786 J.C.S. DaltonPreparation and Thermal Decomposition of some (Butane-1.4-diyl) plat-inum( iv) ComplexesBy Michael P. Brown, Alison Hollings, Kevin J. Houston, Richard J. Puddephatt,' and Mehdi Rashidi,The polymeric (butane-1.4-diyl) (platinum(iv) complexes [{PtXMe[(CH,),]),J (X = Br or 1) have been preparedby reaction of [Pt{(CH,),)(cod)] (cod = cyclo-octa-1.5-diene) with MeBr or Met, and react with ligands to give[PtXMe((CH,),}L,] [X = Br, L = PMe,Ph; X = I, L = 2(2,2'-bipyridine), PMe,Ph, PMePh,, 3 Ph,PCH,CH2-PPh,] or [(PtMe[(CH,),] I(py)),] when L = pyridine. The complexes [PtXMe{(CH,),](PMe,Ph),] have alsobeen prepared by oxidative addition of MeX (X = I, Br, or CI) to [Pt{(CH,),)(PMe,Ph),], and [Pt((CH,),)I,(PMe,-Ph),] has been prepared from iodine and [Pt{(CH2)4)(PMe2Ph)2].A study has been made of the products ofthermal decomposition of the (butane-1.4-diyl) platinum(iv) complexes, and possible mechanisms of decomposi-tion are discussed.Donnan Laboratories, University of Liverpool, Liverpool L69 3BXRECENT thermochemical studies have shown that thePt-C cr bond is strong. Thus values of Pt-C bondenergies have been obtained of 250 kJ mol-l in trans-[PtPh2(PEt,)J,ll63 kJ mol-l in [PtMe,(q-C5H,)],2 144 kJmol-l in fac-[PtMe,I(PMe,Ph),] , and 112-124 k J mol-lin the strained ring compounds [PtX2{ (CH,),)L,](X = C1 or Br, L = nitrogen-donor ligand).* A meanvalue of the Pt-Me and Pt-COMe bond energies in[PtMe,(COMe)Cl(PMe,Ph),] of 158 kJ mol-l and aminimum value of the benzoylplatinum bond strength in1 S.J. Ashcroft and C . T. Mortimer, J . Chem. Soc. ( A ) , 1967,K. W. Eggar, J . Ovgaiaometallic C h e w , 1970, 24, 501.M. P. Brown, R. J. Puddephatt, and C. E. E. Upton, J.C.S.930.Dalton, 1974, 2457.[Pt(COPh)Cl(PPh,)d of 180 kJ mol-l have also beene~tirnated.~.~ It is expected therefore that homolysis ofPt-C cr bonds would require a high activation energy, andit has been established that, under the relatively mildconditions needed to decompose many alkylplatinumcomplexes, alternative concerted mechanisms of decom-position areWhen the alkyl groups contain no p-hydrogen atomsdecomposition has been shown to take place by a con-* P. W. Hall, R. J. Puddephatt. I<. R. Seddon, and C. F. H.Tipper, J . Organometallic Chem., 1974, 81, 423.6 11.1.P. Brown, R. J. Puddephatt, C . B. E. Upton, and S. 117.Lavington, J.C.S. Dalton, 1974, 1613.6 S. J. Ashcroft, A. Maddock, and G. Beech, J.C.S. Dalton,1974, 4621976 787certed intramolecular reductive-elimination r e a c t i ~ n , ~ ? ~ * ~but in the decomposition of the complex fac-[Pt&le,I- Two routes have been used to prepare the (butane-1,4-(PMe,Ph)J to ethane and trans-[PtMeI(PMe,Ph),] the diyl)platinum(Iv) complexes. A series of complexesreductive elimination is accelerated if a phosphine or with dimethylphenylphosphine ligands was prepared byiodide ligand is dissociated first .,p7 Thus the nature of oxidative-addition reactions to (butane-l,4-diyl)bis(di-the supporting ligands may be vital in determining the methylphenylphosphine)platinum(II) , which in turn wasRESULTS AND DISCUSSIONPMe,PhPMe, Ph/\-?Me *Pt! -L IPMe2Ph I /thermal stability of complexes of this type.If the alkylgroups contain a $-hydrogen atom then decomposition ofboth platinum(I1) and platinum(1v) alkyls generally pro-ceeds by the p-elimination rnechani~m.