Organometallics 1995,14,862-868
862
Reactions of the Trinuclear [2.2]Paracyclophane Cluster RU3(C0)9~3-112:112:12-c16H1Thermal 6): Activation uersus Chemical Activation Alexander J. Blake, Paul J. Dyson, Scott L. Ingham, Brian F. G. Johnson,* and Caroline M. Martin Department of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh EH9 3 J J , U.K. Received July 18, 1994@ The reactivity of the known [2.2]paracyclophane triangular cluster R~3(CO)g@3-1;1~:1;1~:q~C16H16) (1) has been studied. Thermolysis of (1) with R u ~ ( C O )in I ~octane yields the known octahedral carbido complex R~6C(C0)14(~3-1;1~:1;1~:1;1~-cl6H16) (2). Reaction of 1 with Me3NO in dichloromethane results in cluster degradation and formation of the bridged dimer Ru2(CO)60,1~-1;1~:1;1~-C16H16) (3).Likewise, treatment of 2 with Me3NO in dichloromethane results in cluster degradation and affords 1. Mild thermolytic action of 1 with the alkyne C2Ph2 affords three products: R~3(C0),(~3-1;1~:1;1~:r~-c2Ph2)(1;1~-cl6H16) (41, in which the cyclophane now adopts a terminally bonding mode, R~3(C0)7~3-q~-PhC2{Ph~o})(1;1~-cl6H16) (5), similar to 4 except t h a t carbonyl insertion has occurred between the alkyne and metal; and the dinuclear product Ru2(CO)6({~2-o:1;12-C2Ph2}2-co) (61,in which a carbonyl has been inserted between two alkynes. 4 is also produced when 1 is treated with Me3NO in the presence of C2Ph2. 1 undergoes reaction either with Me3NO in the presence of PPh3 or by direct thermolysis with PPh3 to yield the monosubstituted derivative Ru~(C0)8(PPh3)@3-1;1~:1;1~:1;1~C16H16) (7). All compounds 3, 4, 6, and 7 have been characterized by both spectroscopic means and single crystal X-ray diffraction methods. 5 has been characterized by spectroscopy only, and the 13C NMR spectrum of cluster 1 is also reported.
Introduction
carbonyl groups on a neighboring molecule, so that the flat arene fragment has effectively been removed.3aThe For a number of reasons we have been concerned with paracyclophane ligand was employed with the expectathe synthesis and structure of arene clusters, and a wide tion that clusters would be linked, one to another, by and diverse chemistry of these compounds has emerged; utilizing both arene rings of the same PCP unit. While this has been recently reviewed.l In a variety of this goal has yet to be achieved, a number of other ruthenium and osmium cluster systems, initial studies were concerned primarily with their interaction with interesting observations have been made.3bFirst, PCP benzene and simple arenes such as toluene, xylene, and prefers to adopt the face-capping bonding mode rather mesitylene.lb Emphasis has been directed toward the than the more commonly observed r6-coordination mode preferred bonding types (viz. y3-r,+2:112~2 face-capping preferred by most simple arenes. Second, facially versus r6 terminal) of competing ligands on the same coordinated PCP adopts different conformations over a cluster. It was found that the face-capping coordination triruthenium face in Ru& clusters, ranging from nearmode is most strongly favored according to the following sequence: C6H6 > C6HsMe > C6H4Me2 > c~H3Me3.~ staggered to near-eclipsed arrangements of alternate C-atoms over the three Ru-atoms. Last, significant However, recently we have extended these studies to distortions of the PCP molecule are observed when PCP more elaborate aromatic systems such as triethylbenis bonded to cluster units. zene or [2.2lparacyclophane (C16H16, PCP).1b,3These ligands not only exhibit a somewhat different chemistry In this paper, we have chosen to discuss our results from that found for the simpler arenes but also bring in several distinct sections. In the first, the 13C NMR about modification of the principal interactions observed spectrum of R ~ 3 ( C 0 ) g ( U 3 - ~ ~ : ~ ~ : ~(1) ~ -isc ldescribed. 6Hl~) in the crystal lattice. For example, ribbonlike ringThis is followed by a discussion of the interconversion ring interactions are usually found in the solid state for between 1 and the hexanuclear carbido cluster Ru6Cmonoarene clusters; in contrast, in the triethylbenzene (C0)14CU3-r2:r2:r2-c16H16) (2) and includes the preparacluster, RusC(C0)14(y6-C6H3Et3),the ethyl groups fold tion of Ruz(C0)6CU2-r3:r3-C16H16)(3).In the next section, in such a fashion that they interlock with the three we describe the products obtained from reaction of 1Abstract published in Advance ACS Abstracts, December 1,1994. with diphenylacetylene, viz. Ru3(C0)7CU3-r':r2:r1-C2(1)(a) Wadepohl, H. Angew. Chem., Int. Ed. Engl. 1992,31, 247. (b) Braga, D.; Dyson, P. J.; Grepioni, F.; Johnson, B. F. G. Chem. Reu., Ph2)(?76-C16H~6) (41, Ru~(CO)~CU~-~~-P~C~{P~CO}) in press. C16H16) (51, and Ru2(C0)6(~2-o:r2-C2Ph2~2-c0) (6). Fi(2)Dyson, P. J.; Johnson, B. F. G.; Reed, D.; Braga, D.; Grepioni, F.; Parisini, E. J. Chem SOC.,Dalton Trans. 1993,2817. nally, the substitution of an equatorial carbonyl in 1 by (3)(a) Braga, D.; Grepioni, F.; Parisini, E.; Dyson, P. J.; Blake, A. triphenylphosphine thereby yielding Rus(CO)s(PPh3)J.; Johnson, B. F. G. J . Chem SOC.,Dalton Trans. 1993,2951.(b)Dyson, P. J.; Johnson, B. F. G.; Martin, C. M.; Blake, A. J.; Braga, D.; Grepioni, @3-);12:?72:r2-C16H16) ( 7 ) is reported. @
