Carborane Complexes of Ruthenium: A Convenient Synthesis of [Ru

Yi-Hsien Liao, Donald F. Mullica, Eric L. Sappenfield, and F. Gordon A. Stone ... M. Haswell, Brian L. Scott, Rebecca L. Miller, Jon B. Nielsen, and K...
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Organometallics 1995,14, 3516-3526

3516

Carborane Complexes of Ruthenium: A Convenient Synthesis of [ R U ( C O ) ~ ( ~ ~ - ~ , ~ - C and ~ Ba~Study H ~ ~ of )I Reactions of This Complex? Stephen Anderson, Donald F. Mullica, Eric L. Sappenfield, and F. Gordon A. Stone* Department of Chemistry, Baylor University, Waco, Texas 76798-7348 Received April 10, 1995@ Treatment of [ R u ~ ( C O )with ~ ~ ] nzdo-7,8-C2BgH13in heptane at reflux temperatures affords

[R~(C0)3(11~-7,8-CzBgHll)] (1)in high yield. Heating thf (tetrahydrofuran) solutions of the latter with [ N E t d gives [ N E ~ ~ ] [ R u I ( C O ) ~ ( ~ ~ ~ - (2a) ~ , ~ which - C ~ Bwith ~ H AgBF4 ~ ~ ) I in thf yields the neutral complex [Ru(C0)2(thD(ll5-7,8-C2B9Hll)l (3). The latter reacts with molecular hydrogen to give, after addition of [NEtJ[BF41, the diruthenium species [NEt41[Ru2(p-H)(C0)4(r5-7,8-C2BgHll)21(4a). The [K(18-crown-6)] salt (4b)of the anionic diruthenium complex is formed on protonation (HBFsEt20) of [K(18-crown-6~1[RuH~CO~~~rlj-7,8-C~B~H~~)l in CH2C12. The structure of 4a was established by X-ray crystallography. Crystals are monoclinic, space group P21/c (No. 141, with a = 11.205(2) b = 20.736(2) c = 13.769(2) p = 96.69(2)", and 2 = 4. The Ru-Ru bond [3.189(6)AI is bridged by the hydrido ligand. The nido-7,8-C2BgHll cages are transoid with respect to each other a s are the two pairs of terminal CO groups on each ruthenium. The reaction between [K( 18-crown-6)1[~uH(CO)2(v5-7,8-C2BgH1l)] and [AuCl(PPh3)] in thf in the presence of either AgBF4 or TlPF6 (2b)the structure of which was unexpectedly gives [Au(PPh3)2][RuC1(CO)z(y5-7,8-C2BgHll)l determined by X-ray crystallography. Crystals are triclinic, space group Pi (No. 21, with a = 11.167(2) b = 11.861(2) c = 17.103(3) a = 99.50(2)",p = 105.01(2)",y = 95.58(2)", and 2 = 2. The anion in 2b has a piano stool configuration with ruthenium being coordinated on one side by the nido-CzBgHl1cage in the usual pentahapto manner and on the other by the two CO groups and the C1 atom [Ru-C1 = 2.452(1) AI. The salt 4b is deprotonated ~ ~An 5 - 7X-ray ,8-C~B~H~~~~l with NaH in thf yielding [ K ~ 1 8 - c r o w n - 6 ~ 1 ~ [ R u ~ ~ p - C O ~ ~ ~ C O ~ ~(5). crystallographic study revealed that crystals are monoclinic, space group P2Jc (No. 141, with a = 12.746(1)A, b = 18.116(4) c = 12.440(2) p = 109.58(1)",and 2 = 2. The Ru-Ru separation in the dianion is 2.793(1) The metal atoms and the two terminal CO ligands lie in a mirror plane and the two q5-7,8-C2BgH1lgroups are transoid on opposite sides of the plane, while the two mirror-related bridging CO groups lie on the crystallographic 2-fold axis. The reaction between [K(18-crown-6)][RuH(CO)~(~5-7,8-C~B~H~~~l and [PtH(Cl)(PEt3)21 (61, the in thf in the presence of TlPF6 yields [RuPt(~1-H)(p-a:yj-7,8-C~BgHlo)(C0)2(PEt3)21 structure of which was determined by X-ray crystallography. Crystals are monoclinic, space group P2Jc (No. 141, with a = 18.774(4) b = 12.094(2) A, c = 13.429(3)A, = 110.78(2)", and 2 = 4. The Ru-Pt bond [2.802(1) is spanned on one side by the hydrido ligand and on the other by a n exopolyhedral B-Pt linkage [2.069(7) AI involving a cage boron atom

A,

A,

A,

A,

A,

A,

A,

A.

A,

A, A]

which is in the a site with respect to the two carbon atoms in the CCBBB ring ligating the ruthenium. The latter carries two terminal CO ligands, and the platinum atom is in a n essential planar environment defined by the Ru, B,, and the two P atoms. The new complexes have been characterized by NMR spectroscopy in addition to the X-ray diffraction studies. Introduction

The formal relationship between the pentahapto bonding modes of the ligands r5-C5Rs and r5-7,n-R2-7,nTo whom correspondence should be addressed. In the compounds described in this paper ruthenium atoms and nido-CnBScages form closo-l,2-dicarba-3-ruthenadodecaborane structures. However, use of this numbering scheme leads to an impossibly complex nomenclature for some of the metal complexes reported. Following precedent (Mullica,D. F.: Sappenfield, E. L.; Stone, F. G. A.; Woollam, S. F. Organometallics 1994,13,157),therefore, we treat the cage as a nido 11-vertex ligand with numbering as for an icosahedron from which the twelfth vertex has been removed. This has the added convenience of relating the metal carborane complexes to similar species with @-CsHsligands. Abstract published in Advance ACS Abstracts, June 15, 1995. :i;

0276-7333/95/2314-3516$09.00/0

CzBgHg (R = H or Me, n = 8 or 9) has long been known and has been exploited to prepare a host of complexes in which transition metal ions occupy vertices in closoicosahedral cage structures. We are exploring the reactivity of metal centers in certain icosahedral metallacarborane structures which are isolobally mapped with cyclopentadienylmetal species. Thus we have recently reported studies on the complexes [M(CO)2(r57,S-CzBgHll)l(M = Ni, Pd, or Pt)2which are related to ( 1 ) f a Hawthorne, ) M.F.: Young, D. C.: Andrews, T. D.; Howe, D. V.: Pilling, R. L.; Pitts, A. D.: Reintjes, M.; Warren, L. F.: Wegner, P. A. J . A m . Chem. SOC.1968,90,879. bj Hawthorne, M. F. Pure Appl. Chem. 1972,29, 547: 1973;33, 475. I C ) Callahan, K. P.; Hawthorne, M.F. Adu. Organomet. Chem. 1976, 24, 145.

0 1995 American Chemical Society

Carborane Complexes of Ruthenium

Organometallics, Vol. 14,No.7,1995 3517 Table 1. Analytical and Physical Data ~~

anal.V% compd

color

yield/%

v,.,iCOp/cm-1 2114 s, 2058 s

red 80 [Ru(CO)~()~~-~,~-CZB~H~~)E (1) [ N E ~ ~ ] [ R U I ( C O ) ~ ( ~(2a) ~ - ~ , ~ - C ~ B ~red H~~~~ 77 [ A U ( P P ~ ~ ) ~ ] [ R U C ~ ( C O ) ~ (2b) ( ~ ~ - ~ , ~ -red C ~ B ~ H ~ ~ )23~

2037 8,1981 s 2037 s, 1981 s [R~(C0)2(thf)(1~-7,8-C2BgHi1)1(3) yellow 60 2055 8,2004 s 2027 s, 1992 s [NEt4l[R~2lu-H)(C0)4i1~-7,8-C2BgHr1)21 (4a) yellow 77 [RUP~(~~-H)(~-U:~~-~,~-C (6) ~B~H~ ~ ) ( C O ) ~ (55P E ~ ~ ) ~2025 I s, 1970 s yellow

C

H

26.1 i26.4P 45.5 (45.9) 25.8 (26.6) 27.6 (27.0Y 27.4 (26.7)

5.7 (5.7) 3.6 (3.9) 5.1 (5.3) 6.6 (6.1) 5.6 (5.7)

a Measured in CH2C12. All complexes show a broad medium-intensity band at ca. 2550 cm-' due to cage B-H absorptions. Calculated values are given in parentheses. See ref 6. N, 2.3 (2.6). e N, 2.0 (2.0).

