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J. CHEM. SOC. DALTON TRANS. 1991 2217Synthesis and X-Ray Crystal Structure of the DimolybdenumAcetaldehyde Complex [ Mo,(q-MeCH0)(CO),(~=C5H5),] *Harry Adams, Neil A. Bailey, J. Trevor Gauntlett, Mark J. Winter and Simon WoodwardDepartment of Chemistry, The University, Sheffield S3 7HF, UKThe reaction of [Mo(MeCHO) (C0),(q-C5H5)] - 1 with [C,H,] [BF,] gives the three organometallicsfirst of which has been characterised by X-ray crystallography [monoclinic, space group P2,/c, a =8.265(4), b = 15.1 91 (1 3), c = 13.51 1 (9) A, p = 97.89(5)", R 0.0362 for 21 04 independentreflections for which //o(/) >3.0]. The molecule consists of two Mo(CO),(q-C,H,) groups linked bya Mo-Mo bond [2.9670(8) A] and bridged by an acetaldehyde ligand (q' through both C and 0 toone metal atom, CF through the oxygen to the second metal).The same three products arise in thereaction of 1 with [Mo(CO),(q-C,H,)] [BF,], together with [{Mo(C0),(q6-C,H,)},]. Addition ofLiBEt,H to [Mo,(p-q2-MeCO)(CO),(q-C5H5),]BF, gives a high yield of 2, as does the reaction ofHBF,*OEt, with 1. The reactions of complex 1 with any of (CF,CO),O, HC=CCH,Br, PhCH,Br,[M(CO),(q-C,H,)][BF,] (M = M o or W), CH,CI,, [Fe(q-C5H5),][PF6] and Fe,(SO,), lead to lowyields of 2. The tungsten complex [W,(p-q2-MeCHO)(CO),(q-C,H,),] is produced in low yield in thereaction of Li [W( H) (COMe) (CO),(q -C,H,)] with H B F,-0 Et,.[Mo2(p-112-MeCHO) (co)4(q-C5H5)21 2, [{Mo(co)3(q-c5H5))21 and [Mo(C0)z(q3-C7H7) hC5H5)I theIn previous papers we addressed the reaction of [MoMe(CO),-(q-C5H5)]' with LiBEt,H.2 This leads to the complexedacetaldehyde anion [Mo(MeCHO)(CO),(q-C5H5)] - 1 whichis nucleophilic and reacts with Me1 to form a Mo-Me bond.Inthe presence of donor ligands such as CO or PPh3 the end resultis evolution of MeCHO and formation of [MoMe(CO),L-(q-C5H5)] (L = CO or PPh,). Other methylating agents(MeS0,F or [Me,O][BF,]) react at the aldehyde oxygenatom., In this paper we address reactions of anion 1 whosecommon feature is the formation of a complex [Mo2(p-y2-MeCHO)(C0)4(q-C5H5)2] 2. Parts of this work are the subjectof a preliminary comm~nication.~Results and DiscussionThe reaction of [Mo(MeCH0)(CO),(q-C5H5)] - with [C,H,]-[BF,] proceeds over 3 h in tetrahydrofuran (thf) at ambienttemperature to give three organometallic complexes character-ised as [MO~(~-~~-M~CHO)(C~)~(~-C~H~),] 2, the knowndimer [(Mo(CO),(~-C~H,)],~,~ and the known q3-tropyl[Mo(CO),(~~-C,H,)(~-C~H~)].~ The second two of these arewell known and isolated in respective yields of 15 and 18%.Complex 2 is isolated in 20% yield and is fully spectroscopicallycharacterised (see Experimental section).During chroma-tography on alumina it appears as a green-brown band but aftercrystallization is a very dark red, virtually black, crystallinesolid. In addition to terminal stretching bands, the IR spectrumshows a relatively low vco stretch at 1815 cm-' in a positioncharacteristic of semibridging carbonyl~.