Inorganic Chemistry, Vol. 18, No. IO, 1979 2803
Metalation of t-Bu,P in PdH Complexes y-LiV205, the magnetic moments of the V4+ ions could not be accurately calculated from eq 4.
(4) B. Di Pietro, V. Filipeschi, M. Lazzari, G. Pistoia, and B. Scrosati in “Power Sources 6”, D. H. Collins,Ed., Academic Press, New York, 1977, nnr -527-16 r -( 5 ) D. W. Murphy, F. J. Di Salvo, J. N. Carides,and J. V. Waszczak, Mater. Res. Bull., 13, 1395 (1978). (6) J. 0.Besenhard and R. Sch6llhorn. J. Electrochem. Soc., 124,968 (1977). (7) P. Hagenmuller and A. Lesaicherre, C.R. Hebd. Seances Acad. Sci., 256, 170 (1963). (8) J. Galy and A. Hardy, Bull. SOC.Chim. Fr., 2808 (1964). (9) A. Hardy, J. Galy, A. Casalot, and M. Pouchard, Bull. Soc. Chim. Fr., 1056 (1965). (10) J. Gendell, R. M. Cotts, and M. J. Sienko, J . Chem. Phys., 37,220 (1962). (11) H. Kessler and M. J. Sienko, J . Solid State Chem., 1, 152 (1970). (12) C. R. Walk and J. S. Gore, Electrochemical Society Extended Abstracts, Electrochemical Society Meeting, Toronto, Canada, May 11-16, 1975, Paper No. 27. (13) G. Brauer, Ed., “Handbook of Preparative Inorganic Chemistry”, 2nd ed.. Academic Press. New York. 1965. D 1270. (14) D. 16,W. 3027 Murphy, (1977). C. Cros, F. J. Di Salvo,and J. V. Waszczak, Imrg. Chem.,
Conclusion The use of LiI in acetonitrile at room temperature as a mild reducing reagent has allowed the preparation and characterization of pure Li,V205 bronzes distinct from those prepared at high temperatures. These low-temperature phases appear to be structurally more similar to V205 than are the hightemperature phases. However, the electronic nature of the low-temperature phases appears to be quite similar to that of the high-temperature phases. These studies indicate that V205 should be regarded as a three-dimensional framework host for lithium rather than a two-dimensional vdW host. This view leads to the conclusion that strengthening the V-0 framework prevent extensive bond breaking under more reducing (15) conditions while still allowing facile lithium i n c ~ r p o r a t i o n . ~ ~ (16) An example is afforded by LixV6OI3bronzes., Acknowledgment. The authors are indebted to H. Gug(17) (18) genheim for the V20s crystals and to S, C, Abrahams and J, L. Bernstein for the Weissenberg photographs. (19) . , Registry No. LiV205, 12162-92-4; V205, 1314-62-1; LiI, (20) 10377-51-2. (21) References and Notes (1) See, for example, “Nonstoichiometric Compounds”, R. Ward, Ed., American Chemical Society, Washington, D.C., 1963. . (2) M. S. Whittingham, J . Electrochem. Soc., 123, 315 (1976). (3) D. W. Murphy, P. A. Christian, F. J. Di Salvo, and J. N. Carides, J . Electrochem. SOC.,126,,497 (1979).
(22) (23) (24) (25)
A Bystrom, K. A. Wilhelmi, and 0.Brotzen, Acta Chem. Scand., 4, 11 19 (1950).
H. G. Bachmann, F. R. Ahmed, and W. H. Barnes, 2. Krisfallogr.,
Kristallgeom., Kristallphys., Kristallchem., 115, 110 (1961). L.D. Frederickson and D.M. Hausen, Anal. Chem., 35,821 (1963). M. Pouchard,A. Casalot, J. Gab, and P. Hagenmuller,Bull. SOC.Chim. Fr., 4343 (1967). H. Mever. A. Weiss. and J. 0. Besenhard. Mater. Res. Bull... 13.. 913 (1978):
’
A. Lerf and R. Schollhorn, Inorg. Chem., 16, 2950 (1977). The bronze LiI+,V308has been reported by R. Schollhorn, F. KleinReesink, and R. Reimold, J . Chem. SOC.,Chem. Commun.. 398 (1979), to undergo ion-exchange reactions and hydration. This behavior is consistent with that expected for a vdW framework. S: Kachi, K. Kosuge, and H. Okinaka, J. SolidState Chem.,6,258 (1973). J. C. Bonner and M. E. Fisher, Phys. Rev. A , 135, 640 (1964). M. E. Lines, J . Appl. Phys., 40, 1352 (1969). D. W. Murphy and P. A. Christian, Science, in press.