the compounds [M(CO)Z($-C~H~)] (M = Co, Rh, or Ir). Although both neutral and anionic cyclopentadienylmetal carbonyls are very important reagents in organometallic syntheses, studies on the chemistry of their metallacarborane analogs with icosahedral cage frameworks have been somewhat limited. However, salts of the anionic complexes [M(C0)3(775-7,8-CzBgH11)32(M = Mo or W), [M(C0)3(175-7,8-C2BgH11)1- (M = Mn or Re), [Fe(C0)2(175-7,8-C2BgHll)12-, and [Rh(CO)2(y5-7,8-C2BgHd1- are known and various reactions of these species have been r e p ~ r t e d . ' ~ These . ~ , ~ anionic complexes are formally analogs of [M(C0)3($-CsH5)]- (M = Mo or W), [M(C0)3(v5-C5Hd1 (M = Mn or Re), [Fe(C0)2(v5-C5Hdl-, and [Rh(CO)2(y5-CsH5)l,respectively. The neutral complexes [M(C0)3(775-7,8-C2BgH11)3(M = FeSalbor Ru5J? are of particular interest because of the ubiquitous and extensively explored chemistry of the fragments M(CO),(q5-C5H5)( n = 2 or 3). The synthesis of [R~(C0)3(17~-7,8-CzBgHll)l (1) (Chart 1) was first reported by Siedle,5 who obtained it in very low yield (ca. 7%)from [RU2C12~-C1)2(CO)sl and Na2[7,8-C2BgHlll. Later Behnken and Hawthorne6 prepared 1 in good yield (ca. 65%) by treating [RuCl~(CO)3(thf)l (thf = tetrahydrofuran) with Na2[7,8-C2BgHlll. They were thereby able to study several reactions of this species, observing in particular the high reactivity of 1 toward nucleophiles. Neither of the reagents [Ru2C12(p-C1)2(co)6] or [RuC12(C0)3(thf)l,'however, are satisfactory precursors to 1 as they are not easy to prepare. Herein we describe a convenient high-yield synthesis of 1 allowing this compound to become a useful synthon for a variety of icosahedral ruthenacarborane complexes. Results and Discussion

The reaction between [Rw(CO)121and cyclopentadiene under reflux in heptane initially gives [RuH(C0)2(vC5H5)Iwhich subsequently releases hydrogen and forms [Ru~~-CO)~(CO)~(~~-C~H~)~I in good yield.8 On the basis (2) Carr, C.; Mullica, D. F.; Sappenfield, E. L.; Stone, F. G. A. Inorg. Chem. 1994, 33, 1666. Fallis, K. A.;Mullica, D. F.; Sappenfield, E. L.; Stone, F. G . A. Inorg. Chem. 1994,33, 4927. (3) (a)Lee, S.; Knobler, C. B.; Hawthorne, M. F. Organometallics 1991, 10, 670. (b)Lee, S.; Knobler, C. B.; Hawthorne, M. F. Organometallics 1991,10, 1054. (c)Do, Y.; Knobler, C. B.; Hawthorne, M. F. J . A m . Chem. SOC.1987, 109, 1853. td) Kim, J.; Do, Y.; Sohn, Y. S.; Knobler, C. B.; Hawthorne, M. F. J . Organomet. Chem. 1991,418, C1. ( 4 ) ( a )Pilotti, M. U.; Stone, F. G. A. J . Chem. SOC.,Dalton Trans 1990,2625. (b)Dossett, S. J.;Mullica, D. F.; Sappenfield, E. L.; Stone, F. G. A.; Went, M. J. J . Chem. SOC.,Dalton Trans. 1993, 281. (c) Dossett, S. J.; Li, S.;Stone, F. G. A. J . Chem. SOC.,Dalton Trans. 1993, 1585. (d)Mullica, D. F.; Sappenfield, E. L.; Stone, F. G. A,; Woollam, S. F. J . Chem. SOC.,Dalton Trans. 1993, 3559. ( 5 )Siedle, A. R. J . Organomet. Chem. 1975, 90, 249. ( 6 )Behnken, P. E.; Hawthorne, M. F. Inorg. Chem. 1984,23,3420. ( 7 ) Bruce, M. I.; Stone, F. G. A. J . Chem. SOC.A 1967, 1238. (8) Humphries, A. P.; Knox, S. A. R. J . Chem. SOC.,Dalton Trans. 1975,1710. Doherty, N. M.; Knox, S. A. R.; Morris, M. J. Inorg. Synth. 1990,28,189.

Chart 1

Y 2a NE\ 2b Au(PPh&

1

X

I Cl

1 0

f

3 Y

4 NEt

4b K(18-crownb)

0

cn 0 en

of this synthesis, a related reaction between [Rw(CO)121 and nido-7,8-C2BgH13in heptane at reflux was investi-C~B~H~~ gated and found to give [ R U ( C O ) ~ ( ~ ~ - ~ , ~(1) in ca. 80%yield. The llB{lH} NMR spectrum of 1 was identical with that reported previously.6 The IR spectrum measured in CHzClz showed two terminal CO bands at 2114 and 2058 cm-l, the latter peak being broad. In heptane, however, three CO absorption's are observed at 2108,2058, and 2044 cm-l. Compound 1 was further characterized by its l3C(lH} and 'H NMR spectra. The former spectrum displays a diagnostic resonance for the cage CH groups at 6 46.4 and a signal for the CO ligands at 6 188.9, while the 'H NMR spectrum shows a peak a t 6 3.54,corresponding to the chemical shift reported earlier for the CH ~ e r t i c e s . ~ Several reactions of 1 have been investigated. Treatment of 1 with [NEtdII in thf gives [NEt4l[RuI(C0)2(175-7,8-C2BgH11)l(2a), characterized by the data listed in Tables 1and 2. As expected, the CO stretching frequencies in the IR spectrum of 2a are a t noticeably lower frequency than those of 1 due to the former complex being anionic. Reaction between 2a and AgBF4 in thf at room temperature leads to the rapid and apparently quantitative formation of [Ru(CO)z(thf)($7,8-C2BgHll)l (31,AgI, and [NEtd][BF41. Complex 3 is a useful reagent for preparing other ruthenacarborane compounds, and for this purpose it is best prepared and used in situ, with its formation being monitored by IR spectroscopy. Freshly generated neutral 3 shows vmax(CO) at 2055 and 2004 cm-l, higher frequencies than

3518 Organometallics, Vol. 14, No. 7,1995

Anderson et al.

Table 2. Hydrogen-1,Carbon-13,and Boron-11NMR Dataa compd

'3CIdC

1Wdb

"Blbd

1

3.54 (s, 2 H, cage CH)

188.9 (CO),46.4 (cage CH)

2a

1.33 ( m br, 12 H, NCHNe), 2.98 (s, 2 H, cage CH), 3.22 (m br, 8 H, NCH2) 1.99 (m br, 4 H, OCHZCH~), 3.29 (s, 2 H, cage CH), 3.90 (m br, 4 H, OCH2) -14.67 (s, 1 H, 3.11 (s, 2 H, cage CHI, 3.62 (s, 24 H, 18-crown-6) -8.87 (d of d, 1H, p-H, JPH) 20,49 Hz, J W H ) = 190 Hz), 1.03 (m, 18 H, C H a e ) , 2.06 (m, 12 H, CH2), 3.20,3.60 (s x 2, 2 H, cage CH)

197.7 (CO),53.8 (NCH2J, 46.4(cage CH), 7.8(NCH&e)

8.9 (1 B), -3.6 (1B), -4.8 (2 B), -8.7 (2 B), -17.6 (3 B) 1.2 (1 B), -7.9 (1 B), -9.0 (4 B), -18.0 (1B), -22.0 (2 B)

196.2 (CO), 71.3 (OCHz), 52.6 (cage CH), 27.6 (OCHzCH2P

3.6 (1B), -7.0 (2 B), -8.5 (2 B), -12.1 (1 B), -18.2 (1B), -20.7 (2 B)

197.4 (CO), 70.4 (18-crown-6), 44.0 (cage CH)

2.9 (1B), -4.0 (1 B), -7.8 (2 B), -9.0 (2 B),-18.9 (1B), -20.7 ( 2 B)

198.4, 195.1 (CO),40.0,39.0 (cage CH), 20.8, 19.1 (m x 2, CHzMe), 8.84 ( C H a e )

49.1 (1B, BR, J ( R B ) = 76 Hz), 0.4 (1B), -2.7 (1B), -3.6 (1B), -9.2 (1B), -14.5 (2 B), -17.9 (1B), -28.0 (1 B)

3

4b 6

,u-m,

a Chemical shifts ( d ) in ppm, coupling constants (J)in Hz, measurements in CD2C12 a t room temperature. Resonances for terminal BH protons occur as broad unresolved signals in the range d ca. -2 to 3. Hydrogen-1 decoupled, chemical shifts are positive to high frequency of SiMe4. Measured in thf-de.

