonds of some carbonyl-containing dinuclear compounds may be stabilized owing to good u-bonding. These compounds may serve as suitable models to help our understanding of the conversion of metal-metal multiply bonded dimers to other polynuclear compounds. Previously, we showed that the metalmetal bond of [ R u z ( O ~ C R ) ~ ( C O )complexes ~L~] displays weakening upon coordination of axial donors (L): similar to that of the d7-d7dimers, [Rh2(02CR)4L2],5or the d4-d4compounds, [Cr2(02CR)4L2]-6 These diruthenium compounds, derived from polymeric catena-[Ru(02CR)(CO)2], can be viewed as possible intermediates to the conversion of the low-valent cluster compounds (LVCs), such as [ R U ~ ( C O )or ~ ~the ] , high-valent cluster compounds (HVCs), such as [Ru2(02CR)&l], as defined by Cotton in 1983.7 In this contribution, however, we wish to show that a slight variation, replacing 1-pyrazolyl (pz) with 1,2,4triazolyl (tz), can lead to the unexpected results of a Ru-Ru and a Ru-L bond length reduction in [ R u ( ~ ~ - H B ( ~ z ) ~ ) (as CO)~]~ compared to its analogue, [Ru(~~-HB(Pz)~~(CO)~]~.~Figure 2. Projection of complex 1 down the Ru-Ru bond. The dimer [Ru{~~-HB(tz)3)(C0)2]2 (1) is prepared by a procedure analogous to that for [Ru{s3-HB(pz)~)(C0)z]2 (2h8 bond length of 2.8688(7) A is significantly shorter than that of The crystal structure of 1 (Figure 1) reveals that the Ru-Ru 2 (d(Ru-Ru) = 2.882(1) A) though both compounds have a similar cis staggered geometry with torsional angles ranging from (1) (a) Cotton, F. A.; Walton, R. A. Multiple Bonds between Metal Atoms, 36.2( 1) to 49.2( 1)O (Figure 2). (The asymmetry parameters, John Wiley & Sons, New York, 1982. (b) Cotton, F. A.; Walton, R. A. Q,9 are calculated to be 2.26 for C( 16)0(16), 2.28 for C( 17)OSrruct. Bonding 1985, 62, 1 . (17), 2.25 for C(36)0(36), and 2.27 for C(37)0(37). These (2) (a) Muetterties, E. L. Bull. Soc. Cltim. Belg. 1975,84, 959. (b) Ugo, R,'Catal. Rev. 1975, 1 1 , 225. carbonylsare consistent with semibridgingcarbonyls.) Contrary (31 (a) . ,Chisholm. M. H.: Cotton, F. A.: Extine. M. W.; Kelly, R. L. J. Am. to the fact that the solid-state structure of 1 has approximate C2 Chem. SOC.1978, 100, 3354. (b) Hertzer, C. A,; Myers, R. E.; Brant, symmetry, only three carbon singlets responsiblefor the two types P.; Walton, R. A. Inorg. Chem. 1978, 17, 2383. (c) Girolami, G.; Andersen, R. A. Inorg. Chem. 1981, 20, 2040. (d) Cotton, F. A.; of carbon atoms located at the 3- and 5-triazolyl ring positions, Darensbourg, D. J.; Kolthammer, B. W. S. J . Organomet. Chem. 1981, and the carbonyl carbon atoms are observed at 298 K in the 217, C14. 