New isocyanide-platinum complexes - American Chemical Society

(11) M. J. Church and M. J. Mays, J. Chem. Soc. A, 3074 (1968). (12) P. M. Treichel .... (15) S. Grim, R. Keiter, and W. McFarlane, Inorg. Chem., 6, 1...
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5424

New Isocyanide-Platinum Complexes P. M. Treichel,* W. J. Knebel, and R . W . Hess Contribution from the Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706. Received November 23. 1970 Abstract: A number of studies of platinum(I1)-isocyanide complexes have been carried out including (1) the ~ ]alkylation [ B F ~ ] Z of K2Pt(CN)4 and (phos)~Pt(CN)z with synthesis of [Pt(CNCH3)4][BF4]2 and [ ( ~ ~ o s ) ~ P ~ ( C N C H ~ )by [(CH&0][BF4]; (2) the reactions of LPtXz and CHaNC(L = several phosphines, (C6HS)&, (CBHs0)3P;X = C1, Br, I) to give LPt(CNCH3)X2,(CH3NC),PtX2,[LSt(CNCH3)X][X],or [L2Pt(CNCH&X][X],depending on L and X and on the conditions of the reaction (the complexes [(phos)2Pt(CNCH3)X][X](X = Br, Cl) on heating in benzene slowly lose CH3X to give (phos),Pt(CN)X); (3) the reactions of [(ph0s)~Pt(CNCH~)21[Al and various anions X- to give [(phos),Pt(CNCH3)X][A] and/or (phos)zPtXs [(phos), = diphos only; X = C1, SCN, CN] and [(phos)zPtor (phos)zPt(CN4CHJ~[(phos), = (CNCH&X][A] (X = I), with azide ion to give [(phos)2Pt(CNCH3)CN4CH3][A] diphos only], with nitrite ion to give [(~~O~)~P~(CNCH,)CONHCH~][A], with CGFsLior CH3Li to give (phos)zPtRz and phosPt(CNCH,)R1, and with alkoxide ion to give [(phos)2Pt(CNCH3)C(OR)=NCHJA] or (phos)zPt { C(OR)= NCH312 [ ( p h ~ s = ) ~ diphos only]. The former compound can be alkylated by [(CH&O][BF4], then treated again with alkoxide ion to give [(ph~s)~Pt {C(OR)=NHCH,) { C(OR)=N(CH& ] ][BF412. The new compounds reported here are characterized fully by analyses, and infrared and nmr spectroscopic studies are reported. Conductivities in acetonitrile have been run on appropriate ionic complexes.

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ost of the early work on platinum-isocyanide complexes' dealt with complexes of the genera1 formulas (RNC)*PtX* and [(RNC)4Pt][A]2 (A = noncoordinating anion), and since these stoichiometries are quite typical for this metal in the divalent state, such complexes would not attract much attention. However, with a general resurgence of research on metal isocyanide complexes in recent months, it is not surprising that new and interesting work has appeared. In particular, two outstanding observations have been made in studies on these complexes. The first, that small molecules such as alcohols and primary and secondary amines add to the carbon-nitrogen multiple bond in a coordinated isocyanide ligand, was accomplished initially using the complex {(C2H&P)Pt(CNCd%)C12. However, this work just preceded two reports3' describing the structural characterization of related complexes derived from [Pt(CNR),][PtCI4] and hydrazine which had been incorrectly identified by C h ~ g a e v ;these ~ complexes apparently originate from additions of N-H units to two coordinated isocyanides. Subsequent to these studies, additions of alcohol to isocyanide ligands in (RNC)2PtC12 complexes,6 and in isocyanide complexes of palladium,' have been reported. The second observation concerned isolation of complexes of the formula [(phos)2Pt(CNCH3)R][X] and their subsequent rearrangement to imino complexes, ( ~ ~ O S ) ~ P ~ ( C R = N C H , This ) X . ~work, reminiscent of carbonylation reactions, has been shown to occur with several other metal^,^^'^ and clearly em(1) The background material in this area is reviewed well in a recent book: L. Malatesta and F . Bonati, "Isocyanide Complexes of Metals," Wiley-Interscience, New York, N. Y., 1969. (2) E. M. Baddley, J. Chatt, R . L. Richards, and G. A. Sim, Chem. Commun., 1322 (1969). (3) A. Burke, A. L. Balch, and J. H . Enemark, J . Amer. Chem. Soc., 92, 2556 (1970). (4) G . Rouschias and B. L . Shaw, Chem. Commun., 183 (1970). (5) L. Chugaev, M. Skanavy Grigorieva, and A. Posniak, 2.Anorg. Allg. Chem., 148, 37 (1925). (6) F. Bonati and G. Minghetti, J . Organometal. Chem., 24, 251 (1970). (7) B. Crociani, T. Boschi, and U. Belluco, Inorg. Chem., 9, 2021 (1970). (8) P. M. Treichel and R . W. Hess, J . Amer. Chem. Soc., 92, 4731 ( 1970).

