Organometallics 1995, 14, 3531-3538
3531
Alkynylcopper(1)Complexes with PPh3 Ligands. Preparation, Structure, and Alkynyl Ligand Transfer to Palladium(I1)Complexes Kohtaro Osakada," Tadashi Takizawa, and Takakazu Yamamoto" Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan Received January 23, 1995@ Reactions of copper alkoxidk complexes Cu(OCH(CF3)z)(PPh3)3,Cu(OCHPhz)(PPh&, and [Cu(OPh)(PPh3)& with HCsCCOOR (R = Me, Et, tBu) give alkynyl copper complexes formulated a s Cuz(C=CCOOR)s(PPh& (1, R = Me; 2, R = Et; 3, R = tBu). The 'H,I3C{'H}, and 31P{'H}NMR spectra agree with the structures containing two bridging alkynyl ligands t h a t are coordinated to Cu(PPh3) and to Cu(PPh3)z units. The copper alkoxide complexes react with alkynes HC=CSiMe3, H C I C P h , and HCsCCsH4-p-Me to give alkynylcopper(1) complexes [Cu(C=CR)(PPh3)14 (4, R = SiMe3; 5, R = Ph; 6, R = CsH*-p-Me). X-ray crystallography of 4*EtzO reveals a molecular structure containing a cubane-like core composed of four copper(1) centers bridged by four alkynyl ligands, each of which is coordinated to three Cu centers as a p3-v1:q1:q'-ligand. Complex 5 undergoes ligand substitution by H C W C O O E t in the presence of PPh3 to give 2. Complexes 1-6 react with PdC12(PEt3)2to cause alkynyl ligand transfer from Cu to Pd. Reactions of 1-3 with 0.5 equiv of PdClz(PEt3)~in the presence of PPh3 give trans-Pd(C~CCOOR)z(PEt3)zaccompanied by formation of CuCl(PPh3)3. Complex 4 undergoes alkynyl ligand transfer to give trunsPdCl(C=CSiMe3)(PEt3)2exclusively, while similar reactions of 5 and 6 give mixtures of trunsPd(C=CAr)2(PEt& and trans-PdCl(C2CAr)(PEt3)2(Ar = Ph, CsH4-p-Me).
Introduction Characterization of several alkynylcopper(1) complexes by X-ray crystallography has been recently reported t o reveal multinuclear structures with bridging alkynyl ligands bonded to two or three Cu No crystal structures of copper complexes with nonbridging alkynyl ligands have been reported, while nonbridging coordination of the alkynyl group is very common among the other transition metals.6 Complexes of group 6-10 transition metals with bridging alkynyl ligands have a pz-q1:q2-or p3-r,+q2:q2-coordination m ~ d e , while ~ - ~ pzql:+ or p3-q1:q1:+coordination of the bridging alkynykligand is often observed in structural studies of akynylcopper(1)complexes (Scheme 1). Alkynylcopper(1)complexes are of structural interest Abstract published in Advance ACS Abstracts, June 15, 1995. (1)Corfield, P. W. R.; Shearer, H. M. M. Acta Crystallogr. 1966,21, 957. (2)( a )ten Hoedt, R. W. M.; Noltes, J. G.; van Koten, G.; Spek, A. L. J.Chem. Soc., Dalton Trans. 1978,1800. ( b )Knotter, D. M.; Spek, A. L.; Grove, D. M.; van Koten, G. Organometallics 1992,11, 4083. ( c ) Knotter, D. M.; Grove, D. M.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. J. Am. Chem. SOC.1992,114,3400. (3)Naldini, L.; Demartin, F.; Manassero, M.; Sansoni, M.; Rassu, G.; Zoroddu, M. A. J. Organomet. Chem. 1986,279,C42. ( 4 ) ( a ) Gamasa, M. P.; Gimeno, J.; Lastra, E.; Solans, X. J. Organomet. Chem. 1988, 346, 277. tb) Diez, J.; Gamasa. M. P.; Gimeno, J.;Lastra, E.; Aguirre, A.; Garcia-Granda, S. Organometallics 1993,12,2213. (5)Edwards. A. J.; Paver, M. A.; Raithby, P. R.; Rennie, M.-A.; Russell, C. A.; Wright, D. S. Organometallics 1994,13,4967. (6)Nasta, R. Coord. Chem. Rev. 1982,47,89. (7)Carty, A. J. Pure Appl. Chem. 1982,54,113. ( 8 )Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. Rev. 1983,83, 203. (9)( a ) Akita, M.; Terada, M.; Oyama, S.; Moro-oka, Y. Organometallics 1990,9,816. ( b )Akita, M.; Ishii, N.; Takabuchi, A,; Terada, M.; Tanaka, M.; Moro-oka, Y. Organometallics 1994, 13, 258 and references therein.
0276-7333i9512314-3531$09.00/0
Scheme 1. Coordination Mode of the Bridging Alkynyl Ligand
due to the above characteristics peculiar to alkynylcopper bonding as well as to versatile multimetallic structures containing three t o six Cu centers bridged by alkynyl ligands. Chemical properties of alkynylcopper complexes are also intriguing since they are involved as the intermediates in copper complexes that promote C-C bondforming reactions. Reports on copper complexes that promote homocoupling of alkyneslOJ1are fewer than reports on the coupling reaction using alkyl, aryl, and vinyl copper reagents due to highly stable Cu-C bond of the copper(1) alkynyl c o m p o u n d ~ . ~The ~ ~ Jhigher ~ (10) Tsuda, T.; Hashimoto, T.; Saegusa, T. J.Am. Chem. Soc. 1972, 94,658. ( 11)Haglund, 0.: Nilsson, M. Synlett 1991,7 2 3 . (12)( a ) van Koten, G.; Noltes, J . G. In Comprehensive Organometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Ed.; Pergamon: Tokyo, 1982;Vol. 2,pp 714-716. tb) Reference 12a, Vol. 2,pp 737-739 and references therein. ( 13)The Cu-C bond of alkynyl copper complexes is believed to be much more stable than that of alkyl- and arylcopper complexes on the basis of comparison of decomposing temperature [ref 12). This tendency is similar to relative bond stability of late transition metal complexes (Bryndza, H. E.; Fong, L. K.; Paciello, R. A.; Tam, W.; Bercaw, J. E. J. Am. Chem. Soc. 1987,109,1444).However, precise determination of the relative bond stability of the CutI)-C bonds has not been examined.