~~~ For this re-action to take place there must be a vacant co-ordinationsite at the platinum centre, and Whitesides et aL8 showedthat the decomposition of dibutylbis(tripheny1phos-phine)platinum(II) to butene, butane, and Pt(PPh,), ’Meprepared by reaction of cis-[PtCl,(PMe,Ph),] with 1,4-di-lithiobutane [equation (2)]. Methyl iodide, bromide,and chloride all reacted with [Pt{(CH,),}(PMe,Ph)J andthe respective products were shown to have structure (I)(X = I, Br, or Cl) by their n.m.r.spectra. Thus themethylphosphorus protons gave two doublets i n then.m.r. spectrum, indicating a structure with mutuallycis-phosphine groups and with no plane of symmetrycis-[PtC12~PMezPh12 J + L i l C H z ) L Li-CH,-CH, PMe,Phtook place by dissociation of a phosphine ligand followedby p elimination of butene. A similar mechanism wasproposed for the decomposition of the platinum(1v) com-plex [PtRIeEt,I(PMe,Ph)J , which was thought toundergo loss of a phosphine ligand followed by p elimin-ation of ethylene, and then loss of ethane or, less likely,methane [equation (1)] .5 A similar mechanism wassuggested to account for the formation of propene in thethermal decomposition of the (propane-1,3-diyl)plat-inum(1v) Complexes, [PtX,((CH,),)L,] (X = halogen,L =I nitrogen-donor ligand).4Whitesides and his co-workers have recently shownthat the heterocyclic compounds [Pt{ (CH,),)(PPh,),J(11.- 7 4-6) are considerably more stable to p eliminationt hail the butylplatinum(I1) complexes studied earlier, andattributed this to the more rigid structure of the ringcompounds which makes abstraction of the p-hydrogenatom by platinum more difficult. We now report anestension of our earlier studies of decomposition ofacyclic alkylplatinum(1v) complexes 33 and of hetero-cyclic (propane-l ,%diyl)platinum( 1v) complexe~,~ andinclude the preparation and thermal decomposition ofsome (but ane-l,4-diyl)platinum(1v) complexes.H.C. Clark and I-. 1:. Manzer, Inorg. Chem., 1973,12, 362.G. Rl. Whitesides, J. F. Gaasch, and E. R. Stedronsky, J.J. X. McDermott, J. F. White, and G. M. Whitesides, J.Amev. Chem. SOG., 1972, 94, 5258.Avnev. Cltiw. SOC., 1973, 95, 4451.containing the PtP, group.1° The methylplatinumprotons gave a triplet, due to coupling with two equiv-alent srP atoms, with satellites due to coupling withMe(1)lg5Pt and 2J(PtH) 66-72 Hz, typical of a methylplat-inum(1v) complex with the methyl group trans tohalogen.lO*ll The data are consistent only with structure(I) and show that trans addition of each methyl halidehas occurred. In these complexes, and in all other(butane-l,4-diyl)platinum complexes which we havestudied, the lH n.m.r.signal of the (CH,), protons ap-peared as a broad peak with unresolved coupling, andgave no useful information about the stereochemistry ofthe complexes.Iodine added to [Pt{(CH2)&PMe2Ph),] to give[Pt{ (CH,),)I,(PMe,Ph)J of stereochemistry (11). Thusthe methylphosphorus protons gave only one doublet inlo J. D. Ruddick and B. L. Shaw, J . Chetn. SOC. ( A ) , 1969,2801.l1 T. G. Appleton, H. C. Clark, and L. E. RIanzer, C o - o v d i ~ u t i o ~ ~Chem. Rev., 1973, 10, 3359188 J.C.S. Daltonthe n.m.r. spectrum indicating the presence of niutuallycis chemically equivalent phosphine groups , consistent(Elonly with structure (11). Again tram-oxidative additionhas occurred. Attempts to prepare similar adducts withchlorine or bromine were unsuccessful however and onlythe complexes cis-[PtX,(PMe,Ph),] (X = C1 or Br) wereisolated.With acetyl chloride we were again unable toisolate the product of oxidative addition. ?