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J. CHEM. soc. DALTON TRANS. 1982 757THE reaction ofMetallation of the lsopropenyl Group by Platinum(ii) : Mechanism ofFormation of Isomeric a-Allylic and a-Vinylic Six-membered ChelateRings. X-Ray Structure of the a-Vinylic Complex Di-p-acetato-bis-{ [ 2 - (0-d i p henyla rsinophen yl ) propen yl - C 'As] plat in urn( 11) 1By Mervyn K. Cooper' and Philip J. Guerney, School of Chemistry, The University of Sydney, Sydney 2006,Hilary J. Goodwin and Mary McPartlin, Department of Chemistry, The Polytechnic of North London,Austra I iaLondon N7 8DBThe (0-isopropenylpheny1)diphenylarsine (ipa) complex [Pt(ipa) (acac)] [BF4] (acac = acetylacetonate) reactswith nucleophiles including acetate to give [Pt{o-CH,C(=CH,)C,H,AsPh,)(acac)] (1 ) in which the ligandis bonded as a a-allylic group.The complex [PtCl,(ipa)] reacts with silver acetate to give the complexI I[{ P~(O-CH=CM~C,H,ASP~,)},(~-O,CM~)~] (2) shown from X-ray analysis to have the deprotonated olefinbonded as a a-vinyl group. Crystals are monoclinic, space group C2/c, a = 31.633(5), b = 11.345(5), c =18.450(5) A, p = 141.37(2)", U = 4 133.6 As, Z = 4, and R = 0.059 for 2 093 reflections. The a-allylic complex(1) is converted to the a-vinylic complex (2) by acetic acid. Mechanisms for the formation, protonation, andinterconversion of the two isomeric forms of the metallated olefin have been deduced ; carbonium ion complexesare strongly indicated as reactive intermediates. The a-allylic and a-vinylic forms appear to be the consequence ofintermolecular and intramolecular attack respectively of a nucleophile on the co-ordinating olefin.PtII complexes of diphenyl(0-vinyl-phen yl) arsine (vpa) ,l, [o- (2-methylpropen yl) phenyll-diphenylarsine (mpa) ,3 and diphenyl[o-(propeny1)-phenyllarsine (ppa) with nucleophiles leads to attackat the p-carbon of the co-ordinated olefin and formationof products containing a five-membered chelate ring withPt a-bonded to the a-carbon and the nucleophile to thep-carbon.IC R ' \'R'xR = H, R'= Me ('ppa')R = R'= Me ('mpa')X = OMeR = R'= H ('vpa')X = OMe, 02CMe.OH, or acacWe now report the interesting observation that re-actions of similar PtII complexes of the ligand (o-isopro-penylpheny1)diphenylarsine (ipa) with nucleophiles donot follow the same pattern.aAsPh2 IIC"2ipaRESULTS AND DISCUSSIONThe reaction of the (o4sopropenylphenyl)diphenyl-mine complex [Pt(ipa) (acac)][BF4] (acac = acetyl-acetonate) with any one of the nucleophiles methoxide,hydroxide, or acetate did not give a product containingthe nucleophile. In each case the a-allylic compound (1)(Scheme 1) was obtained.4 The lH n.m.r. spectrum of(1) shows terminal vinylic proton signals (6 5.29, 5.36)and a singlet due to the a-bonded methylene group (62.99) strongly coupled to Pt [J(Pt-H) 121 Hz]. Amedium-intensity i.r. band assigned to the C=C stretch(1 612 cm-l) and a strong absorption due to the out-of-plane hydrogen deformation mode of the RR'=CH, group(875 cm-1) confirm this structure.The reaction of silver acetate with [PtCl,(ipa)] is alsodifferent from its reactions with the other [PtCl,L] com-plexes (L = vpa, mpa, or ppa); whereas dark tars wereformed with the latter compounds, reaction with achloroform solution of [PtCl,(ipa)] (Ag : Pt > 3 : 1)yielded on filtration a clear solution which developed anorange colour over several hours.Orange crystals of thea-vinylic compound (2) were obtained from this solutionon dilution with methanol (Scheme 1).X-Ray analysis of (2) has shown it to have an acetate-bridged dimeric structure (Figure) which has crystal-lographic C, symmetry. The Pt atom and the fourdonor atoms, C(3), 0(1), 0(2), As, are planar to within0.1 A; the dimer is bridged by two cis acetate groupswith an angle of 141.6" between the co-ordination planes.Acetate bridges occur in tetrameric platinum(I1) acetatein which there is considerable metal-metal bonding ; 6the Pt-Pt distance of 2.989 A in (2) is much longer thanthe average value of 2.495 A observed in the tetramer soit seems probable that any metal-metal bonding in (2) isweak.The Pt-As bond of 2.267 A is the shortest so farreported. From the limited data available on Pt-Asbonds it has been concluded that there is considerableback bonding from PtII to arsenic, and very short Pt-Asbonds have also been observed in other PtII compound758 J. CHEM. SOC. DALTON TRANS. 