1995 American Chemical Society
3532 Organometallics, Vol. 14,No. 7,1995
Osakada et al.
stability of the alkynyl-copper(1) bond compared to the alkyl-copper(1) bond enables selective 1,Caddition of mixed organic cuprate, whose alkynyl ligand plays a n important role as sacrificial ligand.14 Palladium complexcatalyzed cross-coupling reactions of l-alkynes with vinyl and with aryl halides in the presence of CUI and tertiary amine provide 1,3-enynes and arylacetylenes, respectively. The reaction, which was reported at first by Sonogashira and Takahashi et al.,15has been developed for the synthesis of various organic compound^^^-^^ as well as of n-conjugated polymers.20 The reaction seems to involve initial formation of alkynylcopper(1) complex followed by alkynyl ligand transfer to the Pd(11)center giving the aryl (or vinyl) palladium alkynyl complex, Pd(Ar)(C=CR)(PR3)2,which is responsible for reductive elimination of the product. Recently we reported the preparation and structure of several copper alkoxide complexes with PPh3 ligands, Cu(OCH(CF&)(PPh3)3 and Cu(OCHPhz)(PPh3), ( n = 2, 31, which are highly soluble in common organic solvents.21 Since [Cu(OtBu)l,, which is also soluble in organic solvents, reacts with HCECPh to give [Cu(CWPh)l, smoothly,1° the above alkoxide complexes would be suitable precursors of new alkynylcopper(1) complexes with PPh3 ligands. In this paper we report reaction of the copper alkoxide complexes with terminal alkynes to provide various alkynylcopper(1) complexes, such as C U ~ ( C W C O O R ) ~ ( P [Cu(C=CSiMes)(PPh3)14, P~~)~, and [Cu(C=CAr)(PPh3)14. The crystal structure of the tetranuclear (trimethylsily1)ethynyl complex is also shown. The alkynyl copper complexes react easily with PdC12(PEt& to give mono- andor dialkynylpalladium(I1) complexes through the alkynyl ligand transfer from the Cu(1) to the Pd(I1) center.
-
A-
~ . . , . . . , . . . , . . . , . . . , . .
0 -2 -4 PPm Figure 1. 31P{1H}NMR spectra of 1 at (a) 20 "C, (b) -10 "C, (c) -40 "C, and (d) -70 "C. The peak with asterisk in d is assigned to Cuz(CrCCOOMe)2(PPh3)4contained in a small amount in the solution (see text). The spectrum of a mixture of 1 and PPh3 at -70 "C is shown in e. Spectra were recorded at 160 MHz in CD2C12. 4
2
with LiC+?Bu and PCy3, was characterized by X-ray ~rystallography.~ The NMR spectra as well as the elemental analyses Results and Discussion of the complexes agree with the unsymmetrical structures, (PP~~)CU(~-C=CCOOR)~CU(PP~~)~. Figure 1 Preparation and Structures of Alkynylcoppershows temperature dependent 31P{lH) NMR spectra of (I) Complexes. Reaction of Cu(OCHPhz)(PPh& with 1. The spectrum a t -70 "C gives two peaks at -0.1 and 1.2 equiv of HCECCOOMe gives Cu2(m-C=CCOOMe)2-1.9 ppm in a 2:l peak area ratio. These peaks are (PPh3)3 (1) in 63% yield. Complex 1 is also obtained assigned to PPh3 ligands bonded to the four-coordinated from reaction of [Cu(OPh)(PPh3)2]2with the alkyne in Cu center and to the three-coordinated Cu center, 71%. Reactions of copper alkoxide complexes Cu(0CHrespectively. A small peak a t -2.5 ppm can be at(CF3)2)(PPh3)3, Cu(OCHPh2)(PPh&, and [Cu(OPh)tributed to the PPh ligand of the symmetrical dinuclear (PPh31212 with HClCCOOEt and with HC=CCOOtBu which is in equicomplex, CU~@~-C=CCOOM~)~(PP~~)~, give the corresponding alkynylcopper complexes Cu2librium with 1 in the solution since addition of PPh3 to (&-C=CCOOR)2(PPh& (2, R = Et; 3, R = tBu), respecthe solution caused a n increase in the relative peak tively (see eq 1).Very recently, (PCy3)CuCu2-)71:r11-C~Ctintensity (Figure le).22 Raising the temperature of the solution of 1 above -10 "C causes the above three peaks 2 CU(OCHPb)(PPh& + 2 HCsCCOOR
-
- PPh3 Cy(C&COOR),(PPh,),
(1)
1: R = M e , 2: R=Et, 3: R = 'Bu
Bu)&u(PPh3)2, prepared from reaction of CpCu(PPh3) (14) (a)Carruthers, W. In Comprehensive Organometallic Chemistry; Wilkinson, G., Stone, F. G. A,, Abel, E. W., Eds.; Pergamon: Tokyo, 1982;pp 722-724. ( b )Lipshutz, B.H. In Organometallics in Synthesis. A Manual; Schlosser, M., Ed.; John Wiley: Chichester, 1994;pp 300302 and references therein. (15)taJ Sonogashira, K ;Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975, 4467. ( b ) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara, N. Synthesis 1980,627. (16)Sabourin, E. T.; Onopchenko, A. J . Org. Chem. 1983,48,5135. (17)Havens, S.J.; Hergenrother, P. M. J . Org. Chem. 1985,50, 1763. Heck, R. F.Palladium Reagents in Organic Synthesis; Academic (18) Press: London, 1985;p 299.