Contribution from the Guelph-Waterloo Centre for Graduate Work in Chemistry, Guelph Campus, University of Guelph, Guelph, Ontario, Canada
Facile Intramolecular Metalation of Tri- ferf -butylphosphine in Palladium(I1) Hydride Complexes H. C. CLARK,* A. B. GOEL, and S. GOEL Received December 15, 1978 Palladium(I1) hydrides (tr~ns-PdH(X)(P-t-Bu~)~ (I) when X = CI or CF3COO),prepared by the oxidative addition of HX to bis(tri-tert-butylphosphine)palladium(O), have been shown to undergo facile intramolecular metalation in solution producing complexes of the type PdX(P-t-Bu2CMe2CH2)(P-t-Bu3)(€1). These complexes (11) when kept in dichloromethane or benzene solution lose 1 molar equiv of phosphine to give the bridged dimeric complexes [PdX(P-t-Bu2CMe2CH2)I2 (111). Complex 111 (where X = Cl) is also obtained from the reaction of tri-tert-butylphosphinewith PdC12(NCPh)2in CH2C12. Sodium borohydride reduction of complexes I, 11, or 111in ethanol invariably produces bis(tri-tert-butylphosphine)palladium(O). Reaction of n-butyllithium with P ~ H ( X ) ( P - ~ - BinUn-hexane ~)~ also gives the palladium(0) complex. The chloride bridge of complex I11 can be split by a variety of ligands (e.g., pyridine, Ph3As, Ph3P,Et3P, Ph2MeP,i-Pr3P,t-Bu2MeP,Cy3P, and (C,H,),P) to give mononuclear species of the type trans-PdC1(P-t-Bu2CMe2CH2)(L). Introduction The metalation of bulky phosphines in platinum(I1) and palladium(II) dichlorides has been widely studied, by Shaw and co-workers,’J It has been suggested that the process is promoted by the facile formation of five-membered rings., Compared with the intramolecular metalation of aromatic carbon atoms in coordinated phosphines, there are only a few examples known for purely ’aliphatic carbons.2$MFurthermore, it has been reported4 that the n-propyl groups in the complexes PtC12(P-t-Bu-n-Pr2)2and P ~ C ~ , ( P - ? - B U ~ -are ~ - mktalated P~)~ only when the complexes are heated for several hours, whereas similar palladium comp1eTes cannot be metalated under similar conditions. Although, recently, the intramolecular metalation of tert-butylphosphine in the complex’ PdClz(P-t-Bu3)2has been reported,6 no metalation process has been reported for the
corresponding palladium(I1) hydrides. Palladium(I1) hydride trans-PdH(X)(P-t-BU3)2 (where = c1 Or CF,COO) of sufficient stability to examine metalation pro@%3eShave recently been prepared by Otsuka et al? We now wish to report that these Palladium(II) hydrides undergo rapid intramolecular metalation with the elimination of hydrogen. Results and Discussion The preparation of bis(tri-tert-butylphosphine)palladium(O) by the reaction of tert-Bu3P with (q3-C3H5)Pd($-C5H5)has been reported previously.8 The latter reactant must be obtained from the reaction of thallium cyclopentadienide with allylpalladium chloride, which makes that method time consuming. We have now prepared (~-Bu,P)~P~O in about 70% yield by the reaction of sodium naphthalenide with a mixture of PdC12(NCPh)2or (COD)PdC12 and P-t-Bu, in THF. The
0020-1669/79/ 1318-2803$01.OO/O 0 1979 American Chemical Society
2804 Inorganic Chemistry, Vol. 18, No. IO, 1979
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Figure 1. Proton NMR spectra of the complex PdH(Cl)(t-Bu,), in 0 benzene, at various time intervals, showing metalation to PdC1cr, b! (CH2C;H6P-t-Bu2)(P-t-Bu;)(11): (A) fresh solution of PdH(C1)u ( P - ~ - B u ~(B) ) ~ solution , after 2 h, (C) solution after 12 h, (D) solution 6 after 40 h, (E) solution after 4 days, (F) solution after 5 days giving pure complex 11. G is the spectrum of pure Pd2C12(CH2C3H6P-t-Bu2)2. I X
