摘要:

J. CHEM. SOC. DALTON TRANS. 1995 1063Tetraruthenium Cluster Isomers containing Both C6Haand [2.2] Paracyclophane Ligands: A New Face-bridgingCo-ordination Mode for a c6 Aromatic RingtAlexander J. Blake, Paul J. Dyson, Scott L. Ingham, Brian F. G. Johnson* and Caroline M. MartinDepartment of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh, EH9 3JJ, UKThe reaction of [Ru3(CO),(p3-q2 : qz : q2-C16H16)] I with 2.2 molar equivalents of Me3N0 indichloromethane containing cyclohexa-1.3-diene afforded the new tetrahedral complex [Ru4(CO)?(y4-C,H,) (p3-C16Hl,)] 2 in modest yield. The thermolysis of [RU,(CO)~~(~,-C,H,)] 3 in octane containingan excess of [2.2]paracyclophane (C16H16) and Me,NO afforded the two new butterfly isomers[Ru,(CO),(p,-C6HJ (q6-C16H16)] 4 and [Ru,(CO),(p,-C,H,) (p3-q2:q2:q2-C1,Hl6)] 5.Heating com-pound 4 results in its irreversible conversion to 5. Compounds 2 and 4 have been characterised inthe solid state by single-crystal X-ray diffraction and in 2 the [2.2]paracyclophane ring bonds to thecluster via an unusual p3-q1 : q2 : q2 bonding mode unseen before for an arene ring.There is considerable interest in the synthesis of cyclophane-transition-metal complexes, and the majority of studies havefocussed on complexes in which single metal atoms co-ordinateto either one or both of the cyclophane rings,' to form in someinstances precursor units to polymeric systems.2 However, ithas been found that a metal can also be introduced into thecavity between the rings of a cyclophane ~ystem.~ In complexesof C2.2lparacyclophane various features are consistentlyobserved on co-ordination to a metal.unit; for example theinter-arene distance contracts because of a reduction in thecofacial n repulsions as the metal unit(s) withdraw electrondensity, with the consequent redistribution of the remainingx-electron den~ity.~ This latter feature is apparent from the'H NMR spectra of these complexes; the frequencies of theunco-ordinated and co-ordinated ring protons increase anddecrease respectively, relative to that observed in freeC2.2lparacyclophane.Our interests in [2.2]paracyclophane have been concernedwith the preparation, characterisation and reactivity of clustersbearing this compound as a ligand.6-9 Compared to benzeneand other simple arenes this ligand displays some unusualfeatures.Whilst C2.2lparacyclophane has been observed tobond in the simple terminal mode (as it does in mononuclearcomplexes) it prefers to adopt multiple-bonding sites, and hasbeen observed to bond along amedge in a p-q3 : q3 mode in thebinuclear complex,8 and in clusters to form a triple bridge to ametal face in both the p3-q2 : q2 : q2 m ~ d e , ~ . ~ . ~ and also a quasi-p3-q1 : q' : q1 mode established in the solid state.7In this paper we report the synthesis and characterisation ofin which a new face-capping bonding type is observed forthe C2.2lparacyclophane ligand in the sdid state, and thethe tetrahedral Cluster [RU4(C0)9(q4-C6H8)(p3-c16H16)] 2butterfly ClUSterS [RU4(C0)9(p4-C6H8)(r16_C16Hl6)] 4 andCRu4(CO)9(~4-C6Hg!(p3-q2 :q2 3t2-cl6Hl6)I 5; the formerundergoes isomerisation to the latter species over a relativelyshort period at moderate temperatures.Results and DiscussionTo a solution of [Ru3(CO),(p3-q2 : q2 : ?2-c16H16)] 1 preparedfrom the thermolysis of+[Ru,(CO), 2] with C2.2lparacyclophanet Supplementary data available: see Instructions for Authors, J.Chem.Soc., Dalton Trans., 1995, Issue 1 , pp. xxv-xxx.in octane7 in dichloromethane containing an excess ofcyclohexa-1,3-diene at -78 OC, 2.2 molar equivalents ofMe3N0 were added dropwise in dichloromethane. The solutionwas stirred at -78 "C for 20 min then allowed to warm slowlyto room temperature and stirred for a further 3 h. Purificationof the products was achieved by thin layer chromatography onsilica, eluting with dichloromethane-hexane (3 : 7, v/v) whichresulted in the isolation of yellow starting material and the newOrange compound [RU4(CO)9(q4-C6H8)(~3-c~6H,6)] 2 (Ca.10%).Characterisation of compound 2 was initially based onspectroscopic evidence.The mass spectrum exhibits a parentpeak at m/z 945 (calc. 946) followed by peaks which correspondto the loss of nine CO ligands (the largest peak is at m/z 862which corresponds to the loss of three CO groups). The 'HNMR spectrum contains resonances at 6 7.48 (s, 4 H), 5.75 (m, 2H),4.54(m,2H),3.32(m,4H),3.26(~,4H),2.47(m,4H),2.12(m, 2 H) and 1.88 (m, 2 H). The signals at 6 7.48,3.32,3.26 and2.47 are derived from the C2.2lparacyclophane moiety, the firstand third corresponding to the aromatic protons of theunattached and co-ordinated rings respectively, the other twofrom the -CH2CH2- linkages.These signals are typical for a pj-q2 : q2 : q2 C16H16 system, similar spectra having been reportedelsewhere.' A terminal q6-C,6H16 ligand contains a C-Hsinglet resonance at a higher frequency than that of a p3 ligand,typically between 6 4.5 and 6.5 The remaining signals may beassigned to the cyclohexa-l,3-diene ring.Crystals of compound 2 were grown from a solution ofdichloromethane layered with octane after standing for severaldays at room temperature. X-Ray data were collected on asuitable crystal at 150 K. The molecular structure of 2 is shownin Fig. 1; selected bond lengths and fractional atomiccoordinates are listed in Tables 1 and 2 respectively.The metalcore consists of a tetrahedron of ruthenium atoms [range2.780(2)-2.897(2) A, mean 2.84(4) A]. There are nine carbonylligands, three of which form bridging interactions. The mostinteresting feature of this cluster is the presence of theC2.2lparacyclophane ring which bonds to the cluster facedefined by Ru(l)-Ru(2)-Ru(4) in a highly unusual mannermore reminiscent of a p,-cyclohexadienyl ring.' In addition, acyclohexa-l,3-diene moiety is bonded solely to Ru(3) in an q4mode. An alternative view of the c6 ring-Ru, section of themolecule is presented in Fig. 2(a), and as mentioned above, thebonding is quite closely related to that observed in the faciallyboundcyclohexadienyl ring foundin [M,H (C0)9(p3-~ ' : q2 : q 21064O(42)J.CHEM. SOC. DALTON TRANS. 1995Fig. 1in Table 1The molecular structure of [Ru4(CO),(q4-C,H,)(p3-C1,H ,)I 2 showing the atomic labelling scheme. Selected bond lengths are listedTable 1 Selected bond lengths (A) for [ R U ~ ( C ~ ) ~ ( ~ ~ - C , H , ) ( ~ ~ - C ~ ,H 16)] 2Ru( 1 )-Ru(2)Ru( 1 )-Ru(3)Ru( 1 kRu(4)R~i(2)-Ru( 3)Ru(2)-Ru(4)Ru( 3)-Ru(4)Ru( 1)-C(4c)Ru( 1 )-C( 5c)Ru(2)-C( 5c)Ru(2)-C(6c)Ru(4)-C(3c)Ru(1 W(3C)2.868(3)2.842( 2)2.848(2)2.820( 2)2.897(2)2.780(2)2.529( 11)2.116(10)2.506(9)2.473( 10)2.179( 10)2.478( 10)Ru(~)-C(~C) 2.1 73( 1 0)C( 1 c)-C(2c) 1.434( 14)C(2Ctc(3C) 1.444(14)C(3C)-C(44 1.443( 14)C(4CkC(5c) 1.467( 14)C( 5c)-C( 6c) 1.44(2)C(7c)-C(8c) 1.39(2)C(7c)-C( 12c) 1.41(2)C(8C)-c(9C) 1.37(2)C(9c )-C( 1Oc) 1.40(2)C(l lc)-C(I2c) 1.36(2)C( 1 Oc)-C( 1 1 C) 1.4 1 (2)Ru( 3)-C( 1 d)Ru( 3)-C( 2d)Ru( 3)-C( 3d)Ru(3)-C(44C( 1 d)-C( 2d)C( 1 d)-C(6d)C( 2d)-C( 3d)C(3dW(4d)C(4dtc(5d)C(5dW(6d)2.296( 10)2.227( 1 1)2.152( 1 1)2.223( 10)1.39(2)1.524(13)1.43(2)1.49(2)1.54(2)1.442)C,H,)] (M = Ru or Os)," illustrated in Fig.2(b). In cluster 2Ru( 1) bonds to C(4c) [2.116( 10) 8, J while longer interactionsare also formed with C(3c) and C(5c) [2.529(11) and 2.506(9) A,respectively], consequently, C(4c) is considered to form a cjbond with Ru( 1) donating one electron. Two pairs of electronsare formally donated through the two q2 C=C bonds withRu(2) and Ru(4); each of these interactions consists of one longand one short bond, viz.Ru(2)-C(5c) 2.473( lo), Ru(2)-C(6c)2.179(10) and Ru(4)-C(3c) 2.478(10), Ru(4bC(2c) 2.173(10) A.While we have chosen to ascribe the q' : q2 : q2 nomenclature, analternative description