摘要:
J. CHEM. SOC. DALTON TRANS. 1988 2009Kinetics of Nucleophilic Attack on Co-ordinated Organic Moieties. Part 25.tA Nucleophilic Order for Attack upon the [Fe(C0),(1--5-~&H,)]' CationSam G. Evans, Kerry Gilmore, and Leon A. P. Kane-Maguire"Department of Chemistry, University of Wollongong, P.O. Box 1144, Wollongong, N.S. W. 2500, AustraliaBKinetic studies of the addition of a range of phosphine and phosphite nucleophiles (PR,) to thecation [Fe(C0),(7-5-q-C7H,)] + to give [Fe(CO),(7-4-q-R,P-C7H,)] + adducts reveal the generalrate law kobs = k, (PR,]. Combination of these results with analogous data for amine and anionicnucleophiles.provides the first comprehensive nucleophilicity order for attack on this cyclohepta-dienyl substrate. For the neutral phosphorus and nitrogen nucleophiles, this nucleophilicity orderquantitatively parallels that found for the related but much more reactive [Fe(CO),(1-5-q-C,H7)] +substrate, indicating departure from the reactivity-selectivity principle. However, with N,- the C7H,cation reveals exceptional reactivity, suggesting a change in mechanism for this anionic nucleophile.Kinetic data have been reported for the addition of a widerange of phosphorus, nitrogen, and carbon nucleophiles to thecyclohexadienyl ring of the cation [Fe(CO),( l-5-q-C6H7)] + (l), and a nucleophilicity order established.' For tertiaryphosphines,' anilines,, and pyridines,, for which the mostextensive information is available, a strong dependence of rateconstant on nucleophile basicity was noted. Moderate, butfar from complete, nucleophileecarbon bond formation wassuggestedLess detailed studies '-' of nucleophilic addition to othern-hydrocarbon complexes of lower intrinsic reactivity suchas [Fe(CO),( 1-5-q-2-MeOC,H6)] -t or [Cr(CO),(q-C,H,)] +revealed a quantitatively similar nucleophilicity order to thatshown by cation (1).This suggested that relative nucleophilicreactivities towards organometallic [M(~t-hydrocarbon)L,] +electrophiles may be electrophile independent. Confirmation ofthis hypothesis would establish a close parallel with relatedadditions to free carbonium ions. Ritchie' and more recentlyAlavosus and Sweigart have shown that for the addition ofoxygen, sulphur, nitrogen, and phosphorus nucleophiles tocarbocations, the nucleophilicity ( N , ) is independent of thenature or reactivity of the electrophile, being given by relation-ship (1).Here k , is the rate constant for a particular nucleophilein the transition states for these processes.and k, is the rate constant for a standard nucleophile (H,O).This behaviour of free carbonium ions represents a grossdeparture from the reactivity-selectivity principle. Studies ofcationic [M(n-hydrocarbon)L,] + complexes have revealed '** avery broad range of electrophilicities (factor of ca. lo7) towardsnucleophiles (Nu). Such organometallic substrates thereforeprovide an ideal testing ground for the reactivity-selectivityprinciple.6" As part of a programme examining this question,we report here kinetic data for the addition of tertiaryphosphines and phosphites to the cycloheptadienyl complexi.Part 24, S. Chapman, L. A. P. Kane-Maguire, and