(19)( a ) Schreiber, S.L.; Kiessling, L. L. J . A m . Chem. SOC.1988, 110, 631. ( b ) Mascarenas, J . L.; Sarandeses, L. A,; Castedo, L.; Mourino, A. Tetrahedron 1991,47,3485.( c )Curtin, M. L.; Okamura. W. H. J . A m . Chem. SOC.1991, 113, 6958. (20)fa) Sanechika, K.; Yamamoto, T.; Yamamoto, A. Bull. Chem. SOC.Jpn. 1984,57, 752. IbJ Yamamoto, T.; Takagi, M.; Kim, K.; Maruyama, T.; Kubota, K.; Kanbara, H.; Kurihara, T.; Kaino, T. J . Chem. Soc., Chem. Commun. 1993,797. tc) Yamamoto, T.; Yamada, W.; Takagi, M.; Kizu, K.; Maruyama, T.; Ooba, N.; Tomaru, S.; Kurihara, T.; Kaino, T.; Kubota, K. Macromolecules 1994,27,6620. 121)Osakada, K.; Takizawa, T.; Tanaka, M.; Yamamoto, T. J . Organomet. Chem. 1994,473,359. 122) It is not possible to obtain the NMR spectra of 1 free from peaks due to Cu2(/(2-C=CCOOMe)2(PPh& despite purification of the complex by repeated recrystallization. The 'H NMR spectra of 2 and of 3 at -80 "C also show small peaks due to Cuzf,1(*-C~CCOOEt)2(PPh3)4 td 4.2tq, OCH2, J = 9 Hz) and 1.4 It, CH3))and Cu2(u2-C=CC0OtBu)2tPPhlJ4 (0 1.7 Is, C(CH2)3)),respectively. These peaks coalesce with the peaks due to 2 or 3 below room temperature. Appearance of the peaks due to symmetrical dicopper complexes may be attributed to partial disproportionation of CU&(~-C=CCOOR)~( PPhSJS into Cuz(u2CsCCOOR)e(PPh.I)4and Curtir?-C~CCOOR)21PPh.I)2,although the presence of the latter compounds was not confirmed by NMR.
AlkynylcoppertI) Complexes with PPh3 Ligands
Organometallics, Vol. 14, No. 7, 1995 3533
Scheme 2. Plausible Pathways for PPhS Exchange of 1-3 YOOR
COOR
(R = Me, Et, 'Bu; L, L' = PPh,)
Y
c75 c87 to coalesce to give a broadened peak near -1 ppm. Temperature dependent 31P{'H} NMR spectra of 2 and 3 are quite similar to those of 1. The 'H NMR spectra of 1-3 below -40 "C also indicate the presence of small amounts of Cuz@z-C~CCOOR)z(PPh3)4(R = Me, Et, Figure 2. ORTEP drawing of 4-Et20 (from I) at 30% tBu) in the solutions. The 'H NMR spectrum of 1 a t ellipsoidal level. Phenyl carbon atoms are omitted for -70 "C shows a slightly broadened peak at 3.4 ppm simplicity except for the atoms bonded to P atoms. accompanied by a small peak a t 3.9 ppm. Addition of PPh3 to the solution causes growth of the latter peak. The above two peaks are assigned to Me hydrogens of 1 and CUZ@Z-CECCOOM~)Z(PP~~)~, respectively. The 'H NMR spectra of 2 and 3 below -40 "C also show peaks due to ethyl and butyl hydrogens of CUZ(M~-C=CCOOR)Z(PPh3)3 and C ~ Z @ ~ - C = C C O O R ) Z ( P The P ~ ~'H ) ~ .NMR peaks due to Cuz@z-C=CCOOR)z(PPh& and those due to Cuz@z-C=CCOOR)z(PPh3)4 coalesce above -20 "C. Results of the above NMR measurements indicate that complexes 1-3 undergo PPh3 ligand exchange between four-coordinated and three-coordinated Cu centers on the NMR time scale as well as ligand exchange with CU~@Z-C=CCOOR)Z(PP~~)~. Scheme 2 shows plausible pathways for PPh3 ligand exchange of 1-3. Both the associative pathway involving Cu2@2CH!COOR)z(PPh3)4 as the intermediate and the dissociative pathway involving CUZ@Z-C=CCOOR)Z(PP~~)Z would explain the results of the NMR study. We are not able to decide which pathway is operative in the reaction, although the solutions of 1-3 contain small c75 amounts of CUZ@~-C=CCOOR)Z(PP~~)~. Cu(OCH(CF3)2)(PPh3)3reacts with 50 equiv of H C z CSiMe3 to give [ C U @ ~ - C I C S ~ M ~ ~ ) ( P(4) P ~in~ )83% I~ Cll yield (eq 2). Figure 3. ORTEP drawing of 4*Etz0 (from 11) at 50% 4 Cu(OR)(PPh3), + 4 HCsCSiMg ellipsoidal level. Phenyl carbon atoms are omitted for - PPh3 simplicity except for the atoms bonded to P atoms. [Cu(OECSiM@)(PPh& (2)
(3
4
Complex 4 is also obtained in moderate yields (35-57%) from a similar reaction with 1.5 equiv of HCMSiMe3 as well as from reactions of CuMe(PPh3)z(EtzO)o.sand Cu(OCHPhz)(PPha)s with HCaCSiMea. Recrystallization of 4 from Et20 at -30 "C gives single crystals of 4*Etz0 in two crystal forms, both of which are characterized by X-ray crystallography. Figures 2 and 3 show molecular structures of two crystal forms of 4*EtzO. Alkynylcopper cluster molecules of form I and form I1 have similar structures to each other and contain four copper centers bonded to four terminal PPh ligands and to four pus-bridging alkynyl ligands. Two different
structures have been already reported for tetranuclear alkynylcopper complexes with PPh3 ligands formulated as [Cu(C=CPh)(PRdl4. [Cu(u3-C=CPh)(PPhd14 (E), prepared from reaction of [Cu(PPh3)z(BH4)3with phenylacetylene and KOH,3 as well as its PPhz(py) analogue (py = 2 - ~ y r i d y l )has , ~ ~a cubane-like core composed of four Cu and four bridging phenylethynyl ligands. The trimethylphosphine-coordinatedalkynylcopper tetramer, [ C U ~ ~ ~ - ~ ~ : ~ ~ - C = C P ~ ) Z ~ ~ - ~ ~ : ~ ~ : ~ contains three four-membered rings, each of which is composed of two Cu and two bridging alkynyl ligands. The two different structures for tetranuclear alkynylcopper complexes with phosphine ligands are similar
Osakada et al.