~ At - 70 "C the 3CNMR spectrum shows four carbonyl, two cyclopentadienyl, amethyl and a signal at 6 104.5 assigned to the aldehyde carbon.All four carbonyl and the two cyclopentadienyl signals arepresent in the room-temperature spectrum, indicating thestructure is relatively static at ambient temperatures.* p-Acetaldehyde-1 KC', 1 : 2~~0-bis[dicarbonyl(q-cyclopentadienyl)-molybdenum] (Mo-Mo).Supplementury dutu uvailable: see Instructions for Authors, J.Chem.Soc., Dulton Truns., 1991, Issue 1, i)p. xviii-xxii.nFig. 12 showing atom labellingMolecular geometry of [Mo,(CO),(p-q2-MeCHO)(q-C5H5)JThe molecular structure of 2, as determined by X-raycrystallography, is shown in Fig. 1 and its parameters listed inTables 1 and 2. The structure consists of two Mo(CO),(q-C5H,) units linked by the Mo-Mo bond and bridged by anacetaldehyde ligand.The aldehyde is CT bonded (via the oxygen)to Mo(1) and q2 (via the C=O) to Mo(2). The bridged Mo-Mobond is shorter than the unsupported bond in [(Mo(CO),(q-C5H,)),] (3.235 A)* and close to that in bridged Mo-Mocomplexes such as [MO,(CO)~(~-M~,S~CCS~M~,)(~-C~H~)~](Mo-Mo 2.953 A) and [Mo,(CO)~(~-CH,=C=CH~)(~-C5H5)2] (Mo-Mo 3.117 A).'' The aldehyde C=O (1.354 A)distance is lengthened relative to free aldehydes (typically 1.22 A).The plane of the aldehyde is twisted by 68.3" relative to thebridge plane Mo( l),Mo(2),0(5) through the bridging oxygenatom but is more perpendicular (87.2') to the plane definedby Mo(l), Mo(2) and C(5). One of the carbonyl ligands issemibridging and is somewhat bent [Mo(2)-C(4)-0(4) 166.3"2218 J.CHEM. SOC. DALTON TRANS. 1991Table 1 Atom coordinates for [Mo,(~-~~-M~CHO)(CO)~(~-C,H,)~]2Xla0.159 26(7)0.297 30(7)0.008 5( 10)0.664 l(7)0.444 5( 10)0.180 5( 5)0.067 5( 11)0.526 6(9)0.380 7( 1 1)0.325 O(9)0.318 6(11)0.164 5(10)0.320 6( 10)0.402 6( 10)0.298 8(13)0.154 6(12)0.215 4(13)0.075 7(11)0.079 l(12)0.228 6( 17)0.312 9(12)-0.214 6(7)-0.073 7(9)Ylb0.099 77(4)0.073 O(4)0.189 2(5)0.15 1 4(4)0.079 O(5)0.155 l(5)0.086 3(6)-0.032 35(4)- 0.064 9( 5 )-0.039 3(3)-0.051 5 ( 5 )-0.079 2(5)-0.175 4(5)0.150 8(6)0.113 6(5)0.157 4(6)0.225 7(5)0.222 6(5)-0.158 7(7)-0.114 6(7)-0.036 6(7)- 0.030 4(8)-0.110 l(9)ZlC0.142 62(4)0.292 63(4)0.105 8(5)0.314 6(5)0.281 O(6)0.340 l(5)0.147 4(3)0.1 19 O(5)0.252 8(6)0.286 O(6)0.310 6(6)0.140 4(6)0.117 9(7)0.009 2(6)0.114 2(7)0.045 O(7)0.372 4(7)0.339 6(7)0.386 9(7)0.453 7(7)0.441 6(7)-0.019 6(6)0.091 3(7)Table 2 Selected bond lengths (A) and angles (") with estimatedstandard deviations (e.s.d.s) for [Mo,(pq 2-MeCHO)(C0)4(q-C5H5)2]2M O( 1 )-M O( 2)Mo( 1)-C( 1)Mo( 1)-C(2)Mo( 1)-C(7)M O( 1 )-C( 8)Mo( 1)-C(9)Mo(1)-C( 10)Mo( 1)-C( 1 1)Mo( 1)-0(5)Mo( 1) - C(4)0(5)-C( 5 )Mo(~)-Mo( 1)-O(5)Mo(~)-Mo( 1)-C( 1)Mo(~)-Mo( 1)-C(2)0(5)-M0( 1)-C( 1)0(5)-M0( 1)-C(2)C( l)-Mo( 1)-C(2)Mo( 1)-C( 1)-O( 1)Mo(l)-C(2)-0(2)M 0(2)-C( 3)-0(3)M0(2)-C(4)-0(4)Mo( 1)-O( 5)-M0(2)Mo( 1)-0(5)-C(5)Mo( 2)-0(5)-C( 5)2.967 O(8)1.934(7)1.951(9)2.331(8)2.395( 8)2.382(9)2.293( 10)2.282(9)2.120(4)2.721(9)1.354( 8)44.18( 12)106.46(2 1 )85.61(25)85.34(24)116.44(27)73.4(3)175.1(6)177.1 (8)178.5(7)166.3(8)120.9(4)90.22( 17)77.7(4)Mo( 1)-M0(2)-0(5)Mo(l)-Mo(2)<(3)Mo( 1)-M0(2)-C(4)0(5)-M0(2)-C(4)C( 