13C{lH)NMR spectrum in CDzCl2, indicating that the compound (4) Shiu, K.-B.; Peng, S.-M.; Cheng, M.-C. J . Organomet. Chem. 1993, is fluxional in solution. By comparing the variable-temperature 452, 143. ( 5 ) (a) Dubicki, L.; Martin, R. L. Inorg. Chem. 1970, 9, 673. (b) Das, K.; NMR spectra of 1 (Figure 3) and 2,8 it appears that the fluxional Kadish, K. M.; Bear, J. L. Ibid. 1978,17,930. (c) Koh,Y .-B.; Christoph, behaviors of these compounds are quite similar, but fluxional G. G. Ibid. 1978, 17, 2S90. (d) Christoph, G. G.; Koh, Y.-B. J. Am. behavior should involve participation of the carbonyl groups in Chem. Soc. 1979, 101, 1422. (e) Koh, Y.-B.; Christoph, G. G. Inorg. Chem. 1979, 18, 1122. (f) Cotton, F. A,; Felthouse, T. R.Ibid. 1980, the compounds. In this revised mechanism, we propose that the 19, 320. (g) Cotton, F. A.; Felthouse, T. R. Ibid. 1980, 19, 323. (h) two pairs of the semibridging carbonyls undergo painvise Cotton, F. A.; Felthouse, T. R. Ibid. 1980, 19, 2347. (i) Cotton, F. A.; exchangelo with synchronous nondissociative rotationll of the Felthouse, T. R. Ibid. 1981, 20,600. u) Norman, J. G., Jr.; Kolari, H. J. J . Am. Chem. SOC.1978,100,791. (k) Norman, J. G., Jr.; Renzoni, tris(azoly1)boratogroup around the Ru---B bond, probably with G. E.; Case, D. A. Ibid. 1979,101, 5256. (I) Bursten, B. E.; Cotton, F. more or less rotation about the Ru-Ru bond. The spectrum at A. Inorg. Chem. 1981, 20, 3042. (m) Nakatsuji, H.; Ushio, J.; Kanda, 298 K of 1 shows two singlet resonances at 8.28 and 7.71 ppm K.; Onishi, Y.; Kawamura, T.; Yonezawa, T. Chem. Phys. Lett. 1981, 79, 299. (n) Aullon, G.; Alvarez, S.Inorg. Chem. 1993, 32, 3712. for the two protons of the triazolyl rings (Figure 3), indicating .
I
(6) (a) Cotton, F. A.; Extine, M.W.; Rice, G. W. Inorg. Chem. 1978, 17, 176. (b) Cotton, F. A.; Ilsley, W. H.; Kaim, W. J.Am. Chem. Soc. 1980, 102,3464. (c) Ketkar, S.N.; Fink, M. Ibid. 1985,107,338. (d) Cotton, F. A.; Feng, X.;Kibala, P. A.; Matusz, M . Ibid. 1988, 110, 2807. (7) Cotton, F. A. In Inorganic Chemistry towardthe 2lsr Century,Chisholm, M. H., Ed.; ACS Symposium Series 21 1; American Chemical Society, Washington, DC, 1983, p 209. (8) Steyn, M. M. de V.;Singleton, E.; Hietkamp, S.;Lites, D. C. J . Chem. Soc.. Dalton Trans. 1990, 2991.
0020-166919411333-3010$04.50/0
(9) Horwitz, C. P.; Shriver, D. F. Adv. Organomer. Chem. 1984,23,219. (10) Curtis, M. D.; Shiu, K.-B.; Butler, W. M.; Huffman, J. C. J. Am. Chem. Soc. 1986,108, 3335. ( I 1) (a) Shiu, K.-B.; Liou, K.-S.; Cheng, C. P.;Fang, B.-R.; Wang. Y.; Lee, G.-H.; Vong, W.-J. Organometallics 1989, 8, 1219. (b) Shiu, K.-B.; Chang, C.-J.; Wang, Y.;Cheng, M.-C. J. Organomet. Chem. 1991,406, 363.