3534 Organometallics, Vol. 14, No. 7, 1995 Scheme 3. "Cubane-Like"and "Step-Like" Structures
"Cubane-like" structure
"Step-like'' structure
to "cubane-like" and "step-like" isomers of [CuX(PR3)14 (X= C1, Br, and I; R = Et, Pr, and Ph).23s24 Table 1 summarizes bond distances and angles of 4.EtzO. Cu-Cu distances are in the range 2.544(1)2.642(1)A, which is similar t o those of 5 (2.523-2.676 A) and [Cu(C=CPh)(PPhzpy)l4(2.525(1)-2.686(1)Ai)4a but shorter than those of [CuCl(PPh3)14 (3.118(1)3.430(2)A) and [CuBr(PtBu3)I4 (3.479(2) -3.49l(2)A). Cu-C bond distances are in the range 2.13-2.17 A, which is longer than usual transition metal-carbon bond. Similarity of distances among the three Cu-C bonds of the alkynyl ligands in structures of both crystal forms indicates q':vl:ql-coordination of the ligand rather than q1:q1:q2-or q1:v2:q2-coordination.The Cu-C-Cu bond angles are in the range 70.7(1)-75.0(1)"and are as acute as the other copper complexes with bridging alkynyl ligands.4b Similarly elongated Cu-C bonds as well as acute Cu-C-Cu angles in already characterized copper complexes with bridging aryl or alkynyl ligands were attributed t o three-center two-electron or fourcenter three-electron b ~ n d i n g . ' ~ ~ * ~ ~ , ~ ' The structure of 4 is not rigid in solutions. The 31P{'H} NMR spectrum of 4 a t 25 "C shows a broad signal which turns into several peaks on cooling to -70 "C. The 'H NMR spectra from -70 t o 25 "C show three major and four minor SiMes peaks around 0 ppm which shift peak positions and change peak area ratios as the temperature of the solution changes. Temperature dependent change of the NMR spectra is partly attributed t o PPh3 dissociation of 4 to give [Cu4(C= CSiMe&(PPh3)4-,1 ( n = 1, 2, etc.) because addition of PPh3 causes a change in the relative peak intensities. (23)( a )Churchill, M. R.; Karla, K. L. J.Am. Chem. SOC.1973, 95, 5772. ib) Inorg. Chem. 1974, 1 3 , 1065. ic) 1974, 13, 1427. td11974, 13. - , 1899. ----
(24)Goel, R. G.; Beauchamp, A. L. Inorg. Chem. 1983,22, 395. (25)Gill, J. T.; Mayerle, J. J.; Welcker, P. S.; Lewis, D. F.; Ucko, D. A.; Barton, D. J.; Stowens, D.; Lippard, S. J. Inorg. Chem. 1976, 15, 115.5
126)van Koten, G . J . Organomet. Chem. 1990, 400, 283 and references therein. -.(27)Mason, R.; Mingos, D. M. P. J . Organomet. Chem. 1973,50, 53. 128)The NMR spectra and their temperature dependent change are not explained by assuming the presence of species formed only through PPhs dissociation from 4. The complex seems to undergo some other reversible structural changes in the solution. Partial degradation of the complex into two Cu?i,llp-C~CSiMe~Jn(PPhni~ molecules and their redimerization may be also responsible for the spectroscopic change.
Table 1. Selected Bond Distances (A)and Angles (deg) of 4-Et20 (FormsI and 11) Cul-cu2 Cul-cu4 cu2-cu4 Cul-c1 Cul-Cl6 Cu2-Cl1 Cu3-Cl C U-C~ 16 Cu4-C6 C1-C2 Cll-c12 Cul-C1-Cu3 Cu3-Cl-Cu4 Cu3-Cl - c 2 Cul-CG-Cu2 Cu2-C6-Cu4 Cu2-C6-C7 Cu2-Cll-Cu3 cu3-Cll-cu4 c u 3 -c 11- c 1 2 C~l-Cl6-Cu2 Cu2-Cl6-Cu3 Cu2-C 16-C 17 Cul-cu2 Cul-cu4 cu2-cu4 Cul-c1 C~l-Cl6 Cu2-Cl1 Cu3-Cl Cu3-Cl6 Cu4-C6 Cl-C2 Cll-c12 C u l -c 1- c u 3 Cu3-Cl-Cu4 c u 3 -c1 - c 2 Cul-CG-CuQ Cu2-C6-Cu4 Cu2-C6-C7 cu2-Cll-cu3 cu3-c11 - c u 4 cu3 -c 11-c 12 Cul-Cl6-Cu2 Cu2-Cl6-Cu3 C U-C~ 16-C 17
Form 2.568(2 1 2.581(4) 2.566i41 2.13i2) 2.15(2) 2.15(2i 2.13(2) 2.14(2) 2.132) 1.24(2 ) 1.21(2) 74.7(7) 74.6(5i 136.(1) 73.1(7) 73.1(5) 140.(11 73.3( 7) 73.5(5) 134.(1) 73.4(8) 73.5(8) 141.(1) Form 2.642(1) 2.544(2 1 2.544(1) 2.173(4) 2.167(4) 2.13714) 2.14514) 2.149(4 ) 2.179i6) 1.2085) 1.194(51 73.0( 1) 74.8(1) 135.9(3i 75.0(1) 70.7(1) 125.5(3) 73.8(1) 73.711) 126.1(31 74.8(1) 7 4 . a 11 132.4(3)
I Cul-cu3 cu2-cu3 cu3-cu4 Cul-C6 Cu2-C6 Cu2-Cl6 c u 3 - c 11 Cu4-Cl Cu4-Cl1 C6-C7 C16-Cl7
2.586(3i 2.567(3) 2.584(4) 2.152) 2.16(2) 2.15(2) 2.15(2) 2.13(2) 2.16(2i 1.20i3i 1.21(4)
Cul-C1-Cu4 Cul-Cl-C2 Cu4-Cl-C2 c~l-CG-Cu4 Cul-C6-C7 Cu4-C6-C7 cu2-Cll-cu4 Cu2-Cll-C12 Cu4-Cll-Cl2 C~l-c16-C~3 Cul-Cl6-Cl7 Cu3-Cl6-Cl7
74.4(5) 135.(1) 135.(2) 73.7(5) 133.(1) 135.(21 73.0(5) 141.(1i 132.(2) 74.0(8) 134.(1) 132s 1)