$%en oneequivalent of MeCOCl was added a compound wasformed which could not be crystallised but which oncomplexes [PtMe,I (PMe,Ph),] and [PtMe,I (PMePh,),]but PPh, gave mostly methyl iodide and cis-[PtMe,-Reaction of [{PtMe[(CH,),]I),] with 2,2’-bipyridine(bipy) gave the expected complex [PtMe{ (CH,)JI(bipy)],but the n.m.r. spectrum contained two methylplatinumpeaks with coupling constants 2J(PtH) of 75.6 and 71.6Hz. These values are consistent with methylplatinum-(IV) complexes with the methyl group trans to halogen orto bipy respectively,11J3 and so suggest that the productexists as a mixture of isomers, (111) and (IV).Reactionof pyridine (py) with [(PtMe[(CH,),]I),,] gave only a 1 : 1adduct, which is presumably dimeric and analogous tothe known dimer [(PtMe,I(py)),] .14Thermal Decomposition of the Cow@exes.-The (bu-tane-lJ4-diyl)p1atinum(~v) complexes were pyrolysed byheating in zlacuo to ca. 10 ‘C above the melting point.The volatile products were condensed immediately to(PPh,) 21 e3Meco1trans -[Pt (CH zC H ,CH CH ,COMe 1 Ct ( PMe2 P h)J (3 )hydrolysis gave hexan-2-one, identified by g.1.c. and ms.The compound is therefore assumed to be trans-[Pt-(CH,CH,CH,CH,COMe)Cl(PMe,Ph).j. Addition of afurther equivalent of MeCOCl to this gave tram-[PtCl,-(PMe,Ph)J, which then isomerised slowly to the cisisomer.It seems then that oxidative addition followedby reductive elimination occurred [equation (3)].The second route to (butane-lJ4-diyl)platinurn(~v)complexes was via the intermediates [(PtXMe[(CH,),])J(X = Br or I). These complexes were precipitated when[Pt{ (CH,),)(cod)] (cod = cisJcis-cyclo-octa-l,5-diene)was dissolved in the corresponding methyl halide. Theyare expected to be tetrameric by analogy with the wellknown [ (PtMe,I),], but their insolubility precludedmolecular-weight determination and it is possible thatthey exist in a more highly polymeric form. The poly-meric structure in [{PtXMe[(CH,)J}J was broken downon reaction with the ligand PMe,Ph to give (I; X = I orBr), identical with the product formed by reaction ofmethyl iodide or bromide with [Pt((CH,),>(PMe,Ph),] ,and the analogous methyldiphenylphosphine complex[PtMe((CH,),)I(PMePh,),] was formed in a similar way.However, the reaction of [(PtMe[(CH,),]I)J with tri-phenylphosphine led to reductive elimination and only[Pt{ (CH,),)(PPh,),] could be i s ~ l a t e d .~ J ~ A similartrend has been observed in reactions of [(PtMe,I),] withphosphines when PMe,Ph and PMePh, gave the simplel2 C. G. Biefield, H. A. Eick, and R. H. Grubbs, Inovg. Chem.,1973, 12, 2166.l3 D. E. Clegg, J. R. Hall, and G. A. Swile, J . OrganoinetaElicChem., 1972, 38, 403.prevent further reactions catalysed by the platinum-containing products. The results are given in the Table.MeThe simplest case is the decomposition of complex (11)which gave only a mixture of cis- and trans-[PtI,-(PMe,Ph),] and but-l-ene, identified by its g.1.c.re-tention time and mass and n.m.r. spectra. The probablet Tmechanism is shown in equation (4). The reaction in-volves dissociation of a ligand, followed by p elimination14 J. R. Hall and G. A. Swile, J, Organometallic Chem., 1972,42,4791976 789and then reductive elimination