3)-Mo(2)-C( 4)0(5tMoWC(3)Mo( 1 )-Mo(2)-C(5)0(5)-M0(2)-C( 5)C( 3)-Mo(2)-C( 5)C( 4)-Mo( 2)-C( 5)M0(2)-C(5)-0(5)M o (2)-C( 5)-C( 6)0(5W(5)-C(6)1.932(8)1.933(9)2.345( 10)2.374( 10)2.347( 10)2.324(12)2.322(11)2.068(4)2.2 18(7)1.493( 1 1)45.60( 12)110.99(24)63.40(25)106.36(26)106.19(28)79.1(3)70.26( 19)36.63(22)71.45(30)109.6(3)65.6(3)119.9(5)1 16.5(6)with the C(4).Mo(1) distance relatively short (2.721 A).Semibridging carbonyl groups of this type are well known in[M2(CO)4(p-L)(q-C,H5)2] (M = Mo or W; L = four-electronbridging donor ligand, typically alkyne).' The closely planarcyclopentadienyl groups are slightly asymmetrically bonded totheir molybdenum atoms in a manner consistent with the IK-bonding nature of the trans ligands.Thus the carbon atomsmost nearly trans to the carbonyl groups are more remote frommolybdenum.Many small molecules such as CO, phosphines, alkynes,isonitriles, etc., react by addition across the Mo=Mo bond of[{Mo~(CO),(~-C,H,)~}] 3.12 It might be expected thatacetaldehyde would react with [{ MO,(CO),(~-C~H~)~}] 3,since 2 is a formal addition product of MeCHO across theMo-Mo bond of 3.In the event, such an addition does not takeM2 Mo6 W4 3Scheme 1 (i) LiBEt,H; (ii) HBF,-OEt,; (iii) R'RZC=Splace, even in the presence of large excesses of acetaldehyde.However, a number of thioketones,' thioesters, thiolactonesand dithioesters l 5 are known to add across the MEMO bond(Scheme 1). As examples, thiocamphor (1,7,7- trimethylbicyclo-C2.2.llheptane-2-thione) adds to [{Mo2(CO),(q-CSH5),)1 3 toform 4. The nature of the Mo,CS central core is clearly verysimilar to that of the Mo,CO core of 2. A number of relatedcomplexes are also known. Although aldehydes have notapparently been reported bridging two molybdenum atoms, anumber of complexes are known in which aldehydes bridge twoother metals in manners reminiscent of 2, although the formalrepresentations of these species do not include metal-metalbonds.The mechanisms of formation of the complexes are clearly ofinterest.A plausible mechanism for the formation of [Mo(CO),-(q3-C7H7)(q-CsH5)] involves nucleophilic attack of the anion1 at [C7H7]+ to form an 0-C,H, intermediate [Mo(o-C7H,)(MeCHO)(CO),(q-C5H5)]. This loses MeCHO as theq3-allyl interaction is formed. The origin of [{ Mo(CO),(q-C5Hs)}2] is far less clear, but is clearly complex. Complex 2would arise by electron transfer to [C,H,]' followed bydimerisation of two resulting Mo(MeCHO)(CO),(q-C,H 5 )units with loss of MeCHO. It is assumed that this process willresult in some ditropyl, but no attempt was made to detect thiscompound.Electron transfer from complex 1 to other oxidants alsooccurs.For instance, the reaction of ferrocenium cation with 1leads to 2 in 11% yield, together with some [{Mo(CO),(q-C5H5)}2] and ferrocene. The reaction of solid Fe,(SO,), with 1in thf leads to 2 (10%) together with some [Mo(CO),(q-C,H,)] -. The latter is isolable as [MoMe(CO),(q-C,H,)] byaddition of MeI, although a lesser quantity of [MoI(CO),(q-C,H,)] also results. A very reasonable yield of 2 is obtainedthrough the reaction of 1 with HBF,=OEt,. Addition of HBF,.OEt, to a solution of 1 gives a reaction mixture containingMeCHO (GLC analysis). The isolated organometallic productsisolated are [{Mo(CO),(q-C,H,)),] and a 57% yield of 2. ThiJ. CHEM. SOC. DALTON TRANS. 