those of 2a. The lH NMR spectrum of 3 shows peaks would be more stable, it being well-known that replaceat d 3.29 for the cage CH groups and a t d 1.99 and 3.90 ment of CO groups by PPh3 stabilizes metal-hydride bonds. Thus the dihydride [R~(H)z(PPh3)2(71~-7,8-CzBgfor ligated thf. The reagent 3 can be isolated if required by column chromatography, but if this is done, the yield H11)I is readily re-formed from [Ru(PPh3)2(q5-7,8is not quantitative. Interestingly, spectroscopic examiCzBgH11)I and h y d r ~ g e n . ~ nation of solutions of 3 in nondonor solvents like CH2Interestingly, if the ruthenium-tetrahydrofuran comCl2 reveals the presence of another complex present in plex 3 is generated in situ, conditions under which the very minor amount. The latter shows CO peaks at 2064 salt [NEtdBFdI remains present, treatment of these and 2015 cm-l and resonances of weak intensity in the solutions with hydrogen affords 4a in over 70% yield. lH NMR spectrum at d 3.11 for cage CH and at d 1.83 It seems likely that an r2-H2 ruthenium complex is and 3.69 for free thf. We suggest this labile species is involved in the process, with the coordinated hydrogen the 16-electron complex [RU(CO)~(~~-~,~-C~B~H~~)I, disbeing activated toward heterolytic cleavage by the thf cussed further below. present. Studies on isolobal cyclopentadienylruthenium complexes1° provide a good model for this proposal. The It was shown earlier that reaction of 1 with KOH or is dihydrogen complex [RU(CO)~(~~~-H~)(~;~~-C~M~~) K[BH(sec-Bu)sIin the presence of 18-crown-6 gave the readily deprotonated even by the very weak base EtzO, salt ~K~18-crown-6~1~RuH~CO~z(t75-7,8-C~BgH~~~l.6 We The M ~cation ~)~I[BF~I. forming [ R u ~ ~ ~ - H ) ( C O ) ~ ( ~ ~ - C ~ treated the latter in CH2Cl2 with 1 equiv of HBF40Et20 of the latter is structurally and electronically related in an attempt to obtain either a neutral dihydrido to the anion [Ru2~-H)(C0)4(r5-7,8-C2BgHll)21present compound or an r2-H2 complex of ruthenium, but we in 4a. Hence a n attractive pathway for the formation obtained instead the anionic diruthenium complex [Ru2of 4a by treating thf solutions of 3 with hydrogen, in 01-H)(C0)4(r5-7,8-C2BgHll)21-, which we isolated as the the presence of the salt [NEtdBFd], would involve a [ N E W (4a) or [K(18-crown-6)1+(4b)salts. Data for 4 labile intermediate [Ru(C0)2(r2-Hz)(r5-7,8-C2BgHll)1, are given in Tables 1 and 2. The 'H NMR spectrum akin to [Ru(CO)2(y2-H2)(r5-C5Mes)l[BF41. The transient displays a singlet for the p-H group at d -14.67, while might be deprospecies [Ru(CO)2(r2-H2Xr5-7,8-C2BgH11)1 the l3C(lH} NMR spectrum shows resonances for the tonated by thf, the latter a stronger base than OEt2. CO ligands at 6 197.4 and for the cage CH vertices at d 44.1. Crystals of 4a were the subject of an X-ray The [RuH(C0)2(r5-7,8-C2BgHll)lso formed would then combine with molecules of 3 or [Ru(C0)2(r5-7,8-C2B9Hll)1 diffraction study to establish the structure of the anion. The results are given below after discussion of the to yield the [NEt41+ salt 4a and HBF4.thf.lla Indeed, in a separate experiment we found that Behnken's and routes by which 4 may be obtained. Hawthorne's6 salt [K(18-crown-6)l[RuH(C0)~(~5-7,8Formation of 4 by protonating [K(18-crown-6)1[RuHC2BgHdl readily reacts with 3 to give 4b. (C0)2(r5-7,8-C2BgH11)lcan be readily understood by In an attempt to clarify the nature of the intermediassuming that hydrogen is released, possibly by reductive elimination from a dihydride [Ru(H)2(CO)2(r5-7,8- ates involved in the formation of 4a from 3 and H2, solutions of 3 in CD2Cl2, with no [NEt41[BF41present, CzBgH11)I. This would produce the unsaturated species were treated with H2 and the 'H NMR spectrum of the [ R u ( C O ~ ( ~ ~ - ~ , ~ - Cmentioned Z B ~ H ~ ~above, ) ~ , which might mixture was examined. In the 'H NMR spectrum of then be captured by the unreacted [RuH(CO)2(v5-7,8[Ru(H)2(PPh3)2(r5-7,8-C2BgH11)1 the resonance for the C2BgHdl- present in the solutions thus yielding 4b. It hydrido ligands occurs at d -6.9,9 and in the tautomers is noteworthy that the compound [Ru(H)2(PPh3)2(r5-7,8CzBgHldl releases hydrogen to form the 16-electron [Ru(H)2(PPh3)2(r5-C5Me5)l+ and [Ru(r2-H2)(PPh3)2(r5-C5M e d + the RuH and Ru(r2-Hz)signals are seen at 6 coordinatively unsaturated complex [Ru(PPh3)2(r5-7,8-6.72 and -7.60, respectively.'lb In the hydrogenCzBgHd1,9 closely related to the postulated species [Ru(C0)2(r5-7,8-CzBgH11)l.However, with phosphines li(10)Heinekey, D. M.; Oldham, W. J. Chem. Rev. 1993,93,913. gating ruthenium, instead of carbonyls, the dihydride (9) Wong, E. H. S.; Hawthorne, M. F. Inorg. Chem. 1978,17,2863.

(11)la) Chinn, M. S.; Heineky, D. M.; Payne, N. G. Organometallics 1989,8 , 1824. (b)Chinn, M.S.; Heineky, D. M. J. Am. Chem. Soc. 1990,112, 5166.

Organometallics, Vol. 14,No. 7,1995 3519

Carborane Complexes of Ruthenium

Table 3. Selected Internuclear Distances (A)and Angles (deg) for [NEt4l[R~2(lr-H)(CO)4(~~-7,8-CzBsH*1)21 (4a). with Estimated Standard Deviations in Parentheses 1.809 2.285(5) 1.625(6) 1.710(6) 1.786(7) 1.786(7) 1.758(7) 1.789(7) 1.769(7) 2.252(4) 2.264(5) 1.700(7) 1.808(7) 1.767(7) 1.766(8) 1.753(7) 1.782(7) 1.152(6)

2.243(4) 1.866(5) 1.721(6) 1.696(6) 1.843(7) 1.790(7) 1.766(7) 1.766(8) 1.870(5) 2.274(5) 1.696(6) 1.729(7 1.765(7) 1.747(8) 1.763(8) 1.776(8) 1.146(6) Ru( l)-H-Ru(2) H-Ru(2)-C(24)

saturated solutions of 3 no resonance was observed in the region 6 -6 to -9 where peaks due to either Ru-H or Ru(y2-H2) groups of the mononuclear ruthenium species [Ru(H)2(CO)z(y5-7,8-CzBsH11)3or [Ru(C0)dy2H2)(r,75-7,8-C2BgHll)l would be expected. However, the solutions of 3 after treatment with H2 did display in their 'H NMR spectra two very broad peaks at 6 -14.77 and -15.01. This is the chemical shift region diagnostic for a proton in a site bridging a Ru-Ru bond,12 as typified by the very sharp resonance observed at 6 -14.67 in the 'H NMR spectra of the salts 4. Cooling hydrogen-saturated solutions of 3 to -90 K resulted in the 'H NMR resonance a t 6 -15.01 becoming sharp and that at 6 -14.77 resolving into three sharper signals centered at 6 - 14.12. Measurement of relaxation times (TI)on these signals provided no evidence for any being thus eliminating rapid due to an Ru@-y2-H2)Ru equilibration between isomers with classical [Ru2@-H)2(C0)4(y5-7,8-C2BgHll)21and nonclassical [R~z@-r,7~-Hz)(C0)4(y5-7,8-C2BgH11)21 structures. It is also noteworthy that in the 'H NMR spectra of the hydrogen-saturated solutions measured both at room temperature and at -90 K there was a broad signal at 6 8.5, possibly ascribable to protons associated with thf molecules displaced from 3 by hydrogen. From this inconclusive data we infer that heterolytic cleavage of H2 occurs via [Ru(CO)2(y2-H2Xy5-7,8-C2Bs11)1 immediately upon treatment of CH2C12 solutions of 3 with hydrogen and before addition of [NEt4l[BF4] results in formation O f 4a. The solutions would contain protons and a dynamic equilibrating mixture of diruthenium species, probably including cis- and trans-isomers of the anion [Ruz@H)(C0)4(r,75-7,8-C2BgHll)21-, thus accounting for the lH NMR signals seen in the region 6 -14.77 t o -15.01. Subsequent addition of [NEt41[BF41displaces the equilibrium, producing 4a as the most thermodynamically stable entity. The structure of 4a was determined by X-ray crystallography, and the anion is shown in Figure 1, with ~

(12) Kaesz, H. D.; Saillant, R. B. Chem. Rev. 1972, 72, 231. (13)Collman, J. P.; Wagenknecht, P. S.; Hutchison, J. E.; Lewis,

N. S.; Lopez, M. A.; Guilard, R.; L'Her, M.; Bothner-By,A. A.; Mishra, P. K. J . Am. Chem. SOC.1992, 114, 5654. Collman, J. P.; Hutchison, J. E.; Wagenknecht, P. S.; Lewis, N. S.; Lopez, M. A,; Guilard, R. J . Am. Chem. SOC.1990, 112, 8206.

128.8(1) 80.6(1)

Figure 1. Structure of the anion [Ru2(CC-H)(C0)4(rlj-7,8C2B9H&I- of 4a, showing the crystallographic labeling scheme. Hydrogen atoms have been omitted for clarity, and thermal ellipsoids are shown at the 50% probability level.

selected structural parameters listed in Table 3. The hydrido ligand, located by difference Fourier mapping after all other H-atoms had been found, spans the RuRu bond [3.189(6) AI with p-H-Ru(av) = 1.77 A, a distance very similar to that (ca. 1.79 A) in other species with Ru(p-H)Ru groups.14 Each ruthenium atom is coordinated by a nido-7,8-C2BgHll group in the usual pentahapto manner with these cages being transoid to one another. The carbonyl ligands deviate perceptibly from linearity in their bonding to the ruthenium atoms [Ru-C-0 angles, 172.4-177.1(4)"1. The results of the protonation studies on [K(18-crown6)l[RuH(CO)2(y5-7,8-C2BgHll)l which afforded compound 4b, and the isolobal mapping of H+ with Au(PPh3)+, prompted us to study the reaction between the potasand [AuClsium salt of [RuH(C0)2(y5-7,8-C2BgHl~)l(PPh3)I in an attempt to obtain a ruthenium-gold (14)Teller, R. G.; Bau, S. Struct. Bonding 1981, 44, 1.