phasizes the analogy between carbonyl and isocyanide ligand groups. In addition to these papers there have also appeared the syntheses of several complexes, [ {(CzHJ3PI2Pt(CNR)X][CIO,], included in a more general study on { (C2H&P],Pt(L)X][C1O4] complexes," and the description of several trichlorostannatoisocyanideplatinum(I1) complexes.6 We began the work described in this paper with a successful synthesis of several new platinum(I1)isocyanide complexes from cyanoplatinum(I1) species by alkylation reactions, and continued in a study of their reactions with various nucleophiles (X-). Because products such as [ ( ~ ~ O ~ ) ~ P ~ ( C N R ) arise X ] [ Ain] these reactions, we decided to investigate reactions of (phos)zPtXz complexes with isocyanides; this work also fit in with our studies on reactions of platinum alkyls and arylss and methyl isocyanide, which give initially [(phos>,Pt(CNCH,)R][X]. One aspect of the present work, the dealkylation of methyl isocyanide, was published in preliminary form.'* We now wish to present a detailed description of our work on platinum(I1) isocyanide chemistry. Experimental Section Infrared spectra (4000-400 cm-1) were recorded on a Beckman IR-10 spectrometer, using Nujol mulls and KBr plates; highresolution data on Y C = N were obtained on a Perkin-Elmer Model 421 spectrometer using chloroform solutions. Proton nmr spectra were obtained on Varian A-60 and T-60 spectrometers using tetramethylsilane, 7 10.0, as an internal standard. Conductivity measurements were made on -5 x M dichloromethane and acetonitrile solutions with a Beckman conductivity bridge, Model RC-ISA, and a Beckman conductivity cell with cell constant k = 0.20. Analyses were performed by Galbraith Laboratories, Knoxville, Tenn., and by the Schwarzkopf Microanalytical Laboratory, Woodside, N. Y. Conductivity data are summarized in Table I. (9) S. Otsuka, A. Nakamura, and T. Yoshida, J . Amer. Chem. SOC., 91, 7196 (1969). (10) Y . Yamamoto, H. Yamazaki, and N. Hagihara, J . Organometal. Chem., 19, 189 (1969). (11) M. J. Church and M. J. Mays, J . Chem. SOC.A , 3074 (1968). (12) P. M. Treichel and R . W. Hess, Chem. Commun., 1626 (1970).