could also be used in which the ringforms an q3 interaction with Ru(1) and two q' interactions,with distances of 2.721(11) and 2.804(9) 8, being observed forRu(2) C(1c) and Ru(4) . C(1c) respectively, indicatinglittle if any interaction between C(1c) and the metal framework.For a tetrahedral cluster a valence electron count of 60 isrequired to fulfil the electron atomic number rule, hence onefurther electron is required. A hydride bridging the edgeRu(2)-Ru(4), as observed in the analogous position in thedienyl species would be antici atgd, especially as this is thelongest Ru-Ru bond [2.897(2) XI.However, a hydride has notbeen observed by 'H NMR spectroscopy or located directly inthe crystal structure.In contrast to the solid-state structure, the 'H NMRspectrum of 2 suggest that the ring behaves as a six-electrondonor. The ring produces four ,signals in a typical patternobserved for rings attached to clusters in the p3-q2 : q2 : q2 mode(see above). The singlet resonance of the co-ordinated C-H ringprotons at 6 3.26 would not be anticipated from the bondingobserved in the solid state, and it is possible that the ring isundergoing some type of dynamic behaviour in order toequilibrate all the C-H resonances.Nonetheless, a solution IRspectrum of the actual crystal used for the X-ray data collectionis identical to that of the bulk solution, and it would appear thatthe solid-state structure consists of a conformation encounteredin solution during rotation, merely frozen out by crystal-packing forces. As pointed out earlier, the unusual near-eclipsed p3- : q1 : q' : q' orientation has been observed for thisligand in the solid-state, and combined with the conventionalp3-q2 : q2 : q2 mode provides possible snapshots of theorientation of the ligand as it rotates over the metal face.In the solid-state structure of C2.2lparacyclophane the arenerings adopt a non-planar boat configuration, whilst in 2 asimilar deviation from planarity is only observed for one of theenyl units of the bound ring.The angles between the planes ofthe central rectangle and the triangle ends defined byC(2c)-C(lc)-C(6c) and C(5c)-C(4c)-C(3c) are l(1) and 17(1)",respectively ( c - 12.6" for the comparable angle in the freJ . CHEM. SOC. DALTON TRANS. 1995 1065Table 2 Atomic coordinates for [RU,(C~)~(~~-C~H~)(I~~-C,,H,,)I 2X0.661 13(8,0.939 94(8)0.683 96(8)0.718 13(8)0.345 2(8)0.657 2(8)1.192 5(8)1.1 17 l(8)0.498 O(8)0.412 3(8)0.881 O(8)0.517 6(8)0.868 3(8)0.464 4( 1 1)0.661 l(11)1.098 l(11)1.0480(11)0.572 4( 10)0.539 9( 11)0.860 9( 1 1)0.594 5( 1 1)0.811 8(11)0.970 5(10)0.824 2(10)0.719 5(10)0.758 9( 1 1)0.899 4(10)1.006 6( 1 1)1.074 6( 11)0.845 4( 12)0.879 2( 12)1.027 2( 13)1.121 2(13)1.087 5(14)1.145 2(14)0.701 3(12)0.766(2)0.759 8( 10)0.770 6( 11)0.638 8(10)0.512 O(12)0.489 5( 12)0.629 4( 10)0.939 9( 1 1 jY0.757 09(9)0.762 42(10)0.839 41(9)0.564 60(8)0.679 5(8)0.983 4(9)0.930 7(9)0.710 5(8)1.023 2(8)0.651 5(8)1.066 8(9)0.3 17 8(9)0.495 6(9)0.714 2(11)0.898 5( 1 1)0.865 8(11)0.731 8(12)0.930 5( 1 1)0.671 4(11)0.947 3(12)0.413 O(12)0.522 4(11)0.495 O( 1 1)0.441 9(11)0.506 5(11)0.61 1 5(11)0.677 2(11)0.610 2(11)0.301 5(11)0.240 2( 13)0.291 4(12)0.408 8(13)0.451(2)0.400 2( 1 3)0.404(2)0.292 l(14)0.604 8( 13)0.494(2)0.818 9(11)0.953 8(12)1.013 6(12)0.926 5( 13)0.846 2(14)0.768 5(14)z0.179 21(5)0.282 02(5)0.344 46(5)0.308 61(5)0.123 6(5)0.055 O(5)0.236 l(5)0.448 9(5)0.226 O(4)0.333 l(4)0.296 7(4)0.306 6(5)0.479 4(5)0.144 2(7)0.103 l(6)0.252 6(6)0.386 7(7)0.250 3(6)0.331 6(6)0.304 O(6)0.306 8(6)0.414 4(6)0.242 4(6)0.225 3(6)0.163 7(6)O.llOO(6)0.140 5(6)0.199 l(6)0.146 2(7)0.1 19 O(6)0.054 5(7)0.013 3(7)0.030 l(8)0.094 O(7)0.287 l(8)0.234 7(8)0.017 8(7)0.032 9(9)0.481 7(6)0.457 2(6)0.41 5 8(6)0.409 9(7)0.483 3(7)0.520 l(6)molecule)." Hence, the angle of the unit involving the q3interaction has increased while the other has