3520 Organometallics, Vol. 14, No. 7, 1995

Anderson et al.

Table 4. Selected Internuclear Distances (A)and Angles (deg) for [AU(PP~~)~~[RUC~(CO)~(~~-?,~-C (2b),with Estimated Standard Deviations in Parentheses Ru-C(l) Ru-B( 5) C(l)-C(2) C(2)-B(3) B(3)-B(7) B(4)-B(9) B(6)-B(10) B(8)-B(9) B(10)-B( 11) AU- P(2 ) P(2)-C(41) C(3)-Ru-C(4) Ru-C(4)-0(4) C(ll)-P(l)-C(21) Au- P(2 )-C(4 1) C(41)-P(2)-C(61)

2.239(5) 2.284(5) 1.657(6) 1.719(8) 1.833(9) 1.806(8) 1.777(7) 1.800(8) 1.784(9) 2.324(1) 1.810(5) 88.9(2) 175.9(4 ) 106.1t2) 110.3(1) 106.8(2)

Ru-C(2) Ru- C(3) C(l)-B(5) C(2 )-B(6) B(3)-B(8) B(5)-B(9) B(6)-B( 11) B(8)-B( 11) C(3)-0(3) P(l)-C(ll) P(2)-C(51 1 C(3)-Ru-C1 P( 1)-Au-P( 2 ) Au-P(l)-C(31) A u - P ( ~)-C(51) C(51)-P(2)-C(61)

2.267(5) 1.902(5) 1.708(6) 1.733(8) 1.796(81 1.773(8) 1.799(8) 1.771(9) 1.155(6) 1.835(4) 1.840(5) 95.9(2) 172.a 1) 112.4(1) 110.4(1) 106.6(2)

Ru-B(3) RU- C(4) C(l)-B(6) C(2)-B(7) B(4)-B(5) B(5)-B( 10) B(7)-B(8) B(9)-B( 10) C(4)-0(4) P(l)-C(21) P(2)-C(61)

2.254(6) 1.890(6) 1.763(7) 1.695(8) 1.815(9) 1.789(8) 1.782(7) 1.765(9) 1.157(8) 1.818(5) 1.820(4)

C(4)-Ru-C1 AU-P(l)-C(ll) C(ll)-P(l)-C(31) C(41)-P(2)-C(51)

92.5(2) 112.7(2) 106.1(2) 106.6(2)

distances tPh) ring C(ll)-C(16) C(21)-C(26) C(31)-C(36) C(41)-C(46) C(51)-C(56) C(61)-C(66)

mean 1.39(1) 1.39(2) 1.39(2 1 1.39(1) 1.39(1) 1.40(1)

~~

(15)Green, M.; Orpen, A. G.; Salter, I. D.; Stone, F. G. A. J.Chem. Soc., Dalton Trans. 1984, 2497. (16)Carriedo, G. A.; Howard, J. A. K.; Stone, F. G. A,; Went, M. J. J . Chem. Soc.. Dalton Trans. 1984. 2545. (17)Lee, S. S.; Knobler, C. B.; Hawthorne, M. F. Organometallics 1991, 10,1054.

2.273(5) 2.452(1) 1.724(7) 1.860(7) 1.837(8) 1.784(10 1.781(8) 1.797(7) 2.319(1) 1.825(5)

Ru-C(3)-0(3) Au-P(lkC(21) C(21)-P(l)-C(31) Au-P(2)-C(61)

173.3(4) 113.6(2) 105.3(2) 115.8(2)

angles (Ph)

range 1.36-1.41 1.36-1.42 1.36-1.42 1.38-1.41 1.38-1.42 1.38-1.42

complex of formulation [(r5-7,8-C2BgH11)(0C)2Ru(~-H)Au(PPh3)l. Such a product would be formally related to [(OC)5Cr(pc-H)Au(PPh3)1, obtained from the reaction between [N(PPh3)21[CrH(C0)51and [AuC1(PPh3)1,15and would mimic the intermediate [Ru(C0)2(r2-H2)(r5-7,8CzBgHll)] mentioned above. The reaction between [K(18-crown-6)I[RuH(C0)2(r5-7,8-CzBgH11)1and [AuCl(PPh3)I in thf, in the presence of AgBF4 to facilitate removal of C1- as AgC1, did not give the anticipated ruthenium-gold complex but instead yielded the salt [Au(PPh3)21[RuC1(C0)2(~5-7,8-C~BgH11)1 (2b)together with what appeared to be a metallic residue of gold and silver. Compound 2b was also formed when TlPFs was used to remove C1- instead of AgBF4, and the brown intractable residue produced in this reaction may have contained gold metal. In the absence of AgBF4 or TlPF6 the reaction did not proceed. Formation of the cation [Au(PPh&I+ in reactions of [AuCl(PPh3)1, carried out in the presence of T1PF6 to remove chloride, has been observed previously16 and appears to involve displacement of solvent from [Au(solv)(PPh~)l+ by PPh3 molecules released when some of the gold reagent is reduced to the metal. Interestingly, compound 2b is also formed when 4a is treated with [AuCl(PPh3)1. The IR and NMX data for 2b were essentially the same as those for 2a, apart from resonances in the NMR spectra due to the different cations. Evidently a complex sequence of reactions occurs in the formation of 2b,and the nature of this product was not recognized until after a crystal structure determination had been made, the results of which are discussed below. Hawthorne and co-workers17 have observed that treatment of Naz[Fe(C0)2(r5-7,8-C2BgHl1)1 with [AuCl(PPh)]&TO& [Fe(C0)2(PPh3Xr/5-7,8-CzBsH11)1 in an eledron-transfer process instead of the anticipated product with an Fe-Au bond from nucleophilic substi-

Ru-B(4) Ru-C1 C(1)-B(10) B(3)-B(4) B(4)-B(8) B(6)-B(7) B(7)-B(ll) B(9)-B(ll) Au- P( 1) P(1)-C(31)

mean 120.0(10) 120.0(8) 120.0(9) 120.0(10) 120.0(9) 120.0(6)

range 119.0-122.0 118.7-121.1 119.2-121.4 118.7-121.2 118.4- 120.8 119.3-120.9

CI 0141 W

013)

Figure 2. Structure of the anion [RuC1(CO)z(v5-7,8CzBgHll)]- of 2b, showing the crystallographic labeling scheme. Hydrogen atoms have been omitted for clarity, and thermal ellipsoids are shown at the 50% probability level.

tution. In our study failure of Ag+ or T1+ to remove C1as insoluble AgCl or TlCl in the reaction between [K(18c ~ o ~ ~ - ~ ~ I [ R ~ H ~ Cand O [AuCl(PPh3)1, ~~~~~-~,~before chloride coordinates to the ruthenium to form 2b, is not fully explicable at present. However, if Ag+ or [Au(thf)(PPh3)1+ were to oxidize [RuH(C0)2(v5-7,8CzBgH11)l- so generating [Ru(CO)z(v5-7,8-C2BgHll)l as an intermediate, the latter would then react rapidly with C1- t o yield the anion of 2b, as in the similar formation of 2a from 1. The structure of the anion of 2b is shown in Figure 2, and selected internuclear distances and angles are listed in Table 4. On one side the ruthenium atom is coordinated by the nido-7,8-CzBgHll cage and on the other by two essentially terminally bound CO ligands (Ru-C-0 = 174") and the chloride ligand [Ru-Cl = 2.437(19) AI. The anion thus has the familiar piano

Organometallics, Vol. 14,No. 7, 1995 3521

Carborane Complexes of Ruthenium

Table 5. Selected Internuclear Distances (A) and Angles (deg) for

[K( 18crown-8)]z[R~~(lr-CO)z(CO)~(~~-7,8-CzB~H~~)~] ( E ) , with Estimated Standard Deviations in Parentheses 2.313(8) 2.376(11) 2.088(10) 1.739(15) 1.844(12) 1.793(13) 1.761(17) 1.761(14) 1.714(12) 2.088(10) 93.5(4) 94.6(3) 85.4(3)

C(3)-Ru-C(4) C(4)-Ru-C(4a) Ru-C(4)-Ru(a)

Ru-C(2)

C(B)-Ru-Ru(a) Ru(a)-Ru-C(4a) 0(4)-C(4)-Ru(a)

2.314(7) 1.853(10) 1.583(11) 1.716(14) 1.818(14) 1.878(14) 1.747(141 1.782(14) 1.733(17) 91.9(3) 46.5(3) 133.6(9)

2.276(11) 2.031( 11) 1.758(13) 1.707(14) 1.810(15) 1.723(17) 1.760(17) 1.737(15) 1.143(12) C(4) -Ru- Ru(a ) Ru-C(3)-0(3)