by cleavage of the Pt-Hand Pt-CH, bonds in the intermediate. It is possiblethat an isomer with these bonds in mutually cis positionswould be preferred to facilitate this process. As with theplatinum(I1) analogues? no reductive elimination to givecyclobutane or ethene was observed.Decomposition of the (butane-l,4-diyl)met hylplat-inum(1v) complexes always led to a mixture of products,but two mechanisms were clearly important.Theparent complex [(PtMe[ (CH,),] 1)J and its complexeswith py and bipy decomposed to give largely methanewhen L = PMe,Ph, the complex with X = Br gave morepentene than when X = C1 or I, so that no clear trend isapparent.We also examined the isotopic purity of the productsformed by decomposition of [(Pt(CD,)[(CH,),]I}J,formed by reaction of [Pt((CH,),}(cod)] with CD,I, andof [Pt(CD,)((CH,),)I(PMe,Ph),]. In each case thevolatile products were separated by g.1.c. and the massspectrum of each product was recorded. The pyrolysis(PMe,Ph),j gave but-l-ene and some n-butane none ofOf [tPt (CD3) [(CH2)41 I)nI and Of LPt (CD3) {(cH2)4)1-Volatile products of pyrolysis of (butane-l,4-diyl)platinum(1v) complexesVolatile products (yo)A r Pent- trans- cis-Pent- \ But- trans-But- cis-But-100Complex Methane l-ene 2-ene 2-ene Butane 1-ene Pent-2-ene 2-ene Pentane Otliers32 15 16 4 Me1 3313.5 40 13.5 14.5 6 3 4.5 4.5 0.5 Me140 29 9.5 8 3 2 3.5 3.5 1.5 MeI, p y6 8 b 861 2 b 97 b14 21.5 3 2 0.5 46[R 1 (CH2) 4) I a /PMe2Ph) 21[{~MeC(CH2)4II)nl[PtMe{(CH,) 411 (biPY)l $:% pzy $l(&%iPh) 2][ PtBrMe { (CH,) 4) (PMe,Ph) 2]6 G 1 C6H'[PtMe{(CH,),}I(P~rePh2)21 6 1.5 1.5 78 6 6.5 C6H6, bIe1[PtMe((CH2),}1 (PMe,Ph)210 Not analysed quantitatively.Q Total value for butenes or pentenes. The isomers were not separated by the column used.and butene (as a mixture of but-l-ene and cis- and trans-but-2-ene), and a mechanism similar to that in equation(4) is indicated, initiated by p elimination from the(butane-l,4-diyl)platinum group, but the presumed (but-3-en-l-yl)hydrido(rnethyl)plat inum( IV) intermediate candecompose by reductive elimination of either methane(cleavage of Pt-H and Pt-Me bonds) or of but-l-ene(cleavage of Pt-H and Pt-butenyl bonds).In contrast to this behaviour, the phosphine complexesdecomposed to give pent-l-ene as the major product,together with smaller quantities of isomeric pentenes andof methane and butenes. The platinum-containingproducts in each case could be identified as trans-[PtHXL,] (X - C1, Br, or I ; L = PMe,Ph or PMePh,)by comparison of the i.r.spectra with those of authentic~amp1es.l~ I t seems that the first step in the decom-position must be concerted reductive elimination bycleavage of the Pt-CH, and one of the Pt-CH, bonds[equation (5)J.As expected,*.l6 the pentylplatinum(rr)- Me -which contained deuterium, but the methane was mostlyCD,H, and CD,I was also formed. The pentenes formedfrom [Pt(CD,)((CH,),)I(PMe,Ph),] were all of isotopiccomposition C,H,D, (m/e 73). These results are in fullagreement with those expected from the mechanismsproposed, but are not consistent with free-radicalmechanisms.The most important results of this work can be sum-marised thus. (1) The (butane-1,4-diyl)platinum(1v)complexes are, like the platinum(I1) analogues, con-siderably more inert to thermal decomposition byp elimination than are similar acyclic compounds such asethylplatinum(1v) complexes.