1982The structure of the dimeric molecule of (2). The molecule has C, symmetry and the primed atoms are at positions 4 - x, y , 4 - zwhere x, y , and z are given in Table 1where there are no competing x-acid ligands2 The Pt-C(3) bond of 1.99(2) A is shorter than the values of2.026(8) A for the Pt-C (a-vinyl) bond in cis-1,2-bis(meth-oxycarbony1)et hen yl[o-(diphen y1phosphino)phenyl-CIP]-(triphenylphosphine)platinum(II) (3) and of 2.022(8) Afor the a-styryl bond in trans-bromo(trans-styry1)bis-(triphenylphosphine)platinum(rI) * (4) but these dif-ferences are of little significance.However, the dif-ference between the value for the Pt-C(3)-C(4) angles of138(2)" and the angle of 120" which would be expectedfor sp2 hybridisation at C(3) is highly significant. In (3),the corresponding angle is 126.7(7)' and in (4), 123.8(6)".The five atoms, Pt, C(3), C(4), C(5), C(12), are coplanar towithin 0.02 A and this plane is twisted 16.8" from theplane of the phenyl ring.It is well established that 0-bonded carbon atoms show a very large trans influenceHcPh , CH30-cNucleophile "C HH(6) ( 7 )SCHEME 1 A summary of reactions of some PtII complexes of ipJ. CHEM. SOC. DALTON TRANS. 1982 759in platinum(I1) compound^.^ In (2), the Pt-O(1) bondwhich is trans to the a-vinyl group is 0.06 A (40) longerthan the Pt-O(2) bond trans to the arsenic atom. Thisis consistent with the observation that although thearsine group exerts a comparatively strong trans influencein PtII compounds it is significantly less than that of a-bonded carbon atoms.2The presence of the dimeric molecule (2) in solutionwas supported by its lH n.m.r.spectrum [6 1.96 (s, Me),1.43 (s, O,CMe), 7.21 (=CH)] and its reaction with tri-phenylphosphine to yield a pale yellow monomer, (5)(Scheme 1). The latter compound was shown by themagnitude of its 31P-196Pt coupling constant (3 780 Hz) loto have the phosphine ligand trans to the arsenic donor.The formation of the dimeric molecule (2) by the re-action between [PtCl,(ipa)] and excess silver acetate wasshown to occur in two successive steps, reactions (i) and(ii). This mechanism was deduced by following the[PtC12(ipa)] + 2 Ag[O,CMe] - [Pt(O,CMe),(ipa)] + 2 AgCl (i)(ii) 2[Pt(O,CMe),(ipa)] + (2) + 2 MeC0,Hreaction using 1H n.m.r., i.r., and u.v.-visible spectro-scopy. A yellow reaction solution in CDCl,, filteredfrom excess silver acetate, initially gave 1H n.m.r.signals characteristic of a co-ordinated isopropenylgroup [6 2.28 (s, Me), J(Pt-H) 38 Hz; 3.52 (s, =CHtram to Me), J(Pt-H) 56 Hz; 4.72 (s, =CH cis to Me),J(Pt-H) 67 Hz]. In conjunction with two non-equiva-lent acetate group signals ( 6 1.78, 2.08) this spectrumindicated formation of the intermediate species [Pt(O,-CMe),(ipa)]. Infrared absorptions of the same solutionat 1630, 1 370, and 1 310 cm-l are also characteristic ofmonodentate acetate groups5 The 1H n.m.r.spectrumof the initial yellow solution additionally showed smallpeaks due to (2) and these grew in intensity over severalhours at the expense of the resonances of [Pt(O,CMe),-(ipa)]. Conversion to (2) was essentially complete after3 4 h by which time the solution was deep orangeand signals due to the hydroxy and methyl groups ofacetic acid had become strong.Over the same period,the i.r. absorptions of the monodentate acetate groupsbecame less intense and peaks appeared at 1560 and1425 cm-l which are within the usual range for thev(C=O) and v(C-0) vibrations of bridging acetate groups.llThe concomitant appearance and growth of a peak at1715 cm-l was consistent with the formation of aceticacid. The colour change from yellow to orange was dueto the development of a peak in the u.v.