Journal of the American Chemical Society / 93:21 1 October 20, 1971

5425 1163 (vw), 1095 (s), 1055 (vs), 993 (m), 750 (s), 713 (s), 692 (s), 528 (s), and 500 cm-' (s); pmr (CD3CN) T 7.29 (t, J(Pt-CH3) = AM, ohm-' cm2 mol-' 16 Hz, CNCH3) and 2.30 (m, P(CeH6)3). Anal. Calcd for C4aH38Compound CHzClzb CHaCN' B2N2P2Pt: C,49.4; H, 3.70; N, 2.87; P,6.36. Found: C,49.8; H, 4.06; N, 3.13; P, 6.45. [~(C6H6)3P}zPt(CNC~H6)~][BF4]~, white crystals, mp 251-258O, was prepared from ( (ce&hP)~Pt(CN)2 and [(C2H6)30][BF4]: 42% yield; ir (Nujol mull) 2260 cm-' (s) (C=N) and other bands 1593 (vw), 1580 (vw), 1488 (m), 1437 (s), 1340 (w), 1317 (vw), 1290 (vw), 1188 (w), 1167 (vw), 1090 (s), 1050 (vs), 992 (w), 747 (s), 710 (s), 690(s), and 51Ocm-l(s); pmr (CDKN) T 9.47(t, J(CHzCH3)= 7 Hz, CNCH2CH3), 6.92 (m, J(CH2CH3) = 7 Hz, CNCH2CH,], C, and 2.25 (m, P(C8H&). Anal. Calcd for C12H40B2F8N2P2Pt: M . b In dichloroa All solution concentrations were 4X 50.2; H, 4.02; N, 2.79; P, 6.17. Found: C, 50.2; H, 4.15; M solution of (C2H6)4NC104was 53. methane, AM for a 1 X c In acetonitrile, AMfor a 5 x lW4M solution of ( ~ Z - C ~ H ~was ) ~ N I N, 2.68; P, 5.88. trans-[((C&)zPCH3) 2Pt(CNCH3)2][BF4], white crystals, mp 228151. 230", was prepared from ( (C6Hs)zPCH3}2Pt(CN)2 and [(CH3)30]The starting platinum complexes, [(n-C4H9)4N12[Pt(CN)d,'3 [BF4]: 8 2 z yield; ir (Nujol mull) 2264 cm-' (s) (C=N) and other bands 1588 (vw), 1577 (vw), 1483 (m), 1440 (s), 1318 (w), 1287 (vw), CiS-l(C~Hs)aP)zPtCl2,'~ ( (c~H6)3AS}zPfXa ( x = c1, I),14 Cis1190 (w), 1168 (w), 1060 vs), 996 (w), 896 (s), 743 (s), 708 (w), 693 { (C~H6)zPCH3}zPtC1z,15 cis-( (CZH&P}2PtCl~,lBtrans-( (CZH&P}ZPtC12,17 diphosPtC12 (diphos = 1,2-bi~diphenylphosphinoethane),~8 (s), 497 (s), 453 (w), and 428 cm-l (vw); pmr (CD3CN) T 7.38 (m, J(Pt-PCH,) = 32 Hz, J(P-CH3) = 4 Hz, P-CH,), 7.07 (t, J(Ptand ( (CsH60)3P)2A12,14 were synthesized by the literature proNCHa) = 16 Hz, CNCH3), and 2.31 (m, P(c6HS)3). Anal. Calcd cedures; ((CeH6)sP}2PtX2, ((CzH6)3P]~PtXn ( x = Br, I), and difor C30H32B2FsNZP2Pt .0.2C4H802: C, 42.6; H, 3.90; N, 3.62. phosPtII were prepared from the appropriate (phos)zPtClz with Found: C,42.7;H, 3.97; N, 3.26. either lithium bromide in acetone or sodium iodide in methan01.1~ ) ~ ] [ Pcrystals, F & , mp 188-191 was preThe preparations of ((Ce&)3P}zPt(CN)z, { ( C ~ H ~ ) Z P C H ~ } P P ~ ( C N ) Z[,~ ~ ~ ~ O S P ~ ( C N C H ~ white pared from reaction of diphosPt(CN)Z and [(CH3)30][BFJ, followed and diphosPt(CN)z from the corresponding dichlorides and potasby addition of NH4PFesolution in acetonitrile-water to convert it sium cyanide were accomplished by the literature method,20except to hexafluorophosphate salt: 75% yield; ir (Nujol mull) 2291 (s) that these reactions were carried out in refluxing dichloromethane, and 2284 cm-1 (s) (CEN) and other bands 1590 (vw), 1578 (vw), with a somewhat better yield, than reported. Trimethyloxonium 1484 (m), 1439 (s), 1413 (w), 1337 (vw), 1314 (vw), 1187 (vw), 1161 tetrafluoroboratezl and methyl isocyanidez2 were prepared by (vw), 1104 (s), 997 (w), 830 (vs), 750 (w), 714 (s), 687 (s), 553 (s), literature methods. Pentafluorophenyllithium was prepared from 533 (s), and 487 cm-' (m); pmr (CDICN) T 6.60 (t, J(Pt-CH,) = approximately equimolar quantities of bromopentafluorobenzene 15 Hz, CNCH3), 7.38 (m, -CHzP), and 2.31 (m, -P(C6HS)Z). Anal. and n-butyllithium in dry, freshly distilled tetrahydrofuran at Calcd for C30H30FlZN2P4Pt: C, 37.4; H, 3.14; N, 2.90; P, 12.0. - 78 0 . 2 3 Found: C, 37.7; H, 3.30;N, 2.99; P, 12.9. Acetonitrile was dried over calcium hydride, distilled onto Pzos, Reactions of Bisphosphine-, Bisphosphite-, and Bisarsineplatinum and then redistilled for use as a solvent for conductivity measureDihalides with Methyl Isocyanide. Reaction of { (CeH&P}Zments. Manipulations were carried out routinely under nitrogen. PtClz with CH,NC. A solution of 0.08 ml (1.5 mmol) of methyl Preparation of Platinum(IIt1socyanide Complexes by Alkylation isocyanide in 15 ml of benzene was added dropwise to a benzene Reactions Using Trialkyloxonium Salts. The preparation of suspension of 1.13 g (1.42mmol) of ( ( C & ) B P } Z P ~ Cat~ Z25". A [Pt(CNCH3)4][BF4]zfrom [(n-C4H9)4Nl~[Pt(CN)J and trimethylyellow coloring formed around each drop as it reached the benzene oxonium tetrafluoroborate illustrates the general procedure for suspension which then rapidly faded. After 