1991 2219reaction needs to be worked up promptly, isolated yields fallsharply if the reaction mixture is left stirring.Duringchromatography of the reaction mixture a yellow material isalso evident. This yellow band turns to pink [{Mo(CO),(q-C5H5)),] during elution under air, suggesting that the yellowmaterial is probably [MoH(CO),(q-C,H,)], although this isnot confirmed. A moderate yield of 2 (31%) is also obtained ifthe thf solvent is removed from the reaction producing 1 andreplaced with CH2C12. This is probably a consequence of tracesof acid in the CH2C12 when used as supplied.We recently described the formation of the anion cWH(C0-Me)(CO),(q-C,H,)] - 5 by treatment of [WMe(CO),(q-C,-H,)] with LiBEt3H.17 Its reaction with HBF4-OEt, leads to alow yield of complex 6, the tungsten analogue of 2.Insufficientquantities of this compound were obtained for a 13C NMRspectrum but the other spectroscopic data (see Experimentalsection) are clearly closely related. No complex 6 is observed inthe reaction of 5 with [Fe(q-C,H,),][PF,], the only observedorganometallic products of this reaction being ferrocene and alittle [WMe(CO),(q-C,H,)].The p-acetyl complex 7 is known.” It is made by the reactionof [Mo(C0),(FBF3)(q-C5H5)] with [MoMe(CO),(q-C,H,)].Addition of LiBEt,H to a suspension of 7 in thf represents arational synthesis of 2. This approach is successful and the yieldof 2 is 59%. Very small amounts of [{Mo(CO),(q-C,H,)),] arealso isolated.The reaction of [M(CO),(q-C,H,)][BF,] (M = Mo or W)with 1 also leads to moderate quantities of 2.In the former case[{Mo(CO),(q-C,H,)),] is also formed, in the latter a mixtureof ~(Mo(co),(~-csH~)),1, ~{W(CO),(q-CsHs)),] and [(q-C ,H 5)( OC),M 0-W( CO),(q -C ,H ,)I also arises. In both cases,quantities of [MoMe(CO),(q-C,H,)] are seen. This materialwas not present in the original solution of 1. This reflects atendency of the cations [M(C0),(q-C5H5)]BF4 (M = Mo orW) to abstract hydride from 1 in pathways competing with theformation of 2. The result of such an abstraction is theintermediate [Mo(COMe)(CO),(q-C,H,)] which decarbonyl-ates rapidly to form [MoMe(CO),(q-C,H,)].Very small amounts of complex 2 are also formed in thereactions of 1 with (CF3C0)20, HC=CCH,Br, PhCH,Bror [Mo(C0),(q7-C,H,)][BF,].In the last case, substantialquantities of [MO(CO)~(~~-C~H~)(~-C,H,)] are formed. Thiswould arise from an intermediate structure 8 from which theMo(CO), fragment is lost as the q3-tropyl interaction isformed. A further product is [{ MO(CO)~)~(~~,~’~-C,~H~~)] 9(14%) previously identified in the reaction of [M0(CO),(q7-C7H7)]+ with 1.”ExperimentalInfrared spectra were recorded on a Perkin-Elmer 257 spectro-meter calibrated using the absorption of polystyrene film at1601.4 cm-’ or on a Perkin-Elmer FT1710 instrument linked toa 3600 data station. Proton NMR spectra were recorded usingJEOL