-visible spec-trum at 362 nm [for a pure sample of (2), E = 1.0 x lo4dm3 mol-l cm-l]. Compound (2) is stable in CDCI,solution free from strong acids and can be recrystallisedfrom acetic acid without change.On warming (1) in acetic acid, the pale yellow soliddissolved to give an orange solution from which crystalsof (2) appeared on cooling. A two-step mechanism(below) for this interconversion between the two iso-meric forms of deprotonated ipa was determined bymonitoring the 1H n.m.r. spectrum as the reaction tookplace in CDCl, solution to which a little acetic acid hadbeen added, see reactions (iii) and (iv).The reaction(1) + 2 MeC0,H - [Pt(O,CMe),(ipa)] + Hacac (iii)(iv) 2 [Pt(O,CMe),(ipa)] + (2) + 2 MeC0,Hperiod decreased at higher temperatures and withincreased concentrations of acetic acid.Interesting differences from the previously discussedreactions were observed when thallium(1) acetate wassubstituted for silver acetate. For example, the filteredsolution from the reaction of [PtCl,(ipa)] with excessthallium(1) acetate did not turn orange as it did when thesilver salt was used.Moreover, the lH n.m.r. spectrumof the CDCI, reaction solution showed signals charac-teristic of both the a-vinyl and a-ally1 forms of thedeprotonated ipa ligand. To interpret these observ-ations the orange solution of the dimer (2) in CDCI, wastreated with two molar equivalents of thallium(1) ace-tate. This gave a clear yellow solution which appears tocontain complex (6) (Scheme l ) , the thallium(1) salt of thediacetatoplatinum anion containing the a-vinyl form ofdeprotonated ipa [lH n.m.r. of (6): 6 7.02 (s, Pt-CH=CMe), 2.35 (s, Pt-CHXMe), 2.13 (s, O,CMe), 1.77 (s,O,CMe)]. Treatment of this solution with two equi-valents of PPh, yielded a solution of (5) and whitecrystals identified as thallium(1) acetate by their i.r.spectrum. This explains why, unlike the reaction withsilver acetate, the reaction of [PtCl,(ipa)] with excessthallium(1) acetate does not give the orange dimer (2).The stable yellow solution obtained (see above) can beseen by lH n.m.r. spectroscopy to contain some com-pound (6).The remaining signals can be accounted forby the isomeric cis-diacetatoplatinum complex (7)(Scheme 1) containing the a-ally1 form of deprotonatedipa [(7) : 6 5.52 (m, =CH trans to phenyl), 5.20 (m, =CHcis to phenyl), 3.07 (m, Pt-CH,-), 2.16 (s, O,CMe), 1.79There is evidence that the isomers (6) and (7) do notinterconvert in solution. A solution of (6) prepared from(2) and thallium(1) acetate gives no l H n.m.r.signals dueto (7) even after extended reaction periods. It seemslikely that the two isomers are formed simultaneouslybut independently from the intermediate [Pt (O,CMe),-(ipa)]. We reserve discussion of the mechanisms untilafter the evidence presented below.The i.r. spectra of chloroform solutions of thallium(1)acetate adducts such as (6) and (7) exhibit two verystrong absorptions at 1 570 and 1 395 cm-]. Since thesefrequencies are in the usual range of bridging rather thanterminal acetate groups,ll it is possible that in solutionthe thallium(1) ion, unlike silver(r), stabilises cis-&-acetatoplatinum(I1) species by some association with theacetate groups, e.g.as shown below. All attempts toisolate (6) and (7) failed. Concentration of theirchloroform solutions, or the addition of other solvents(s, 0,CMe)l760 J. CHEM. soc. DALTON TRANS. 