30 min the benzene these alkylation reactions. was evaporated and the white solid which remained was recrystalTetrakigmethyl isocyanide)platinum(II) Tetrafluoroborate, [Ptlized from benzene to give ( (C&&P} Pt(CNCH3)C12'0.5C6H6: (CNCH&I[BF412. To a solution of [(~-C~H~)~N]Z[P~(CN)J)~] (2.5 g, 0.70 g, 7 0 z yield; mp 264-267"; ir (CHCI,) 2259 (s) and 2243 3.2 mmol) in anhydrous dichloromethane (80 ml) was added excess cm-1 (sh) ( C z N ) and other bands (Nujol mull) 1587 (vw), 1572 [(CH&O][BF4] (2.8 g, 19 mmol). The initial pale green suspension (vw), 1480 (s), 1435 (s), 1410 (vw), 1313 (vw), 1180 (w), 1155 (vw), became colorless over a 4-hr reflux period. The solvent was 1095 (s), 1070 (vw), 1025 (vw), 995 (vw), 820 (vw), 747 (s), 742 (s), evaporated and the resulting residue was dissolved in a small 703 (s), 687 (vs), 610 (vw), 540 (vs), 507 (vs), 473 (w), 452 (w), and volume of acetonitrile. The solution was filtered and, on addition 425 cm-' (vw); pmr (CDC1,) T 7.22 (t, J(Pt-CH,) = 19 Hz, of ethyl acetate, crystallization occurred. Two crops of white CNCH,) and 2.46 (m, P(C6HS)I). Anal. Calcd for CZOHI~CIZcrystalline [Pt(CNCH3)4][BF4]2 (1.6 g, 94773 yield) were collected. NPPt.O.5CsH6: C,45.4;H, 3.46; N,2.30;P, 5.10. Found: C, The compound could be recrystallized from acetonitrile-ethyl acetate; mp 224-227 '. Anal. Calcd for CsHlZB2F8N4Pt .0.7- 46.0; H, 3.05; N, 2.49; P, 5.11. In acetone, this reaction took a different course. An acetone C4H802: C, 22.0; H, 2.99; N, 9.56. Found: C, 22.4; H, solution of 0.06 ml (1.2mmol) of methyl isocyanide was added 3.00; N, 10.0. The infrared spectrum shows a band at 2300 cm-' dropwise to a suspension of 1.00g (1.27mmol) of { ( C ~ H & P } ~ P ~ C ~ Z (s) (Nujol mull) for C z N stretching frequency, and other bands at in 30 ml of acetone. No transient color formation was noted a s 1333 (w), 1299 (w), 1060 (vs), 795 (w), 716 (w), 520 (m), and 497 in benzene solution. The suspension dissolved over a 5-min period; cm-l (m). The pmr spectrum (CD,CN) shows a methyl proton then acetone was evaporated until crystals began to form. The multiplet (1:4:1 triplet due to ls6Pt coupling) at T 6.32 with J(Ptwhite solid was recrystallized from acetone-ethyl ether to give CNCH3) = 16Hz. Using an identical procedure the following compounds were [ ((C6Hj),P)2Pt(CNCH3)Cl][Cl]: 0.95 g, 90% yield; mp 325prepared. 335" dec; ir (CHC13)2264 cm-1 (s) ( C z N ) and other bands (Nujol mull) 1588 (vw), 1574 (vw), 1482 (m), 1436 (vs), 1310 (vw), 1175 [( (CBH&P}zPt(CNCH3)2][BF4]Z,white crystals, mp 269-272", (w), 1157 (vw), 1097 (s), 1025 (vw), 998 (w), 762 (m, sh), 742 (s), was prepared from ( ( C B H S ) S P } ~ P ~ and ( C N[(CH3)30][BF4]: )~ 77 Z 710 (s), 688 (vs), 630 (vw), 522 (vs), 510 (vs), 502 (s, sh), 487 (w), yield; ir (CHC13) 2275 cm-' (s, C z N ) and other bands (Nujol and 455 cm-l (vw); pmr (CD,CN) T 7.73 (t, CNCH,) and 2.38 mull) 1587 (vw), 1574 (vw), 1484 (m), 1437 (s), 1313 (w), 1187 (w), (m, P(C&5)3). Anal. Calcd for C38H33C1~NP~Pt:C, 54.9; H , 4.00; N, 1.85. Found: C, 53.8; H, 4.38;N, 2.41. (13) R. Mason and H. Gray, J . Amer. Chem. Soc., 90,5722 (1968). When [((C,Hj)3P}2Pt(CNCH3)Cl][C1] (0.95g, 1.10 mmol) was (14) L. Malatesta and C. Cariello, J . Chem. Soc., 2323 (1958). dissolved in a chloroform-benzene mixture, and the mixture was (15) S. Grim, R. Keiter, and W. McFarlane, Inorg. Chem., 6 , 1133 worked up as above, {(C6H6),P}Pt(CNCHa)CI2 (0.58 g, 80% yield) (1967). (16) H. C. Clark and K . R. Dixon, J . Amer. Chem. Soc., 91, 596 was obtained. Likewise, when a suspension of 0.55 g (0.83mmol) (1969). of ((C6Hj)3P)Pt(CNCH3)C12 was added to a solution of 0.30 g (17) J. Chatt and R. G . Wilkins, J . Chem. Soc., 273 (1952). (1.15 mmol) of triphenylphosphine in acetone, and the mixture was (18) A . Westland, ibid., 3060 (1965). stirred for 15 min, [ ((C6Hj)3P}ZPt(CNCH3)C1][C1] was formed (19) J. Chatt and B. L. Shaw, ibid., 5075 (1962). (0.48 g, 7 0 % yielj). Both products obtained in these intercon(20) J. Bailar and H. Itatani, J . Amer. Chem. Soc., 89, 1592 (1967). versions were shown to be identical with the sample obtained in the (21) H. Meerwein, Org. Syn., 46, 113 (1966). direct reaction in benzene by comparison of infrared and nmr (22) R. E. Schuster, J. E. Scott, and J. Casanova, ibid., 46, 75 (1966). (23) P. L. Coe, R. Stephens, and J . Tatlow, J . Chem. Soc., 166 (1959). spectra and melting point.