R. Kanitz, .I.Organornet. ChPni., 1987, 329, C 1 1.Table 1. Infrared data of [Fe(CO),( 14-q-R3PC,H,)]+ adducts inCH&NPR3P(2-MeOC,H,),P(4-MeC6H,) ,P(4-MeC,H,)Ph,PPh,P(2-CNC,H,)Ph,P(2-CNC2H4)3P(OBu)3v(CO)/cm- '2049, 19782 054, 19832053, 19832 056, 19842052, 19822058, 19862 055, 19826* 7'3 - \4Fe(C0):Figure 1. Phosphonium adducts [Fe(CO),(1-4-q-R3P.C,H9)J + (3)[Fe(CO),( l-5-q-C7H9)] + (2) [equation (2)], which limitedearlier studies 2-4 had shown to be intrinsically less reactivethan (I).ExperimentalMaterials.-The salt [Fe(CO),( 1-5-q -C,H,)] BF, wasprepared and purified using established procedures.' Thephosphorus nucleophiles were purchased in the purest gradesavailable (Strem or Aldrich) and used as supplied.Acetonesolvent was analytical grade, and was deoxygenated by passingthrough it a stream of dinitrogen for 20 min. Solutions of theappropriate phosphorus nucleophile were prepared underdinitrogen immediately prior to use.Preparation of Plzosphonium Adducts.-Some of the newphosphonium adducts were isolated and characterised, whileothers were prepared in situ and characterised by their 'H n.m.r.and/or i.r. spectra (Table 1). Proton n.m.r. spectra wer2010 J. CHEM. SOC. DALTON TRANS. 1988recorded in CD,COCD, using [Fe] = [PR,] = 0.08 moldrn-,. Refer to Figure 1 for the labelling of atoms.Tricarbonyl{ 1 4 - q - 5- [ tris(p-methoxyphenyl )phosphonio] -eyclohepta- 173-diene} iron tetrajluoroborate.Tris(4-methoxy-pheny1)phosphine (28 mg, 0.0079 mmol) was added to asolution of (2) (25 mg, 0.0078 mmol) in acetone ( 1 cm3). Rotaryevaporation and treatment with diethyl ether gave the pro-duct as a pale yellow solid (37 mg, 70% yield) (Found: C, 55.4;H, 4.7. Calc. for C,,H,,BF4Fe06P: C, 55.4; H, 4.5%). 'HN.m.r. (CD,COCD,): 6 8.@-7.1 (m, aromatic), 5.45 (dd, 1 H,H2, J,,' 7.5, J2.3 4.9), 5.31 (m, 1 H, H3, J3,4 7.0, J3.1 2.0), 4.28 (dt,1 H , H5', Jsz,6 = J 5 r , p 13.0, J5,,6, 2.8 Hz), 3.90(s, 9 H, OCH,), 3.30(m, 1 H, H', J1.2 7.5, Jl,7 6.0), 3.10 (dd, 1 H, H4, J4,p 15.5, J4,,7.2, J4,5, 0 Hz), 2.25 (m, 2 H, H7 and H7'), 1.99 (m, 1 H, H6'), and1.25 (m, 1 H, H6).Triearbunyl( 14-q-5-[tris(o-rnethoxyphenyl )phosphonio] -cjduhepta- 1,3-diene) iron tetrajluoroborate. 'H N.m.r.(CD,COCD,): 6 7.95-7.1 (m, aromatic), 5.58 (dd, 1 H, H'),5.40 (m, 1 H, H3), 4.12 (dt, 1 H, H5', J5,,6 - Js,,p - 13,J5s,6, - 3), 3.90 (s, 9 H, OCH,), 3.34 (t, 1 H, H', J 1 , 2 -J1-7 - 6.5 Hz), 3.02 (dd, 1 H, H4), 2.16 (overlapping multiplets,2 H, H7 and H7'), 1.76 (m, 1 H, H6'), and 1.32 (m, 1 H, H6).TricarbonylC 1 4 - q - 5 - ( tri-p-to1ylphosphonio)cyclohepta- 1,3-dieneliron tetrajuoroborate.This was isolated in a similarmanner to the above (Found: C, 58.6; H, 4.9. Calc. forC,,H,,BF,FeO,P: C, 59.6; H, 4.8%). 'H N.m.r. (CD,COCD,):6 7.95-7.1 (m, aromatic), 5.44 (dd, 1 H, H 2 ) , 5.28 (m, 1 H, H3),4.40 (dt, 1 H, H"), 3.30 (m, 1 H, H'), 3.12 (dd, 1 H, H4, J4,p 15.2,J4,, 7.2, J4,5f 0 Hz), 2.40 (overlapping multiplets, 2 H, H7 andH7'), 2.29 (s, 9 H, CH,), 2.05 (m, 1 H, H6', partly masked byCH,COCH, resonance), and 1.25 (m, 1 H, H6).Tricarbonyl{ 1 4 - q -5-[tris(2'-cyanoethyl)phosphonio]cyclo-hepta- 173-diene)iron tetrajluoroborate.This was isolated in asimilar manner to the above (Found: C, 44.4; H, 3.8; N, 7.9. Calc.for C,,H,,BF4FeN,O3P: C, 44.5; H, 4.1; N, 8.2%). 