F. Organometallics 1994,13, 2113.
0276-7333l95l2314-0862$09.00lO
0 1995 American Chemical Society
Organometallics, Vol. 14,No. 2, 1995 863
Scheme 1. Reactions of 1 Involving a Change in Nuclearity"
3
I
Reagents and conditions: (i) Rus(CO)~doctane, A; (ii) 10 molar equiv of Me3NO/CH2C12; (iii) 3 molar equiv of Me3NO/ CH2C12. a
Results and Discussion We have previously reported the preparation of Ru3(C0)9CU3-r2:r2:r2-c~6H16) (I)from the thermolysis Of [2.2]paracyclophane with Ru3(C0)12 in either heptane or octane.3bOther products from this reaction include the two hexanuclear clusters Ru6C(C0)14CU3-r2:r2:r2-C16H16) (2) and RU~C(CO)11~3-~2:~2:~2-c~6H16)(~6-c~~H~~). It appeared that 1 was an intermediate in the formation of the hexaruthenium cluster 2, and in agreement, we Figure 1. Molecular structure of Ru2(CO)6CU2-r3:r3-C16H16) (3)in the solid state. The C-atoms of the CO ligands bear have found that on heating equimolar amounts of 1 and the same numbering as the corresponding O-atoms. PrinRu3(CO)12in octane under reflux, 2 is formed in modercipal bond parameters (A)are as follows: Ru(1)-Ru(2) ate yield. 2.838(3),mean Ru-C(c0) 1.916, mean C-O(CQ 1.145, RuSince crystals of 1 suitable for a n X-ray diffraction C(Y&,phane) Ru(l)-C( IC) 2.264(7),Ru(l)-C(5C) 2.295(7),RUstudy have eluded us to date, we have further charac(1)-C(6C) 2.191(7), Ru(2)-C(2C) 2.278(7), Ru(2)-C(3C) terized 1 from an examination of its 13CNMR spectrum. 2.187(7),and Ru(2)-C(4C) 2.253(7).Coordinated ring C-C The 13C NMR spectrum of 1 in CDC13 is entirely distances, C(lC)-C(2C) 1.481(10),C(2C)-C(3C) 1.399(10), consistent with the other spectroscopic data, and seven C(3C)-C(4C) 1.412(10), C(4C)-C(5C) 1.486(10), C(5C)resonances are observed. We consider that the signal C(6C) 1.408(10), and C(6C)-C(lC) 1.437(10). Uncoordiat 6 197.6 ppm is derived from the nine equilibrating nated ring C-C distances, C(9C)-C(1OC) 1.393(11),C(1OC)C(l1C) 1.380(12), C(llC)-C(12C) 1.408(11), C(12C)carbonyl groups and it does not alter on cooling. This C(13C) 1.389(11),C(13C)-C(14C) 1.372(11),and C(14C)is followed by two signals from the unattached ring at C(9C) 1.398(11). Linkage C-C distances, C(6C)-C(7C) 6 138.5 and 132.1 ppm. Coordinated ring carbon signals 1.529(10),C(7C)-C(8C) 1.569(10),C(SC)-C(SC) 1.505(11) occur at 6 76.0 and 54.7 ppm. Lastly, the CH2-CH2 C(12C)-C(15C) 1.498(11),C(15C)-C(16C) 1.564(10), and linkages give rise to two signals at 6 40.7 and 35.2 ppm, C(16C)-C(3C) 1.541(10). for the C-atom neighboring the bonded ring and furthest from this ring, respectively. These assignments were the paracyclophane ligand remains attached, has been made with assistance from a C, H correlation spectrum. the subject of a preliminary report.6 Spectroscopic data Reactions with Me3NO only. The use of Me3NO obtained for 3 are entirely consistent with the molecular as an oxidative decarbonylation reagent (removing CO structure obtained in the solid state by a single crystal as CO2) is well documented. This reagent is generally X-ray diffraction analysis. The mass spectrum exhibits used in combination with a coordinating solvent (typia parent peak at 579 amu (calculated 579 amu) followed cally MeCN), which may be displaced by the appropriate by the loss of six carbonyl groups in succession. The ligand in a subsequent step.4 Alternatively, Me3NO can infrared spectrum is devoid of bands in the carbonyl be used in a noncoordinating solvent containing the bridging region, only showing bands between 2060 and appropriate ligand so that direct substitution takes 1950 cm-l typical of terminally bonded CO. The lH place.5 As far as we are aware, the use of Me3NO as a NMR spectrum in CDCl3 exhibits signals at 6 7.06 (s), reagent to bring about cluster degradation has not been 3.59 (s), 2.93 (m), and 2.56 (m) ppm with equal relative previously recognized. In this case, the reaction with intensities; this pattern is consistent with the presence Me3NO in a noncoordinating solvent is thought to bring of a coordinated PCP moiety. about the formation of an unstable, unsaturated cluster The molecular structure of the new diruthenium (by loss of CO) and result in the controlled degradation complex 3 is depicted in Figure 1, together with relevant of the parent compound. structural parameters. The most important feature of The reaction of Ru6C(C0)14CU3-r2:r2:r2-C16H16 (2) ) with the molecule is the method by which the PCP ligand a large excess of Me3NO in dichloromethane affords bonds to the two ruthenium atoms, each ruthenium compound 1 in modest yield (Scheme 1). In a similar interacting with three carbon atoms of the "bonded" fashion, addition of 3 molar equiv of Me3NO to a solution ring. A close examination of this p2-q3:q3 interaction of Ru3(CO)9CU3-r2:r2:r2-C16H16) (1) in dichloromethane reveals that the coordinated ring adopts a boat results in the formation of the new dinuclear species, conformation: the angle between the two enyl planes R~2(CO)~CU2-r~:y1~-C16H16) (3). This product, in which defined by C(lc)-C(Gc)-C(5c) and C(2c)-C(3c)-C(4c) (4) Chen, H.; Johnson, B. F. G.; Lewis, J.; Braga, D.; Grepioni, F.; Parisini, E. J. Chem. SOC.,Dalton Trans. 1991, 215. (5) Dyson, P. J.; Johnson, B. F. G.; Lewis, J.; Martinelli, M.; Braga, D.; Grepioni, F. J. Am. Chem. SOC.1993, 115, 9062.
is 56". Although the rings in free [2.2]paracyclophane (6) Blake, A. J.; Dyson, P. J.; Johnson, B. F. G.; Martin, C. M. J. Chem. SOC.,Chem. Commun. 1994, 1471.