Table I. Conductivity Data on Ionic Complexes ~

(1

O,

Treichel, Knebel, Hem

1 New Isocyanide-Platinum Complexes

5426 Reaction of { (C~Hs)3P}2PtBr2 with CH3NC. A benzene solution 678 (vw), 630 (w), 473 (m), and 413 cm-l (w); pmr (CDClr) 6.05 (t, J(Pt-NCH3) = 20 Hz, CNCHa), 7.70 (m,J(CH2CH8) = 7 of 0.90 ml(1.7 mmol) of methyl isocyanide was added dropwise to a Hz, PCH2CHa),and 8.80 (m, J(CH2CHa) = 7 Hz, J(P-CHr) = 8 suspension of { ( C B H S ) P P ) Z P(1.20 ~ B ~ g, ~ 1.39 mmol) in benzene Hz, PCHzCHa). Anal. Calcd for C14Ha3ClzNP2Pt: C, 30.9; at 25" with no perceptible color change. The pale orange solid H, 6.12; N, 2.5. Found: C, 30.8; H, 6.64; N, 2.44. left on evaporation of the benzene was dissolved in chloroform to For the dibromide adduct, the following were observed: ir give a deep orange solution. Yellow needle-shaped crystals (0.13 (CHC1,) 2251 cm-l (SI ( C e N ) and other bands (Nujol mull) 1420 g) were obtained on addition of ethyl ether. Proton nmr indicated a phosphine-to-isocyanide ratio of 1 :1 ; analysis confirmed the (s), 1263 (m), 1238 (w), 1140 (vw), 1030 (s), 1005 (m), 763 vs), 733 identity of the complex as [ {C6Hs)3P)zPt(CNCH3)zBrl[Brl (13 (vs), 720 (s, sh), 678 ( W , 628 (w), 472 (m),and 413 cm-1 (m); pmr (CDC13) 7 6.05 (t, J(Pt-NCHa) = 20 Hz, CNCH8), 7.70 (m, yield). The compound melted at 100" turning yellow-green, and 8.80 (m,J(CHzCHa) = 7 Hz, J(CHzCH3) = 7 Hz, PCHZCH~), resolidified -120°, and began to remelt with decomposition above J ( P C H 3 ) = 8 Hz, PCH2CH3). Anal. Calcd for C14HaaBrlNP2Pt: 300": ir (CHCla) 2258 cm-l (s) (C=N) and other bands (Nujol C, 26.6; H , 5.26; N, 2.21. Found: C, 26.8; H, 5.41; N, 2.16. mull) 1590 (vw), 1572 (vw), 1481 (m),1437 (m), 1413 (w), 1308 For the diiodide adduct, the following were observed: ir (VW), 1247 (vw), 1232 (vw), 1181 (vw), 1155 (vw), 1095 (s) 1070 (Nujol mull) 2230 cm-l (vs) (CEN) and other bands 1410 (s), (vw), 1023 (vw), 996 (w), 750 (vs), 740(vs), 708 (m), 690(s), 654(w), 1260 (w), 1030 (s), 980 (vw), 765 (m), 750 (m, sh), 735 (s), 715 (m, sh), 523 (s), 512 (s), and 496 cm-1 (s); pmr (CDCl,) T 7.20 (t, CNCH3) 625 (vw), 497 (m),and 410 cm-1 (w); pmr (CDCI,) T 6.13 (s, .2.5and 2.39 (m, P(cEH5)3). Anal. Calcd for C40Ha6BrzNzP~Pt CNCH,), 7.67 (m,J(CHzCH3) = 7 Hz, PCH2CH3),and 8.75 (m, CHC13: C, 40.0; H, 3.12; N, 2.22; P, 4.92. Found: C, J(CH2CH3) = 7 Hz, J(P-CH,) = 8 Hz, PCH2CH3). Anal. Calcd 39.9; H,3.13; N,2.34; P,4.97. for ClrHaa12NP2Pt: C, 23.2; H, 4.58; N, 1.93. Found: C, Repeated recrystallization from chloroform-ethyl ether resulted 24.0; H, 4.80; N, 2.66. in slow loss of methyl isocyanide, giving eventually [ {(CeHs)aP)zThe reaction of trans- ( (C2Hs)3P)~PtC12with methyl isocyanide Pt(CNCH3)Br][Br]. This loss was followed by the increasing which was gave a 90% yield of [ {(CzHs)3P}zPt(CNCH3)Cl][CI] phosphine-to-isocyanide intensity ratio in the nmr. identical with the product obtained from the cis dichloride, Additional ethyl ether was added to the mother liquor from Reactions of ((C6Hs),As)PRXZ (X = C1, I) with Methyl Isocyanide. which the bisisocyanide adduct was originally obtained. After 2 To a suspension of ((C&)&}zPtClz (0.314 g, 0.357 mmol) in 20 days at 0" an orange oil separated from this solution which solidified ml of dichloromethane was added methyl isocyanide (0.0146 g, after 2 more days at 0". Crystallization from acetonitrile-ethyl 0.357 mmol). The resulting solution was stirred for 1 hr at 25", ether and two recrystallizations from chloroform- ethyl ether gave then evaporated to dryness, and the residue was taken up in excess 0.50 g of pale yellow crystals identified as [ {(CGHS)~P}ZP~(CNCH~)dichloromethane and filtered. After concentrating the solution Br][Br].0.5CHCla (37% yield), mp >335" dec. This compound to a small volume, addition of excess ethyl ether gave the white has infrared and nmr spectra identical with those of the complex (0.204 g, 96% yield), which formed by isocyanide loss from [ {(C8H5),P\zPt(CNCH3)~Brl[Brl: crystalline { (CGH5)3A~]Pt(CNCH3)C12 was recrystallized from dichloromethane-ethyl ether : mp 247ir (CHCl,) 2261 cm-1 (s) (C=N) and other bands (Nujol mull) 248"; ir (CHC1,) 2255 (s) and 2241 cm-1 (sh) (C=N) and other 1590 (vw), 1574 (vw), 1483 (m), 1434 (s), 1409 (vw), 1310 (vw), 1186 bands (Nujol mull) 1580 (vw), 1480 (m), 1436 (s), 1308 (w), 1184 (w), 1155 (vw), 1098 (s), 1070 (w), 1022 (vw) 992 (w), 750 (s), 740 (vw), 1156 (vw), 1077 (m), 1022 (w), 997 (w), 740 (s), 687 (s), 477 (s), 705 (s, sh), 698 (s, sh), 688 (s), 523 (s), 512 (s), 492 (s), 470 (w), (s), and 463 cm-1 (w); pmr (CDC13) 7 7.17 (t, J(Pt-CH3) = 18 Hz, and 453 cm-1 (w); pmr (CDC13) 7 7.35 (t, J(Pt-CH3) = 20 Hz, CNCHa) and 2.39 (m, P(C6HS),). Anal. Calcd for CasHaaBrz- CNCH,) and 2.47 (m, As(CEff&). Anal. Calcd for C Z ~ H ~ S AsClzNPt: C, 39.1; H, 2.94; C1, 