I1 Cul-cu3 c u 2 -c u 3 cu3 -c u 4 Cul-CG Cu2-C6 Cu2-C 16 Cu3-Cl1 Cu4-Cl c u 4 - c 11 C6-C7 C16-Cl7
2.568(1) 2.6269(8i 2.628(2) 2.119(4) 2.220(4) 2.184(4) 2.235i4i 2.180(4) 2.143(4) 1.211(5) 1.197(5)
cu1-c10-cu4 Cul-Cl-C2 Cu4-Cl-C2 c~l-CG-Cu4 Cul-C6-C7 Cu4-C6-C2 c u 2 -c 11- c u 4 c u 2 -c 1 1-c1 2 c u 4 - c 1 1-c1 2 c~l-ClG-Cu3 Cul-Cl6-Cl7 Cu3-Cl6-Cl7
71.5(1) 139.2(3i 134.4(3) 72.6(1) 142.2(3) 140.6(3) 72.9(1) 140.2(3) 141.2(3) 73.0(1) 136.1(3) 139.1(3)
However, unambiguous assignment of the species in the solution is not feasible due t o the complexity of the spectra.28 Complexes 5 and [Cu(C~CCsH4-p-Me)(PPh3)14 (6)are obtained from reactions of Cu(OCHPh2)(PPh3)2with HCSCPh and with HCWC6H4-p-Me, respectively (eq 3). 4 C U ( O C H P ~ ) ( P P t~ ~ 4) ~HC=CAr
- PPh3
ICu(C=CAr)(PPh)I,
(3)
5: Ar=Ph, 6: Ar = C,H,-p-Me
The reactions proceed smoothly on addition of 1.2equiv of alkynes to the alkoxide complex, while reaction of [Cu(OtBu)l, with HCGCPh, giving [Cu(C=CPh)l,, was reported to require 20 equiv of the alkyne to Cu.'O Elemental analyses of the complexes agree well with the proposed formula. The IR spectra of 5 and 6 show v(C=C) vibrations at 2018 and 2014 cm-l, respectively. The former peak position is quite similar t o the corre-
AlkynylcoppedI) Complexes with PPhy Ligands sponding peak of 5 (2020 cm-l), which was prepared by an alternative reaction and has a cubane-like structure as determined by X-ray ~rystallography.~ Another structural isomer of [Cu(C=CPh)(PPh3)],, which was prepared previously and not characterized well, showed two v(C=C) vibrations at 2060 and 1935 ~ m - l . ~ Many late transition metal alkoxide and amide complexes react smoothly with terminal alkyne t o give the corresponding alkynyl c o m p l e ~ e s ~ due ~ -to ~ ~the high stability of the metal-alkynyl bond. Re(OMe)(CO)3(PMe3)2 shows exceptionally low reactivity toward ligand substitution by an alkynyl probably because the coordinatively saturated complex does not dissociate phosphine or CO ligands. Displacement of the alkoxide ligand of the copper complexes having coordinatively saturated structures21 by an alkynyl group proceeds smoothly, probably through PPh3 dissociation due to the labile d10 configuration of the Cu center. The alkynylcopper complexes with PPh3 ligands obtained as above undergo substitution of the alkynyl ligand on addition of terminal alkynes. Complex 5 reacts with HCWCOOR in the presence or absence of PPh3 to cause substitution of the alkynyl ligands (eq 4).
Reaction of 5 with equimolar amounts of HC=CCOOEt and PPh3 gives 2 (84%), which is characterized by IR and NMR spectra as well as elemental analyses. Similar reaction of 5 without addition of PPh3 gives a mixture of copper complexes containing CECCOOMe ligands. The 31P{lH} NMR spectrum of the product a t -70 "C shows the peaks due to 1,although several other peaks due to uncharacterized species are also observed. The 'H NMR spectrum shows several peaks due to COOMe hydrogens in a peak area ratio of 3:15 between the Me and Ph hydrogens. All the results indicate that a Cu-CWCOOR bond is formed during the reaction due t o its thermodynamically higher stability than a Cu-CWPh bond. Similarly a phenylethynyl ligand of Rh(C=CPh)(L) (L = triphosphine) was readily replaced by a C=CCOOR group on reaction with HC%!COOR.35 Reactions of 3 with 2 equiv of HCWZCOOMe and with 4 equiv of HCWCOOEt in Et20 give 1 (63%) and 2 (73%), respectively. These results indicate that facile exchange of the alkynyl group between the alkynylcopper complex and alkyne occurs in solution. Preferential separation of 1 or 2 from the reaction mixtures is due to the lower solubility of complexes 1 and 2 compared to 3 rather than due to the difference in relative stability of the complexes. Estimation of relative stability among Cu-CWCOOR bonds is not feasible due to the pres(29) Appleton, T.G.;Bennett, M. A. Inorg. Chem. 1978,17,738. (30)Michelin, R. A.; Napoli, M.; Ros, R. J . Organomet. Chem. 1979, 175,239. 131)Fernandez, M. J.;Esteruelas, M. A.: Covarrubias, M.: Oro, L. A.; Apreda, M.-C.; Foces-Foces, C.; Cano, F. H. Organometallics 1989, 8. ., 1158. ~ _
_ .