1982likely to induce precipitation, resulted in a mixture of - -thallium acetate and unideMified products.form Compoundy 3IH3ontaining either isomeri f thedeprotonated isopropenyl group react immediately withhydrochloric acid to regenerate the parent compound[PtCl,(ipa)]. As a result of this we were able to deter-mine the fate of the proton incorporated into the ligandin these reactions by the use of deuterium chloride, thedeuteriated products being characterised by lH n.m.r.In this way it was shown that treatment of (1) and (2)with a solution of DC1 gave respectively (8) and (9).The deuteriation patterns of (8) and (9) alone are notsufficient to determine the mechanism(s) of the deuteri-ation reactions. For instance, (8) may have beenformed from (1) by attack of a deuteron at either the sp3carbon &-bonded to platinum, or at the terminal spzcarbon of the olefin accompanied by a shift in thepositions of the double bond.Using the two forms ofdeuterium-labelled [PtCl,(ipa)] (8) and (9), two indepen-dent experiments were designed to distinguish betweenthe alternative sites of protonation. Similarly, theterminal olefinic carbon that receives the proton with aconcomitant shift in the position of the double bond. Asimilar mechanism for protonation of a a-ally1 group has( 8 )Observed proton ratios H ( 1 ) : H (2):H(3) = 2.3:1:1Ph,( 9 )Observed proton ratios H ( l ) : H ( Z ) : H ( 3 ) = 3 : 1 : 0 .2been postulated by Green and Nagy12 for an iron(1r)complex.The course of these reactions may be rationalised interms of the tendency of platinum to stabilise car-bonium ions in the reactions of a-bonded unsaturatedH(l):H(2):H(3)= 2*5:1 : 1( 9 ) H ( l ) : H ( Z ) : H ( 3 ) = 1*2:1:1 H(l):H(Z):H(3) = 3 . 0 : 0 . 6 4 :0.64Observed patterns of deuteriation and proton integral ratios on deprotonation of the ligand to give the a-ally1 group SCHEME 2followed by protonation to regenerate the co-ordinated olefin: (u) for complex (8), (b) for complex (9)source of the proton abstracted in the formation of thea-vinyl and a-ally1 functions from the co-ordinated iso-propenyl group was determined.Scheme 2 displays the patterns of deuteriation obser-ved through the cycle of reactions from both forms of[PtC12([2H]ipa)] to the o-ally1 complex and back to[PtC1,([2H]ipa)]. These results reveal that the co-ordinated isopropenyl group was deprotonated at themethyl carbon to form the a-ally1 complex (1).Further,they show that on treatment of (1) with HC1 it is thehydrocarbons.13 As shown in Scheme 3 (B = base), thetransfer of charge to and from the metal may be deter-mined by the intermediate formation of platinum-stabilised carbonium ions.With the aid of the labelled complexes (8) and (9), wehave also investigated the mechanisms of the reaction of[PtCl,(ipa)] with acetate to form the a-vinylic compound(2) and of the reaction of (2) with acid to regenerate[PtCl,(ipa)]. The deuteriation patterns observedthrough this cycle of reactions starting with each of (81.CHEM. SOC. DALTON TRANS. 1982 761H3CHtH,C-Pt-Ic. I' 'H1: ;: Pt-c*' I1H2C-Pt -ISCHEME 3 The postulated roles of platinum-stabilised car-bonium ions in the formation and protonation of the o-ally1POUPand (9) are shown in Scheme 4. These observations implythat the terminal olefinic proton trans to the methylgroup is lost in the formation of the a-vinyl complex andregained on treatment with acid without re-arrangementof the olefinic group. To account for this mechanism offormation of the a-vinyl group, we postulate an inter-action between the co-ordinated acetate cis to the olefinin [Pt(O,CMe),(ipa)] and the isopropenyl proton trans tothe ligand methyl group, followed by elimination ofacetic acid.In conclusion, we note that the formation of the Q-(1)ally1 and a-vinyl complexes is an interesting example ofthe different consequences of cis and trans attack, in thiscase by the same nucleophile on the same co-ordinatedligand. The a-ally1 group appears to result from anintermolecular nucleophilic attack (trans attack) byacetate on the co-ordinated olefin of [Pt(ipa) (acac)]-[BFJ or [Pt(O,CMe),(ipa)].In contrast, we proposethat an intramolecular cis attack by co-ordinated acetateon the co-ordinated olefin of [Pt (O,CMe),(ipa)] results information of the a-vinyl complex (2).EXPERIMENTALAppavatus a d Techniques.