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-
These complexes are characterized by infrared (v(Pd-H) = 2190-2215 cm-*), proton NMR [Pd-H: 6 -(16.2-18.3) (t); J(P-H) = 4.3-6.9 Hz], and 31PN M R (6 -(67-79)) spectra (Table I). Although these complexes (I) are quite stable in the solid state, they undergo intramolecular metalation within a few hours when kept in benzene or methylene chloride solutions to give I1 (eq 3). trans-PdH(X)(P-t-B~,)~ I PdX(P-t-Bu2CMe2CH2)(P-t-Bu3) + H, (3) I1 This metalation process has been followed by observing the proton N M R spectrum where the conversion of the original triplet due to tert-butyl groups into three sets of doublets due to metalated complexes is clearly observed (Figure 1). Completion of the metalation reaction is indicated by the loss of the 'H NMR resonance due to the hydride proton as well as by the disappearance of v(Pd-H) at (2190-2210 cm-') in the infrared spectrum. The rate of metalation is markedly enhanced by the addition of a small amount of alcohol and we find that the rate of metalation of the chloro complex is faster than that of the trifluoroacetate analogue. For example, complex I with X = C1 in benzene solution containing a small amount of alcohol was converted into the corresponding complex I1 within 0.5 h, while the similar metalation process in the complex I with X = CF3CO0 was completed in 2-3 h. The complexes I1 are characterized by their proton N M R spectra which show the expected three sets of doublets due to protons of Pd-P-t-Bu,, Pd-P-t-Bu,, and P-CMe2 groups. In particular, the spectrum of [Pd(CF,COO)(P-tBu2CMe2CH2)(P-t-Bu3)]shows signals at 6 1.28 (P-t-Bu,),
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Inorganic Chemistry, Vol. 18, No. 10, 1979 2805
Metalation of t-Bu,P in PdH Complexes Scheme Ia
CPdCI(P- C ) ( A $ P h s ) I
Key to reaction conditions: (i) sodium naphthalenide, NaC,,H,, reaction in THF at 20 “C; (ii) reaction in CH,Cl, for - 2 h ; (iii) HC1 reaction in benzene or n-hexane; (iv) NaBH, reduction in C,H,OH; (v) BuLi reaction in n-hexane; (vi) metalation in benzene solution; (vii) NaBH, reduction in C,H,OH; (viii and ix) in CH,Cl, or benzene in the presence of alcohol; (x) AgX; (xi) tertiary phosphines, PR,, = PEt,, PPh,, PPh,Me, P-i-Pr,, PCy,, P-t-Bu,Me, P(o-tolyl),; (xii) pyridine; (xiii) triphenylarsine.
6 1.45 (P-t-Bu2), and 6 1.38 (P-CMe,), in the ratio 9:6:2, with J(P-C-C-H) = 12.2, 14.6, and 15.0 Hz, respectively (Table I). The proton signals of the C-CH2-Pd group could not be observed and are probably masked by other strong signals. The 31PN M R spectrum in benzene shows two singlets at 6 +13.8 (due to metalated phosphine) and 6 -63.9 (due to unmetalated phosphine) (Table I). These complexes (11) do not show coupling between the two phosphorus nuclei, which may suggest that the coordinated phosphine in the complexes is labile.6 These complexes (11) are soluble in hexane and could be crystallized from cold hexane. Interestingly, when these complexes were allowed to stand in a mixture of benzene/ hexane for 1 day, loss of 1 equiv of P-t-Bu, occurred (followed by NMR), followed by rearrangement to give halogeno- or acetato-bridged dimeric complexes Pd2X2(P-t-Bu2CMe2CH2), (111) (es 4).