2.280( 11)2.793(1) 1.691(14) 1.70%14) 1.808(16) 1.716(14) 1.744(13) 1.656(18) 1.153(10)

48.2(3 ) 176.1(10)

Chart 2

I I c

[K(lt-m~d)]

B(31 8141

5

h

BIf

6 0 CH O B H

OB

Figure 3. Structure of the anion [Ru01-CO)z(C0)~(17~-7,8C Z B ~ H ~ of ~ )6~, showing ]~the crystallographic labeling scheme. Hydrogen atoms have been omitted for clarity, and thermal ellipsoids are shown at the 50% probability level.

metal separations found in the isolobal cyclopentadienyl stool arrangement. In the isolobally mapped molecules species [ R U ~ @ - C O ) ~ ( C O ) Z ( ~ [2.735(2) ~ - C ~ H ~Allga ) ~ ~and [RuCl(PPh3)~(17~-CsHs)l and [ R u C ~ ( P P ~ ~ ) Z ( ~ ~ ~ - [R~2@-CO)2(C0)2(17~-CsMe4Et)21[2.7584(5) C~M~~CH~which Cl)] the Ru-C1 distances are 2.453(2) Alas and 2.422(3) have similar CZh symmetry. The ruthenium atoms of &lab respectively. The atoms Ru, C1, and B(3) and the the dianion of 5 and the two terminal CO groups lie in midpoint of the cage C-C connectivity lie on a plane of a mirror plane with the two pentahapto-bonded carbosymmetry. Consequently, in the 'H and l3C(lH} NMR rane groups lying across the mirror plane. The two spectra of the species 2 (Table 2) the CH groups of the mirror-related bridging CO ligands lie on the crystalcage are equivalent and therefore display a single lographic 2-fold axis. Not surprisingly, the Ru-Ru resonance. distance in 5 is appreciably shorter than that in 4a due Treatment of compound 4b in thf with NaH results to the presence of the p-H group in the latter.14 The in deprotonation and formation of the dianion [Ru2@symmetrical molecular geometry of 5 found in the CO)2(CO)2(~5-7,8-C~BgHll)212isolated as its [K(18crystal evidently predominates in solutions of the crown-6)]+ salt 5 (Chart 2). It has been previously complex since the IR spectrum displays a very strong shown6 that reduction of 1 with sodium amalgam also terminal CO stretch (1974 cm-') when measured in thf. , ~ -it C ~ BThere ~ H ~ is, ~ )however, ~ I ~ - ,a very weak absorption at 1930 cm-l produces [ R u ~ ~ - C O ) ~ ( C O ) ~ ( ~ ~ - ~and was proposed, on the basis of the observation of only indicating the presence of another isomer in low conone terminal CO stretch in its IR spectrum (1910 cm-l centrations. A broad absorption for the bridging carin Nujol), that it has a centrosymmetric structure with bonyl groups is seen at 1760 cm-l. a trans configuration of the carborane ligands. We can The reaction between [K(18-crown-6)1[R~H(CO)~(~~confirm this structure for the solid state as a result of 7,8-C2BgHll)land [PtH(Cl)(PEt&]in thf in the presence an X-ray diffraction study. of TlPF6 was next investigated. In donor solvents, in The structure of the anion is depicted in Figure 3 and the presence of the salts TlBF4 or TlPFs, the platinum selected internuclear distances and bond angles are complex affords the reactive species [PtH(solv)(PEt3)21+ ven in Table 5. In 5 the Ru-Ru distance is 2.793(1) (solv = acetone or tho. Earlier results revealed that a and may be compared with the very similar metalcombination of the reagents [PtH(Cl)(PEt3)21and TlBF4

f

~

(18)( a )Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J . Chem. SOC.,Dalton Trans. 1981,1398. cb) Fan, L.;Turner, M. L.: Adams, H.: Bailey, N. A.; Maitlis, P. M. Organometallics lS96,14, 676.

(19)( a )Mills, 0.S.; Nice, J. P. J. Organomet. Chem. 1967,9, 339. ( b )Bailey, N. A,; Radford, S. L.; Sanderson, J. A.; Tabatabaian, K.: White, C.; Worthington, J. M. J. Organomet. Chem. 1978,154, 343.

3522 Organometallics, Vol. 14, No. 7, 1995

Anderson et al.

Table 6. Selected Internuclear Distances (di) and Angles (deg) for [ R u e t O l - H ) ~ - c c p 6 - 7 , 8 - C ~ B ~ ~ ~ ) ( C O )(6), ~ ( Pwith E t ~ Estimated )~l Standard Deviations in Parentheses

82.4(2) 106.5(2) 176.2(81 88.412) 144.9(1j 110.8(3) 101.1(4) 103.8(4)

2.238(7) 1.881(7) 1.617(10) 1.736(13) 1.792(13) 1.762(12) 1.738(14) 1.761(111 1.763111 2.369(2) 1.859(10)

2.236(7) 2.219(6) 1.557 1.698(9) 1.830(10) 1.774(10) 2.069(7) 1.763(12) 1.780(14) 1.166(11) 1.833(7 1

1.817 2.323(7) 2.802(1) 1.716(10) 1.673(10) 1.850(13) 1.838(12) 1.758(12) 1.747(14) 1.157(9) 1.792(8) 1.826(7)

2.25717) 1.837(9) 1.791(111 1.704(11) 1.782(10) 1.807(10) 1.797(11 1.752(11) 1.785(12) 2.248(21 1.813(10)

1.810(8)

H-Ru-C(4) C(4I-Ru-R Ru-C( 4 )- O(4) Ru-Pt-P( 1) H- Pt -P(2 1 Pt-P(l )-a131 C(l3)-P(l)-C(l5) Pt-P(2)-C(25)

89.3(2) 108.8(2) 178.6(6) 107.0(1) 172.7(1) 125.1(2) 103.8(4) 114.2(3)

C(3)-Ru-C(4) RU-H -Pt Ru-Pt-H H-Pt-P(l) B(5)-Pt-P(2) C(ll)-P(l)-C( 13) Pt -P(2 )-C( 2 1) C(21 )-P(2 )-C( 25 1

88.6(3) 112.1(1)

36.9(1) 70.7(1) 93.6(2) 105.214) 114.8(2) 103.914 1

H -Ru- Pt Ru-B( 5 1-Pt Ru-Pt-B( 5 1 B(5 )-Pt-P( 1) P(1)-Pt-P(2 ) Pt -P( 1)-Ci 151 Pt-P(2)-C(23) C123)-P(2)-C(25)

31.0(1) 81.5(2) 5 1.6(2 157.9(2) 108.011) 108.2(3) 115.1(2 103.6(4)