11.6; N, 2.28. Found: C, NPzPt.0.5CHC13: C, 47.2; H, 3.45; N, 1.43; P, 6.32. Found: 38.8; H, 2.93; C1, 12.0; N, 2.27. C,47.3; H , 3.58; N, 1.73; P, 6.41. Utilizing the same procedure, { ( C ~ H ~ ) Q A S ) Z(0.500 P ~ C ~g,Z 0.570 Reaction of { (C6H&P)2PtIz with CH3NC. A benzene solution mmol) and excess methyl isocyanide (0.0584 g, 1.42 mmol) gave of 0.80 ml(1.5 mmol) of methyl isocyanide was added dropwise to known ~is-(CH3NC)~PtC1~24 (0.153 g, 75 % yield), which was purified a benzene suspension of 1.08 g (1.12 mmol) of {(C&&P}ZP~IZ at by recrystallization from dichloromethane-methanol, mp 229-231 25". The yellow-orange color of the suspension changed to dec. bright yellow. After 10 min the benzene was evaporated and the Utilizing the same procedure, { (C6H5)~As)2Pt12 (0.478 g, 0.450 remaining yellow solid was recrystallized from chloroform-ethyl mmol) and methyl isocyanide (0.0184 g, 0.450 mmol) gave the ether to give 0.43 g of bright yellow needles identified as [ { (C6H5)3yellow crystalline { (C6H5),As]Pt(CNCH3)12(0.307 g, 86% yield), P}ZP~(CNCH,),I][I](55 yield based on methyl isocyanide): which was recrystallized from dichloromethane-ethyl ether, mp mp 127-128"; ir (CHC13) 2252 cm-1 (s) (C=N) and other bands (0.600 g, 0.565 mmol) and excess 226-228"; and { (CeHa)3As)2Pt~2 (Nujol mull) 1620 (vw), 1587 (vw), 1572 (vw), 1482 (m), 1435 ( s ) , methyl isocyanide (0.0533 g, 1.30 mmol) gave the yellow crystalline 1410 (vw), 1400 (vw), 1312 (vw), 1183 (w), 1158 (vw), 1095 ( s ) , 1024 (CH3NC)zPt12 (0.272 g, 91 % yield), which was recrystallized from di(vw), 995 (w), 853 (vw), 754 (m), 640 (m), 707 (m),685 (s), 522 (s), chloromethane-ethyl ether; turns white without melting at 203-205' : 510 (s), and 497 cm-1 (s); pmr (CDC13) 7 7.22 (s, CNCH3) and ir (CHCl,) 2247 (s) and 2239 cm-l (s) (C=N) and other bands 2.38 (m, p(Cdf5)3). Ana/. Calcd for C ~ & & N Z P Z P ~ C, : 45.4; (Nujol mull) 1582 (vw), 1483 (m), 1437 (s), 1408 (w), 1313 (VW), H, 3.41; N, 2.62; P, 5.88. Found: C, 45.2; H,3.13; N,2.82; 1183 (vw), 1154 (vw), 1076 (w), 1022 (vw), 997 (w), 738 (SI, 992 (m), P, 5.76. 484 (w), 470 (w), and 460 cm-I (w); pmr (CDCI,) T 6.27 (t, J(RReaction of ( (CZH5),P] zPtXz(X = CI, Br, I) with CH3NC. SoluCH,) = 19 Hz, CNCH3) and 2.46 (m, AS(C6ffS)3). Anal. Calcd tions of 0.40 ml (0.75 mmol) of methyl isocyanide in 10 ml of for CZ0Hl8AsI2NPt:C, 30.2; H, 2.27; I, 31.8; N, 1.76. Found: benzene were added dropwise to benzene solutions of cis-((CZC, 30.3; H,2.25; I, 31.3; N, 1.69. Hi)3P]2PtX2 (0.5 mmol, X = C1, Br, I) at 25". Colorless solutions Reaction of { (CaHs0)3P} 2Pt12 with Methyl Isocyanide. To a of the dichloride and the dibromide grew cloudy and a white solid 2Pt12(1.07 g, 1.00 "01) in 30 ml of chlorosolution of { (C6Hb0),P} formed over a 5-min addition period. The bright yellow diiodide form was added methyl isocyanide (0.0902 g, 2.20 mmol). A Yellow solution more rapidly faded on addition of methyl isocyanide and a suspension immediately formed and the solution phase turned white solid settled out. The benzene suspensions were filtered and yellow-orange. After 1 hr at 25", the solvent was evaporated and the white solids recrystallized from acetone-ethyl ether. The the residue dried in Cacm overnight, The oily residue was taken (0.26 g, 96% dichloride adduct [ {(C2H5)3P]2Pt(CNCH3)C1][C11 up in excess chloroform, filtered, and concentrated. Addition of yield, mp 139-140.5") and the dibromide adduct [ ( (CzH&P]zexcess hexane gave the yellow crystalline product (CH3NC)zPtIz Pt(CNCH3)Br][Br] (0.29 g, 92% yield, mp 141.5-142.5") thus ob(0.332 g, 68% yield), which was recrystallized from chloroformtained both gave proton nmr spectra in which coupling between ether. the methyl protons on the methyl isocyanide ligand and platinum Attempted Reaction of diphosPtX2 with CNCH3. When a drop were observable. The diiodide adduct [ { (C2HJ3P}2Pt(CNCH~)zilof methyl isocyanide was added to a chloroform suspension of [I] gave, after one recrystallization from acetone-ethyl ether, an diphosPtX2 (X = C1, I) the solids dissolved gave a bright yellow extremely sharp methyl resonance which showed no platinum solution. The nmr of this solution showed a sharp singlet due to coupling; integration of the spectrum gave a phosphine-to-isomethyl isocyanide which is shifted 0.2 ppm downfield from the cyanide ratio of 1 : 1. Subsequent recrystallizations resulted in loss of methyl isocyanide giving eventually pure [ {(C2H&P ]zPt(CNCH3)l][l] (0.25 g, 70% yield, mp 139-140"). For the dichloride adduct, the following were observed: ir (CHC13) 2252 cm-l (s) (C=N) and other bands (Nujol mull) 1418 (s), 1262 (m), 1145 (24) L. Chugaev and P. Teearu, Chem. Ber., 47, 568 (1914). (w), 1030 (vs), 1005 (m), 970 (vw), 763 (vs), 732 (vs), 720 (s, sh), Journal of the American Chemical S o c i e t y