Blake et al.
864 Organometallics, Vol. 14, No. 2, 1995
Scheme 2. Reactions of 1 with Diphenylacetylene" also adopt boat conformation^,^ the angle between the two enyl planes is only 23", indicating a dramatic change upon coordination to the cluster unit that is rather unusual for aromatic systems. A related bonding mode has been observed previously in the compound I Rh2(Cp)2CU2-q3:q3-C6H6)in which similar distortions are I I i apparent in the benzene unit.3 It is also worth noting It 1t I that the mean C-C bond lengths of the enyl sections of the ring, uiz. C(lc)-C(Gc), C(5c)-C(6c), C(2c)-C(3c), and C(3c)-C(4c), are shorter than the C-C bonds linking the two enyl units, uiz. C(lc)-C(2c) and C(4c)C(5c) [1.414(10)uersus 1.484(10)A, respectively]. There is no recognizable pattern of long and short C-C bond lengths in the unattached ring of Ru2(co)6(u2-q3:q3a Reagents and conditions: (i) C2PhdCH2C12, A; (ii)2 molar C16H16),the mean distance for the C-C bonds in the ring equiv of Me3NOK2PhdCH2C12. being 1.385(11) and 1.390(11) respectively. In this work, the high quality of the low-temperature formed in highest yields when the longest reaction X-ray data has made it possible to locate the ring period is employed. Cluster 5 is not observed under hydrogen positions, and for the coordinated ring, all four such conditions and is present in modest yields on hydrogen atoms are observed to bend out of the plane heating for a short time. Since 5 is a minor product of defined by C(lc), C(2c), C(4c), and C(5c) and away from the reaction, it has been characterized only from a the ruthenium atoms. The mean deviation from the comparison of its infrared spectrum with that observed plane is 0.20(8>A. In the unattached ring, the distorfor the benzene analogue, which has also been charactions described above are not present. The ring is terized crystallographically. The spectra are almost almost planar, and the angle between the two enyl identical; hence, one may assume that the compounds planes is 18", less than in the free ligand itself (cf. 23"). are isostructural and therefore a carbonyl is inserted Also the hydrogen atoms are in the plane defined by between one of the C-atoms of the alkyne and a metal C(lOc), C(llc), C(13c),and C(14c) [mean deviation 0.05of the cluster. (8) AI. The same method of characterization for compound It is clear that the attack by Me3NO on 1 selectively 4 was used in the first instance, uiz. a comparison of its removes one Ru moiety from the triangular cluster. infrared spectrum with that of the osmium benzene Although it is difficult to monitor the reaction pathway s p e ~ i e s .Again ~ the two spectra showed a clear simiof this degradation reaction, it would appear that attack larity. Hence, formulation of 4 as Ru3(C0)&-q1:q2:q1of the Me3NO occurs successively a t the same Ru(CO)3 C2Ph2)(q6-C16H16)appeared reasonable. This was subsite. It certainly raises interesting synthetic possibilistantiated by the mass spectrum which contains a ties, and the scope of this reaction and its applicability parent ion at 885 amu (calculated 886 amu) and shows to other related cluster systems is currently under the sequential loss of seven CO groups. The lH NMR investigation. spectrum exhibits a multiple resonance which may be Reactions with Diphenylacetylene. On reaction assigned to the phenyl protons between 6 6.75 and 7.09 with alkynes, the benzene cluster M3(C0)9(u3-q2:q2:q2ppm. The ring protons of the uncoordinated ring give C6H6) (M = R u , ~Os9 ) affords compounds in which the rise to a singlet at 6 6.72 ppm while those on the bound benzene has undergone migration from a face-bridging ring produce two multiplets a t 6 4.60 and 5.29 ppm. to a terminal site, while the alkyne straddles the Similarly, the CH2 groups neighboring the unattached triangular face of the cluster. The only difference ring produce one mutiplet centered a t 6 3.12 ppm, with between the corresponding reactions of the ruthenium two multiplets a t 6 2.55 and 2.719 ppm for those and osmium derivatives is that, in the case of the adjacent to the coordinated ring. The relative intensiruthenium complex, a carbonyl group is inserted beties of all these signals are correct for the proposed tween the alkyne ligand and the metal atom carrying assignments, which are in complete agreement with the the benzene moiety. We have found that cluster 1 reacts structure observed in the solid state. with diphenylacetylene under two sets of conditions, the The molecular structure of 4 has been established in same major product, 4, being formed in each case. First, the solid state and is shown in Figure 