2PdX(P-t-Bu2CMe,CH2)(P-t-Bu3) I1 Pd2X2(P-t-Bu2CMe2CH2)z+ 2P-t-Bu3 (4) I11 X = C1, CF3COO This reaction is the reverse of the bridge splitting reactions reported earlier by Shaw and c o - w o r k e r ~for ~ . ~several other bridged complexes of platinum and palladium. The proton N M R spectra of complexes I11 invariably show three sets of doublets due to protons of Pd-P-t-Bu,, P-CMe2, and C-CH2-Pd groups in a 9:3:1 ratio. The 31PNMR spectra contain only one singlet at about 6 +13 indicative of metalated phosphine (Table I). Shaw has suggested that the intramolecular metalation process in complexes MX2(PR3), (M = Pd, Pt) involves oxidative addition of 2C-H or 3C-H to the metal, followed by elimination of hydrogen halide. The acidic nature of 2C-H in the phosphine has been demonstrated by Kiffen et al.,’O who have reported that complexes of the type Pt2C14L2(L = nBu3P, n-Pr3P, and t-Buz-n-PrP) undergo hydrogen-deuterium exchange at the C-3 position of n-butyl or n-propyl groups and also at the C-2 position of the tert-butyl groups. Otsuka et al.,’ in their structure determination of Pd(P-t-Bu,Ph),, have observed a short distance (2.70 %I) between Pd and the hydrogen of the tert-butyl group. They infer an interaction between Pd and the hydrogen of the tert-butylphosphine. Such an interaction is probably also present in P t l H c l ( P - t - B ~ , ) ~ which contains the more bulky P-t-Bu, !igand. Moreover, the occurrence of such an interaction combined with the presence of the hydridic ligand” and with the steric crowding about Pd suggests that intramolecular metalation may well occur
as a consequence of the direct facile elimination of molecular hydrogen rather than by oxidative addition of C-H to Pd-H followed by H 2 elimination. The conversion of complexes I1 into the dimeric bridged complexes I11 is presumably a consequence of the steric crowding at Pd in 11, resulting from the presence of both the bidentate, metalated phosphine ligand and the monodentate tertiary phosphine or arsine ligand. Dissociation of the monodentate ligand relieves the steric crowding and gives the more stable 111. Bridge-Splitting Reactions of the Complex [Pd2C12(P-C)2] (111), Where (P-C) = CH2C3H6P-t-Bu2 The chlorine bridges of the binuclear compound I11 are readily cleaved by various ligands to give the mononuclear complexes [Pd(Cl)(P-C)L] (IV). Similar bridge-splitting reactions of other halogen-bridged binuclear platinum( 11) and palladium(I1) complexes have previously been r e p ~ r t e d . ~ J ~ - ’ ~ The present reactions are summarized in Scheme I, and analytical, ‘H NMR, and 31PN M R data are given in Table 11. Complex IV with L = pyridine shows, in its infrared spectrum, a band due to u(Pd-C1) at -280 cm-’ indicative of trans-[PdCl(P-C)py] .3 Its proton N M R spectrum shows three sets of sharp doublets at 6 1.52, 1.44, and 0.95 ppm in ratios 9:3:1 due to t-Bu,-P, C-Me,, and C-CH,-Pd (J(P-H) = 14.0, 13.8, and 4.0 Hz, respectively). The 31P N M R spectrum also shows only one singlet at 6 +13.1 ppm which supports the presence of only one isomer. The addition of a tertiary phosphine, R3P (where R3P = Et3P, Ph3P, Ph,MeP, i-Pr,P, Cy3P, t-Bu,MeP, or (C,H,),P), to a solution of [Pd,Cl,(P-C),] in benzene also gave complex IV with a trans configuration. This geometry is indicated by the 31PNMR spectra (Table 11) which show two doublets due to each nonequivalent phosphorus nucleus, with a large coupling constant ,J(P-P’) (402-440 Hz) characteristic of mutually trans phosphorus atoms., For example, the 31PNMR spectrum of the complex [PdCl(P-C)(Ph,P)] shows two sets of doublets at 6 +19.6 ppm (due to metalated phosphorus) and 6 -19.2 ppm (due to unmetalated P of Ph3P) with ,J(P-P’) = 422 Hz. The ‘H N M R spectral parameters for these complexes [PdCl(P-C)(R,P)] (IV) are given in Table 11. The signals due to di-tert-butyl protons are observed as a double doublet due to splitting by both phosphorus nuclei. For example, the spectrum of complex IV (R3P = Ph3P) shows a double doublet due to the tert-butyl group at 6 1.64 ppm with ,J(P-H) = 12.8 Hz and 5J(P-H) = 1.1 Hz. However, the methyl protons (P-CMe,) show only one doublet at 6 1.34 (“J” = 3J(P-H) 5J(P-H) = 12.5). The methylene protons