considerablydecreased to such an extent that it is almost planar.Whilst it ispossible that a hydrogen atom is connected to C(1c) therebyturning the ligand into a dienyl system, the approximate sp2hybridisation of this carbon atom tends to rule out thispossibility, as does the 'H NMR spectrum.The formation of 2 from 1 involving an increase in nuclearityis not entirely unexpected.We have previously described thereaction of compound 1 with Me,NO, triphenylphosphine anddiphenylacteylene and observed that dinuclear products may beproduced.' Hence, in this reaction fragmentation of 1 mustoccur, followed by recombination to form the tetrahedralcluster.The thermolysis of the butterfly cluster [Ru,(CO), t(p4-C6H8)] 3 (prepared from the reaction of [RU~(CO)~J withcyclohexa- 1,3-diene) ' in octane containing an excess of[2.2]paracyclophane for 4 h results in the formation of a darkbrown solution. Purification of the products from this reactionsolution by thin layer chromatography using dichloromethane-hexane (2:2, viv) as eluent resulted in the isolation of twonew complexes [Ru4(CO),(p-C,H,)(q6-Cl6Hl6)] .4 and[ R u , ( C ~ ) ~ ( ~ , - C , H , ) ( ~ , - ~ ~ : q : q2-Cl6HI6)] 5. Addition of3.2 molar equivalents of Me,NO to the reaction mixtureimproves the yield of these products. Characterisation ofFig. 2 Comparative views of the metal-ring interaction in(p3-q1 : q2 : q2-C6H,)] (b); distances in A CRu4(C0),(r4-C6H,)(C~-c16H~ 611 (a) and [Ru3H(Co)9-compounds 4 and 5 was based on spectroscopic evidence. Bothcompounds exhibit the same strong molecular ion in the massspectrum at m/z 946 (calc. 946). Peaks corresponding to theloss of nine carbonyl groups are also present.The 'H NMRspectrum of 4 is quite complicated since some of the signalsoverlap. However, experiments have shown that the C2.2 Jpara-cyclophane unit gives rise to three signals; singlet resonances at6 6.80 and 4.34 for the C-H protons of the unco-ordinatedand co-ordinated rings respectively and one mutiplet centred atS 3.2 which integrates appropriately for all the protons inthe -CH,CH,- linkages. The cyclohexyne ring produces threemultiplets centred at 6 3.29, 2.88 and 1.7, with relativeintensities of 1 : 1 : 2. In 5 the 'H NMR spectrum contains sixsignals of equal relative intensity, four of which can beattributed to the cyclophane moiety, the remaining two fromthe cyclohexyne unit.Singlet resonances at 6 7.21 and 3.16result from the ring C-H protons of the unco-ordinated and co-ordinated rings, respectively. The latter value is low andcomparable to that observed in 2 and indicative of a facially co-ordinated ligand. Multiplets at 6 3.17 and 2.56 can be assignedto the -CH2CH,- linkages of the cyclophane ring system, theformer corresponding to those closer to the co-ordinated ring.The hexyne entity produces two multiplets centred at 6 3.77 and1.90, similar to that in 4.The molecular structure of compound 4 has been establishedin the solid state by an X-ray diffraction study on a crystalgrown from a solution of dichloromethane-octane by slo1066 J . CHEM. SOC. DALTON TRANS. 1995Fig. 3 The molecular structure of [ R U , ( C O ) , ( ~ ~ - C , H ~ ) ( ~ ~ ~ - C ~ ~ H 6 ) ] 4 showing the atomic labelling scheme.Selected bond lengths are listedin Table 3Table 3 Selected bond lengths (A) for [ R U , ( C ~ ) ~ ( ~ ~ - C ~ H ~ ) ( ~ ~ ~ - C ~ , H ~ ,)] 4Ru( 1 kRu(2)Ru( l)-Ru(4)Ru(2)-Ru(3)R U( 2)-R U( 4)Ru( 3)-Ru(4)Ru(4)-C( Ic)Ru( 4)-C(2~)R U( 4)-C( 4 ~ )Ru(4)-C( 5 ~ )Ru(~)-C(~C)C( 1 C)-C(2C)Ru(4)-C(3c)2.7 12(2)2.635(2)2.729(2)2.844( 2)2.6 36( 2)2.36(2)2.23(2)2.24(2)2.36(2)2.19(2)2.164( 14)1.39(2)C( 1 c)-C( 6 ~ )C(2c)-C( 3c)C( 3C)-C(4C)C(4C)-C(5C)C(7c)-C( 12c)C(7C)-C(SC)C( 8c)-C(9~)C(9c)-C( 10)C( 1 0c)-C( 1 1 c)C( 1 1 c)-C( 12c)Ru( 1)-C( Id)C(~C)-C(~C)1.37(2)1.40(2)1.39(2)1.40(2)1.42(2)1.35(2)1.38(2)1.38(2)1.36(2)1.41(2)1.33(2)2.29(2)Ru( 