'H N.m.r.(CD,COCD,): 6 5.77 (m, 1 H, H3), 5.65 (dd, 1 H, H2, J2,' 7.6,H', J , , = J , 7.0 Hz), 3.3-3.1 (overlapping multiplets, ca. 7H, CH,CH,P and H4), 2.4-2.1 (overlapping multiplets, 2 H,H7 and H"), 2.00 (m, 1 H, H", partly masked by CH,COCH3resonance), and 1.68 (m, 1 H, H6).TricarbonglC 1 - 4-q-5-( tributoxyphosphoniu)cyclohepta- 1,3-dieneliron tetrajuoroborate.'H N.m.r. (CD,COCD,): 6 5.72(m, 1 H, H3), 5.64 (dd, 1 H, H2), 4.72 (m, 6 H, OCH,), 3.35 (t, 1H, H', J l , , = J1,7 6.9 Hz), 3.22 (m, 1 H, H"), 3.03 (dd, 1 H, H4,J4,p 15.9, J4,, 7.1, J4,5, 0 Hz), 2.35-1.40 (overlapping multiplets,H7, H7', H6' and OCH,CH,CH,Me, partly masked byCD,COCD, resonance), and 0.97 (t, 9 H, CH,).J,,34.9),3.49(dt,1H,H5',J5,.6 = J5.,,13.2,J5,,,.2.7),3.35(t,1 H,Spectroscopic Studies.-Infrared spectra were recorded on aPerkin-Elmer 783 spectrophotometer using matched 0.5-mmCaF, solution cells. 'H N.m.r. spectra (400 MHz) in ['H6]-acetone were measured on a JEOL GX 400 spectrometer.Kinetic. Studies.-All of the reactions were rapid and weremonitored at 380 nm with a thermostatted (kO.1 "C) stopped-flow spectrophotometer.At this wavelength a large decrease inabsorbance occurs during the reaction, associated with the dis-appearance of the original dienyl salt (2).All the processes were studied under pseudo-first-orderconditions using a large excess of phosphorus nucleophile and[Fe] = 3.0 x 10-4-5.0 x mol dm-,. Pseudo-first-orderrate constants, /cobs,, were calculated from the slopes of plots oflog ( A , - A , ) us. time t using a least-squares program. Theseplots were generally linear for at least 80% of reaction. Each runwas carried out in quadruplicate, with /cobs, values showing anaverage reproducibility better than & 5%.Second-order rate constants, k , were generally calculated fromTable 2.Kinetic data for the addition of P-nucleophiles to [Fe(CO),-( 1-5-q-C,H9)]+ (2) in acetone at 20.0 "C1 O3[PR3j/Nucleophile mol dm-, ~ , , , J s - ~ k,/dm3 mol-' s-l aP(2-MeOC6H,), 1 .OO 28.30 28 300P(4-MeOC6H,), 5.00 4.54P(4- M eC,H ,) , 3 .00 1.1210.00 8.68 850 (7)30.00 25.66.00 2.49 435 (14)10.00 4.32P(4-MeC,H4) P h 2.50 0.41 15.00 0.89 1 175 (3)10.00 1.74PPh, 5.00 0.62410.00 1.32 120 (3)30.00 3.603.00 0.126'8.00 0.320 '15.00 0.658 ' 41.7 (0.5)'30.00 1.21 '60.00 2.51 'P( 2-CNC2H,)Ph2 5.00 0.37710.00 0.748 76.0 (0.4)25.00 1.9025.00 0.209 8.3 (0.7)P( 2-CNC,H4), 10.00 0.100P(OBu"), 40.00 0.46 1100.00 0.930200.00 1.92 7.9 (0.4)320.00 2.89500.00 3.92P(OMe), 200.00 0.168 0.84a Derived from equation (3).Estimated standard deviations are given inparentheses. Temperature 0.0 "C.I 1 1 1 14 . 6 4.4 4.26 I p.p.m.Figure 2. H5' N.m.r. signal for exo-[Fe(CO),{ (4-MeOC,H4),P.C,H,).IBFJ. CHEM. SOC. DALTON TRANS. 1988 201 1the slopes of plots of kobs, us. [PR,] using a least-squaresanalysis. Table 3. Nucleophilicity order for addition to [Fe(CO),( 1-5-q-C,H,)]+ (2) at 20 "CResults and DiscussionNature of'the Reactions.