PFT-100 (100.00 MHz), Bruker WP-8OSY (80.13 MHz),AM-250 (250.13 MHz), WH-400 (400.13 MHz) and Perkin-Elmer R34 (200 MHz) instruments, carbon-13 NMR spectrausing JEOL PFT-100 (25.15 MHz), Bruker AM-250 (62.88MHz) and WH-400 (100.13 MHz) instruments.Mass spectrawere recorded using Kratos MS 25 [electron impact and gaschromatography (GCFmass spectrometry] or MS 80 (chemicalionisation and fast atom bombardment) instruments. Allreactions were performed under nitrogen or argon atmospheresgenerally in Schlenk glassware dried by heating under vacuum.Solvents were used as supplied, except thf which was distilledfrom sodium-benzophenone immediately prior to use and lightpetroleum (fraction boiling at 4&60 “C throughout) which wasdistilled from LiAlH,. Alumina was Brockmann activity Ideactivated with water (5% w/w) to activity I1 or supplied asBrockmann activity 11. The reagent LiBEt,H (Aldrich ‘SuperHydride’) was used as supplied.The compounds [MoM~(CO)~-(q-CSHs)],20 Li[Mo(MeCHO)(CO),(q-C5H5)], 1, Li[WH-( C ~ M ~ ) ( C ~ ) , ( ~ ~ C ~ H S ) ~ , ’ [Mo2(P-17 2-MeCO)(C0)4(rl-[Mo(CO),(q7-C7H7)][BF4] 2o were synthesised according toliterature procedures.C,H,),ICBF41, CFe(~-CSH5)21CPF61,”’ Cc7H,ICBF,I 22 andReactions of [Mo(MeCHO)(CO),(q-C5H5)]- l.-WWith[C7H,][BF4]. Solid [C7H,][BF4] (0.50 g, 2.81 mmol) wasadded to a solution of complex 1 (1.9 mmol in thf) at ambienttemperature. The solution darkened to red-brown as the soliddissolved (30 min). After filtration of the reaction mixturethrough an alumina plug, the solvent was removed underreduced pressure and the resulting brown material chromato-graphed on alumina (25 x 3 cm) using light petroleum-dichloromethane (7: 1 increasing to 4: 1).Elution gave orange[Mo(CO)2(rl 3-C7H7)(.rl-C5H5)1 (0.088 g, 18%), Pink [{ Mo-(C0),(q-C5H5)],] (0.085 g, 15%), and black [Mo,(p-q2-Me-~ ~ ~ ) ( ~ ~ ) ~ ( ~ - ~ s ~ s ) ~ ~ (0.093 g, 20%)-[Mo~(~-~~-M~CHO)(CO)~(~-C~H,)~] 2: m.p., decomp.without melting, too dark to observe (Found: C, 40.1; H, 2.9%;M + , 478. C16H14M02O5 requires C, 40.2; H, 3.0%; A4 478);v,,/cm-’ (light petroleum) 1959m, 1932s, 1871s and 1833m; ‘HNMR, 6(400 MHz, CDCl,) 5.53 ( 5 H, s, C,H,), 5.22 (5 H, s,C5H5), 2.16 [l H, q, J(HH) = 5, CHI and 1.86 [3 H, d,J(HH) = 5 Hz, Me]; 13C NMR (63 MHz, C6D5CD3, -70 “C)253.2 (CO), 247.9 (CO), 229.2 (CO), 227.8 (CO), 104.5(MeCHO), 98.2 (C,H,), 96.0 (C,H,) and 30.0 (Me).With [Mo(C0),(q7-C7H7)][BF4].Solid [Mo(CO),(q-C,H,)][BF4] (0.54 g, 1.5 mmol) was added to a solution ofcomplex 1 (1.15 mmol in thf). The solution darkened from theoriginal orange-brown instantly but was left to stir (18 h).Removal of solvent under reduced pressure resulted in a brownsolid. Chromatography on alumina (30 x 3 cm) eluting withlight petroleum-dichloromethane (7: 1 changing to 4: 1) gaveorange [Mo(CO),(q3-C,H,)(q-C5H5)] (0.17 g, 47%) followedby black [MO~(~-~~-M~CHO)(CO)~(~-C~H~)~] 2 (0.005 g,1%). Further extraction of the brown solid into CH,Cl,followed by filtration through a short alumina plug resulted ina red solution containing [{ M O ( C O ) ~ } ~ ( ~ ~ , ~ ’ ~ - C ~ ~ H ~ 9isolated