1 )-C(2d)Ru(2)-C( I d)Ru(3)-C( 1 d)Ru( 3)-C(2d)Ru(4)-C(2d)C( Id)-C(2d)C( 1 dFC(6d)C(2d)-C(3d)C(3d)-C(4d)C(4d)-C( 5d)C(5d)-C(6d)2.22 1 ( 14)2.12(2)2.25(2)2.236( 14)2.07(2)1.44(2)1.57(2)1.55(2)1.54(2)1.51(2)1.49(2)evaporation. Its molecular structure is illustrated in Fig.3;selected bond lengths and fractional atomic coordinates arelisted in Tables 3 and 4 respectively. This compound is anisomer of 2, however, the four ruthenium atoms adopt abutterfly geometry rather than a tetrahedron since the C6Hgligand constitutes that of a cyclohexyne ligand rather than acyclohexa- 1,3-diene moiety, thereby formally contributing sixelectrons to the cluster framework rather than four.The Ru-Rubond lengths are rather unusual with the wing-tip rutheniumatoms being closer to the hinge ruthenium atom which carriesthe [2.2]paracyclophane ring. This unusual metal atomdistribution is analogous to that found in the isostructuralwith that typically observed in butterfly clusters. Thecvclohexyne unit lies between the wings of the butterfly via ap4-q ' : q' : q2 : q2 interaction. The Ru(4) atom carries the[2.2]paracyclophane moiety, the remaining three Ru atomseach bearing three terminal carbonyl groups. The multiple bondof the cyclohexyne ring is short in comparison to the singlebonds [I .44(2) 8, uersus a mean value of 1.53(3) 8, for the fiveremaining bonds]. The C2.2lparacyclophane moiety is co-ordinated in a terminal fashion to Ru(4) via four short and twolong interactions as the ring is not planar but boat shaped withfour carbon atoms [C(2c), C(3c), C(5c) and C(6c)f lying closerto Ru(4) [mean 2.21(4) A] than the two carbons to which thealiphatic bridges attach [C(lc) and C(4c), mean 2.36(2) A].TheComplex [RU4(CO),(C14-C6Hg)(q6-c6H6)], but Contrast&angle between the two enyl planes defined by C(2c)-C(lc)-C(6c)and C(3c)-C(4c)-C(5c) and the central rectangle are 18(1) and15(2)", respectively, these values being essentially the samewithin estimated errors. The angles are similar to that observedin free [2.2]paracyclophane, uiz. 12.6"," albeit slightly lessacute. The angles between the enyl planes in the unattached ringdefined by C(7c jC(8c j C ( 12c) and C(9c)-C( 10c)-C( 1 Ic) are1 1 (2)", relatively unperturbed from that of the free molecule.Cluster 4 is the kinetic product from the thennolysis reaction,which is apparent from the fact that it undergoes isomerisationvia migration of the C2.2lparacyclophane unit to the facialposition affording the thermodynamic product 5.This processhas not been found to be reversible. For most arenes whichcan bond in both terminal and facial co-ordination sitesthe terminal bonding site is preferred. This is in contrast tothe situation observed here with the face-capping ligand beingmost stable. However, C2.2lparacyclophane is unusual inthis respect, and out of all the arene derivativesof [R~~C(CO)~,(arene)] [arene = C,H,-.Me, (n = 1-3),C6H3Et3 or CI6Hl6] the only species to contain a p3-q2 : q2 : q2ligand is the [2.2)paracyclophane derivative.6ExperimentalGeneral Procedures and Materials.-All reactions werecarried out using freshly distilled solvents under an atmospherJ.CHEM. SOC. DALTON TRANS. 1995 1067Table 4 Atomic coordinates for [ R U , ( C O ) ~ ( C ~ ~ - C , H ~ ) ( ~ ~ ~ - C ~ ~ H ~ 6)] 4X0.109 18(12)0.019 19(11)0.247 29(12)0.263 41( 1 1)0.286 9(11)- 0.092 O( 12)-0.025 l(11)-0.022 5(12)- 0.097 8( 12)-0.239 3(13)0.168 4(13)0.230 l(10)0.532 5(12)0.21 7(2)0.027(2)- 0.0 lO(2)-0.053(2)- 0.138(2)0.202(2)0.234 7( 14)0.422(2)0.423 5(14)0.308 8(13)0.260 O(14)0.325 9( 13)0.419 4(14)0.466 2(14)0.599(2)0.508(2)0.460( 2)OSOO(2)0.6 1 O(2)0.656(2)0.506(2)0.609(2)0.3 12( 2)0.41 3(2)0.1 354( 14)0.2569( 1 3)0.3626( 14)0.307(2)0.222(2)0.104 7(14)-0.013 9(14)Y0.456 54(7)0.447 44(7)0.394 23(7)0.506 12(7)0.480 5(7)0.374 2(7)0.599 O(7)0.595 3(7)0.353 7(7)0.445 5(7)0.263 O(8)0.500 