0 1994 American Chemical Society
Inorganic Chemistry, Vol. 33, No. 13, 1994 3011
Notes
Table 1. Crystal Data for [Ru(+-HB(tz)3)(CO)~J2(1) 298K
formula
M
1
n
cryst syst space group cell params at 296 K
I
278 K
,
~
b, A
1
x
258K
a, A c, A
i3, deg
v,A3
Z D d e , 8 cm4 h mm-1 ~ ( M Ka), o Tmim Trmx no. of unique obsd data R , O Rwb
238 K
CidhBzChNi604RU2 831.10 monoclinic P 2 1 / ~(NO. 14) 8.9687(21) 14.444(4) 23.1 14(5) 99.241(20) 2955.q 12) 4 1.868 0.709 30 1.243 0.816-1.000 4467 0.026,0.024 w =
Table 2. Atomic Coordinates and Bh4 for 1 atom X Y
218 K J
198 K
L
I1
1881
I I U I
I
d
L
equilibration of the three triazolyl rings by rotation about the Ru---B bond. No BH proton is observed due to broadening by the quadruple moment of the boron isotopes. As temperature decreases, both resonances broaden with the latter one gradually unseen. The barrier to rotation about the Ru-B bond in 1 and 2 is similar as reflected by a similar Tc of ca. 258 K with AG* = 12.7 kcal/mol at this temperature. (Knowing that Tcdepends on the observing frequency and that Tc shifts upward by ca. 10 K when doubling the frequency,'" the Tcvalues used for 2 were estimated from the published spectra of this compound.*) The singlet at 8.28 ppm then decomposes at 238 K into one broad resonance at 8.16 ppm and one broader peak at 8.30 ppm with an integration ratio of 1:2, while the singlet at 7.71 ppm decomposes into only one observed peak at 8.23 ppm (Figure 3). A second Tc is shown at ca. 220 K (AG*= 10.2 kcal/mol) for 1, much lower than that of ca. 236 K for 2. The broad singlet at 8.30 ppm then decomposes at 218 K into two singlets at 8.1 1 and 8.59 ppm. Finally, the spectrum at 188 K represents the low-temperaturelimitingspectrum, containingsix singletsat 8.98,
8.59,8.24,8.16,8.1l,and5.87ppm,andcorrespondstothesolidstate structure. Apparently, the lower Tc(i.e.,the faster pairwise exchange of semibridgingcarbonyls) observed for 1is compatible with the shorter Ru-Ru bond found in 1, compared to that in 2. (Impurity resonances appear pronounced due to the low solubility of 1. The low solubility in the usual organic solvents precluded variable-temperaturemeasurementsof 13C(IHj spectra for further confirmation of the fluxional mechanism.) Each ruthenium in 1 (Figure 1) has a distorted octahedral geometry with three 2-N nitrogen atoms of the hydridotris( 1,2,4(1 2) Friebolin, H. Basic One- and Two-Dimensional NMR Spectroscopy, 2nd 4.;VCH: New York. 1993: (a) p 294; (b) p 295.
Ru(1) Ru(2) B(l) B(2) N(l) N(2) C(3) N(4) C(5) N(6) N(7) C(8) N(9) C(10) N( 11) N(12) C(13) N(14) C(15) C( 16) O(16) C(17) O( 17) N(21) N(22) C(23) N(24) C(25) N(26) N(27) C(28) N(29) C(30) N(31) N(32) C(33) N(34) C(35) C(36) O(36) C(37) O(37) C C1( 1) Cl(12)