in 14% yield (0.055 g) by crystallisation from lightpetroleum-dichloromethane.A similar ratio of products wasisolated when the reaction was carried out under a carbonmonoxide atmosphere.With (CF3C0),0. An instant colour change to dark brownresulted on addition of (CF3C0),0 (0.2 cm3, 1.5 mmol) to asolution of complex 1 (1.0 mmol in thf, 60 cm3). The reactionmixture was filtered through short alumina and Florisil plugs.Chromatography on alumina (10 x 2 cm) eluting with lightpetroleum-dichloromethane (7: 1 changing to 4: 1) afforded~ { M O ( C O ) ~ ( ~ - C S H S ) ) ~ ~ (0.005 g, 2%) and [Mo3(P-q2-MeCHO)(C0)4(q-C,H,)2] 2 (0.048 g, 20%).With HC=CCH,Br. Prop-2-ynyl bromide (0.2 cm3, 80% w/win toluene, 1.9 mmol) was added to a solution of complex 1 (1.0mmol in thf, 40 cm3) at -70 “C and the solution allowed towarm to ambient temperature. The solvent was removed underreduced pressure and the resulting brown solid dissolved inCH,Cl, (10 cm3) and filtered through Kieselguhr.Removal ofsolvent under reduced pressure and extraction of the resultingbrown gum into light petroleum (3 x 20 cm3) gave a greensolution from which black crystals of [Mo,(p-q’-MeCHO)-(CO)4(q-CsHs)2] 2 (0.012 g, 5%) separated on cooling2220 J. CHEM. SOC. DALTON TRANS. 1991With [Mo(CO),(q-C,H,)][BF,]. A solution of [Mo(CO),(q-C,H,)][BF,] (0.83 g, 2.5 mmol in 40 cm3 thf) was addeddropwise to a solution of complex 1 (2.5 mmol in thf, 40 cm3) atambient temperature. The solution darkened to red-brown (4h). Removal of solvent under reduced pressure resulted in a darkbrown solid.Chromatography on alumina (20 x 3 cm) undernitrogen in the absence of light, eluting with light petroleum-dichloromethane (4: 1 changing to 3: 1), provided yellow[MoMe(CO),(q-C,H,)] (0.088 g, 14%) followed by pink[{Mo(CO),(q-C,H5)},] (0.080 g, 13%) and black [Mo2(p-q2-MeCHO)(CO),(q-C,H5)2] (0.121 g, 20%).With [W(CO),(q-C,H,)][BF,]. A solution of [W(CO),(q-C,H,)][BF,] (0.59 g, 1.4 mmol in 40 cm3 thf) was added to asolution of complex 1 (1.4 mmol in thf, 35 cm3) at ambienttemperature and the solution stirred (2 h) during which timeit darkened to red-brown. The solvent was removed underreduced pressure. Chromatography on alumina (15 x 3 cm)under nitrogen, eluting with light petroleum-dichloromethane(4: l), gave yellow [MOM~(CO)~(~-C,H,)] (0.035 g, 13%), apink mixture (0.1 1 g total) containing [{Mo(CO),(q-c 5H 5 ) ) 21, [M 0w(co)6(q -c ,H 5 ) and [{ W(C0) -C5H5)),], and black [MO~(~-~~-M~CHO)(CO),(~-C~H~)~](0.064 g, 19%).With [Fe(q -C5 H 5)2] [ PF,].Solid [Fe(q -C H5),] [PF,] (0.84g, 2.6 mmol) was added to a solution of complex 1 (1.7 mmol inthf, 80 cm3). The solution was stirred (2 h) during which timethe solid dissolved and the solution darkened to red-brown.After removal of solvent under reduced pressure, chromato-graphy on alumina (15 x 3 cm) under nitrogen and elutingwith light petroleum-dichloromethane (4: 1) gave orangeferrocene (0.142 g, 3473, pink [{ MO(CO)~(~-C,H~)}~] (0.008 g,2%) and black [Mo2(p-q2-MeCHO)(C0),(q-C5H5),] 2 (0.045With Fe,(SO,),.A solution of complex 1 (1.0 mmol in thf, 50cm3) was