l(7)0.366 8(7)0.469 5(9)0.404 4(8)0.544 4( 10)0.538 5(10)0.392 O(10)0.447 4(9)0.312 4(1 I)0.458 8(9)0.374 8(9)0.564 8(9)0.602 7(8)0.625 2(8)0.609 l(8)0.555 l(9)0.532 l(9)0.671 9(9)0.725 3(9)0.747 O(9)0.716 8(9)0.673 2(9)0.651 8(9)0.564 O(10)0.628 2(10)0.655 7(9)0.715 7(10)0.369 9(8)0.401 3(8)0.359 l(8)0.291 4(10)0.250 5( 10)0.290 5(8)Z0.862 30(8)0.694 19(8)0.648 51(9)0.750 92(8)1.024 2(8)0.950 5(8)0.863 5(7)0.614 9(8)0.549 4(9)0.369 9(8)0.540 2(9)0.500 9(7)0.639 8(8)0.962 7(10)0.917 4(10)0.861 7(10)0.645 3( 1 1)0.602 2( 11)0.742 7(10)0.586 O(12)0.556 5(10)0.641 8(10)0.679 O( 10)0.675 8(9)0.752 3(9)0.830 9(9)0.833 5(10)0.754 9(9)0.692 l(11)0.689 8( 1 1)0.765 O(10)0.842 2(10)0.842 3( 1 1)0.769 4( 10)0.602 O( 1 1)0.612 O(12)0.910 O(10)0.916 4(1 I)0.762 l(9)0.792 l(9)0.846 7(10)0.884 6(12)0.818 3(12)0.784 3( 10)of nitrogen gas.Subsequent work-up of products was carriedout using standard laboratory grade solvents withoutprecautions to exclude air. Infrared spectra were recorded on aPerkin-Elmer 1 7 10 Fourier-transform spectrometer. Positiveion mass spectra were obtained by fast atom bombardment on aKratos MSSOTC instrument.Proton NMR spectra wererecorded using a Bruker AM360 or WM250 spectrometer.[Ru~(CO)~ &-C6H8)] 3 were prepared according to literaturemethods. 7 , 1 Trimethylamine N-oxide (Me3NO) andcyclohexa- 1,3-diene were purchased from Aldrich, [2.2]para-cyclophane from Fluka. The Me3N0 was dried and sub-limed prior to use, whilst other materials were used withoutfurther purification.Products were isolated by thin layer chromatography (TLC)using commercially prepared glass plates, precoated to 0.25 mmthickness with Merck Kieselgel60G.The clusters [Ru,(C0)g(p,-q2 :q2 :q2-C16H16)] 1 andReaction of [Ru,(CO),(p,-q2 : q2 : ?12-c16H16)] 1 withMe3N0 and Cyclohexa-l,3-diene in Dichloromethane: Synthesisof 2.-Timethylamine N-oxide (2.2 equivalents, 11 mg) indichloromethane (20 cm3) was added dropwise to a solution of[Ru,(CO),(p3-q2 : y2! q2-c16H16)] 1 (50 mg) in dichlorometh-ane (40 cm3) containing excess cyclohexa-1,3-diene (2 cm3) at-78 "C.The solution was allowed to warm to roomtemperature (1 h) where it was stirred for a further 3 hduring which the colour of the solution darkened. The solventwas removed in uacuo, and the residue chromatographed usingdichloromethane-hexane (3 : 7, v/v) as eluent. Two mainproducts were observed which, in order of elution, werecharacterised by spectroscopic methods as starting material 1Spectroscopic data for 2: IR vco (CH,Cl,): 2038m, 2014vs,2005vs, 1973m, 1952m, 1852m, 1795m m-'.Positive ionFAB mass spectrum: mlz.945 (calc. 946) loss of 9 CO ligandsobserved; the largest peak at m/z 862 which corresponds tothe loss of three CO groups. 'H NMR (CDCl,): 6 7.48 (s, 4 H),5.75 (m, 2 H), 4.54 (m, 2 H), 3.32 (m, 4 H), 3.26 (s, 4 H), 2.47 (m,4 H), 2.12 (m, 2 H), 1.88 (m, 2 H).(25%) and [RU4(C0)9~~4-C6H8)(~3-c16H16)1 (Orange, O%)*Thermolysis of [Ru,(CO),~(~~-C~H,)] 3 with C16H16 inOctane: Synthesis of 4 and 5.--Compound [Ru~(CO)~ 2(p4-C,H,)] 3 (30 mg) in octane (30 cm3) containing an excess ofC16H16 (15 mg) was heated to reflux for 4 h. Monitoring thereaction by spot TLC indicated this to be an optimum time inwhich the balance between remaining starting material anddecomposition products was achieved. The solvent wasremoved in uacuo, and the residue purified by TLC, eluting withdichloromethane-hexane (2 : 3, v/v).Together with unreactedstarting material (1 8%), two bands were characterised byspectroscopy, as [RU4(C0)9(p4-C6H8)(q66_C16H16)] 4 (red,14%) and [Ru4(C0)9(p4-C6H8)(p3-q2 : q2 q2-c16H16)l 5(brown, 1879, respectively.Spectroscopic data for 4: IR vco (CH,Cl,): 2069w, 2055m,2030vs, 2004s, 1977s, 1960 (sh) cm-'. Positive ion FAB massspectrum: m/z 946 (calc. 946) loss of 9 CO ligands observed. 