+
2806 Inorganic Chemistry, Vol. 18, No. 10, 1979
Clark, Goel, and Goel
Inorganic Chemistry, Vol. 18, No. 10, I979 2801
Metalation of t-Bu3P in PdH Complexes
at room temperature. However, other manipulations such as purifications were carried out under open conditions. Tetrahydrofuran (THF) was dried and distilled over NaA1H4; other solvents used were of spectroanalytical grade and used without further purification. (Benzonitrile)palladium(II) dichloride, PdC12(NCPh)2,'8 and allylpalladium(I1) cyclopentadiene, (q3-C3H,)Pd(qS-CSHs),19were prepared as reported earlier. Bis(tri-tert-butylphosphine)palladium, ( ~ - B u ~ P ) was ~ P ~prepared , by the reaction of t-Bu3P with allylpalladium(I1) cyclopentadiene in hexane at room temperature.* Elemental analyses were performed by M.H.W. Laboratories, Phoenix, Ariz. Proton N M R spectra were recorded on a Varian A-60 or a Bruker HFX-90 Fourier transform spectrometer. 31PN M R not observed in the tertiary phosphine complexes. This may spectra were recorded on a Bruker PW-60 Fourier transform be due to the weaker coordination tendency of the arsine spectrometer. Phosphoric acid (85%) was used as external standard; compared with that of a phosphine. No complex formation those 31Pchemical shifts to high field (low frequency) are reported was observed when a mixture of Ph3Sb was added to a benzene as positive. Infrared spectra were obtained on a Beckman IR-12 or CH2C12 solution of [Pd2C12(P-C)2]. The 31P N M R spectrophotometer. Melting points were determined with a Galspectrum of the resulting solution at various temperatures from lenkamp melting point apparatus in glass capillary tubes. -60 to +60 OC showed the presence of only unreacted Physical, analytical, and spectroscopic data are given in Table I. [Pd2C12(P-C),]. Similarly, no complex of the type [PdPreparation of (t-Bu3P)Pdofrom the Reaction of PdC12(NCPh)2 Cl(P-C)(CO)] could be obtained by bubbling carbon monoxide with Sodium Naphthalenide in THF. To a well-stirred slurry of PdC12(NCPh)2(6.0 mmol) and t-Bu3P (12 mmol) in T H F (20 mL) into a solution of complex IV in benzene. was added dropwise a solution of sodium naphthalenide (1 2.0 mmol) The stability of complexes IV, obtained by the bridgein T H F (10 mL) under nitrogen. The reaction mixture was stirred splitting reactions of I11 with tertiary phosphines, depends on at room temperature for -30 min and the solvent was removed in the size of the tertiary phosphine and follows the trend Et3P vacuo. The residue was extracted with 50 mL of n-hexane and filtered Ph2MeP Ph3P > i-Pr3P > Cy3P t-Bu2Me > t-Bu3P. under nitrogen. The complex ( Z - B U ~ P ) ~was P ~ Ocrystallized in -70% Thus, compared to complexes PdCl(P-C)(L) (where L = Et3P, yield upon cooling the concentrated solution. Anal. Calcd for ( t Ph2MeP, Ph3P), which are quite stable in the solid state as B U ~ P ) ~C, P ~56.4; : H, 10.67. Found: C, 56.5; H, 10.71. The proton well as in solution, the complexes of IV (I, = Cy3P, t-Bu2Me, NMR spectrum shows a triplet at 6 1.51 ppm due to tert-butyl protons or t-Bu3P) are less stable and tend to dissociate in solution, with J(P-H) = 12.0 Hz. giving the starting dimeric complex I11 over 1-5 days. These Oxidative Addition of Protic Acids HX (X = C1 or CF3COO) to P(~-Bu,P)~P~O. To a solution of ( ~ - B U ~ P )(2 ~ Pmmol) ~ ' in hexane observations support our earlier statement that the conversion (-50 mL) was added slowly with continuous stirring a solution of of the complex PdCl(P-C)(P-t-Bu3) (11) to Pd2C12(P-C)2is