(2) The complexes [PtMe-((CH,),}IL,] decompose largely by p elimination withinthe platinum(1v) complex when L is a nitrogen-donorligand ( e g . L, = bipy), to give butene and methane, butby reductive elimination when L is a tertiary phosphineligand to give, after p elimination from the pentyl-platinum(I1) complex formed, pentene and traits-[PtHILz]complex so formed undergoes p elimination of pent-l-eneto give trans-[PtHXL,] as the final product. The buteneand methane are presumably formed in a competing re-action as described earlier. When X = I, the complexwith L = PMePh, gave considerably more pentene thanwhen L = PMe,Ph, suggesting that increased bulk orelectron-withdrawing power of the ligand enhances de-composition of the platinum(1v) complex by reductiveelimination rather than by p elimination.However,15 H. C. Clark and H. Kurosawa, J . Organometallic Chem., 1972,26, 399.as the major products. (3) In the reductive eliminationfrom [PtXMe{ (CH,),}(PR,)J described above cleavage ofthe Pt-CH, bond and one of the Pt-CH, bonds takesplace to give a pentylplatinum(I1) intermediate, ratherthan cleavage of both Pt-CH, bonds to give cyclobutane.This effect may be due to the Pt-CH, bonds beingstronger than the Pt-CH, bond, or, more likely, to thehigher activation energy needed to close the C, ring togive the strained-ring product cyclobutane.l5 J. Chatt, R. S. Coffey, A. Gough, and D. T. Thompson, J.Chem.Soc. ( A ) , 1968, 190790 J.C.S. Daltondoublets, each with 2J -+ *J(PH) 7.4, 3J(PtH) 8.4 Hz(Found: C, 37.75; H, 5.20. Calc. for C,,H,,IP,Pt: C,37.65; H, 4.95%).(b) A solution of PMe,Ph (0.04 g) in CH,Cl, (1 cm3) wasadded to a suspension of [PtMe{(CH,),)I] (0.06 g) in CH,Cl,(5 cm3). The mixture was stirred a t room temperature for30 h when the precipitate slowly dissolved. The solutionwas filtered, the volume reduced to 1 cm3, and methanol(10 cm3) was added to precipitate the product, yield 100%.It was identical (m.p. and n.m.r.) wit11 the product preparedby method (a).The iollowing complexes were prepared similarly :[PtBrMe( (CH,),}( PMe,Ph),], yield 96" ; [PtMe( (CH,),]I-(PMePh,),], yield 55%, m.p. 121 'C (decomp.), n.xi1.r.spectrum in CH,Cl,, G(RCH3) 0.70 p.p.rir., triplet, "(PH)7.8, ,J(PtH) 67.8 Hz, G[(CH,)J 1.37 p.p.m., broad un-resolved multiplet, G(PCH3) 2.17 p.p.~ii.~ doublet, ,J(PH)7.8, "(PtH) 0.6 Hz (Found: C, 47.2; H, 4.75.Calc. forC3,H3,1P,Pt: C, 46.9; H, 4.700/;) ; [PtMe{(CH,),)I(bipy)],yield 6076, n1.p. 257 "C (decomp.), 1i.m.r. spectrum inCH,Cl,, G(PtCH,) 0.75 p.p.m., singlet, 2J((EYH) 75.6 Hz, 1.49p.p.m., singlet, ,J(PtH) 71.6 Hz, S[(CH,),] 1.43p.p.m., broadunresolved multiplet (Found: C, 32.8; H, 3.50; N, 5.10.Calc. for C,,H,,IS,Pt: C, 32.8; H, 3.50; N, 5.100,/,);[{PtMe[(CH,),]I(py)),], yield 7076, m.p. 220 "C (decomp.),n.m.r. spectrum in CH,Cl,, G(PtCH,) 1.34 p.p.m., singlet,,J(PtH) 72.0 Hz, 1.48 p.p.ni., singlet, "(PtH) 72.0 Hz,S[(CH2)4) 1.41 p.p.m., broad unresolved multiplet (Found :C, 25.1 ; H, 3.35; N, 3.00; Pt, 42.36.Calc. for C1,H,,INPt :C, 25.4; H, 3.40; N, 2.95; Pt, 41.3:;); and [PtMe{(CH,),)I-(Ph,PCH,CH,PPh,)], m.p. 154 "C (decomp.) (Found: C,46.15; H, 4.50. Calc. for C,,H,,IP,Pt: C, 47.16; 13,Bromo (buta7te- 1,4-diyZ) bis (dimethylfih e pzy Zflhosphine) met11 -yZpZatznuuz(1v) .