'HNMR (CDCl,): 6 6.80 (s, 4 H), 4.34 (s, 4 H), 3.29 (m, 2 H), 3.2(m, 8 H), 2.88 (m, 2 H), 1.7 (m, 4 H).Spectroscopic data for 5: IR vco (CH,Cl,): 2071m, 2030m,2002vs, 1978m, (sh), 1937w cm-'. Positive ion FAB massspectrum: m/z 946 (calc. 946) loss of 9 CO ligands observed.HNMR (CDCl,): 8 7.21 (s, 4 H), 3.77 (m, 4 H), 3.17 (m, 4 H), 3.16(s, 4 H), 2.56 (m, 4 H), 1.90 (m, 4 H).Thermolysis of [ R u ~ ( C O ) , ~ ( ~ ~ - C ~ H ~ ) ] 3 with C16H16 andMe,NO in Octane: Synthesis of 4 and 5.-Compound[Ru4(CO),,(p4-C6H8)] 3 (50 mg) was suspended in octane (30cm3), and excess C16H16 (25 mg) and Me,NO (15 mg, 3.2 molequivalents) were added. The reaction mixture was heated toreflux for 4 h, by which stage IR spectroscopy indicated thecomplete consumption of starting material. The solvent wasremoved under reduced pressure and the products separated byTLC, using dichloromethane-hexane (2 : 3, v/v) as eluent. Twomajor bands were isolated and characterised by spectroscopyas [RU4(C0)9(p4-C6H8)(116_C16H16)1 4 (red 20%) and [Ru4-respectively .(C0)9(p4-C6H8)(p3'q2 :q2 :q2-C16H16)1 5 (brown, 28%),Crystal-Structure Determination of Compound 2.-A deepred crystal of 2 (approximate dimensions 0.08 x 0.12 x 0.31mm) suitable for X-ray structural analysis was grown bylayering a dichloromethane solution with octane.Crystal data.C3,H,,09Ru4, M = 944.78, monoclinic,space group P2,, a = 9.224(6), b = 9.775(4), c = 16.638(11) A,p = 98.59(7)", U = 1483(2) A3 (from least-squares refinementof the 28 values of 37 reflections; 26 > 28 > 30"), Mo-Ka,radiation, h = 0.710 73 A, 2 = 2, D, = 2.115 Mg mP3,F(OO0) = 916, p(Mo-Ka) = 2.053 mrn-l1068 J. CHEM. SOC. DALTON TRANS. 1995Data collection, structure solution and refinement. StoeStadi-4 diffractometer operating at 150 K, 01-28 scan mode withgraphite-monochromated Mo-Ka radiation and diffractiondata measured to a maximum value for 8 of 22.5'. Threestandard reflections were monitored every 60 min and showed a5% decrease in standard intensity during the data collectiontime (max.and min. corrections of 1.0510 and 0.9954).Absorption corrections were applied by the use of semi-empirical \v scans (max. and min. transmission coefficients0.844 and 0.741 respectively). A total of 4893 reflections weremeasured within the ranges -9 c h c 9, 0 c k < 10,0 < 1 < 17 and averaged to yield 2065 unique reflections(Rint = 0.03 10) of which 1923 were judged as significant by thecriterion that Fobs2 > 20(F0bs2). Corrections for Lorentz andpolarisation effects were applied.Structure solution was by acombination of direct methods and Fourier techniques.Hydrogen atoms were placed in calculated positions and refinedusing a riding model. Anisotropic thermal motion was assumedfor ruthenium atoms only. Full-matrix least-squares refinementon Fobs2 for 2065 data, 197 parameters and one restraintconverged to wR2 = 0.0679 (all data), conventional R1 =0.0288 (observed data), = 0.001, goodness-of-fit =1.059. The function minimised was xw(Fobs2 - Fcalc2)2, w =2FCalc2)/3 and 0 was obtained from counting statistics. A finaldifference electron density Fourier synthesis revealed maximumand minimum residual electron density peaks of 0.69 and-0.54 e A-3, respectively. The absolute configuration wasassigned by the refinement of an absolute structure parameter14to a value of - 0.06(6).1/[02(Fobs2) + (0.0381P)2 -k 2.2849PI where P = (Fobs2 +Crystal-structure Determination of Compound 4.