2, together with on heating 1 in dichloromethane under reflux in the the principal bond distances. It can be appreciated that presence of diphenylacteylene and, second, by treatment the diphenylacetylene lies over the face of the cluster of 1 with 2 mol equiv of Me3NO in the presence of such that it forms one n and two a bonds [the distances diphenylacetylene at -78 "C (followed by warming to between the acetylene carbons and the ruthenium atoms room temperature). In the former reaction two other C(1a)-Ru(1) 2.237(9), C(2a)-Ru( 1) products, R u 3 ( C 0 ) 7 ~ 3 - q 2 - P h C ~ { ~ h ~ ~ } ) (5) ( q 6 - ~are ~ ~ ~as ~ ~follows: ) 2.216(9), C(la)-Ru(3) 2.108(9) and C(2a)-Ru(2) 2.294(9) and Ru2(CO)6(Cu2-a:q2-C2Ph2}2-CO) (6) (Scheme 2), have A]. Hence, the a interaction involving the metal to also been isolated. It has been found that the relative which the PCP ring is attached [Ru(2)] is longer than yields of compounds 4-6 depend critically on the the other 0 interaction [A = 0.186 A]; in contrast, the thermolysis time, with the diruthenium complex 6 being carbonyl that bridges the same two metals, Ru(2) and Ru(3), shows a shorter distance than the metal carrying (7)Cram, D.J.;Wilkinson, D. I. J.Am. Chem. SOC.1960,82,5721. (8)Braga, D.;Grepioni, F.; Johnson, B. F. G.; Parisini, E.; Martinelli, the PCP ligand [Ru(2)-C(21) 1.894(10)A uersus Ru(3)M.; Gallop, M. A.; Lewis, J. J. Chem. SOC.,Dalton Trans. 1992,807. C(21) 2.384(11)A, A = 0.490 A]. The unsaturated bond, (9)Braga, D.;Gallop, M. A.; Grepioni, F.; Johnson, B. F. G.; Lewis, J.; Martinelli, M. J. Chem. SOC.,Chem. Commun., 1990,53. C(la)-C(2a), in the acetylene is 1.409(13)A; this value I
A,
Organometallics, Vol. 14,No. 2, 1995 865
I 0
Figure 3. Molecular structure of Ruz(CO)~(Cuz-a:+C2Ph2}2-CO)(6) in the solid state. The C-atoms of the CO ligands bear the same numbering as the corresponding O-atoms. Principal bond parameters (A)are as follows: Ru(l)-Ru(2) 2.751(3), mean Ru-C(co) 1.90,mean C-O(co) 1.16, Ru(l)-C(7A) 2.07(2), Ru(l)-C(7B) 2.23(2), Ru(1)C(8B) 2.17(2), Ru(2)-C(7A) 2.24(2), Ru(2)-C(8A) 2.27(2), Ru(2)-C(8B) 2.06(2),C(7A)-C(8A) 1.44(3),C(8A)-C1.54(3), Figure 2. Molecular structure of R U ~ ( C O ) ~ ~ ~ - ~ ~ : ~C-0 ~ : ~1.20(2), ' - C ZC-C(7B) 1.55(3),C(7B)-C(8B) 1.31(3),C(7A)C(6A) 1.48(3),C(8A)-C(9A) 1.54(3),C(7B)-C(6B) 1.57(3), Phz)(r6-C16H16)(4) in the solid state. The C-atoms of the CO ligands bear the same numbering as the corresponding C(8B)-C(9B) 1.60(3),and mean C-C(phenyls) 1.38. O-atoms. Principal bond parameters (A)are as follows: Ru(l)-Ru(2) 2.6969(13),Ru(l)-Ru(3) 2.6957(12),Ru(2)from the characteristic carbonyl stretches between 2090 Ru(3) 2.8006(13), mean Ru-C(co) 1.910, mean C-O(co) and 2028 cm-l indicative of terminal M-CO ligands, a 1.150,RU-C(qyclophane) Ru(2)-C(lC) 2.246(9),R u ( ~ ) - C ( ~ C ) strong C-0 stretch is also found a t 1672 cm-l which 2.294(9), Ru(2)-C(3C) 2.403(9), Ru(~)-C(~C) 2.241(9), may be associated with that of a ketone. The mass Ru(2)-C(5C) 2.251(10), and Ru(2)-C(6C) 2.403(9). Coorspectrum exhibits the expected parent peak at 756 amu dinated ring C-C distances,C(lC)-C(PC) 1.417(14),C(2C)(calculated 755 amu) followed by a complicated fragC(3C) 1.408(13), C(3C)-C(4C) 1.415(14), C(4c)-c(5C) mentation pattern. The lH NMR spectrum is simple, 1.394(14), C(5C)-C(6C) 1.405(14), and C(6C)-CUC) containing two multiplets of equal relative intensities 1.380(14). Uncoordinated ring C-C distances, C(9C)C(1OC) 1.40(2), C(lOC)-C(llC) 1.39(2), C(llC)-C(12C) at 6 7.26 and 7.14 ppm, characteristic of phenyl groups 1.39(2), C(12C)-C(13C) 1.38(2), C(13C)-C(14C) 1.38(2), in two different environments. The above data are and C(14C)-C(9C) 1.385(14). Linkage C-C distances, consistent with the structure obtained in the solid state C(6C)-C(7c) 1.496(14), C(7C)-C(8C) 1.601(14), C(8C)from a single crystal X-ray diffraction study. The C(9C) 1.519(14), C(12C)-C(15C) 1.52(2), C(15C)-C(16C) molecular structure is not of high quality because of the 1.582(14), and C(16C)-C(3C) 1.497(14).Diphenylacetylene poor crystals obtained after months of effort. However, distances, Ru(l)-C(lA) 2.237(9), Ru(l)-C(2A) 2.216(9), because of the highly unusual nature of the molecule, Ru(2)-C(2A) 2.294(9),Ru(3)-C(lA) 2.108(9),C(lA)-C(2A) and since spectroscopic data and microanalytical results 1.409(13), C(lA)-C(3A) 1.482(13), and C(2A)-C(9A) are in good agreement with the established structure, 1.480(13).mean C-C(phenyls) 1.39. we feel the gross features of the structure are worth describing, although caution must be taken in reading is typical for such a moiety in this coordination mode. too much into the