reacts readily with [NE4l[Rh(COXPPh3)(17j-7,8-CzBgH11)1 3,1,2-MC2Bg framework. Moreover, there is ample to yield [RhPt(~-H)(~-CO)(PEt3)2(PPh3)(1;15-7,8-CzBg- precedent for the facile transformation of such threecenter two-electron bonds into structures having M(pH11)1.20aIn view of this work it seemed likely that a H)Pt and B-Pt bonds.20 However, it always remains metathetical reaction would occur between [RuH(C0)2to be established whether it is the boron atom in the a (~5-7,8-C2BgHll)l-and [PtH(solv)(PEt3)21+to yield a ruthenium-platinum complex. Moreover it would be or p sites with respect to the two carbons in the n interesting to establish if in any product of this reaction pentagonal CCBBB face of the nido-CzBg unit v5the cage adopts a spectator role as in [RhI?t+-H)(p-CO)coordinated to M which forms the B-H-Pt or B-Pt (PEt3)2(PPh3)(r15-7,8-C2BgH11)l or whether it plays a linkages. In the majority of instances it is the Bp atom nonspectator role as is often observed,21 as in for n example [R~P~@-U,~~-~,~-C~B~H~O)(CO)(PE~~)~(PP~~)I.~~~ in the CCBBB ring which is involved in exopolyhedral It was found that if [K(18-crown-6)I[R~H(C0)2(~~-7,8bonding, especially if the nido-cage fragment is 7,8-Me2C2BgHll)l and [PtH(Cl)(PEt&I are mixed in thf and 7,8-C2BgHg rather than 7,8-CzBgHll. In compound 6, TlPF6 is added, hydrogen is released and the complex however, the 'H and 13C{'H} NMR data indicate asym[RuPt(~-H)(~-a:gj-7,8-C2BgHlo)(CO)2(PEt3)21 (6) is obmetry in the molecule providing strong evidence that it tained. The NMR data for this complex (Table 2) are is the B, atom which forms the B-Pt bond. The CH in accord with the presence of a hydrido ligand bridging groups are nonequivalent with IH NMR resonances a t the Ru-Pt bond and with the cage forming an exopoly6 3.20 and 3.60 and 13C{lH)NMR signals a t 6 39.0 and hedral B-Pt bond to the Pt(PEt3)z group. The 'H NMR 40.0. If a B,j-Pt bond were present, the cage CH groups spectrum has a diagnostic resonance for a p-H group at would lie on either side of a symmetry plane through 6 -8.87 [J(PP) = 49 and 20 Hz, J(PtH) = 190 Hzl and the Pt, Ru, P, ,u-H, and B,j atoms and the midpoint of the llB{lH} NMR spectrum has a peak at 6 49.1 with the C-C connectivity. This assumes the usual planar lg5Ptsatellite signals [J(PtB) = 590 Hzl, a resonance geometry around platinum with the two P atoms and pattern characteristic for a B-Pt a-bond.22 In the the p-H and B,j atoms being coplanar with the Pt atom. complex [RhPt(CO)@-a,t15-7,8-C2BgHlo)(PEt3)2(PPh3)l, The appearance of one resonance for CH in both the lH which also has an exopolyhedral B-Pt bond, the signal and 13C(1H) NMR spectra would result from this for the boron nucleus is at 6 48.3 with J(PtB) = 598 geometry. Hz.20b In order to unequivocally establish the structure of It is very likely that the formation of 6 proceeds by a 6 a single-crystal X-ray diffraction study was compound pathway which involves an intermediate species with carried out. Selected structural parameters are listed an exo-polyhedral B-H-Pt linkage which then underin Table 6, and the molecule is shown in Figure 4. It is goes oxidative addition across the Ru-Pt bond yielding immediately evident that it is the B, atom which forms the Ru@-H)Ptand B-Pt groups present in the product. the exopolyhedral bond with a B(5)-Pt distance of Exopolyhedral B-H-Pt linkages are common in species 2.069(7) A. Exopolyhedral B-Pt bonds are also found where a PtL2 (L = PR3 or CO) fragment is linked to a in [WPt(p-H){p-a,v5-7,8-Me2-lO-(CH2C~H4Me-4)-7,8-C2metal atom which forms a vertex in a closo-icosahedral BSH.~}(CO)~(PM~~)(PE~~)~I [2.123(5) [WPt@-CC&Me2-2,6)~-o,1;1j-7,8-Me2-7,8-C2BgH~)(CO)3(PEt3)1[2.16(1) 120)(a1Goldberg, J. E.; Howard, J . A. K.; Muller, H.; Pilotti, M. U.; Stone, F. G. A. J . Chem. SOC.,Dalton Trans. 1990,3055.lb) Goldberg, and [WPt(p-CCd&Me-4)( -o,v5-7,8-Me2-7,8-C2BgJ. E.; Mullica, D. F.; Sappenfield, E. L.; Stone, F. G. A. J . Chem. SOC.. The Ru-Pt bond Ha)(C0)2(PMe2Ph)21[2.17(1) Dalton Trans. 1992,2693. (21)Stone, F. G. A. Adu. Organomet. Chem. 1990,31,53.Brew, S. [2.802(1)A] in 6 is spanned by the hydrido ligand [RuA.;Stone, F. G. A. Adu. Organomet. Chem. 1993,35, 135. Jelliss, P. H = 1.82, Pt-H = 1.56 A] as expected. It was located A.; Stone, F. G. A. J . Organomet. Chem. 1995,in press. by difference Fourier mapping after all other H-atoms 122)la) Attfield, M. J.; Howard, J. A. K.; Jelfs, A. N. de M.; Nunn, C. M.; Stone, F. G. A. J . Chem. SOC.,Dalton Trans. 1987,2219. tb! were found. Most Ru-Pt separations occur in the range Devore, D. D.; Howard, J. A. K.; Jeffery, J. C.; Pilotti, M. U.;Stone, F. 2.609-2.875 A, variations resulting from the presence G. A. J. Chem. SOC.,Dalton Trans. 1989,303. IC! Carr, N.;Gimeno, M. C.; Stone, F. G. A. J . Chem. SOC.,Dalton Trans. 1990,2617. or absence of bridging groups.23 In [Ru~P~z@-H)@~-CH)-

a"

Organometallics, Vol. 14, No. 7, 1995 3523

Carborane Complexes of Ruthenium

Table 7. Data for X-ray Crystal Structure AnalysesO 2b 4a 5

~~

cryst dimens1mm formula Mr cryst color, shape cryst system space group (No.)

a/A

blA CIA ddeg [jldeg yldeg VIA3 Z

dcalcdg ,u(Mo Kal1cm-l F(OOOYe 20 range1deg

T/K no. of reflns measd no. of unique reflns no. of obsd reflns criterion for obsd n [F,z ndF,)I weighting factor1g (w-1 = [U2(Fo) +glFo121) reflcn limits h

k 1

R(R')b final electron density diff features (max/min)/eA-3 S (goodness-of-fit)

0.20 x 0.28 x 0.44

0.21

orange irregular crystal teclinic P1 (No. 2) 11.167(2) 11.861(2) 17.103(3) 99.50(2) 105.01(2) 95.58(2) 2134.6(6) 2 1.628 39.40 1024 3-40 292 4229 3890 3790 n=4 0.0010

0.25 x 0.61

6

0.12 x 0.48 x 0.59

0.13 x 0.49 x 0.53

orange prism monoclinic P21k (NO.14) 11.205(2) 20.736(2) 13.769(2)

orange irregular crystal monoclinic P21k (NO.14) 12.746(1) 18.116(4) 12.440(2)

yellow triangular plate monoclinic P21k (NO.14) 18.774(4) 12.094(2) 13.429(3)

96.69(2)

109.58(1)

110.78(2)

3177.5(8) 4 1.485 9.58 1424 3-40 292 3269 2951 2571 n=4 0.0007

2706.4(8) 2 1.455 7.57 1212 3-40 292 2771 2500 2231 n=4 0.0073

2850.8(10) 4 1.680 55.96 1400 3 -40 292 2983 2652 2396 n=4 0.0012

0 to 10 -11 to 11 -16 to 15 0.0264 (0.0301) 1.471-1.14

0 to 10 0 to 19 -13 to 13 0.0229 (0.0293) 0.241-0.22

0 to 11 0 to 17 -12 to 11 0.0461 (0.0634) 1.071-0.36

-18 to 16 0 to 11 0 to 12 0.0267 (0.0353) 0.621-0.79

1.06

1.14

1.14

1.13

x

Data collected 05 an Enraf-Nonius CAD4-F automated diffractometer operating in the (0-28 scan mode; graphite-monochromated Mo Ka X-radiation, = 0.710 73 A. Refinement was block full-matrix least-squares on F with a weighting scheme of the form w - l = [u2(Fo) + glFo1*1where oc2(F0)is the variance in F, due to counting statistics. R = zllFol - IFcllalFol,R' = &d'211F0~- ~ F c ~ ~ ~ w l ' z ~ F o ~ .

with slight slippage toward B(5) [Ru-C(l) = 2.236(7), Ru-C(2) = 2.238(7), Ru-B(3) = 2.257(7), Ru-B(4) = 2.323(7), Ru-B(5) = 2.219(6) AI as is usual in such systems. The Ru atom also carries two terminally bound CO groups (Ru-C-O(av) = 177.4'). The P-Pt distances are normal with P(l)-Pt [2.369(2)A] transoid to the boron atom B(5)being longer than P(2)-Pt L2.248(211 as expected.22a*C Ignoring p-H, the platinum atom lies in a plane defined by P(1), P(2), B(5), and Ru, and the maximum deviation of any atom from this plane is 0.11 A. As mentioned above, on the basis of earlier work21 formation of 6 likely proceeds through an intermediate having a B-H-Pt linkage, and because 6 has a Ba-Pt bond the precursor would have a Ba-H-Pt rather than a B,j-H-Pt group. However, along the pathway to 6 the existence of a species with a Bp-H-Pt bridge cannot be ruled out. Interconversion between Ba-H-M and Figure 4. Structure of [RuPt(p-H)~-a:~~-7,8-C2BgHlo)-B,j-H-M (M = Ir or Pt)groups has been observed, as (CO)2(PEt&I (81, showing the crystallographic labeling has the overall transformation of a Bp-H-Pt linkage scheme. Hydrogen atoms have been omitted for clarity, into a product with Ba-Pt and M(p-H)Pt (M = Mo or and thermal ellipsoids are shown at the 50% probability W) units.4b,22b.24 The interconversion between a struclevel. ture having an exopolyhedral Bp-H-M linkage and one with a Ba-H-M unit could be facile. It could occur via Cu-CO)(C0)2(PPri3)2(~5-C5H5)~1 the Ru-Pt bonds are a momentarily breaking of these bridge bonds with bridged in a variety of ways, but the Ru-Pt linkage with concomitant rotation of the cage about an axis through a p-H group is 2.820(1) A,23bvery similar to that found the centroid of the CzB3 ring and the metal atom to in 6. The ruthenium atom in 6 is ligated by the nidowhich it is v5-coordinated, followed by re-formation of 7,8-CzBs fragment in the usual q5-bonding mode but a B-H-M group in which the boron is in either the a or /3 site with respect to the carbons. (23)(a)Davies, S. J.; Howard, J. A. K.; Pilotti, M. U.; Stone, F. G. A. J. Chem. SOC.,Dalton Trans. 1989, 303. Ib) Davies, D. L.; Jeffery, J. C.; Miguel, D.; Sherwood, P.; Stone, F. G. A. J . Organomet. Chem. 1990,383, 463.

( 2 4 )Jeffery, J. C.; Ruiz, M. A.; Sherwood, P.; Stone, F. G. A. J.Chem. SOC.,Dalton Trans. 1989, 1845.

3524 Organometallics, Vol. 14, No. 7, 1995

Anderson et al.