-Methyl bromide (5 an3) was added to asolution of [Pt{(CH,),)(PMe,Ph),] (0.15 g) in diethyl ether(5 cm3). After 48 h the white crystals which formed wwefiltered off and washed with dietliyl ether, yield 0.10 g(77%), m.p. 162-164 "C (decomp.). 3.xn.r. spectrum inCH,Cl,: G(PtCH,) 0.48 p.p.m., triplet, 3J(PH) 7.2, 2J(PtH)70.2 Hz; 6[(CH,),] 1.46 p.p.ni., complex multiplet ;G(PCH,) 1.56 and 1.64 p.p.ni., two doublets, ,J + ,J(PH)8.4, 3J(PtH) 8.4 H z (Found: C, 40.25; H, 5.30.Calc.for C,,H,,BrP,Pt: C, 40.5; H, 5.30:;).(Butme- 1,4-diyl)chlorobis(dimethyZ~henyl~hos~J~ine)~~~etli-yZpZatimm(1v) .-Methyl chloride (ca. 5 cm3) was condensedinto a Pyrex tube containing [Pt((CH,),)(PMe,Ph),] (0.32 g).The tube was sealed, and the mixture allowed to stand a troom temperature for 2 weeks. The tube was opened, thesolvent allowed to evaporate, and the pitoduct was washcdthoroughly with diethyl ether and dried in vacuo, yield 9 1 L,m.p. 154-158 "C (decomp.). N.m.r. spectrum in CH,CI,:G(PtCH,) 0.47 p.p.m., triplet, "(PH) 7.2, 2J(PtH) 72.2 H z ;S[(CH,),J 1.20 p.p.m., complex unresolved multiplet ;G(PCH,) 8.40 and 8.46 p.p.m., two doublets, 2J + ,JJ(PH) 8,3J(PtH) 8 Hz (Found: C, 43.35; H, 5.70.Calc. forC,,H3,C1P2Pt: C, 43.65; H, 5.700/,).(Butane- 1,4-diyZ) bis (dinzetJzylphenyZphosphine)di-iodofllcrt-inuwz(Iv).-A solution of iodine (0.048 g) in diethyl etlicr(5 cm3) was added to a solution of [Pt{(CH,),)(PMe,Ph),](0.10 g) in diethyl ether (5 cm3). Orange crystals preci-pitated immediately. After leaving the solution for 16 h a t0 "C, the crystals were filtered off and recrystallised fromdichloromethane-methanol, yield 48y6, m.p. 214 "C (de-camp.). N.m.r. spectrum in CH,CI,: 6[(CH,),] 4.48 p.p.m.,4.45%).EXPERIMEXTALGeneral techniques have been described previously.3* 5Solutions of 1,4-dilithiobutane in diethyl ether were pre-pared by the method of West and Rochow l7 from lithiumshot and lJ4-dibromobutane.The solutions were filteredunder nitrogen before use in order to remove excess oflithium.(Butane- 1,4-diyZ)bis(dimethyZ~henyZ~hosphine)~Zut~nu~ (11).-1,CDilithiobutane [5 cm3 of a solution prepared from Li(1.14 g) and lJ4-dibromobutane (5.53 g) in diethyl ether (40cm8)] was added to a suspension of cis-[PtCl,(Phle,Ph),](0.5 g ) in diethyl ether (10 cm3). The solution was allowedto react at 0 "C for 16 h, then hydrolysed with ammoniumchloride solution at 0 "C, and the dried ether layer wasevaporated t o yield the product, which was recrystallisedfrom diethyl ether-hexane, yield 35%, n1.p. 128-133 "C,v(PtC) at 528 and 535 cm-l. N.m.r. spectrum in benzene:G(PCH,) 1.27 p.p.ni., doublet, ,J + 4J(PH) 7 Hz, 3J(PtH)18 Hz; 8[(CH,),] 2.36 p.p.m., broad unresolved multiplet(Found: C, 45.35; H, 5.75.Calc. for C,,H,,P,Pt: C,46.55; H, 5.701/,). In a reaction on a larger scale, from(PtCl,(PA!le,Ph),] (3.95 g), the yield was 56%.(Butane-1,4-diyZ) (cyclo-octa- 1,5-diene)pZatinun~(11) .- Thiscomplex was prepared in a similar way, but to niinimise de-composition of the product the reaction mixture was stirredfor only 2 h at - 10 "C, yield 45%. It was recrystallised byallowing a solution in light petroleum (b.p. 30-40 "C) toevaporate slowly, m.p. 74 "C. N.m.r. spectrum in CH,Cl,:6[(CH2),] 1.29 p.p.m., broad unresolved multiplet; 6(CH)4.78 p.p.m., ,J(PtH) 38.4 Hz; 6(CH,) 2.21 p.p.m., 3J(PtH)16.2 Hz (Found: C, 40.15; H, 5.55. Calc. for C,,H,,Pt:C, 40.1 ; H, 5.55%).The mass spectrum gave a parent iona t nz/e 359 and peaks a t m/e 303 [P - C4Ha]+, 251 [P -C,H,,]+, and 195 [Pt]', all with the correct isotope pattern.