actual bond lengths and angles The non-linearity of the acetylene introduced upon obtained. The molecular structure of 6 is illustrated in coordination is also typical, the angles between C(2a)Figure 3, together with relevant bond parameters. The C(la)-C(3a) and C(la)-C(Ba)-C(ga) being 124.2(8) and two diphenylacteylene units are linked through a car125.9(8)",respectively. The PCP unit is bonded to Ru(2) bonyl group, and each of the alkyne moieties bonds to in an v6 fashion. This bonded ring is not planar but the ruthenium dimer via one n and one (T interaction, boat shaped with four C-atoms [C(lc), C(2c), C(4c) and therefore providing the metals with a total of six C(5c)l lying closer to Ru(2) [mean = 2.258(10) AI than electrons. Apart from this, each metal also has three the two carbons to which the aliphatic bridges attach terminal carbonyl groups, and with the Ru-Ru bond, [C(3c) and C(6c), mean 2.403(9) AI. It should be the effective atomic number rule is obeyed. To our appreciated that this distortion forms an angle of knowledge the behavior observed here is unprecedented, 23.9(12)"between the two enyl planes defined by C(1c)and from our experiments, we can speculate a mechaC(5c)-C(6c) and C(2c)-C(4c)-C(3c), which is essentially nism for the formation of the (CzPh2)2CO entity. the same as that observed in the free PCP molecule, i.e., 23".? The angle between the enyl planes in the While the mechanism by which 6 is produced in the unattached ring defined by C(9c)-C(lOc)-C(14c) and thermal reaction is not easily rationalized, the formation C(llc)-C(12c)-C(13c) also remains unperturbed from of 4 from the reaction utilizing Me3NO under ambient that of the free molecule. conditions is less complicated; one may assume that the Characterization of 6 as R U ~ ( C O ) G ( C U ~ - U : ~ ~ - C ~ Premoval ~ ~ } ~ - of two carbonyl ligands from R U ~ ( C O ) & ~ - ) ~ ~ : v2:q2-ClsHls)(1)takes place with the direct substitution CO) required both spectroscopic and crystallographic of the acetylene onto the cluster face. This would yield analyses. The infrared spectrum of 6 is unusual. Apart
866 Organometallics, Vol. 14, No. 2, 1995
Blake et al. c112c1
Scheme 3. Reaction of 1 with Triphenylphosphineu
%Ty . .
,
\ .
1
-
.
I
* I
,
PPh, 7
Reagents and conditions: (i)1 molar equiv of Me3NOPPhd CH2Cl2 or PPhDHF, A. a
311
R~3(CO)7CU3-q~:q~:q~-C2Ph2)CU3-q~:q~:q~-Cl6Hi6), as yet unobserved, which must undergo rapid rearrangement of the ligands on the surface of the cluster to yield 4, probably while the solution is stirred at room temperature for 1h prior to workup of the reaction mixture (see Figure 4. Molecular structure of Ru3(CO)8(PPh3)@3-q2: Experimental Section). q2:V2-C16H16)(7) in the solid state. The C-atoms of the CO Heating clusters containing face-cappingarenes often ligands bear the same numbering as the corresponding causes migration of the arene to a terminal site. Such 0-atoms. Principal bond parameters (A)are as follows: arene migration processes have been established to Ru( l)-Ru( 2) 2.905(2), Ru( l)-Ru( 3) 2.840(2), Ru(~)-Ru(3) involve a nondissociative mechanism, and clearly, a 2.830(2), mean Ru-C(c0) 1.89, mean C-O(c0) 1.145, RuC(cy&phane) Ru(l)-C(lC) 2.305(4), Ru(l)-C(GC) 2.313(4), simultaneous movement of carbonyl ligands in the Ru(2)- C(2C) 2.309(4), Ru( 2)-C(3C) 2.227(4), Ru( 3)- C(4C) opposite direction is also required. In the presence of 2.451(4),and Ru(3)-C(5C) 2.268(4).Coordinated ring C-C an alkyne, one can envisage the stepwise replacement distances, C(lC)-C(2C) 1.461(5), C(2C)-C(3C) 1.419(5), of these two carbonyl ligands for the four-electronC(3C)-C(4C) 1.450(5),C(4C)-C(5C) 1.399(5),C(5C)-C(6C) donating diphenylacetylene ligand, the alkyne possibly 1.440(5), and C(6C)-C(lC) 1.407(5).Uncoordinated ring coordinating to one metal atom initially, and then C-C distances, C(7C)-C(SC) 1.399(5), C(8C)-C(9C> migrating to two and then finally three metal. The 1.382(6),C(9C)-C(lOC) 1.394(6),C(lOC)-C(llC) 1.399(6), simultaneous movement of the PCP ligand from three C(llC)-C(12C) 1.385(6),and C(12C)-C(8C) 1.389(6).Linkto two to one metal atom would also be required. age C-C distances, C(lC)-C(lSC) 1.532(5), C(13C)Reactions with Me3NO in the Presence of PhosC(14C) 1.562(6), C(14C)-C(7C) 1.499(5), C(4C)-C(15C) 1.517(5), C(15C)-C(16C) 1.571(5), and C(16C)-C(lOC) phines. We have found that 1 readily undergoes 1.505(6). Triphenylphosphine distances, Ru(2)-P 2.351(2), substitution reactions in which one carbonyl can be P-C(lP) 1.828(4),P-C(7P) 1.820(4),P-C(13P) 1.846(3),and replaced by a number of phosphine ligands. This can mean C-C(phenyls) 1.38. be achieved