0.34506(3) 0.19288(3) 0.2783(5) -0.1671(5) 0.1360(3) 0.1358(3) 0.0004(4) -0.0910(3) -0.0022(4) 0.4499(3) 0.4007(3) 0.4800(4) 0.5799(4) 0.5578(4) 0.3797(3) 0.3364(3) 0.3721(4) 0.4362(4) 0.4390(4) 0.3 179(4) 0.3085(3) 0.5242(4) 0.6344(3) 0.0386(3) -0.1090(3) -0.1769(4) -0.0857(4) 0.0448(4) 0.0758(3) -0.0774(3) -0.1 117(4) 0.0076(4) 0.1203(4) 0.0084(3) -0.1358(3) -0.2236(4) -0.1487(3) -0.0068(4) 0.3441(4) 0.4363(3) 0.3143(4) 0.3875(3) 0.8424(6) 1.01831(15) 0.71594(16)
0.185282( 19) 0.276719(19) 0.2052(3) 0.3201 (3) 0.16929( 18) 0.17567(19) 0.1502(3) 0.12830(22) 0.14133(25) 0.1 1530(19) 0.13196( 19) 0.0767(3) 0.02613(23) 0.0529(3) 0.30497(18) 0.29750( 19) 0.3770(3) 0.43687(21) 0.38884(25) 0.07783(24) 0.00892(17) 0.20429(23) 0.21585( 19) 0.34562(19) 0.3572 1(19) 0.4049(3) 0.42608(23) 0.3880(3) 0.35568(19) 0.36679(19) 0.4189(3) 0.44209(23) 0.4015(3) 0.1 8061(1 8) 0.21532(20) 0.1446(3) 0.06547(21) 0.09 148(24) 0.36330(24) 0.41876( 18) 0.21 218(25) 0.17377(20) 0.3658(3) 0.33428( 10) 0.27434( 11)
z
B h , A'
0.053543(12) -O.049443(12) 0.18790( 18) -0.08890(20) 0.08689( 12) 0.14602(12) 0.1 564O( 16) 0.107 11(13) 0.06609( 15) 0.13337(12) 0.18505( 12) 0.22488( 16) 0.20259(15) 0.14595( 17) 0.1 1138(12) 0.16582(12) 0.19387( 16) 0.16163(14) 0.11209(16) 0.01030( 15) -0).01401(12) 0.02522( 15) O.O0753( 12) -O.O0087(13) -0.02705(13) O.OlOOS( 19) 0.05926( 15) 0.05018(17) -O.12307(12) -0.13177( 13) -0.17991 (17) -0.20288(15) -0.16618(16) -O.07544(12) -O.08999(13) -0.1 l060( 17) -0.1 1063(15) -O.08936(17) -0.03360( 15) -0.02942( 12) -0.09262( 15) -0.12105( 13) 0.2316(3) 0.27082(6) 0.23070(9)
1.774(11) 1.792(11) 2.52(18) 2.84(20) 2.10( 12) 2.27( 13) 2.88(17) 3.07 ( 15) 2.55(16) 2.24( 12) 2.32(13) 3.45(19) 4.19( 17) 3.35(19) 2.19(12) 2.24(12) 3.1 O( 17) 3.7 1( 17) 2.94( 17) 2.32(15) 3.90( 13) 2.45( 16) 4.05( 14) 2.25( 13) 2.47( 13) 3.46(19) 3.90(16) 3.06(17) 2.39( 12) 2.60( 13) 3.60( 19) 4.10( 18) 3.23(19) 2.19( 12) 2.48(14) 3.19(18) 3.54(16) 2.93(17) 2.45( 15) 3.98( 14) 2.58( 16) 4.64( 15) 6.9(3) 6.24(7) 9.18(11)
B h is the mean of the principal axes of the thermal ellipsoid.
triazoly1)borato anion occupying two equatorial (Ne) sites and one axial (N,) site (octahedral angles around the Ru atom range from 81.30(10) to 100.10(7)0). The other octahedral positions are occupied by the other Ru atom and two semibridging carbonyl carbon atoms, each situated trans to the Ne atoms. Like 2: the carbonyls lean slightly toward the metal-metal bond whereas the equatorial nitrogen atoms are pulled toward the boron atom,
3012 Inorganic Chemistry, Vol. 33, No. 13, 1994
Notes
Table 3. Selected Bond Lengths (A) and Bond and Torsion Angles (deg) for 1 2.8688(7) Ru( l)-Ru(2) Ru(l)-N(6) 2.180(3) 1.841(3) Ru( l)-C( 16) Ru(2)-N(2 1) 2.160(3) Ru(2)-N(31) 2.170(3) 1.844(4) Ru(2)-C(37) 1.140(4) C( 17)-0( 17) 1.144(4) C(37)-0(37) Ru(~)-Ru(1)-N(6) Ru(Z)-Ru(l)-C( 16) Ru( l)-Ru(2)-N(21) Ru(l)-R~(2)-N(31) Ru( l)-Ru(2)