hydrogen chloride prepared by the reaction of acetyl chloride (2 mmol) driven by the steric crowding at Pd in 11, which is relieved by with methanol. The reaction mixture was stirred for 15 min and dissociation of the bulky P-t-Bu3 ligand. the solvent was removed in vacuo; trun~-PdH(Cl)(t-Bu,P)~ was In the reaction of sodium borohydride with PtH(Cl)(Pobtained as colorless crystals in almost quantitative yield. t-B~3)2,we have observed the formation of the stable ditr~ns-PdH(CF~C00)(t-Bu~P)~ was prepared similarly by the hydridoplatinum complex PtH2(P-t-B~3)215 (V). However, in reaction of CF3COOH with the palladium(0) complex. Analyses and the reaction of P ~ H ( C ~ ) ( P C with Y ~ )NaBH4, ~ Green et a1.16 spectroscopic data are given in Table I. obtained the borohydride complex Metalation Reactions of Complexes P ~ H ( X ) ( ~ - B U , (X P ) ~= Cl or CF,COO) in Benzene. The internal metalation of the complexes was H followed by recording the 'H N M R spectra of the solutions at various / \ (CY,P),HPd BH, time intervals, a t room temperature. When the metalation was \ / complete, the solution was transferred into a flask, benzene was H removed, and the resulting pale yellow solid was extracted with hexane to give light, pale yellow crystals on cooling. The analytical data for VI these crystals corresponded to the formula PdX(CH2C3H6P-tIn an effort to prepare an analogous complex of type V or VI, Bu2)(P-t-Bu,). The complete conversion of the complexes PdHwe attempted the reduction of P ~ H ( C I ) ( P - Z - B U with ~ ) ~NaBH4 (X)(~-BU,P)~ into the corresponding PdX(CH2C3H6P-t-Bu2)(t-Bu3P) in ethanol but found, surprisingly, that the palladium(0) took place over 5 days and 1 week, respectively, for X = chloride and trifluoroacetate. Figure 1 shows the 'H N M R spectra for the complex P d ( p - t - B ~ is ~ )obtained. ~ metalation reaction of p d H ( c l ) ( t - B ~ , P )at~ different time intervals ethanol in benzene. P d H ( c l ) ( p - t - B ~ ~ )NaBH4 ~ Preparation of PdX(CH2C3H6P-t-Bu2)(t-Bu3P). In a typical p d ( P 4 - B ~ ~ )NaCl ~ reaction, to a solution of PdH(Cl)(t-Bu3P)* (1 mmol) in benzene (-25 mL) was added a few drops of ethanol. The colorless solution turned Similarly, in the reaction of PdCl(P-t-Bu2CMe2CH2)(Pyellow immediately. After 30 min the solvent was removed under t-Bu3) (11) with NaBH4, P d ( p - t - B ~ is ~ )also ~ obtained, alreduced pressure and the residue obtained was extracted with hexane. though the similar reaction of the platinum analogue produced The extract on drying gave a pale yellow crystalline solid. The 'H PtH2(P-t-Bu3)2 and PtH(P-t-Bu2CMe2CH2)(P-t-Bu3).17 N M R spectrum and analyses of this product showed it to be Palladium analogues of V and VI may be transient products P ~ C ~ ( C H ~ C ~ H ~ P t-Bu3P). -~-BU~)( of the above reactions but then undergo reductive elimination The complex Pd(CF3COO)(CH2C3H6P-t-Bu2)(t-Bu3P) was obto give the stable zerovalent palladium product. In support tained similarly from its hydride in 2-3 h under similar conditions. of this, we have observed that when n-butyllithium is allowed Preparation of [Pd2X2(CH2C3H6P-t-Bu2)2] (X = C1 or CF3COO). to react with a solution of P d H ( c l ) ( t - B ~ in ~ )n-hexane, ~ the (A) From [PdX(CH2C3H,P-t-Bu)z(t-Bu3P)]. In a typical reaction, only stable product was bis(tri-tert-buty1phosphine)palladia solution of [PdC1(CH2C3H$-t-Bu2)(t-Bu3P)](2 mmol) in a mixture of benzene and n-hexane was left overnight for slow crystallization. um(O), p d ( P - t - B ~ ~and ) ~ , not the expected PdH(n-Bu)(PThe unmetalated phosphine was cleaved and the resulting pale yellow t-B~3)2. The same zerovalent palladium complex was also crystals were identified as Pd2C12(CH2C3H6P-t-Bu2)2.Other obtained in low yield in the reaction of the dimeric complex complexes were obtained similarly. I11 with NaBH4. (B) By the Reaction of t-Bu3Pwith (PhCN)2PdC12in CH2C12. To Experimental Section a solution of (PhCN)2PdC12 (2 mmol) in CH2C12 (-40 mL) was added slowly t-Bu,P (2 mmol) with continuous stirring. The reaction Reactions involving tri-tert-butylphosphine and the oxidative mixture was further stirred for -2 h, during which the color turned reactions of (t-Bu3P),Pd0 with acids were carried out under nitrogen