using Me3N0, which removes a carbonyl group leaving a vacant coordination site on the cluster analysis and is illustrated in Figure 4 together with to which two electron-donor ligands may attach. Using relevant bond distances. The structure consists of a triphenylphosphine, a red product was produced in good ruthenium triangle capped on one side by a p3-q2:q2:q2 yield, and was characterized by spectroscopic means as PCP ligand. Ru(1) and Ru(3) also bear tricarbonyl units RU3(CO)8(PPh3)CU3-q2:q2:q2-C16H16) (7) (Scheme 3). Alwhile Ru(2) carries two carbonyl ligands and an equaternatively, heating l to reflux in THF containing PPh3 torially disposed triphenylphosphine moiety. The cofor a few hours affords the same product. The mass ordinated ring is flattened somewhat in comparison to spectrum of 7 exhibits a strong molecular ion a t 705 free PCP [the angle between the plane defined by C(IC)amu (calculated 998 amu) which corresponds to the C(2c)-C(6c) and C ( ~ C ) - C ( ~ C ) - C (is~ 15.7(5)", C) cfi free weight of the cluster without a CO and the phosphine PCP 23"].7 The unattached ring is far more contorted unit. The 31P NMR spectrum of 7 contains one signal toward a boat shape, the angle between the enyl planes at 6 38.01 ppm which is readily assignable to the defined by C(7c)-C(12c)-C(8c) and C(Sc)-C(llc)phosphorus atom of the PPh3 fragment. The lH NMR C( 1Oc) being 24.2(4)". Hence, the opposite distortions spectrum of 7 is more complicated, but is nonetheless have occurred to the face-bound PCP ligand compared readily assigned. It consists of five resonances at d 7.40, to those observed when PCP bonds to two metal atoms 7.32,3.12,2.95, and 2.41 ppm with relative intensities in the p2-q3:q3 mode. The PPh3 unit occupies an of 15:4:4:4:4. The first signal at 6 7.40 ppm is a equatorial site, although displaced slightly above the multiplet and corresponds to the protons of the phenyl ruthenium triangular plane, uiz. 0.236(1)". The strucrings attached to the phosphine ligand. The remaining ture of 7 is analogous to the triosmium-benzene species, signals are derived from the cyclophane unit, a t 6 7.32 Os3(C0)8(PPh3)CU3-q2:q2:1;12-CgHg), which exhibits the and 3.12 ppm the resonances, a singlet and doublet, Unlike other comsame gross structural features.1° respectively, can be attributed to the C-H protons of plexes containing p3-q2:q2:q2 PCP ligands, the ring the unbound and coordinated rings, respectively. The adopts a staggered conformation over the triruthenium remaining two signals are multiplets corresponding to face. This is reflected in the Ru-C(ring) bond distances the protons in the -CH2CH2- linkages. These data are which only vary very slightly [Ru(1)-C( lc) 2.305(3),Ruentirely consistent with the structure observed in the solid state. (10) Gallop, M. A.; Gomez-Sal, M. P.; Housecroft, C. E.; Johnson, The molecular structure of 7 was also established in B. F. J.; Lewis, J.; Owen, S. M.; Raithby, P. R.; Wright, A. J. J. Am. the solid state by a single crystal X-ray diffraction Chem. SOC.1992,114,2502.
Ru~(CO)S(C~~-~:~:~'-C~~~~ (1)-C(6~)2.313(3), R u ( ~ ) - C ( ~ C 2.309(3), ) Ru(2)-C(3~) 2.227(3), Ru(3)-C(4c) 2.451(3)and Ru(3)-C(5c) 2.268(3)
AI. Retention of the face-capping ligand is not uncommon in this type of reaction, nor is equatorial substitution by an entering ligand. The triosmium-benzene cluster Os3(C0)9CU3-r2:r2:r2-C6Hs) undergoes a similar chemistry with Lewis bases.1° The difference in this system is that CO is initially displaced for a labile acetonitrile group, which is then subsequently replaced by the appropriate ligand. No substitution chemistry has yet been developed for the triruthenium-benzene cluster, which is probably due to the relative instability of this species t o this type of chemistry.
Concluding Comments We have demonstrated various ways of manipulating the triruthenium-cyclophane cluster in a series of reactions that employ either mild thermal action or chemical initiation with Me3NO. While very different products are obtained between these two reaction types when ligands are not employed, in the presence of a ligand, both thermolysis and chemical activation tend to give the same products although in the reactions involving diphenylacetylene the chemical activation method is far more selective. Some of these reactions have been employed in the analogous complexes, M3(C0)9CU3-);12:);12:);12-CgH6) (M = Ru, Os), and in general tend to be similar to the chemistry played by the osmium complex. We are currently attempting to prepare an osmium-cyclophane analogue in order to compare its reactivity with these other systems.