132)Kim, Y.-J.; Osakada, K.: Yamamoto, A. J. Organomet. Chem. 1993,452, 247. (33,Rahim, M.: Bushweller. C. H.: Ahmed. K. J. Organometallics 1994, 13,4952. (34) Simpson, R. D.;Bergman. R. G. Organometallics 1992,11,3980. 135) Bianichini, C.; Mealli, C.: Peruzzini. M.: Vizza, F.: Zanobini, F. J . Organomet. Chem. 1988.346.C53.
Organometallics, Vol. 14, No. 7, 1995 3535 ence of several uncharacterized species observed in the NMR spectra of the reaction mixture. Alkynyl Ligand Transfer from Copper to PdCl2(PEtsh. Reactions of 1-3 with 0.5 equiv of PdC12 (PEt& in the presence of PPh3 give the corresponding dialkynylpalladium complexes, trans-Pd(C=CCOOR)s(PEt3)2 (7a, R = Me; 8a, R = Et; 9a, R = tBu), respectively, accompanied by formation of CuCl(PPh3)3 (eq 5).
+
Cy(C&COOR)Z(PPh3)3
+
PPh,
PdClz(PEt3)~ PEt3
I
+
ROOC-C-Pd-CECOOR
I
C U C I ( P P ~ )(5) ~
PE13 7 a R=Me 8 a R = Et, 9 a R = 'Bu
The 13C{lH} NMR spectra of the complexes show the signals of the alkynyl carbons at 114.1-117.8 and 103.7-105.8 ppm as triplets due to 31P-13C coupling. The former signals, which show larger coupling constants (16-17 Hz) than the latter (3 Hz), are assigned to the carbon atoms bonded to the palladium center. The above results as well as the 31P(1H} NMR spectrum showing a single peak indicate the trans structure of the complex. Formation of the monoalkynylpalladium complex, PdCl(C=CCOOR)(PEt& is not observed. CuCl(PPh3)3, separated from the reaction mixture as an EtzO-insoluble solid, gives IR and 'H NMR spectra which are identical with the authentic compound. Crystallographic parameters of single crystals of the product by X-ray measurement agree with the parameters already reported for C U C ~ ( P P ~ &Reaction .~~ without addition of PPh3 gives Cu&12(PPh3)3 which is characterized on the basis of the IR spectrum as well as by comparison of crystallographic parameters of the single crystals .25 Complex 4 reacts with 0.6 equiv of PdC12(PEt& in the presence of PPh3 to give CuCl(PPh3)3 and PdC1(C=CSiMe3)(PEt& (lob,82% based on PdC12(PEt3)2) (eq 6). 1
+
[Cu(C=CSiMe 3)(PPh3)]4+ PdCI,(PEt&-
PPh,
PEf
I
+ CUCI(PPhJ3 (6)
CI-Pd-CsCSiMe,
I
PEt, 1 Ob
Complex lob gives satisfactory analytical and NMR results. Reaction of complex 5 with 0.63equiv of PdC12(PEt& in the presence of PPh3 gives a mixture of trunsPd(C=CPh)z(PEt& (lla)(39%), trans-PdCl(C=CPh)(PEt& (llb)(56%), and CuCl(PPh3)3(eq 7). Complexes 1
[Cu(&CAr)(PPb)], 2
+
PEt3
I
ArCEC-pd-CCrCAr
I
PEt3 l l a Ar=Ph 1 2 a Ar = C,H,-p-Me
PdCb(PEt3)2
+
PPh3
PEt3
I
+ CI-Pd-C5CAr
I
+
PEt3 l l b Ar=Ph 1 2 b Ar = C&i,-p-Me
CuCI(PPh& (7)
3536 Organometallics, Vol. 14, No. 7, 1995
Scheme 4. Plausible Pathway of Alkynyl Ligand Transfer from Cu to Ni, Pd, and Pt
Cu = Cu(amine), or Cu(PR,),
M = NiCI(PR,),,
PtCI(PR,)2, etc.
Osakada et al.