-Proton n.m.r.spectra wereobtained on Varian XLlOO or Perkin-Elmer-Hitachi R-24Bspectrometers and chemical shifts (6) were measured in p.p.m.downfield from the internal standard, SiMe,. Phosphorus-31 n.m.r. spectra were recorded on a Bruker HFX-90 (36.43MHz) spectrometer operating in the Fourier mode withbroad-band proton decoupling.Infrared spectra were obtained on a Perkin-Elmer PE457grating i.r. spectrophotometer as either Nujol mulls betweenCsI plates, or as solutions in 0.1-mm pathlength cells andcalibrated against polystyrene.Microanalyses were performed by the Australian Micro-analytical Service (CSIRO, Melbourne) or by Alfred Bern-hardt, Elbach, West Germany.Cvystal Data.-Compound (2), C,,H,,As,O,Pt,, M 1 200.9,Monoclinic, space group C2/c, a = 31.633(5), b = 11.345(5),Mo-K, radiation, h = 0.710 69 A, p(Mo-K,) = 80.79 cm-l.Data Collection.-Intensity measurements in the range3 4 0 < 25" on a crystal of dimensions ca.0.10 x 0.10 x0.12 mm were made on a Philips PWllOO four-circle dif-fractometer using a 0-20 scan technique and Mo-K, radi-ation from a graphite crystal monochromator. Weak re-flections which gave It - 2(It)f < I b on the first scan wereomitted; I t is the intensity at the maximum of the reflec-tion peak and Itj is the mean of two preliminary 5-s back-ground measurements at the extremities of the scan. Thebackground measuring time for each reflection was propor-tional to Ib/li, where Ii is the total count recorded in thefirst scan. Reflections for which Ii was less than 500 countswere scanned a second time. A constant scan speed ofc = 18.450(5) A, p = 141.37(2)", U = 4 133.6 AS, Z = 4,(1)(1 1H (l):H(2): H(3) H(1): H( 2) H(1): H(2):H(3)2.3 : 1 : 1 2.3: 1 2.3: 1 : 1(1)H(1): H(2): H(3) H(1) :H(2) H(1): H(2): H(3)3 : 1 : 0-2 3 : l 3 : ' 1 : 1SCHEME 4 Observed patterns of deuteriation and proton integral ratios of ligands on deprotonation to form the a-vinyl groupfollowed by protonation to regenerate the co-ordinated olefin: (a) for complex (€9, (b) for complex (9J.CHEM. SOC. DALTON TRANS. 19820.05" s-l and a scan width of 0.6" were used. Three standardreflections were measured at intervals of 6 h during datacollection and showed no significant variation in intensity.The standard deviation of the intensity ( I ) was taken as[G~(I)~ + (0.041)2]*, where cc(l) is the standard deviationfrom counting statistics and the term in la was introducedto allow for other sources of e1~0r.l~ I and a(I) were cor-rected for Lorentz and polarisation factors using a programwritten for the PW1100 diffractometer,'b and equivalentreflections were averaged giving a total of 2 093 data withI/c(I) 2 3.0.Absorption corrections were not applied.TABLE 1Fractional atomic co-ordinates * with estimatedstandard deviations in parenthesesAtom x(a) Independent atomsPt 0.121 5(0)As 0.171 3(1)0.164 O(5)0.069 9(4)0.065 6(6)0.027 5(8)0.080 8(6)0.082 l(7)0.039 3(7)0.162 l(7)0.120 4(6)0.116 3(7)0.149 5(8)0.190 9(8)0.196 5(7)(b) Rigid group atoms0.17120.18630.18700.17260.15750.15680.23010.25390.29500.31230.28860.2475OP)OMC(1)C(2)C(3)C(4)C(5)C(11)C(WC(13)C(14)W 5 )C(WC(21)C(22)C(23)C(24)C(25)C(26)(331)C(32)C(33)C(34)C(35)C(36)Y0.104 6(1)0.251 7(14)0.212 2(13)0.264 O(19)0.351 4(23)-0.014 2(2)-0.027 O(19)-0.138 5(20)-0.207 8(22)-0.172 8(19)-0.219 2(19)-0.335 l(20)-0.417 5(24)-0.369 8(24)-0.252 l(21)- 0.0206-0.1185-0.1176-0.01880.07910.07820.02150.09060.12590.09220.0231-0.0122z0.060 2(0)0.028 0(1)0.080 5(7)0.075 l(6)0.118 9(9)0.114 7(11)0.039 5(9)0.034 9(10)0.018 5(10)0.044 4(9)0.045 7(8)0.052 8(9)0.056 6(10)0.057 4(11)0.051 8(10)-0.0551-0.0827- 0.1426-0.1750-0.1475- 0.08750.05540.02130.04300.09870.13270.1110* For the F2/d cell, a = 31.633, b = 11.345, c = 23.208 A,$ = 96.95".Structure Solution and Refinement.