Experimental Section General Procedures and Materials. All reactions were carried out using freshly distilled solvents under an atmosphere of nitrogen gas. Subsequent workup of products were carried out using standard laboratory grade solvents without precautions to exclude air. Infrared spectra were recorded on a Perkin-Elmer 1710 Fourier transform spectrometer. Mass spectra were obtained by positive fast atom bombardment on a Kratos MS50TC. lH and 31P NMR spectra were recorded using a Bruker AM360 or WM250 spectrometer. The cluster RU~(C0)9CU3-r~:r~:r~-C16H16) (1) was prepared according to a literature method (using heptane as solvent and a 2 h reaction time).3b Trimethylamine N-oxide (Me3NO), diphenylacetylene (CZPhz), and triphenylphosphine (PPh3) were purchased from Fluka chemicals. Me3NO was dried and sublimed prior to use, while the other materials were not treated to any other purification process. Products were isolated by thin-layer chromatography (TLC) using plates supplied by Merck coated with silica gel-60. The same eluent was used in each case, this being dichloromethanehexane (1:4, v/v). Thermolysis of Ru3(CO)g013-r2:r2:r2-C16H1 16with ) Ru3(CO)lz. A suspension of 1 (30 mg) and R u ~ ( C O )(25 ~ Z mg, 1 molar equiv) in octane (20 mL) was heated t o reflux for 2 h, after which time IR spectroscopy indicated a significant amount of conversion to Ru6C(C0)14CU3-r2:rz:r2-Cl6H16) (2). The solvent was removed under vacuum and the orange 2 (18 mg) was extracted from the resulting brown residue by TLC. 2 was characterized spectroscopically by a comparison with the literature values, which were in excellent agreement. Spectroscopic data for 2: IR (CHzC12) v(C0) 2076 (w), 2039 (s),2024 (vs), 1982 (w, br), 1940 (w, br), 1814 (w, br) cm-'; IH NMR (CDC13)6 7.44 (s, 4H), 3.43 (s, 4H), 3.40 (m, 4H), 2.98
Organometallics, Vol. 14,No. 2, 1995
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(m, 4H) ppm; MS, M+ = 1219 (calc = 1219) amu. Anal. Found (Calc): C 30.51 (30.54), H 1.38 (1.31). Reaction O f RUeC(CO)i401s-r2:r2:r2-C16Hi6) (2) with MesNO. 2 (20 mg) was dissolved in dichloromethane (20 mL). To this solution was added a 10-fold excess of Me3NO (0.012 mg) in dichloromethane (4 mL) in a dropwise fashion. The reaction mixture was stirred for a total period of 30 min, after which time the solvent was removed in vacuo. The residue was redissolved in a small amount of dichloromethane and subjected to TLC. The major yellow product was characterized spectroscopically as R U ~ ( C O ) ~ ( ~ ~ - ~ (1) ~ :(6~mg). ~ : ~ ~ - C ~ ~ H Spectroscopic data for 1: IR (CHzC12)v(C0) 2067 (SI, 2024 (vs), 1993 (m), 1980 (m), 1959 (w, sh) cm-'; lH NMR (CDC13) 6 7.22 (s, 4H), 3.76 (s, 4H), 3.23 (m, 4H), 2.67 (m, 4H) ppm; MS: M+ = 763 (calc = 763) amu. Reaction of Ru3(CO)g013-r2:r2:r2-C~6Hl6) 1 with MesNO. To a solution of 1 (50 mg) in dichloromethane (20 mL) was added a %fold excess of Me3NO (0.015 mg) in dichloromethane dropwise over a few minutes. The reaction mixture was stirred for 20 min and then the solvent was removed under reduced pressure. Extraction of the products by TLC revealed two yellow bands which were characterized spectroscopically as Ru2(C0)6CUz-r3:r3-C16Hl6)(3)(5 mg) and starting material 1 (29 mg), in order of elution. Crystals of 3 suitable for the single crystal X-ray diffraction analysis were grown by vapor diffusion from dichloromethane-pentane at room temperature. Yellow crystals were produced which did not deteriorate on removal from their mother liquor. Spectroscopic data for 3: IR (CHzC12) v ( C 0 ) 2060 (SI, 2022 (vs), 1993 (s), 1950 (w, sh); 'H NMR (CDC13) 6 7.06 (s,4H), 3.59 (s, 4H), 2.93 (m, 4H) and 2.56 (m, 4H); MS, M+ = 579 (calc = 579) amu. Insufficient sample available for microanalysis. Thermolysis of (1) with Diphenylacetylene. 1 (50 mg) was dissolved in dichloromethane (30 mL), and an excess of diphenylacteylene (30 mg) was added. The reaction mixture was heated to reflux for 18 h, after which time the solvent was removed under reduced pressure, and the products were separated by TLC. Three bands were extracted from the TLC plate; they were characterized spectroscopically as Ru3(C0)7~3-~':rZ:r1-CzPhz)(r6-C16H16)( 4 )(8 mg), Ru3(C0)7(~3-r2-PhC~(PhcO})(r6-ci6Hi6) (5) (2 mg), and R U ~ ( C ~ ) ~ ( ( ~ Z - ~ ~ : ~ ~ - (6) ~ Z (6 P ~mg), Z}Z-CO) respectively. Spectroscopic data for 4: IR (CH2C12) v(C0) 2056 (s), 2020 (vs), 1982 (s), 1958 (w, sh), 1923 (w); 'H NMR (CDC13) d 6.92 (m, lOH), 6.72 (s, 4H), 5.29 (m, 2H1, 4.60 (m, 2H), 3.12 (m, 4H), 2.719 (m, 2H), 2.55 (m, 2H); MS, M+ = 885 (calc = 886) amu. Anal. Found (Calc): C 50.23 (50.17), H 3.04 (2.96). Spectroscopic data for 5: IR (CHzClZ) v(C0) 2065 (SI, 2032 (vs), 1993 (s). Insufficient sample available for microanalysis. Spectroscopic data for 6: IR (CH2C12) v(C0) 2090 (m), 2069 (vs),2028 (s), 1672 (m); 'H NMR (CDC13) 6 7.14 (m, lOH), 7.26 (m, 10H); MS, M+ = 756 (calc = 755) amu. Anal. Found (Calc): C 55.75 (55.701, H 2.70 (2.67). Reaction of R ~ ( c o ) ~ ~ 3 - ~ 2 : ~ 2(1) :~ with 2-c Diphe~~16) nylacetylene and Me3NO. Diphenylacetylene (15 mg) and 1 (30 mg) were dissolved in dichloromethane (25 mL), and the solution was cooled t o -78 "C. A solution of Me3NO (7 mg, 2.2 molar equiv) in dichloromethane (10 mL) was added dropwise over a 10 min period. The reaction mixture was allowed to warm to room temperature over a period of 1h and stirred for a further 1h at room temperature, after which time the solvent was removed in vacuo. The products were extracted by TLC, and the major orange product was characterized spectroscopically as Ru3(C0)7~3-y1:r2:r1-CzPhz)(r6-Ci6Hi6) ( 4 )(10 mg). Crystals of 4 were nucleated from toluene at -25 "C over a period of several days. Stable, red crystals were produced which were suitable for the single crystal X-ray diffraction analysis. Reaction of Ru3(CO)g0*3-r2:r2:r2-ci6Hi6) (1) with Triphenylphosphine and MeDO. 1 (50 mg) and triphenylphos-
868 Organometallics, Vol. 14, No. 2, 1995
Blake et al.