1 93:21 1

O c t o b e r 20, 1971

5427

at -78" was added [diphosPt(CNCH&][PF& (0.76 g, 0.79 "01). position for free ligand (3.08 ppm). However, attempts at crystalThe initial red-brown suspension changed rapidly to a pale yellow lization led only to recovery of starting material. solution. No further apparent change occurred as the system was Dealkylation of the Isocyanide Ligand in Platinum-Isocyanide stirred continuously at -78" for 1 hr and at 0" for 4 hr. After Complexes. Demethylation of [(phos)zPt(CNCH,)X][X]. The reacsolvent removal, the residue was dissolved in benzene and filtered. was typical. A sustion using [ { (CeH6)3P}~Pt(CNCH,)cl][Cl] A white crystalline solid, diphosPt(CeF& (0.70 g, 94% yield), pension of this complex (0.18 g, 0.22 mmol) in 50 ml of heptane precipitated upon the addition of excess methanol; it was idenwas refluxed for 1.5 hr. The solvent was evaporated and the tified by infrared and melting point data,2smp 265-267". remaining white solid was washed thoroughly with acetone and Reaction of [diphosPt(CNCHa)2][PFe]~and CHsLi. To a susrecrystallized from chloroform-benzene to give [ {(C&)3P)d+ pension of [diphosPt(CNCH&][PF& (0.60 g, 0.62 "01) in dry, (CN)Cl: 0.60 g, 36% yield; mp 325-330"; ir (Nujol mull) 2125 freshly distilled tetrahydrofuran (50 ml) was added methyllithium cm-l (m) (C=N) and other bands 1587 (vw), 1572 (vw), 1480 (m), (1.43 mmol) in ethyl ether, The pale yellow solution was allowed 1434(vs), 1330(vw), 1305 (vw), 1182 (vw), 1155 (VW), 1095 (SI, 1023 to stir for 7 hr at 25". After solvent removal, the residue was (vw), 995 (w), 742 (s), 704 (s), 687 (vs), 520 (vs), 508 (s), 502 (SI, washed with water and dried. Recrystallization from acetone gave 472 (vw), 452 (vw), and 436 cm-1 (vw). colorless needles of diphosPt(CH& (0.29 g, 76% yield), which were { (C6Hs)aP)zPt(CN)Br was obtained from [ ( ( C ~ H J ) ~zPt(CNCH3)P) identified by infrared and nmr spectroscopy, mp 260" dec. Br][Br] in an analogous reaction except using benzene reflux for Reactions of [ ( ~ ~ O ~ ) ~ P ~ ( C N C H with ~ ) Alkoxide ~ ] [ A ] ~ Ion and with 3.5 hr: yield 8 2 z ; mp >340°; ir (Nujol mull) 2125 cm-l (m) and MethAlcohols. Reaction of [ ( (C&)3P} zPt(CNCH3)~][BF4]~ (C-N) and other bands 1588 (vw), 1570 (vw), 1468 (m), 1433 (s), (0.37 F ~ ~ Zg, oxide. A solution of [ ( (C6H5)3P)~ P ~ ( C N C H ~ ) Z I [ B 1308 (w), 1182 (w), 1156 (vw), 1095 (s), 1068 (vw), 1025 (w), 995 0.38 mmol) and sodium methoxide (0.48 mmol, from 0.011 g of (w), 756 (vs), 737 (m, sh), 702 (m), 688 (s), 660 (vw), 520 (vs), 510 sodium) in methanol (40 ml) was stirred for 3 hr at 25". The (vs), 498 (m), 452 (w), and 428 cm-l (w). Anal. Calcd for C37H30mixture was then evaporated to dryness. The white residue was BrNPzPt.I.75CHCl3: C, 45.0; H, 3.09; N, 1.35. Found: C, dissolved in chloroform and filtered and the filtrate was evaporated 44.9; H, 3.04; N, 1.49. ((CzH&P)zPt(CN)CI was obtained from [ {(C2HHj)2Pt(CNCH3)- to a small volume. A white crystalline product, [{(C&)~P}TPt(CNCH3)C(OCH3)=NCH3][BF4](0.29 g, 