treated at ambient temperature with solid Fe2(S04),(0.4 g, 1 .O mmol) and the solution stirred (3 h) during which timethe solid dissolved. The IR spectrum of the reaction mixturecontained bands assigned to the anion [Mo(CO),(q-C,H,)] -.This was converted into [MoM~(CO)~(~-C,H,)] by additionof Me1 (0.18 cm3, 0.4 g, 2.8 mmol) followed by stirring (40 h).The cloudy brown solution was filtered through alumina (6 x 1cm) and the solvent removed under reduced pressure.Extraction into light petroleum-dichloromethane (7 : 1 v/v3 x 10 cm3) followed by chromatography on alumina (15 x 3cm) resulted in yellow, orange and green bands. Eluting withlight petroleum-dichloromethane (4 : 1 v/v) gave yellow[MoMe(CO),(q-C,H,)] (0.048 g, 19%), orange [MoI(CO),(q-C,H,)] (0.01 5 g, 4%), and black [Mo2(p-q2-MeCHO)(C0),(q-With HBF,-OEt,.A solution of complex 1 (0.42 mmol in thf,20 cm3) was mixed with HBF4*OEt2 (0.22 g, 1.36 mmol) and thesolution stirred ( 5 min). Gas-liquid chromatography showedthe presence of MeCHO. Prompt filtration of the red-brownsolution through alumina (4 x 1 cm) and removal of solventunder reduced pressure gave a dark brown solid. This wasextracted into light petroleumdichloromethane (7: 1 v/v, 10cm3) and chromatographed on alumina (5 x 2 cm) undernitrogen using the same solvent. This gave yellow, pink andgreen bands. The yellow band slowly turned pink on thecolumn. The fractions collected were pink [(Mo(CO),(q-C5H5)I2] (0.01 g, 10%) and black [Mo,(p-q'-MeCHO)-(co)4(q-C5H5)21 2 (0.058 g, 57%)-g, 11%).C5H5)21 2 (0.024 g, 10%)-Dissolution U~[MO(CO>~(M~CHO)(~-C,H,)I - 1 in CH,Cl,.-The solvent was removed from a solution of complex 1 pre-pared from [MoMe(CO),(q-C5H,)] (0.26 g, 1.0 mmol) andLiBEt,H (1.2 cm3, 1.2 mmol). The resulting brown gum wasdissolved in deoxygenated, reagent-grade dichloromethane.Removal of the solvent followed by extraction into lightpetroleum-dichloromethane (7: 1 v/v, 100 cm3) and filtra-tion through alumina (10 x 2 cm) resulted in a faint pinkand a green band.The former was discarded and the secondgave black [MO~(~-~~-M~CHO)(CO)~(~-C~H~)~] 2 (0.05 g,3 1%).Reaction of [Mo2(p-q2-MeCO>(CO),(q-C5H5),][BF4] 7and LiBEt,H.-A suspension of the cationic complex [Mo,(p-q2-MeCO)(C0),(q-C5H5),][BF4] 7 (0.1 g, 0.18 mmol) in thf(20 cm3) was cooled to 0 "C and LiBEt,H (0.25 cm3, 1 mol dmP3solution in thf, 0.25 mmol) added dropwise over 5 min.Thesolution darkened slowly to green-black as the solid dissolved.Filtration of the reaction mixture through an alumina plugfollowed by chromatography on alumina (12 x 2 cm) resolvedpink and green fractions, the latter being eluted by lightpetroleum-dichloromethane (2 : 1). The pink band contained alittle [(MO(CO),(~-C,H,>}~] and the green band containedcomplex 2 (0.051 g, 59%).Reaction bet ween Li[ W H(COMe)(CO),(q -C5 H ,)I andHBF,*OEt,.