(C-CH2-Pd) are observed as a triplet due to the splitting by both phosphorus nuclei at 6 0.71 with J(P-H) = 11.8 Hz. For complex IV with L = AsPh3 the 31PN M R spectrum shows a strong singlet at 6 +16.2 ppm and a weaker singlet at 6 +12.7 ppm. The former is due to the metalated phosphorus of the pure complex and the weak singlet at 6 -12.7 ppm is due to dimeric [Pd2C12(P-C)2]suggesting that the complex dissociates in solution (eq 5). This dissociation is 2[PdCl(P-C)(Ph,As)] + [Pd2C12(P-C)2] + 2Ph3As (5)
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-
+
2808 Inorganic Chemistry, Vol. 18, No. 10, 1979 dark brown-red. The solvent was removed and the blackish mass obtained was extracted with benzene. The complex was crystallized from a benzeneln-hexane mixture to give pale yellow crystals identified as [Pd2C12(CH2C3H6P-t-B~2)2]. Preparation of [PdCl(CH2C3&P-t-Bu2)(L)](L = PEt,, PPh,, PCy,, PPh2Me,t-PBu2Me, P(o-CH3C6H4),i-PF’r3,and AsPh,). In a typical reaction to a solution of [Pd2C12(CH2C3H6P-t-B~2)2] (0.2 mmol) was added PPh, (0.4 mmol) and the reaction mixture was stirred overnight. Benzene was removed, and the white solid was crystallized from a benzeneln-hexane mixture. All other complexes were prepared similarly. Physical, analytical and spectroscopic data are given in Table 11. Reaction of [Pd2C12(CH2C3H6P-t-B~2)2] with Pyridine. To a solution of [Pd2C~2(CHzC3H6P-t-Buz)z] (0.15 mmol) in benzene was added pyridine (0.45 mmol) and the reaction mixture was refluxed for -2 h. The solvent was removed in vacuo, and the white solid was crystallized from a benzeneln-pentane mixture. Reaction of KaBH4 with PdH(Cl)(t-Bu,P), (I), PdCl(P-C)(P-t-Bu,) (III), and [Pd2C12(P-C),](111) [(P-C) = t-BuzPCMe2CH2].‘To a solution of PdH(Cl)(t-Bu,P), (I) (1.0 mmol) in dried ethanol was added excess of NaBH4 (5.0 mmol) and the reaction mixture was stirred for -2 h. The ethanol was removed under reduced pressure and the residue was extracted with n-hexane. On cooling of the n-hexane solution, white crystals were obtained in 65% yield. Physical, analytical, and spectroscopic data for this product showed it to be (~-BU~P)~P~O. Similarly, the reaction of NaBH, with PdCl(P-C)(t-Bu,P) (11) or [PdzC1z(P-C)2](11) gave the complex ( ~ - B U , P ) ~ Pin~ O 62 and 30% yields, respectively. Reaction of P ~ H ( C I ) ( ~ - B U ,with P ) ~ BuLi. To a suspension of P ~ H ( C I ) ( ~ - B U , (1.0 P ) ~ mmol) i n dry n-hexane (30 mL) was slowly added a solution of n-BuLi (1.1 mmol) in n-hexane with continuous stirring. The reaction mixture was stirred overnight and the contents were filtered. The filtrate was concentrated and cooled, and the white crystals thus obtained were identified as (t-Bu3P),Pd0.
Acknowledgment. T h e continued financial support of this work by the N a t u r a l Sciences a n d Engineering Research
Brown et al. Council of C a n a d a is greatly appreciated. Registry No. trun~-PdH(Cl)(t-Bu~P)~, 63166-71-2; trans-PdH( C F ~ C O O ) ( ~ - B U ~62922-33-2; P)~, PdCI(P-C)(t-Bu,P), 63230-80-8; P~(CF,COO)(P-C)(~-BU~P), 69721- 10-4; Pd2CI,(P-C),, 69393-58-4; Pd,(CF3C00)2(P-C),, 69796-89-0; PdCI(P-C)(Et,P), 7 1000-98-1; PdC1(P-C) (Ph,P), 7 1000-99-2; PdCl(P-C) (Ph,MeP), 7 100 1-00-8; PdCl(P-C)(t-Bu2MeP), 7 1031-53-3; PdCI(P-C)(i-Pr,P), 7 1001-01-9; PdCI(P-C)(Cy,P), 7 1001-02-0; PdCl(P-C)( (C,H,)P,), 7 1001-03-1; PdCI(P-C)(Ph,As), 71001-04-2; PdCl(P-C)(py), 71001-05-3; PdC12(NCPh)2, 14873-63-3;(t-Bu,P)zPd, 53199-31-8;HCI, 7647-01-0; CF,COOH, 76-05-1.