84 2 yield), precipiCl][Cl] on benzene reflux for 2 hr: yield 50%; mp 146-149"; tated upon the addition of excess ethyl ether; it was purified by ir (Nujol mull) 2120 cm-l (s) (C5.N) and other bands 1415 (m), recrystallization from chloroform-ethyl ether: mp 172-174"; 1265 (w), 1240 (w, sh), 1155 (vw), 1035 (s), 1005 (m), 762 (vs), 730 ir (CHC1,) 2245 (m) (C=N), 1626 cm-' (m) (C=N), and other (vs), 708 (m), 628 (m), 458 (m), and412cm-'(w). bands (Nujol mull) 1483 (m), 1437 (s), 1387 (w), 1183 (vw), 1139 Demethylation of I{ (C6HS)IP)zPt(CNCH3)~I][I]. A benzene sus(w), 1097 (s), 1053 (vs), 996 (w), 744 (m), 707 (w), 687 (m), 612 (w), pension of 0.2 g (0.19 mmol) of this complex was refluxed for and 510 cm-l (s); pmr (CDCI,) T 7.42 (t, J(Pt-C=NCH,) = 4 hr. The yellow solid remaining on filtration was dissolved in 12 Hz, CNCH,), 7.25 (t, J(Pt-C=NCH,) = 8 Hz, >C=NCHz), acetone and filtered. A small amount of white solid insoluble in 7.30 (s, OCH3), and 2.45 (m, P(CGH&). Anal. Calcd for C41H39acetone as well as a small amount which crystallized out of the BF4N20PzPt.0.2CHC13:C, 52.5; H, 4.19; N, 2.97. Found: acetone on cooling to 0" (-20 mg total) were identified as C, 52.7; H,4.25; N,3.16. ( (C6H&P}~Pt(CN)z,20 mp 332-335". Addition of ethyl ether to A reaction was run utilizing the same procedure but using excess the acetone filtrate gave an additional 0.12 g of an approximate 1 :2 and {(C6Ha)3P}2Pt(CN)~ sodium methoxide (2.05 mmol, formed from 0.047 g of sodium) mixture of [( (C6Hj)3P)~Pt(CNCH3)~11[1] (0.40 g, in methanol (30 ml) and [{(C6Hj)3P)2Pt(CNCH3)~][BF4] which was not separated further (identified by infrared spectra). Attempted Demethylation of [ ( (C6H&P} 2Pt(CNCH3)zI][BF4]. 0.41 mmol). The only product isolated from this reaction was [ ( (CsHj)3P}2Pt(CNCH3)C(OCH3)=NCHs][BF4] (0.33 g, 90% yield). The above compound (0.20 g, 0.20 mmol) was refluxed in benzene. Using the same procedure the following reactions were carried out. Little demethylation occurred after 8 hr; however, the desired Reaction of [ ( (C6H5),P)2Pt(CNCH3)2][BF4]2 and ethoxide gave change became significant after 24 hr. The solvent was then white crystalline [ { (C6H;),P }2Pt(CNCH3)C(OC~H:)=NCH3][BF4] removed and the resulting residue was dissolved in chloroform. (74% yield), which was purified by recrystallization from chloro(0.084 g, 50% The product, [ ( (CGH5)3P}2Pf(CNCH3)CNI[BF4] form-hexane: mp 192-193"; ir (Nujol mull) 2240 (m) ( C z N ) , yield), was obtained on addition of hexane: mp 240-242"; ir (CHCI3) 2273 (m) and 2152 cm-l (m) (C-N) and other bands (Nujol 1620 cm-l (s) (C=N), and other bands 1483 (m), 1437 (s), 1310 (vw), 1280 (vw), 1185 (w), 1152 (w), 1093 (s), 1050 (vs), 996 (w), mull) 1590 (vw), 1578 (vw), 1484 (m), 1435 (s), 1310 (vw), 1185 (vw), 747 (s), 705 (w), 692 (s), 610 (w), and 518 cm-l (s); pmr (CDC13) T 1160 (vw), 1096 (s), 1050 (vs), 997 (w), 740 (s), 708 (m), 687 (s), and 12 Hz, CNCH,), 7.25 ( t , J(Pt-C= 7.43 (t, J(Pt-C=N-CH,) 510 cm-l (s); pmr (CDCI,) T 7.47 (t, J(Pt-CH3) = 15 Hz, CNCH,) NCHa) = 8 Hz,