-A solution of the salt Li[WH(COMe)(CO),(q-C,H,)] (0.57 mmol in thf, 15 cm3) was cooled (-90 "C) and astandard diethyl ether solution of HBF,-OEt, (1.0 cm3, 0.46mmol) added over 15 min.The reaction mixture turned darkorange and was allowed to warm to room temperature (1 h)during which time it turned black. The solvent was removed andthe residue extracted with diethyl ether (2 x 25 cm3). Filtrationthrough an alumina plug and crystallisation afforded [W2(p-q 2-MeCHO)(CO),(q-C,H,),] 6 as brown microcrystals (0.016 g,579, m.p. 108-1 10 "C (decomp.) (Found: C, 29.4; H, 1.9%; M',654. C1,H,,05Wz requires C, 29.4; H, 2.2%; M, 654); vco/cm-l(CH,Cl,) 1953w, 1913s and 1834m, NMR(CDC1,): 'H (250.13q, ,J(HH) = 5 Hz, CHI and 1.97 (3 H, d, Me); I3C (100.61MHz), 6 101.0 (CH), 96.7 (q-C,H,), 93.5 (q-C5H5) and 29.8(Me).An inadequate signal-to-noise ratio prevented assign-ment of the carbonyl signals.MHz), 6 5.74 (5 H, S, q-CgHg), 5.49 (5 H, S, q-C5H5), 2.10 [l H,X-Ray Crystal Structure of [Mo(p-q2-MeCHO)(CO),(q-C,H,),] 2.-CrystaZdata. C,,H,,Mo,O,, M = 478.08,crystal-lises from light petroleum as thick red plates, crystal dimensions0.6 x 0.2 x 0.35 mm, monoclinic, space group P2Jc (C;,,, no.14), a = 8.265(4), b = 15.191(13), c = 13.511(9) A, p =97.89(5)", U = 1680.2(20) A3, Z = 4, D, = 1.890 g cm-,,Mo-Ka radiation (x = 0.71069 A), p(Mo-Ka) = 14.77 cm-',F(OO0) = 936.Three-dimensional X-ray diffraction data were collected inthe range 3.5 < 28 < 50" on a Nicolet R3m diffractometer bythe a-scan method. The 2104 independent reflections for whichI/o(r) > 3.0 were corrected for Lorentz and polarisation effectsand for absorption.The structure was solved by standardPatterson and Fourier techniques and refined by block-diagonal least-squares methods. Hydrogen atoms were placedin calculated positions [C-H 0.97 A, C-C-H(methy1) 11 1'3;their contributions were included in structure-factor calcul-ations (B = 7.0 A2) but no refinement of positional parameterswas permitted. Refinement converged at R 0.0362 withallowance for anisotropic thermal motion of all non-hydrogenatoms and for the anomalous scattering of molybdenum. Table2 lists the atomic positional parameters with estimated standarddeviations. Scattering factors were taken from those published.',Unit weights were used throughout the refinement; computerprograms form part of the Sheffield X-ray system.Additional material available from the Cambridge Crystal-lographic Data Centre comprises H-atom coordinates, thermalparameters and remaining bond lengths and angles.AcknowledgementsJ.T. G. and S. W. are pleased to be recipients of SERC researchstudentships. We are grateful to the Royal Society and to theSERC for generous supportJ. CHEM. SOC. DALTON TRANS. 1991 222 1References1 T. S. Piper and G. Wilkinson, J. Inorg. Nucl. Chem., 1956, 3,104.2 J. T. Gauntlett, B. F. Taylor and M. J. Winter, J. Chem. SOC., DaltonTrans., 1985, 1815; J. T. Gauntlett, B. F. Taylor and M. J. Winter, J.Chem. SOC., Chem. Commun., 1984, 420 J. T. Gauntlett and M. J.Winter, Polyhedron, 1986,5,451.3 H.Adams, N. A. Bailey, J. T. Gauntlett, I. M. Harkin, M. J. Winterand S. Woodward, J. Chern. SOC., Dalton Trans., 1991, 11 17.4 H. Adams, N. A. Bailey, J. T. 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ISSN:1477-9226    

DOI:10.1039/DT9910002217

出版商:RSC    

年代:1991

数据来源: RSC