References and Notes (1) C. E. Jones, B. L. Shaw, and B. L. Turtle, J . Chem. Soc., Dalton Trans., 992 (1974), and references therein. (2) H. D. Empsall, P. N.Heys, and B. L. Shaw, J . Chem. Soc., Dalton Tram., 257 (1978); H. C. Empsall, E. M. Hyde, and B. L. Shaw, ibid., 1690 (1975). (3) A. J. Cheney and B. L. Shaw, J . Chem. Soc. A , 754, 860 (1972). (4) A. J. Cheney, B. E. Mann, B. L. Shaw, and R. M. Slade, J. Chem. SOC. A , 3833 (1971). ( 5 ) R. Mason, M. Textor. N. AI-Salem, and B. L. Shaw, J. Chem. Soc., Chem. Commun., 292 (1976). (6) R. G. Goel and R. G. Montemayor, Inorg. Chem., 16, 2183 (1977). (7) T. Yoshida and S. Otsuka, J . A m . Chem. Soc., 99, 2134 (1977). (8) S. Otsuka, T. Yoshida, M. Matsumoto, and K. Nakatsu, J . A m . Chem. Soc., 98, 5850 (1976). (9) D. G. Gill, B. E. Mann, and B. L. Shaw, J. Chem. Soc., Dalton Trans., 270 (1973). (1 0) A. A. Kiffen, C. Masters, and L. Raymond, J . Chem. Soc., Dalion Tram., 853 (1975). (11) J. Chatt, Proc. Chem. Soc., London, 318 (1962). (12) G. Booth, Ado. Inorg. Chem. Radiochem., 6 , 1 (1964). (13) J. Chatt, M. L. Vallarino, and L. M. Venanzi, J . Chem. Soc.,2496 (1957). (14) B. Crociani, T. Boschi, R. Pietropaolo, and U. Belluco, J . Chem. Soc. A. 531 (1970). (1 5) H: C. Ciark, A. B. Goel, R. G. Goel, and W. 0. Ogini, J . Organomet. Chem., 157, C16 (1978). (16) M. L. H. Green, H. Munakata, and T. Saito, J . Chem. Soc. A , 469 (1971). (17) H. C. Clark and A. B. Goel, to be submitted for oublication. (18) D. Drew and B. J. R. Doyle, Inorg. Synth., 13, 4? (1972) (19) B. L. Shaw, Proc. Chem. Soc., London, 247 (1960).
Contribution from The Donnan Laboratories, Liverpool University, Liverpool L69 3BX, United Kingdom, and The Department of Inorganic Chemistry, Oxford University, Oxford OX1 3QR, United Kingdom
Synthesis and Characterization of Bis[~-[bis(diphenylphosphino)methane]]-~-methylene-dichloro~iplatinum and Related Complexes. Insertion of Methylene into a Pt-Pt Bond MICHAEL P. BROWN,*la J O H N R. FISHER,la RICHARD J. PUDDEPHATT,laxCand KENNETH R. SEDDONlb
Received January 19, 1979 Reaction of the diplatinum(1) complex [Pt2C12(p-dppm),],dppm = bis(diphenylphosphino)methane, with CH2N2,SOz, and S8 gives the adducts [Pt2C12(p-X)(pdppm),]where X = CH2, S02, or S, respectively. Where X = CHI, this represents the first example of simple addition of methylene to a metal-metal bond. Reaction of [Pt2H2(~-H)(fi-dppm)2] [PF,] with MeSH gives [Pt2H2(fi-SMe)(r-dppm)2][PF,]. The structures of the complexes were deduced primarily with ‘H and 31P N M R spectroscopy, and it is concluded that Pt-Pt bonding is absent or very weak in all cases.
Introduction Recently we have shown that platinum, when complexed with bis(dipheny1phosphino)methane (dppm), readily forms a number of binuclear complexes in which the ligand adopts An example is [Pt2C12(p-dppm),] (I), a n a bridging air-stable complex containing two directly bonded platinum atoms in t h e formal oxidation state of P h 2 PJ
CI-
I
H2\P P h2
I
Pt-
Pt-CI
I
I
Ph 2 P\CH2/PPh2
I
0020-1669/79/1318-2808$01.00/0
T h e platinum-platinum bond in this complex may, a s we have previously shown, be reversibly protonated4 or undergo reversible addition of carbon monoxide3q5 to give complexes in which t h e added group, viz., H+ or CO, bridges t h e two platinum atoms. T h e related ligand bis(diphenylarsin0)methane ( d p a m ) also gives a similar platinum-carbonyl complex, namely, [Pt2C1,(p-Co)(p-dpam),l, although t h e d p a m analogue of I is ~ n k n o w n . T~ h e ability of d p p m and similar ligands t o promote t h e formation of binuclear complexes by bridging two atoms rather t h a n chelating to one is demonstrated by t h e chemistries of other metals. Indeed, recent publications show that a concurrent a n d independent investigation of palladium gave remarkably similar results. T h u s X-ray structural studies show that [Pd2Br2(pL-dppm),l6,’
0 1979 American Chemical Society