-A redcrystal of 4 (approximate dimensions 0.06 x 0.16 x 0.16 mm)suitable for X-ray structural analysis was grown by slowevaporation of a dichloromethane-octane solution.Crystal data. C31H2409R~4, A4 = 944.78, monoclinic,space group P2,/a, a = 10.419(2), b = 18.787(3), c =15.589(3) A, p = 94.92(3)", U = 3043.9(9) A3 (from least-squares refinement of the 28 values of 30 reflections;20 < 28 < 32"), Mo-Ka radiation, h = 0.710 73 A, 2 = 4,D, = 2.064 Mg mP3, F(000) = 1832, p(Mo-Ka) = 2.003mm-'.Data collection, structure solution and refinement.StoeStadi-4 diffractometer operating at 295 K, a-28 scan mode withgraphite-monochromated Mo-Ka radiation and diffractiondata measured to a maximum value for 8 of 20".Three standardreflections were monitored every 60 min and showed nosignificant loss in standard intensity during the data collectiontime. Absorption corrections were applied by the use of semi-empirical v, scans (max. and min. transmission coefficients0.598 and 0.527 respectively). Corrections for Lorentz andpolarisation effects were applied. A total of 3614 reflectionswere measured within the ranges - 10 < h < 9, 0 < k < 18,0 < I < 15 and averaged to yield 2806 unique reflections(Rint = 0.0402) of which 1940 were judged as significant by thecriterion that Fobs2 > 20(F0bs2). Structure solution was by acombination of direct methods and Fourier techniques.Hydrogen atoms were placed in calculated positions and refinedusing a riding model.Anisotropic thermal motion was assumedfor the ruthenium atoms only. Full-matrix least-squaresrefinement on Fobs2 for 2802 data and 197 parametersconverged to wR2 = 0.1080 (all data), conventional Rl =0.0524 (observed data), ( A / c F ) ~ ~ ~ = 0.001, goodness-of-fit =1.088. The function minimised was &(Fobs2 - F'ca,c2)2, w =1/[0'(Fobs2) + (C1.0201P)~ + 29.2266133 where P = (Fobs2 +2FCalc2)/3 and CF was obtained from counting statistics. A finaldifference electron density Fourier synthesis revealed maxi-mum and minimum residual electron density'peaks of 0.85 and- 0.54 e respectively.For both structures computations were performed with theSHELXTL-PC1 package and SHELXL 93 l 6 program.Additional material available from the Cambridge Crystallo-graphic Data Centre comprises H-atom coordinates, thermalparameters and remaining bond lengths and angles.AcknowledgementsWe thank the University of Edinburgh, the EPSRC and ICI(Wilton) for financial assistance. We are grateful to Dr.S.Parsons for collection of single-crystal X-ray diffraction data.References1 D. J. Cram and D. I. Wilkinson, J. Am. Chem. SOC., 1960,82,5721;H. Ohno, H. Horita, T. Otsubo, Y. Sakata and S. Misumi,Tetrahedron Lett., 1977,265.2 R. T. Swann, A. W. Hanson and V. Boekelheide, J. Am. Chem. SOC.,1986,108,3324.3 C. Elschenbroich, R. Mockel and U. Zenneck, Angew. Chem., Znt.Ed. Engl., 1978, 17, 53 1.4 Y. Kai and N. Kasai, Acta Crystallogr., Sect. B, 1978, 34, 2840.5 E. D. Laganis, R. H. Voegeli, R. T. Swann, R. G. Finke, H. Hopfand V. Boekelheide, Organometallics, 1982, 1, 141 5.6 D. Braga, F. Grepioni, E. Parisini, P. J. Dyson, A. J. Blake andB. F. G. Johnson, J, Chem. SOC., Dalton Trans., 1993,2951.7 P. J. Dyson, B. F. G. Johnson, C. M. Martin, A. J. Blake, D. Braga,F. Grepioni and E. Parisini, Organometallics, 1994,13,2113.8 A. J. Blake, P. J. Dyson, B. F. G. Johnson and C. M. Martin,J. Chem. Soc., Chem. Commun., 1994, 147 1.9 A. J. Blake, P. J. Dyson, S. L. Ingham, B. F. G. Johnson andC. M. Martin, Organometallics, in the press.10 D. Braga, F. Grepioni, E. Parisini, B. F. G. Johnson, C. M. Martin,J. G. M. Nairn, J. Lewis and M. Martinelli, J. Chem. Soc., DaltonTrans., 1993, 1891.11 H. Hope, J. Bernstein and K. N. Trueblood, Acta Crystallogr., Sect.B, 1972,28, 1733.12 D. Braga, F. Grepioni, J. Byrne, C. M. Martin, B. F. G. Johnson andA. J. Blake, Organometallics, in the press.13 S. Aime, L. Milone, D. Osella, G. A. Vaglio, M. Valle, A. Tiripicchioand M. Tiripicchio Camellini, Znorg. Chim. Acta, 1979,34,49.14 H. D. Flack, Acta Crystallogr., Sect. A , 1983,39, 876.15 G. M. Sheldrick, SHELXTL-PC, release 4.3, Siemens Analytical16 G. M. Sheldrick, SHELXL 93, Program for structure refinement,X-ray Instruments, Madison, WI, 1992.University of Gottingen, 1993.Received 12th September 1994; Paper 4/05509

ISSN:1477-9226    

DOI:10.1039/DT9950001063

出版商:RSC    

年代:1995

数据来源: RSC