-S yn t hetic and spectroscopic studieshave established that neutral amine (pyridines,, anilines,'imidazole,8 or aliphatic amines 9, and phosphorus nucleo-philes generally add to the cycloheptadienyl ring of cation (2) asshown in equation (2). In particular, Brown et aL9 have shownthat tertiary aryl and alkyl phosphines add to (2) to yield exo-phosphonium adducts of type (3, Nu = PR,).Formation ofanalogous tricarbonyl( 173-diene)iron products of type (3) wasconfirmed for each of the phosphorus nucleophiles studied herein acetone solvent by the production of typical v(C0) productbands at ca. 2 055 and 1 980 cm-' in each case (Table l), andfrom their in situ n.m.r. spectra.In contrast to the complex spectra previously observed 2*9for related species at 100 MHz, the 400-MHz 'H n.m.r. spectraof adducts [Fe(CO),( 1-4-q-R,PC7H9)]+ (3) [PR, = P(2-MeOC,H,),, P(4-MeOC,H4),, P(4-MeC,H4),, P(4-MeC,H,)Ph,, PPh,, P(2-CNC,H,)Ph,, P(2-CNC'H,),, orP(OBu"),] show discrete signals for each of the diene ringprotons, except H7 and H7' which appear as ogerlappingmultiplets (see Experimental section).This permitted un-equivocal assignment of each of the ring protons via a series ofspin-decoupling experiments. Details will be reported in asubsequent paper correlating the configurations of a range ofsubstituted diene and triene iron tricarbonyl complexes via 300-MHz n.m.r. spectroscopy. Of particular concern to the presentstudy is the unequivocal assignment of an exo-configuration tothe PR, substituent at C(5) (R = 2-MeOC,H4, 4-MeOC,,H4,4-MeC,H4, 2-CNC2H,, or OBu"). In each case, the H5' protonappears as a characteristic double triplet (e.g. Figure 2). Thiscollapses to a triplet ( J 5 , , , - J5,,p - 13 Hz) upon irradiation atH6', and to a double doublet ( J 5 , , , - 12, J5,,6, - 3 Hz) uponirradiation at H6.The signal for H5' is unaffected by irradiationat H4, confirming no or very weak coupling between H4 and H5'.The near zero J4.5' value is predicted from the CH4-CH5'dihedral angle determined from a molecular model of the exo-adduct (3). An exo configuration has been similarly assigned tothe related phosphonium adduct (3, R = Et) on the basis of themagnitude of J 4 , 5 s . For the alternative endo isomers, a modelpredicts J4.5. 2 5 Hz on the basis of the Karplus equation."With some sterically non-demanding trialkylphosphines andspecific solvent conditions, rearrangement of the exo-phos-phonium adducts to the related endo derivatives has beenreported.' However, no evidence was observed here in acetonefor the conversion of any of the pale yellow exo adducts to thebrown endo isomers, either with the bulky triarylphosphines orwith the much smaller trialkyl phosphite nucleophiles.Kinetics und Mechanism.-Kinetic data for the addition ofvarious tertiary phosphines and phosphites to cation (2) inacetone at 20 "C are collected in Table 2.The rate law (3) is seento be generally obeyed. In the case of P(2-MeOC,H,),, only onephosphine concentration could be conveniently studied becauseof its high reactivity. For this nucleophile and P(OMe),, ratelaw (3) has been assumed. Second-order rate constants, k,, thuscalculated for each phosphorus nucleophile are summarised inTable 2.Rate = k,b,.