-The platinum andarsenic atoms were located from a Patterson synthesis.The remaining non-hydrogen atom positions were obtainedfrom a difference-Fourier synthesis.The platinum andarsenic atoms were assigned anisotropic temperature factorsand the non-chelating phenyl rings were refined as rigidgroups (C-C 1.395 A). Hydrogen atoms of the phenylrings were included at calculated positions (C-H 1.08 A).Full-matrix refinement of the positional and thermal para-meters with the reflections weighted as l/02(F,,) gave afinal R of 0.059, R' = 0.058 (R' = Cl~~IF,-F,I/Ca*lF,().*The final atomic fractional co-ordinates are listed in Table 1and the bond lengths and angles in Table 2.Intermolecu-lar contact distances of less than 3.5 for (2), details of least-squares planes, thermal parameters, and the observed andcalculated structure factors are in Supplementary Public-ation No. SUP 23196 (20 pp.).t* As the standard unit cell (C2/c) had an angle of p = 141.37",the solution and refinement was carried out using the non-standard space group F2/d which had an angle of 96.95". t For details see Notices to Authors No. 7, J. Chem. Soc.,Dalton Trans., 1981, Index issue.The scattering factors used for all atoms were those ofCromer and Mann l6 and corrections for the real and theimaginary part of the anomalous dispersion were includedfor all atoms.SHELX computer programs17 were usedthroughout the solution and refinement.TABLE 2Principal bond lengths (A) and angles (") with estimatedstandard deviations in parenthesesPt-AS 2.267 (2) 0 (l)-C( 1') 1.29 (2)Pt-Pt 2.989(2) C(l)-C(2) 1.55(3)Pt-O(1) 2.16(2) C(4)-C(5) 1.57(3)1.27(3) E[i{zt!2) 1.51 (3)C (1 l)-C (1 2) 1.42 (3):2[;)1) 1.87(2)As-C(Z1) 1.93(1) *As-C(31) 1.93(1) *(a) Bond lengthsPt-C(3) 1.99(2) 0(2)-C(1) 1.20(2)2.10(1)(b) AnglesAs-Pt-O(1) 95.4(4)AS-Pt-0 (2) 169.9 (4)0(1)-Pt-0(2) 89.5(6)AS-Pt-C (3) 86.0(6)O( 1)-Pt-C( 3) 177.8(7)0 (2)-Pt-C (3) 89 .O( 7)Pt-0 (2)-C( 1) 126 (1)Pt-As-C( 1 1)Pt-As-C(21) 115.7(4) *Pt-As-C(31) 116.5(5) *Pt-C (3)-C (4) 138 (2)Pt-O( 1)-C( 1') 12 1 (1)1 12 .O( 6)* E.s.d calculation based solnot in rigid group.As<( 1 I)-€( 12)As<( 1 l)-C( 16)C( 1 l)-As-C(21)C( 1 l)-As-C( 3 1)C(2 l)-As-C (3 1)O( 1 ')-c ( 1)-O( 2)O(l')-C( 1)-C(2)0 (2)-C(l)-C (2)C(5)-C(4)-C(3)C(4)-C( 12)-C( 13)C( 5)-C (4)X (1 2)C (3)-C (4)-C ( 12)ely on contribution122(2)120(2)100.7(8) *107.8(8) *102.8(6) *129(2)115(2)115(2)119(2)113(2)128(2)122(2)from atoms(o-Isopropenylphenyl) diphenylarsine (ipa) .-o-Bromo-(isopropenyl) benzene was prepared from o-bromobenzoicacid by treatment of its methyl ester with excess MgMeI,yielding upon hydrolysis 2-(o-bromophenyl)propan-2-01which was dehydrated to the alkene by heating with 85%H,PO, (yield 59%).o-Bromo(isopropeny1)benzene (10.5 g, 53 mmol) wasreacted with magnesium ( 1.23 g, 5 1 mmol) in dry tetrahydro-furan (thf) (200 cm*) for 4 h a t room temperature.To theresulting clear solution cooled to 0 "C, a diethyl ether solu-tion of chlorodiphenylarsine (13.4 g, 51 mmol) was addedslowly and the mixture allowed to come to room temperatureand stirred for 2 h before pouring into a saturated solutionof NH,CI (100 cm3). The ether extracts of this mixturewere washed with water, dried (Mg[SO,]), and concentratedat reduced pressure to give a yellow oil. The oil was dis-solved in hot ethanol and cooled to - 70 "C (dry ice-acetone)to yield a white powder (29 g, 47% based on o-bromobenzoicacid). A second recrystallisation from hot ethanol gaveclear colourless crystals, m.p.79.5-80.0 "C (Found: C,72.7; H, 5.45; As, 21.6. Calc. for CZIHl,As: C, 72.8; H,5.55; As, 21.6%).