the alkynyl groups and Ir(1) or Re(1) centers, although the chloro ligand is eliminated from the p r o d u ~ t s . ~ ~ , ~ ~ Change of the coordination mode of the p2-v1:v2alkynyl ligand of bimetallic complex into a ~ 2 - 1 7 ~ : ~ ~ structure is kinetically favored since rapid and reversible switching of the coordination between and p2-v2:v1-bondinghas been observed in an NMR study of Fe and Mo multimetallic complexes containing bridging alkynyl ligand^.^ The irreversible alkynyl ligand transfer reactions from copper t o other late transition metals shown above suggest lower thermodynamic stability of the Cu(1)-alkynyl a-bond than of the a-bond between the alkynyl group and group 6-10 transition metals. Yields of dialkynylpalladium complexes in reactions 5-7 vary, depending on the alkynyl groups, in the order C=CCOOR > C e P h and C=CCs&-p-Me > CeSiMe3. Electron-withdrawing groups, such as COOR, promote formation of the dialkynylpalladium complexes through stepwise displacement of two chloro ligands of PdC12(PEt3)2. However, SiMe3-substituted alkynyl groups coordinated to Cu centers do not undergo transfer to trans-PdCl(C=CSiMe3)(PEt3)2 under similar conditions. One of the possible reasons for enhancement of the alkynyl ligand transfer by the COOR group seems to be the significant stabilization of the Pd-C bond of the product caused by the electron-withdrawing group on the alkynyl
l l a and l l b are isolated from each other by fractional crystallization of the reaction product after separation of CuCl(PPh&. Both complexes are characterized by the 1H and 13C{lH} NMR spectra and are distinguished from each other on the basis of the peak area ratio of the lH NMR spectra as well as by elemental analyses. Similar reaction of 6 with PdC12(PEt3)2 also gives a (12a)and mixture of trans-Pd(C=CCsH4-p-Me)z(PEt3)2 trans-PdCl(C=CC6H4-p-Me)(PEt3)2 (12b) (76:24 molar ratio) accompanied by formation of CuCl(PPh3h. There have been no reports on reaction of alkynylConclusion copper phosphine complexes with dichloropalladium(I1) complexes, although alkynyl ligand transfer from Cu to Labile alkoxide ligands bonded to copper(1) complexes with PPh3 ligands undergo facile substitution by alkynyl late transition metals was observed in reactions of phosphine-free copper alkynyl compounds with chloro groups on addition of terminal alkynes, giving the complexes of late transition metals. The alkynylcopper corresponding alkynylcopper complexes. The structure of the complexes varies depending on the kind of the compound, [Cu(C=CPh)l,, reacts with PtC12(PEt3)2 in the presence of TMEDA to give P ~ ( C I C P ~ ) ~ ( P E ~ ~alkynyl ) ~ . ~ ~groups. Reactions of the alkoxide complexes with propiolic acid esters give unsymmetrical dinuclear Reactions of [Cu(C=CR)I,, prepared in situ from tercomplexes with two bridging alkynyl ligands, (PPh3)minal alkynes CUI, and amines, with chloro complexes of Ni(II), Pd(II), and Pt(I1) also give alkynyl complexes CU+~-C=CCOOR)~CU(PP~~)~. Products of the reactions of these group 10 metals.37 The reactions are believed with HC=CSiMe3 and with HC=CAr show tetranuclear to proceed through alkynyl ligand transfer from Cu(1) structures having cubane-like cores composed of four to Ni(II), Pd(II), and Pt(I1) accompanied by transfer of Cu and four alkynyl ligands, although the structures the chloro ligand to the Cu center as shown in Scheme in the solutions are not rigid, which is mainly due to 4. Intermediate bimetallic or multimetallic complexes PPh3 dissociation. Ligand exchange of the alkynylcopin which the alkynyl group is a-bonded to the group 8 per complexes with alkynes occurs under mild condiand 10 metals and n-bonded to the Cu center of the tions to give the thermodynamically more-favored alkyCuCl moiety are obtained from the reaction mixture of nylcopper complexes. PdCMPEtd2 activates the alky[Cu(C=CPh)]n and chloro complexes of Fe(II), Pt(II1,and nyl-copper bond of the complexes to give alkynyl of similar reactions of [CuR U ( I I ) . ~ ~Products -~~ palladium complexes. (C=CPh)]n with Ir(1) and Re(1) chloro complexes have multimetallic structures containing a-bonding between Experimental Section (36) Sonogashira, K.; Fujikura, Y.; Yatake, T.; Toyoshima, N.; Takahashi, S.; Hagihara, N. J . Organomet. Chem. 1978, 145, 101. 137) la) Fujikura, Y.; Sonogashira, K.; Hagihara, N. Chem. Lett. 1975, 1067. (b) Sonogashira, K.; Yatake, T.; Tohda, Y.; Takahashi, S.; Hagihara, N. J . Chem. Soc., Chem. Commun. 1977,291. I C ) Ogawa, H.; Joh, T.; Takahashi, S.; Sonogashira, K. J . Chem. SOC.,Chem. Commun. 1988, 561. l 3 8 ) ( a ) Bruce, M. I.; Clark, R.; Howard, J.; Woodward, P. J . Organomet. Chem. 1972,42, C107. IbJ Abu Salah, 0. M.; Bruce, M. I. J . Chem. SOC.,Dalton Trans. 1974, 2302. (c) Bruce, M. I.; Abu Salah, 0. M.; Davis, R. E.; Reghavan, N. V. J . Organomet. Chem. 1974,64, C48. td) Abu Salah, 0. M.; Bruce, M. I. J. Chem. SOC.,Dalton Trans. 1975,2311. (39)Clark, R.; Howard, J.; Woodward, P. J. Chem. SOC.,Dalton Trans. 1974, 2027. I401Yamazaki, S.; Deeming. - A. J. J.Chem. Soc., Dalton Trans. 1993, 3051. 141)Tanaka, S.; Yoshida, T.; Adachi, T.; Yoshida, T.; Onitsuka, K.; Sonogashira, K. Chem. Lett. 1994, 877.
General Procedures, Measurements, and Materials. All manipulations of the complexes were carried out under nitrogen or argon using Schlenk techniques. Cu(OCH(CF3M(PPh3)3, Cu(OCHPhdPPhd3, and [Cu(OPh)(PPh3)212 were prepared according to the IR spectra were measured on a JASCO 810 spectrophotometer. NMR spectra (lH, 13C,and 31P)were recorded on JEOL FX-100, GX-270, EX(42)(aJ Abu Salah, 0. M.; Bruce, M. I. J . Chem. SOC.,Chem. Commun. 1972,858. lb) Abu Salah, 0. M.; Bruce, M. I.; Redhouse, A. D. J. Chem. SOC.,Chem. Commun. 1974, 855. 143) Churchill, M. R.; Bezman, S. A. Inorg. Chem. 1974, 13, 1418. 144)Masai, H.; Sonogashira, K.; Hagihara, N. Bull. Chem. SOC.Jpn. 1977, 44, 2226. 145)( a )Kubota, M.; Yamamoto, A. Bull. Chem. SOC.Jpn. 1978.51, 2909. lb) Kubota, M.; Yamamoto. T.; Yamamoto, A. Bull. Chem. SOC. Jpn. 1979, 52, 146.