Table 8. Atomic Coordinates ( x 104) and Equivalent Isotr pic Displacement Parameters ( X 2 x 10s) for 4a atom

X

7718(1) 6580(4) 5866(3) 8919(4) 9732(3) 8130(4) 6848(4) 7003(4) 8589(4) 9302(4) 7518(5) 6818(5) 7936(5) 9345(5) 9065(4) 8267(5j 7470(1) 9136(4) 0169(3) 7390(4j 7336(3) 6878(4) 5745(3) 5910(5) 7325(4) 7923(5) 5558(5) 4941(5) 5951(5) 7201(5) 6938(5) 5718(5) 7843(3) 9023(4) 9013(5) 7507(4) 8397(5) 8070(4) 7021(5) 6804(5) 6952(6)

V

6434(1) 6976(2) 7316(2) 6744(2) 6952(2) 5683(2) 6033(2) 6853(2) 70 13(3) 6221(2) 5628(3) 6376(2) 6979(3) 6589(3) 5752(3) 6226(3) 5440(1) 5441(2) 5429(2) 4676(2) 4188(2) 62 18(2) 5796(2) 4997(3) 4918(3) 5728(3) 6258(3) 5476(3) 4927(3) 5383(3) 6209(3) 5702(3) 1815(2) 1545(2) 841(3) 1468(2) 1501(3) 2528(2) 2897(3) 1718(3) 2021(4)

z

U(eaP

4147(1) 4610(3) 4854(3) 5077(3) 5566(2) 3048(3) 2725(3) 2691(3) 3005(3) 3268(4) 1846(4 ) 1604(3) 1778(4) 2128(4) 2171(4) 1244(4) 5878(1) 58583) 5907(2) 5150(3) 4771(2) 6857(3) 6345(3) 6563(4) 7331(3) 7464(3) 7361(4) 7208(4) 7844(4) 8396(4) 8096(4) 8335(4) 5730(2) 5435(3) 5 186(5) 6616(3) 7506(4) 5932(3) 6247(4) 4945(3) 3962(4)

a Equivalent isotropic U defined as one-third of the trace of the orthogonalized U, tensor.

Conclusions The work described shows that compound 1 is capable of being the starting point for the synthesis of organoruthenium complexes having qs-7,8-C2BgH1l ligands. The thf complex 3 in particular is likely to be a useful synthon, and preliminary studies indicate that it reacts readily with alkenes, alkynes, and alkylidyne-metal complexes. Moreover, the synthesis and exploration of the chemistry of ER~(C0)3(t1~-7,8-Me2-7,8-C2BgHg)l will also be important since previous results have demonstrated that the groups q5-7,8-C2BgH11and q5-7,8-Me27,B-CzBgHg often differ in their influence on the reactivity a t metal centers just as v5-CsH5 and q5-CsMes ligands can promote different reactivity patterns. Experimental Section General Considerations. Solvents were distilled from appropriate drying agents under nitrogen prior to use. Petroleum ether refers t o that fraction of boiling point 40-60 "C. All reactions were carried out under an atmosphere of dry nitrogen using Schlenk line techniques. Chromatography columns (ca. 15 cm in length and ca. 12 cm. in diameter) were packed with silica gel (Aldrich, 70-230 mesh). Celite pads for filtration were ca. 3 cm. thick. The reagents nido-7,8C ~ B ~ H I[~A, u' C ~ ~ ( P P ~ ~ )and I , ' ~[F%H(C1)(PEt~~~lz7 were pre-

Table 9. Atomic Coordinates ( x 104) and Equivalent Isotropic Displacement Parameters ( A 2 x 109) for 2b atom

X

5488(1) 5445(4) 5371(4) 6564(5) 7534(5) 6733(5) 5786(5) 6540(6) 7922(5) 8028(5) 6710(5) 7468(5) 5907(5) 6278(3) 5330(5) 5306(4) 3232(1) 1718(1) 887(1) 280(4) 788(4) 296(5) -673(5) -1201(4) -719(4) -400(4) -411(4) -1333(5) -2291(5) -2301(4) -1357(4) 2043(4) 1771(5) 2688(5) 3815(5) 4081(5) 3219(4) 2311(1) 1138(4) 939(4) -12(4) -761(4) -586(4) 369(4)

Y

1700(1) 289(4) -251(4) 426(5) 1448(5) 1310(4) -1123(5) -1036(5) 1(5) 565(5) -134(5) -934(5) 3260(5) 4183(3) 2238(4) 2599(3) 1569(1) 3041(1) 381U 1) 2703(4) 2686(4) 1804(4) 973(4) lOOO(4) 1866(4) 4604(3) 5230(4) 5881(4) 5945(4) 5333(4) 4670(4) 4834(4) 5914(4) 6626(4) 6289(4) 5237(5) 4517(4) 2286(1) 2394(4) 1610(4) 1694(4) 2555(4) 3334(4) 3260(4)

z

UeqP

2025(1) 2744(3) 1772(3) 1475(3) 2423(3) 3207(3) 2488(3) 1695(4) 2116(3) 3 179(3) 3388(4) 2729(3) 2608(3) 2992(2) 1028(3) 436(3) 1874(1) 2859(1) 1709(1) 761(3) 93(3) -608(3) -662(3) O(3) 711(3) 1798(3) 2575(3) 2636(3) 1936(3) 1171(3) 1095(3) 1505(3) 1296(3) 1099(3) 1098(3) 1304(3) 1521(3) 4049(1) 4605(3) 5108(3) 5487(3) 5377(3) 4884(3) 4509(3)

a Equivalent isotropic U defined as one-third of the trace of the orthogonalized U,]tensor.

pared as previously described. Tetrafluoroboric acid was a n 85% solution of HBFd.Et20 in OEt2, as supplied by Aldrich. The NMR spectra were recorded in CD2C12 a t ambient temperatures, unless otherwise stated, a t the following frequencies: 'Ha t 360.13 MHz, 13Ca t 90.56 MHz, 31Pa t 145.78 MHz, and IlB a t 115.5 MHz. Synthesis of [Ru(CO)s(t15-7,8-C2BsH11)1(1). The compounds [RuQ(CO)IZI (3.0 g, 4.69 mmol) and nido-7,8-C2BgH13 (1.92 g, 15 mmol) were heated in heptane (50 mL) for 4-5 h a t reflux temperatures, during which time the mixture became dark red. After being cooled t o room temperature, about half the heptane was removed in vacuo and the remaining solvent decanted from the residue. The latter was extracted with CHzClz-petroleum ether (2:1, 30 mL) and the extracts filtered through a Celite pad. Solvent was removed in vacuo and the residue washed with petroleum ether ( 2 x 10 mL) giving a dark red precipitate of 1 which is of satisfactory quality for most reactions without further purification. However, analyti( 1 ) (3.59 g) can be obcally pure [R~(CO)s(~~-7,8-C2BgH11)1 tained by column chromatography eluting with CHsC12(25)Hlatky, G. G.; Crowther, D. J. Inorg. Synth., in press. Young, D. A. T.; Wiersma, R. J.; Hawthorne, M. F. J.A m . Chem. SOC.1971, 93, 5687. (26)Uson, R.; Laguna, A. Organomet. Synth. 19863,325. 127) Parshall, G. W. Inorg. Synth. 1970, 12. 28.

Organometallics, Vol. 14, No. 7, 1995 3525

Carborane Complexes of Ruthenium

Table 10. Atomic Coordinates ( x 104) and Equivalent Isotro ic Displacement Parameters x 10s) for 6

Table 11. Atomic Coordinates ( x 104) and Equivalent Isotro ic Displacement Parameters x 10s) for 6

atom

atom

(&

X

Y

z

U(eda

(&

X

z

.Y ~

5548(1) 6238(6) 7226(6) 7233(8) 6079(8) 5463(8) 7536(9) 8200(8) 7474(7) 6406(8) 6436(9) 7679(8) 5136(71 4924(6) 3983(8) 3170(4) 2287(2) 1004(8) 2058(8) 2280(5) 3241(9) 3316(91 3392(4) 3535(9) 3602(9) 2613(5) 2553(9) 1503(10) 1459(41 471(9) 489(8) 395(4) 358(8) 211(8) 1147(5)

5295(1) 6425(4) 5854(5) 5425(5) 5869(5) 6530(6) 6773(6) 6161(6) 6207(6) 6883(6) 7181(6) 7009(5) 4502(6) 4027(4) 5446(51 5757(3) 6023(1) 4135(5) 4072(6) 4752(3) 4701(5) 5393(6) 6019(4) 6680(7) 7301(7) 7363(3) 7972(5) 7983(6) 7376(3) 7345(6) 6691(6) 6057(3) 5407(6) 4778(5) 4697(3)

4296(1) 5085(7) 5286(7) 4059(9) 2929(8) 3630(9) 5393(10) 4729(9) 3267(9) 3045(10) 4314(11) 4077(9) 3302(8) 2659(6) 4339(8) 3870(5) 1543(1) 905(9) 670(9) 228(5) -94(9) -749(9) -37(5) -589(9) 216(10) 454(5) 1083(8) 1297(9) 1998(4) 2309(11) 3005(8) 2314(5) 2920(8) 2139(9) 1780(6)

Equivalent isotropic U defined as one-third of the trace of the orthogonalized U, tensor.