(Buta~ze-l,4-diyZ)iodo(~~ethyZ)pZatinunz (IV) .-A solution of[Pt{(CH,),)(cod)] (0.63 g) in methyl iodide (3 cm3) wasallowed to stand a t room temperature for 3 d. The de-posited crystals were washed thoroughly with CH,Cl, anddried in vacuo, yield 0.49 g . The complex decomposedwithout melting at 195 "C (Found: C, 14.9; H, 2.55; Pt,49.25. Calc. for C,H,,IPt: C, 15.25; H, 2.80; Pt, 49.6%).The mass spectrum gave a parent ion a t nz/e 393 and otherpeaks at mz/e 378 [P - Me]+, 337 [P - C,H,]+, 322 [P -C,Hll]+, 266 [P - I]', and 251 [P - CH31]'-, all with thecorrect isotope pattern.Bromo(butane- 1,4-diyZ)methyZPZatinum( IV) .-A solution of[Pt{(CH,),)(cod)] (0.32 g) in methyl bromide (2 cm3) wasallowed to stand in a sealed tube at room temperature for 1month, during which time white crystals slowly formed.The tube was opened, the solvent was allowed to evaporate,and the crystals were washed thoroughly with CH,Cl,, yield0.2 g.The complex decomposed without melting at 227 "C(Found: C, 17.55; H, 3.45; Pt, 56.7. Calc. for C,H,,RrPt:C, 17.35; H, 3.20; Pt, 56.35%).(Butane- 1 ,4-diyl) bis(dimethyZphenylphosphine)iodo (methyl) -pZatinum(xv) .-(a) The complex [Pt( (CH,),}(PMe,Ph),](0.11 g ) was dissolved in methyl iodide (2 cm3). After 5min the solvent was evaporated and the product was re-crytallised from dichloromethane-hexane, yield 6 1 %, m.p.150-151 "C (decomp.), v(PtC) a t 530 and 546 cni-l.b4.m.r.spectrum in CH,CI,: G(PtCH,) 0.60 p.p.m., triplet, "(PH)7.4 Hz, ,J(PtH) 66.6 Hz; 6[(CH,),] 1.66 p.p.m., broad un-resolved multiplet; G(PCH3) 1.56 and 1.64 p.p.m., twoR. West and E. G. Rochow, J . Chem. SOC., 1953, 17391976 791broad unresolved multiplet, J(PtH) 64 Hz; G(PCH,) 8.65p.p.m., doublet, zJ + "J(PH) 9.3, 3J(PtH) 12.0 Hz.Reaction of [{ PtMe[(CH,),]I),] with TriphenyZphosphine.-The reaction of PPh, with a suspension of [{PtMe[(CH2)4JI),Jin CH2C12 for 2 d gave an insoluble yellow product whichcould not be identified. The filtrate from the reaction wastreated with methanol, and crystals of [Pt( (CH,),)(PPh,),] ,yield ca. 50%, were precipitated and identified by com-parison with an authentic specimen prepared by reaction ofPPh, with [Pt{ (CH,) (cod) 1.Pyrolysis Experime.1.tts.--Complexes were pyrolysed invacua at ca. 10 "C above the melting point. Volatileproducts were usually collected immediately in a liquid-nitrogen-cooled trap, but in some cases the volatiles wereallowed to remain in contact with the platinum-containingresidue. The volatiles were analysed using a Pye 104 gaschromatograph with either Porasil B or Carbowas 2019columns , coupled to a Mikromass mass spectrometer.3~6Identification of products was made by comparison of re-tention times and mass spectra with those of authenticsamples.For the phosphine complexes the residues were identifiedby their i.r. and n.m.r. spectra; [PtI,(PMe,Ph),J formedfrom [PtI,(C,H,) (PMe,Ph) ,] existed as a cis-trans mixture.'*The compounds trans-[PtHX(PMe,Ph) ,] showed character-istic v(PtH) bands at 2 140 (X = I), 2 181 (X = Br, lit.,162 185), and 2 200 cm-l (X = C1, lit.,16 2 195cm-l), as well asthe characteristic triplets for the PCH, protons in the n.m.r.spectra.[6/1783 Received, 17ih Sepfembev, 197451l8 J. M. Jenkins and B. L. Shaw, J . Chew. SOC. ( A ) , 1966, 770