[PtCl,(ipa)] .-A stirred suspension of platinum(I1) chloride(1 g, 3.8 mmol) in chloroform was treated with a solution ofipa (1.43 g, 4.1 mmol) in chloroform dropwise over 10 min.The mixture was refluxed for 30 min, after which only a smallamount of brown material remained in suspension, and thenfiltered through a pad of Kieselguhr. Concentration of theyellow-orange filtrate to a small volume at reduced pressurefollowed by dilution with ethanol gave yellow crystals (yield2.2 g, 95% based on Pt) . If an unscratched flask was used, asupersaturated solution could be formed that gave, onstoring at -15 "C overnight, a high yield of large yelloJ.CHEM. soc. DALTON TRANS. 1982 763crystals. Analytical samples were recrystallised from di-chloromethane-methanol, m.p. > 200 "C (decomp.) (Found :C, 40.65; H, 3.25; C1, 12.1. Calc. for C,,H,,AsCl,Pt: C,41.2; H, 3.15; C1, 11.6%).[Pt(ipa) (acac)][BF,] .-A dichloromethane solution of[PtCl,(ipa)] (1 g, 1.6 mmol) was added to an excess quantityof Ag[BF,] (1 g) and stirred vigorously for 5 min. A threemolar excess of acetylacetone was then added and stirringwas continued for 10 min. The mixture was filteredthrough a bed of Kieselguhr and the solvent evaporatedunder reduced pressure. The residual oil was taken up byacetone (1 cm3) and then diethyl ether was added dropwisewhile inducing crystallisation.The white microcrystalswere filtered and dried under high vacuum (yield 95%).The product [Pt(ipa) (acac)][BF,] was recrystallised foranalysis from acetone-diethyl ether, m.p. 176-178 "C(Found: C, 43.15; H, 3.55; F, 10.4; Pt, 26.6. Calc. forC,,H,,AsBF,O,Pt: C, 42.95; H, 3.60; F, 10.45; Pt,26.8%).[h{o-CH,C(=CH,)C,H,ksPh,}(acac)] (1) .--(A) A solutionof [Pt(ipa)(acac)][BF,] (95 mg, 0.13 mmol) in chloroform(1 cm3) was treated with two drops of triethylamine andallowed to stand for 15 min. Light petroleum (15 cm3,b.p. 60-80 "C) was added and the yellow lower layer thatformed was removed. The upper layer was filtered throughphase-separating filter paper, diluted with more light petro-leum (2 cm3), and kept at - 15 "C for 2 days.Colourlesscrystals were filtered off, washed with light petroleum, anddried under vacuum (yield 46 mg, 55%).(B) A solution of [Pt(ipa)(acac)][BF,] (100 mg, 0.14 mmol)in methanol (10 cm3) containing potassium acetate (0.1 g)was kept just below the reflux point for 30 min. Duringthis time the colour of the solution changed from yellowto orange and a crop of cream crystals formed. The productwas filtered off and washed with methanol (yield 69%).(C) A solution of [Pt(ipa)(acac)][BF,] (100 mg, 0.14 mmol)in CDCl, (0.5 cm3) was vigorously stirred with an aqueoussolution of sodium hydroxide (0.1 mol drn-,, 1.5 cm3) for6 min. The organic layer was separated and dried (Na,-[SO,]).The lH n.m.r. spectrum of this solution was identi-cal to solutions of (1) as obtained above. Complex (1):m.p. 180-183 "C (Found: C, 48.75; H, 3.95; As, 11.8;Pt, 30.6. Calc. for C,,H,,AsO,Pt: C, 48.85; H, 3.95; As,11.7; Pt 30.5%).[{Pt(o-CH=CMeC,H,AsPh,)),(y-0,CMe)J (2).-A solu-tion of [PtCl,(ipa)] (0.5 g, 0.83 mmol) in chloroform (30 cm3)was stirred with silver acetate (0.30 g) for 15 min. Thefiltered solution was allowed to stand overnight then con-centrated at reduced pressure to ca. 2 cm3 and dilutedwith methanol (15 cm3). On storing a t - 15 "C overnightorange crystals were formed. These were filtered off,washed with methanol (0.39 g, SO%), and recrystallised fromCH,Cl,-CH,OH. Complex (2) : m.p. > 220 "C (decomp.)(Found: C, 46.05; H, 3.6; Pt, 32.3.Calc. for C,,H,,As,-I 7O,Pt,: C, 46.1; H, 3.55; Pt, 32.55%).[bt { o- (trans-CH=CMe) C,H,ksPh, 1 (0,CMe) (PPh,)] (5) .