3150(1) 1980(4) 2463(4) 2843(5) 2500(5) 1998(4) 1496(5) 2024(5) 2009(5) 1499(5) 1174(5) 1202(5) 3672(4) 4030(3) 4076(4) 4656(3) 2456(1) 3409(1) 3822(5) 3260(5) 3281(4) 3979(5) 4238(5) 4060(5) 1353(1) 572(5) 768(5) 1394(41 647(4) 979(5) 1568(51

2073(1) 2526(5) 3614(5) 3522(6) 2216(6) 1522(6) 3727(6) 4342(7) 3473(6) 2276(6) 2404(6) 3577(6) 2109(6) 2127(5) 2013(6) 1970(4) -9(1) -1343(2) -1113(7) - 1179(7) -2843(6) -3569(6) - 1060(7) -910(8) -907(1) -476(6) -604(7) -2403(6) -3039(5) -756(6) - 1054(7)

~____

U(ea )"

3070(1) 3005(5) 2939(5) 1938(6) 1246(6) 2034(6) 2513(7) 1831(7) 769(6) 825(6) 1915(7) 1124(6) 4551(6) 5452(4) 2894(6) 2759(5) 2602(1) 3416(2) 4824(6) 5356(7) 3262(7) 3781(7) 3004(7) 1873(7) 1791(2) 2195(7) 3358(7) 1989(7) 1506(7) 357(6) -150(6)

" Equivalent isotropic U defined as one-third of the trace of the orthogonalized U,-tensor. mL) a t 0 "C and treated dropwise with HBF4.Et20 (0.06 mL, 0.34 mmol). After the mixture was slowly warmed to room

temperature, solvent was reduced in volume to ca. 5 mL, and the mixture was chromatographed as above for 4a, yielding petroleum ether (l:l), removing solvent in vacuo, and washing [ K ( ~ ~ - C ~ O W ~ - ~ ) ~ [ R ~ ~ ( ~ - H(4b) ) (t 0.12 C Og). )~(~~-~, the residue with petroleum ether (20mL). (ii) A 0.36 mmol sample of 3 was prepared in situ in CH2Synthesis of [NEt~l[RuI~C0)~~~s-7,8-C~B~H~~)l (2a). A Cl2 (20mL) a t room temperature, and [K(18-crown-6)1[RuHmixture of 1 (1.5g, 4.7mmol) and [NEtdlI (1.21g, 4.7 mmol) (C0)2(115-7,8-C2BsH11)] (0.20g, 0.34 mmol) was added. After was heated in thf (30 mL) at reflux temperatures for 2-3 h. 1 h, solvent was reduced in volume to ca. 5 mL and the mixture Solvent was removed in vacuo and the oily residue extracted chromatographed, as described above for 4a, giving the salt with CHzCl2-light petroleum (2:1,30 mL), and the extracts 4b (0.24g, 74%). were filtered through a Celite pad. Solvent was then partially (iii)A mixture of [K(18-crown-6)l[RuH(CO)2(~j-7,8-C2BgH11)1 removed and light petroleum added (ca. 20 mL). The solution was cooled to give a red precipitate of [NEt4l[RuI(C0)~(11~-7,8-(0.20g, 0.34 mmol), [AuCl(PPh3)1 (0.17g, 0.34mmol), and AgBF4 (0.06 g, 0.34 mmol) was stirred in thf (20mL) a t room C2BgHll)l (2a)(1.93g), dried in vacuo. temperature for 30 min. Solvent was removed in vacuo and Synthesis of [Ru(CO)2(thf)(tls-7,8-C2B~Hll)l (3). Comthe residue extracted with CHzCl2-petroleum ether (2:1, 2x pound 2a (0.20g, 0.36 mmol) in thf (20 mL) was treated with 15 mL). The extracts were filtered through a Celite pad, and AgBF4 (0.07g, 0.36 mmol). After 10 min the solvent was the solvent was reduced in volume to ca. 5 mL and chromatoremoved in vacuo and the residue extracted with CHzCl2 (20 graphed. Elution with CHzClz-thf (5:l)removed a yellow mL), and the extract was filtered through a Celite pad to yield fraction from which red microcrystals of [Au(PPh&l[RuCla solution of 3 in essentially quantitative yield and suitable (CO)2(115-7,8-C2BgH11)](2b) (0.08 g) were recovered after for most purposes. Pure [Ru(CO)2(thf)(11j-7,8-C2BgHu)l (3) evaporation of solvent and washing the product with petroleum (0.08 g, ca. 60%) if desired may be isolated by column ether (20mL). chromatography a t -20 "C, eluting the broad yellow band (iv)A mixture of [ K ( ~ ~ - C ~ O ~ ~ - ~ ) I [ R ~ H ( C O ~ ~ ( ~ ~ - ~ , which develops with CHzCl2-thf (5:l). 0.25 Synthesis of [ N E ~ ~ I [ R U ~ ( ( ~ - H ) ( C O(4a). ) ~ ( ~ ~(0.15 - ~ g, ,~ C ~mmol) ~ I )and ~ [F'tH(Cl)(PEt&)] (0.12g, 0.25mmol) in thf (20mL) was treated with TlPFs (0.09g, 0.25mmol). A A CH2C12 (20mL) solution of 3 was prepared as described precipitate formed instantly, but the reactants were stirred above; under these conditions 1 molar equiv of [NEt41[BF41 is together for 1 h before removal of solvent in vacuo. The present. The mixture was treated with a stream of hydrogen, residue was extracted with CHzCl2-petroleum ether (2:1,2x the color changing from yellow to red. Solvent was reduced 15 mL), and the extracts were filtered through a Celite pad. in volume (ca. 5 mL) and the mixture chromatographed. The volume was reduced to ca. 5 mL before chromatography. Elution with CHzCl2 removed a yellow fraction which on Elution with CHzCl2-petroleum ether (2:l) gave, aRer removal evaporation of solvent in vacuo and washing the residue with of solvent, yellow crystals of [R~F't(~c-H)(~(-o:11~-7,8-CnBgHlo)petroleum ether (20mL) gave yellow microcrystals of [NEtd(CO)z(PEts)zl(6)(0.11 g). [Ru2(iu-H)(CO)4(11j-7,8-C2BgHll)~I (4a)(0.10 g). Crystal Structure Determinations and Refinements. Reactionsof [K(l&rrownb)l[RuH(C0)2(tlS-7,8-C2BaH11)1. The crystal data and other experimental details for compounds (i) The salt (0.20g, 0.34mmol) was dissolved in CH2C12 (20

3526 Organometallics, Vol. 14, No. 7, 1995

2b, 4a, 5, and 6 are given in Table 7. Crystals of 2b, 4a, 5, and 6 were selected on the basis of optical purity using a Zeiss Photomicroscope 11, and a conoscopic study verified their optical homogeneity. For each data set, final unit cell parameters were obtained from the setting angle values of 25 accurately centered reflections. Periodic intensity measurements of three control reflections for each compound, monitored at 2 h intervals of collection time, revealed no sign of deterioration for compounds 2b, 4a, and 6. Thus, the electronic hardware reliability and crystal stability were confirmed. For complex 5, a decay of 6.1% dictated the use of the SDP program Decay,28 which applied a linear decay correction to the data set. After removal of these check reflections and systematic absences, the data for each complex were corrected for Lorentz, polarization, and X-ray absorption effects. The latter corrections were based on a n empirical method employing high-angle ip scan data.2g The data for 2b, = 0.018 (2b),0.020 (4a), 0.023 4a, 5, and 6 were averaged (5), 0.035 (6)land a n additional examination of each data set using a n N ( Z ) analysis (cumulative probability distribution test) provided evidence that all were centrosymmetric and that none possessed higher symmetry.30 Crystallographic analyses employing the heavy-atom Patterson technique of the reduced and averaged data and successive difference Fourier syntheses revealed the location of all non(28)Enraf-Nonius VAX Structure Determination Package, Delft, The Netherlands, 1985. (29)North, A. C. T.; Phillips, D. C.; Rogers, D. Acta Crystallogr. 1968,A24, 351.

Anderson et al. hydrogen atoms. All hydrogen atoms except the bridging hydrogen atoms in 4a and 6 were included at geometrically calculated positions (C-H = 0.96 A and B-H = 1.10 A) using a riding model with fixed isotropic thermal parameters (U,,, = 80 x and 60 x A*, respectively). The bridging hydrogen atoms in 4a and 6 were located by difference Fourier mapping after anisotropically refining the non-hydrogen atoms while including the hydrogen atoms. All calculations were performed using the SHELXTL-PC package of programs.31 Atomic scattering factors with related anomalous dispersion correction factors were obtained from the usual source.32 Final atomic positional parameters for non-hydrogen atoms are given in Tables 8-11.

Acknowledgment. We thank the Robert A. Welch Foundation for support (Grants AA-1201 and -0668). Supporting Information Available: Complete tables of bond lengths and angles, anisotropic thermal parameters, and atom positional and thermal parameters and ORTEP diagrams for 2b, 4a, 5, and 6 (35 pages). Ordering information is given on any current masthead page. OM950251U (30)Howells, E. R.; Phillips, D. C.; Rogers, D.Acta Crystallogr. 1960, 3,210. (31) Siemens, SHELXTL-PC Siemens X-ray Instruments, Madison, WI, 1989. (32)International Tables for X-ray Crystallography; Kynoch Press: Birmingham, U.K., 1974;Vol. 4.