[complex](3)The rate law (3) is most readily rationalised in terms ofdirect addition, k , , to the cycloheptadienyl ring of (2).DirectNucleophile(i) P-nucleophilesPBu",P( 4-M eC H 4) ,P(4-MeC,H,)Ph,PPh,P( 2-M eOC6 H 4) 3P(4-MeOC6H4),P(2-CNCZH,)Ph,P(2-CNC,H,),P(OBu"),P(OMe),(ii) N-nucleophiles4-MethylanilineImidazolePyridine2-Methylaniline2-Methylpyridine2,6-Dimet h ylpyridineN3-k , / dm3Solvent NFea mol-' ssl3.83 283003.52 1 1 1002.81 8502.45 4352.13 1751.87 120 1 Acetone7.90.841.720.800.00-0.532.16 9392.10 3 743 20113 CH,CN :::;1.34 61.3-0.55 1.7Water 1.93 2 620Ref.Thiswork38434416a Nucleophilicity parameters for reference substrate [Fe(CO),( 1-5-?l-C6 €3 7 )I + .3 3Figure 3. View of co-ordinated C6H, and C7H, rings from above thedienyl planes.Only hydrogen atoms bonded to methylene carbons areshown32a-004 100 8 /' P000/0lo,/P00I I I I I1 2 3 4 5PKllFigure 4. Brernsted plot of log k , us. pK, (of conjugate acid) for theaddition of tertiary phosphines and phosphites to [Fe(CO),( 1-5-q-C,H,)]+ (2) in acetone at 20 "C; key as in Figure 20124 -3 -a-2cn0 -1 -0 -J. CHEM. SOC. DALTON TRANS. 1988-432c tol0 -10I I I I4 10 16 22= XFigure 5. Plot of logk, DS. Tolman Xx values for the addition of tertiaryphosphines and phosphites to [Fe(CO),( l-5-q-C,H9)] + (2) inacetone at 20 "C: 1, P(2-MeOC,H4),; 2, PBu",; 3, P(4-MeOC,H4),;4, P(4-MeC,H4),; 5, P(4-MeC,H4)Ph,; 6, PPh,; 7, P(2-CNC2H,)Ph,;8, P(OBu"),; 9, P(2-CNC2H,),; 10, P(OMe),approach from above the dienyl ring is supported by the e mconfiguration established above for adducts (3, Nu = PR,).Also consistent with this mechanism is the considerably fasterreaction observed ' for each nucleophile with the relatedcyclohexadienyl cation [F'e(CO),( l-5-q-C6H7)] + (1).Forexample, rate constant ratios, kChH7/kC7H9, of ca. 60 areobserved for addition of triarylphosphines. [The somewhatsmaller kC6H,/kC7H9 ratio of 24 for P(2-MeOC,H,), is believedto arise from an underestimation' of the k , value for attack ofthis highly reactive phosphine on cation (I).] As is clear fromFigure 3, which gives a view from above the dienyl rings, theC7H9 ligand will generate considerably greater steric hindranceto e m attack at C(5) than will a C6H7 ligand." In the C,H,case, one H atom on each methylene group effectively eclipsesthe adjacent C(5) [or C(l)] atom.In contrast, the two Hatoms on the methylene group of C6H7 are symmetricallydisposed at considerable distance from C( 1) and C(5).The k , values summarised in Table 2 for addition ofvarious phosphorus nucleophiles to cation (2) reveal a strongdependence on nucleophile basicity. A Brsnsted plot of log k ,us. pK, is linear for triarylphosphines with a slope of ca. 0.45(Figure 4). This slope is very similar to that previouslyreported ' for the analogous addition to cation (1). A separateBrsnsted plot is followed by trialkyl phosphites (Figure 4), witha similar strong dependence of k , on nucleophile basicity.Thetrialkylphosphine P(2-CNC2H,), does not fit on either of theabove linear free-energy relationships.In general, the reactivity order of the phosphorus nucleo-philes towards (2), P(2-MeOC,H,), (3.4 x lo4) > PBu",(1.3 x lo4) > P(4-MeOC,H4), (1.0 x lo3) > P(4-MeC,H4),(5.2 x 10') > P(4-MeC,H4)Ph, (2.1 x 