Table 1. Crystal Data, Measurement Details, and Structure Parameters for 3,4,6, and 7 4
3 formula MW temperature ("C) crystal system space group a
(A)
b (A)
c (A) P (d%) u (A3)
Z Qcaic
(g ~ m - ~ )
cc ("-9
max and min absorptn corrcn crystal size (mm) crystal color diffractometer radiation
a. ('4
monochromator 2 9 scan range (deg) No. of reflections collected No. of independent reflections R(int)
6
7
C2zH1606RU2 578.5 150(2) monoc1inic P2 1In 9.183(10) 2 1.912(10) 10.366(10) 106.84(10) 1996(3) 4 1.925 1.550 0.749, 0.654
Crystal Data C37H2607RU3'1.75CH2C12 1030.9 150(2) monoclinic P2 1In 15.408(4) 10.127(3) 25.289(9) 105.65(2) 3800(2) 4 1.802 1.472 0.744, 0.685
C~~HZOO~RU~ 754.7 150(2) monoc1inic P21h 11.96(1) 10.58(1) 24.05(2) 104.21(8) 2950(5) 4 1.699 1.074 0.549, 0.508
caH3iOeR~ 997.9 150(2) monoclinic P21In 14.421(12) 16.265(10) 16.27(2) 1OO.66(12) 3751(5) 4 1.767 1.289 0.449, 0.399
0.30 x 0.15 x 0.10 yellow
0.48 x 0.10 x 0.10 red
0.18 x 0.27 x 0.35 red
0.5 x 0.38 x 0.38 red
Stoe Stadi-4 Mo 0.710 73 graphite 5-45 3658 3498 0.1427
Stoe Stadi-4 Mo 0.710 73 graphite 5-50 7698 6589 0.0182
0.103 0.272 1.110 187 1.208 -1.518
0.0269 0.0730 1.146 511 0.471 -0.869
Stoe Stadi-4 Mo 0.710 73 graphite 5-45 2605 2605 0 0.0363 0.1301 1.063 296 0.794 -0.172
Data Collection Stoe Stadi-4
Mo 0.710 73 graphite 5-45 5649 4935 0.0396 Structure Refinement 0.0443 0.1631 1.066 478 1.053 - 1.006
phine (30 mg) were dissolved in dichloromethane (20 mL), and the solution was cooled to -78 "C. To this solution was added a 1.2 mole equivalent of Me3NO (5 mg) dropwise. The solution was then allowed to warm to room temperature over a 25 min period and was accompanied by a color change from yellow to brown. The solvent was removed under vacuum, and the brown residue subjected to TLC, which produced a red product 7 ~(32 - c ~mg). ~i6) characterized as R ~ 3 ( C O ) s ( P P h 3 ) ~ 3 - r ~ : ? 7 ~ : ?(7) Red crystals of 7 of varying quality were nucleated at room temperature from slow evaporation of a dichloromethanehexane solution. Spectroscopic data for 7: IR (CHzC12)v(C0) 2049 (s), 2012 (s), 1986 (vs), 1975 (s, sh); IH NMR (CDC13) S 7.40 (m, E H ) , 7.32 (s,4H), 3.12 (m, 4H), 2.95 (m, 4H), 2.41 (m, 4H); 31PNMR (CDC13) 6 38.01 (s, 1P); MS, M+ = 705 (calc = 998). Anal. Found (Calc): C 52.95 (52.171, H 3.34 (3.23). Thermolysis of Rus(CO)~~s-y2:?72:~2-c16H16) (1) with Triphenylphosphine. 1 (30 mg) was dissolved in tetrahydrofuran (20 mL), and an excess of triphenylphosphine (30 mg) was added. The reaction mixture was heated to reflux for 3 h, after which time the solvent was removed in uucuo, and the products were separated by TLC. The major red band was extracted and characterized spectroscopically as Rus(C0)s(PPh3)(~3-r2:r2:r2-Ci6Hi6) (7)(6 mg). Structural Characterization. X-ray diffraction data for species 3,4, 6,and 7 were collected at a temperature of 150 K on a Stoe Stadi-4 diffractometer, equipped with an Oxford Cryosystems low-temperature device.ll Relevant data collection, structure solution, and refinement parameters are summarized in Table 1. The crystals of 6 were of poor quality and diffracted rather weakly; unfortunately no other suitable crystals could be obtained. Whereas the X-ray structural determination of 6 was not accurate enough for an in-depth investigation of the structural parameters for this compound, it does show the gross structural features and hence has been (11)Cosier, J.; Glazer, A. M. J.Appl. Crystallogr. 1986,19, 105.
included for this reason. The structures were solved by a combination of direct methods and Fourier techniques, with refinement being performed using the least-squares method on F.12Anisotropic thermal motion was assumed for all nonhydrogen atoms, except for 6 where only the two ruthenium atoms were refined by use of a n anisotropic thermal model, due to the poor quality of the X-ray diffraction data. All hydrogen atoms, except the phenyl hydrogens in 3, were placed in calculated positions and were refined by use of a riding model. The phenyl hydrogen atoms in 3 were refined subject t o the constraint that the C-H distances were 0.96(1) A. A difference electron density Fourier synthesis for 4 exhibited large peaks well seperated from the cluster, these being attributed to two molecules of solvated dichloromethane, one of which had an occupancy factor of 75%. These two molecules of solvent were included in subsequent cycles of refinement.
Acknowledgment. We thank the SERC and IC1 (Wilton), The University of Edinburgh, and NATO financial assistance. Supplementary Material Available: Tables of crystal data and structure refinement, anisotropic thermal parameters, fractional atomic coordinates, and isotropic thermal parameters for the non-hydrogen atoms, complete lists of bond lengths and angles, and fractional atomic coordinates for the hydrogen atoms (18 pages). Ordering information is given on any current masthead page. OM940564+ (12) Sheldrick, G. M. SHELX93; University of Gottingen: Gottingen,
Germany, 1993.