-A solution of (2) (0.10 g, 0.083 mmol) in chloroform wastreated with a solution of triphenylphosphine (44 mg, 0.17mmol) in chloroform (2 cm3). On warming, the orangecolour of the solution changed to yellow. The solution wasdiluted with light petroleum (5 cm3) and cooled to - 15 "C.Scratching of the flask wall initiated the formation of paleyellow crystals which were filtered off and washed with lightpetroleum (0.110 g, 77%) ; recrystallisation was from CHC1,-light petroleum. Complex (5) : m.p. > 200 "C (decomp.)(Found: C, 56.8; H, 4.1; Pt, 22.35. Calc. for C,,H,,AsO,-PPt,: C, 57.15; H, 4.2; Pt, 22.65%).Tl[bt(o-CH=CMeC,H,lsPh,) (O,CMe),] (6) .-A solutionof (2) (80 mg, 0.067 mmol) in CDC1, (0.5 cm3) was vigorouslystirred with thallium acetate (35 mg, 0.14 mmol) for 10 min.The mixture was centrifuged and the yellow supernatantsolution removed by syringe and filtered into an n.m.r.tube.Mixture of (6) and T1[Pt{o-CH,-C(=CH,)C,H,AsPh,}(02-CMe),] (7).-A solution of [PtCl,(ipa)] (100 mg, 0.16 mmol)in CDCl, (0.5 cm3) was vigorously stirred with thalliumacetate (0.13 g, 0.48 mmol) for 18 h. The reaction vesselwas centrifuged and the yellow supernatant solution re-moved by syringe and filtered into an n.m.r. tube.The Deuteriated Ligand Reactions.-Formation of thedeuteriated Zigand complexes [PtCl,( [2H]ipa)]. A solution of(1) or (2) (0.15 g) in chloroform (5 cm3, which was purifiedby passage down a column of activated alumina) was shakenwith two or three drops of a 20% solution of DCl in D20.The mixture was diluted with [2H,]ethanol causing crystal-lisation of the complexes [PtCl,( [2H]ipa)] (nearly quantita-tive yields).Formation of the deuteriated forms of (1).The complexes[PtCl,( [,H]ipa)] were converted to [Pt([*H]ipa) (acac)]-[BF,] and then to (1) by method (C) above.Solutions ofthe deuteriated forms of [PtCl,(ipa)] (100 mg, 0.16 mmol) inchloroform (2 cm3) were stirred with silver acetate (0.13 g,0.48 mmol) for 10 min. The reaction vessels were centri-fuged and the supernatant removed by syringe and dilutedwith methanol (8 cm3). Storage a t - 15 "C overnight gaveorange crystals of the products (2) (yields about 65%).Re-formation of [PtCl,(ipa)] from the deuteriated forms of (1)and (2). A solution of (1) or (2) (0.15 g) in chloroform (5om3) was shaken with a 36% solution of HC1 in water.Addition of ethanol precipitated the complexes [PtCl,-([eH]ipa)] (yields ca. 95%).I IFormation of the deuteriated forms of (2).[0/1782 Received, 19th November, 19801REFERENCESM. K. Cooper, P. J. Guerney, J. H. Ling, and R. S. Nyholm,a M. K. Cooper, P. J. Guerney, and M. McPartlin, J . Chem.P. J. Guerney, Ph.D. Thesis, University of Sydney, 1978.M. K. Cooper, P. J. Guerney, H. J. Goodwin, and M. Mc-L. J. Bellamy, ' The Infra-red Spectra of Complex Molecules,'M. A. A. F. de C. T. Carrondo and A. C. Skapski, J . Chem.N. C. Rice and J. D. Oliver, J . Orgunornet. Chem., 1978, 146,J. Rajaram, R. G. Pearson, and J. A. Ibers, J . -4m. Chem.R. McWeeny, R. Mason, and A. D. C. Towl, Discuss. Furuduylo J. F. Nixon and A. Pidcock, Annu. Rev. NMR Spectrosc.,11 R. N. Haszeldine, R. J. Lunt, and R. V. Parish, J . Chem. SOC.l2 M. L. H. Green and P. L. I. Nagy, J . Chem. SOC., 1963,l3 M. H. Chisholm and H. C. Clark, Acc. Chem. Res., 1973, 6,J . Organomet. Chem., 1975, 91, 117.SOC., Dalton Trans., 1980, 349.Partlin, J . Chem. SOC., Chem. Commun., 1978, 861.Chapman and Hall, London, 1975.SOC., Chem. Commun., 1976, 410.121.SOC., 1974, 96, 2103.SOC., 1969, 47, 20.1969, 2, 354.A , 1971, 3705.189.202764 J. CHEM. SOC. DALTON TRANS. 1982l4 P. W. R. Codield, R. J. Doedens, and J. A. Ibers, Inorg.Chem., 1967, 6, 197. 321.Program, Philips Research Laboratories, Eindhoven, The Nether-lands, 1972.la D. Crorner and J. Mann, Acta Crystallogv., Sect. A , 1968, 84,J. Hornstra and B. Stubbe, PWllOO Data Processing G. M. Sheldrick, SHELX program for crystal structuresolution, University of Cambridge, 1976

ISSN:1477-9226    

DOI:10.1039/DT9820000757

出版商:RSC    

年代:1982

数据来源: RSC