10') > PPh, (1.4 x10') > P(2-CNC,H4)Ph2 (90) > P(2-CNCZH4), (10) >P(OBu"), (9) > P(OMe), (l), parallels that of decreasingelectron availability at the phosphorus centres. This is shown bythe excellent correlation between logk, and the nucleophile Zxvalues (Figure 5, correlation coefficient Y = 0.99). The Zx2 k/-1 0 1 2 3 4NFeFigure 6. Plot of log k , for the reactions of various nucleophiles with[Fe(CO),(1-5-q-C7H9)]+ (2) us.NFe; key as in Figure 5 andI 1,4-methylaniIine; 12, imidazole; 13, pyridine; 14, 2-methylaniline; 15,2-methylpyridine; 16, 2,6-dimethylpyridine; 17, N,-values, derived by Tolman,I2 are a measure of the relative 0-donating and x-withdrawing ability of the various phosphorusligands. A Hammett plot of log ( k / k H ) us. Cop for the attack ofp-substituted triarylphosphines on (2) gives a slope, p, of 1.08(correlation coefficient Y = 0.99). This is similar to the Hammettslopes found for analogous reactions with ethyl iodide (p = - 1.1in acetone) l 3 and benzyl chloride (p = - 1.08 in benzene-m e t h a n ~ l ) , ' ~ and slightly smaller than that reported ' for therelated cyclohexadienyl cation (1) (p = - 1.32).However, ourlog (k/kH) values correlate poorly with Co', showing only asmall demand for resonance stabilisation of the transition state.These observations, together with the strong dependence of rateon phosphine basicity suggest a transition state for reactions (2)(Nu = PR,) in which there is significant, but far from complete,phosphorus<arbon bond formation and build up of positivecharge on the phosphorus centre.Further support for this transition-state structure comes fromthe exceptionally rapid reaction of (2) with P(2-MeOC6H4),.From Table 2 this sterically blocked phosphine is seen to beca. 230 times more reactive than triphenylphosphine. Inkeeping with similar observations with organic substrates theunexpected reactivity of P(2-MeOC6H4), towards (2) may beexplained in terms of anchimeric assistance in which a pair of21, electrons on the methoxy oxygen overlap with a vacant 3dorbital on the phosphorus.This interaction facilitates thedelocalisation of the positive charge built up on the phosphoruscentre in the transition state, thereby causing a rapid reaction.Interestingly, the k2-Meo/kH ratio of 230 for cation (2) is muchhigher than that observed for analogous reactions with benzylchloride (kz-Meo/kH = 27). This suggests significantly greaterphosphorus<arbon bond formation in the transition states forreactions (2) (Nu = PR,) than in the related processes withbenzyl chloride. Rate constants have been reported 1 ~ 4 * 8 * 1 6 forthe addition of a wide range of nucleophiles to the relatedcyclohexadienyl cation (l), and nucleophilicity constants (NFe)calculated according to equation (5)J.CHEM. SOC. DALTON TRANS. 1988 201 3The NFe values listed in Table 3 differ slightly from thosepublished previously’ due to a redetermination of ko for thereference nucleophile P(OBu”),. If, as preliminary observationssuggest,’-4 nucleophilicities towards organometallic [M(.n-hydrocarbon)L,] + substrates are electrophile independent, thenplots of log k , us. NFe should be linear with unit slope for allelec trophiles.Figure 6 shows such a plot for cation (2) using the presentresults with phosphorus nucleophiles and reported k , values forvarious amines 3 3 4 and the azide ion.’ These nucleophiles varyin reactivity by a factor of ca.2 x lo4. For the neutralnucleophiles, a satisfactory correlation ( r = 0.98) is observedwith a slope of 1.06 (0.06), confirming a constant nucleophileselectivity for the cations (1) and (2) despite their differingintrinsic reactivities. However, the log plot disguises someminor differences between the reactivity patterns of cations (1)and (2). Thus, while kC6H,/kC7H9 ratios of ca. 60 are observed forthe additions of triarylphosphines, this ratio decreases to ca.2-0 for anilines and pyridines. These differences probablyarise from the smaller steric demands of the nitrogen nucleo-philes.The only large deviation from the correlation in Figure 6 isthe point (A) for the azide ion. In contrast to the behaviour withneutral phosphorus and nitrogen nucleophiles, cations (1) and(2) have similar reactivities towards the N,- anion.Thisstrongly suggests that addition of N3- proceeds uia a differentmechanism to that observed for the neutral nucleophiles. It ispossible that, as has been suggested elsewhere,16 addition ofN,- to cations (1) and (2) proceeds uia an ‘early’ ion-pair liketransition state, whereas the present study supports considerablecarbon-phosphorus bond formation in reactions (2).AcknowledgementsThe Australian Research Grants Committee is thanked forfinancial support. Dr. T. Ghazy is thanked for recording someof the n.m.r. spectra.References1 L. A. P. Kane-Maguire, E. D. Honig, and D. A. Sweigart, Chem. Rev.,1984, 84, 525 and refs. therein.2 G. R. John and L. A. P. Kane-Maguire, J. Chem. Soc., Dalton Trans.,1979, 873; J. G. Atton and L. A. P. Kane-Maguire, ibid., 1982, 1491.3 L. A. P. Kane-Maguire, T. I. Odiaka, S. Turgoose, and P. A.Williams, J. Chem. SOC., Dalton Trans., 1981, 2489 and refs. therein.4 T. I. Odiaka and L. A. P. Kane-Maguire, J. Chem. Soc., DaltonTrans., 1981, 1162.5 C. D. Ritchie, J. Am. Chem. SOC., 1983, 105, 3573 and refs. therein.6 (a) T. J. Alavosus and D. A. Sweigart, J. Am. Chem. SOC., 1985,107,985; (b) C. D. Johnson, Chem. Rev., 1975, 75, 755 and refs. therein.7 M. A. Hashmi, J. D. Munro, and P. L. Pauson, J. Chem. SOC. A, 1967,240.8 D. J. Evans and L. A. P. Kane-Maguire, Znorg. Chim. Acta, 1982,62,109; unpublished work.9 D. A. Brown, S. K. Chawla, W. K. Glass, and F. M. Hussein, Inorg.Chem., 1982, 21, 2726.10 M. Karplus, J. Chem. Phys., 1959, 30, 11.11 L. A. P. Kane-Maguire, E. D. Honig, and D. A. Sweigart, J. Chem.12 C. A. Tolman, J. Am. Chem. SOC., 1970, 92, 2953.13 W. A. Henderson and S. A. Buckler, J. Am. Chem. Soc., 1960, 82,14 G. I. Keldsen and W. E. McEwen, J. Am. Chem. SOC., 1978,100,7312.15 W. E. McEwen, A. B. Janes, J. W. Knapczyk, V. L. Kyllingstad, W-I.Shiau, S. Shore, and J. H. Smith, J. Am. Chem. Soc., 1978,100,7304.16 J. G. Atton, G. Shaw, and L. A. P. Kane-Maguire, unpublishedwork.Soc., Chem. Commun., 1984, 345.5794.Received 1st September 1986; Paper 6 / 175
ISSN:1477-9226
DOI:10.1039/DT9880002009
出版商:RSC
年代:1988
数据来源: RSC