Alkynylcoppedl) Complexes with PPh3 Ligands
Organometallics, Vol. 14,No. 7,1995 3537
400, and GX-500spectrometers. Elemental analyses were Table 2. Crystal Data and Details of Structure Refinement of 4*Eta0 carried out by Yanagimoto type MT-2 CHN autocorder. Preparation of 1-3. To a toluene (5 mL) solution of Cuform I form I1 (OCHPhd(PPhd3 (580 mg, 0.56 mmol) was added HC= formula C9sHl~CuOP4Si4 C96Hio6CU40P4S4 CCOOMe (56 mg, 0.67 mmol) at room temperature. Stirring mw 1766.32 1766.32 the pale green solution caused the color to change to yellow, cryst size (mm3) 0.4 x 0.4 x 0.6 0.5 x 0.3 x 0.4 which was accompanied with gradual deposition of a white cryst syst triclinic triclinic solid. After the reaction had proceeded for 7 h the insoluble space group Pi Pi material was dissolved by addition of toluene (9 mL) and a a (A) 25.650(4) 15.59(1) b (A) 15.234(2) 20.47(1) small amount of insoluble materials was removed by filtration. c (A) 15.229(2) 14.844(5) The filtrate was evaporated to dryness, and the remaining a (deg) 119.96(1) 90.89(4) solid was washed repeatedly with hexane to give 1 as a white P (de@ 107.23(1) 94.60(5) solid (190 mg, 63%). IR (KBr) v(C=C) 2042 cm-l, v(C-0) 1683 72.74(1) 92.78(5) cm-l; lH NMR (CDzC12) d 3.4 (s, 6H, CH3), 7.1-7.5 (m, 45H, 4844 4717 Cd.15); 13C{lH)NMR (CD2Clz)d 53.4 (s,CHd, 113.1and 119.4 z 2 2 (s, C=C), 128-135 (C6H5), 154.2 (s, C-0). Anal. Found: C, i (A) 0.710 69 0.710 69 69.0; H, 5.1. Calcd for C ~ Z H ~ ~ C UC, ~ 68.9; O ~ PH, ~ 4.8. : 1.211 1.244 &led (gem-') p (cm-l) 10.23 10.51 Similar reactions with HC=CCOOEt and HC=CCOOtBu F(OO0) 1844 1844 gave 2 (67%) and 3 (60%),respectively. Spectroscopic data R 0.060 0.036 for 2: IR (KBr), v(C=C) 2048 cm-l, v(C=O) 1682 cm-l; lH 0.028 RW" 0.087 NMR (CD2C12)d 1.1(t, 6H, CH3, J = 9 Hz), 3.8 (q, 4H, CH2), no. of variables 1044 1090 7.1-7.5 (m, 45H, Cd.15); 13C{lH)NMR (CD2C12)b 14.5 (s, C H 3 ) , no. of measd reflns 12799 11980 60.6 (s, 0 3 2 1 , 113.8and 119.2 (s, C=C), 128-135 (C6H5), 153.9 no. of reflns used 5589 8913 (s, C-0). Anal. Found: C, 69.1; H, 5.1. Calcd for C64H55(I ' 3dZ)) Cu204P3: C, 69.4; H, 5.0. Spectroscopic data for 3: IR (KBr) " w = [dFo)1-2. v(C=C) 2038 cm-', v(C=O) 1671 cm-'; 'H NMR (CD2C12)b 1.3 (s, 18H, CH3), 7.1-7.6 (m, 45H, Cd.15); 13C{lH)NMR (CDzC12) 0C.46 Crystallographic data and results of structure refinement b 28.3 (s, CH3), 80.1 (s, C(CH&), 115.7 (br, C W ) , 128-134 are summarized in Table 2. The unit cell parameters were (C6H5), 153.2 (s, C=O). Anal. Found: C, 70.8; H, 5.6. Calcd obtained by least-squares refinement of 28 values of 25 for C68H6&U204P3: c, 70.2; H, 5.5. reflections with 25" 5 28 5 35". Intensities were collected on Preparation of 4-6. To an Et20 (6 mL) solution of CuRigaku AFC-5R automated four-circle dieactometer by using ( O C H ( C F ~ ) Z ) ( P (200 P ~ ~ )mg, ~ 0.20 mmol) was added HCI Mo Ka radiation ( I = 0.71069 A) and the w-28 method. CSiMe3 (1.4 mL, 9.9 mmol) at room temperature. After the Calculations were carried out by using the program package reaction mixture had been stirred for 4 h the colorless solution TEXSAN on a DEC Micro VAXII computer. was filtered t o remove a small amount of insoluble material. Of the 13 217 collected reflections for form I of 4.Et20 12 799 Addition of hexane (ca. 1mL) to the filtrate followed by keeping were unique (R,,t = 0.039). No decay correction was applied. the resulting mixture at -30 "C caused crystallization of [CuAn empirical absorption correction based on azimuthal scans (C=CSiMes)(PPh3)34(4) (70 mg, 83%). of several reflections was applied, which resulted in transmisReaction of Cu(OCHPhz)(PPh& (300 mg, 0.29 mmol) with sion factors ranging from 0.97 to 1.00. The data were corrected HC=CSiMe3 (43 mg, 0.43 mmol) for 25 h in toluene (3 mL) at for Lorentz and polarization effects. The structure was solved room temperature resulted in formation of 4, which was by heavy-atom Patterson methods and expanded using Fourier recrystallized from Et20 to give 4%20 (90 mg, 72%). IR (KBr) techniques. The non-hydrogen atoms of the complex molecule v(C=C) 1958 cm-l; 'H NMR (CD2C12) b -0.9 to 0.2 (9H, Siwere refined anisotropically, while the oxygen in the Et20 (CH3)3),7.2-7.7 (m, 15H, Cd.15); 13C{lH}NMR (CD2Clz)d -0.3 molecule was refined isotropically. The hydrogen atoms were to 35.3 (Si(CH3)3),90.3 and 93.3 (s, CEO, 128-137 (C6H5). located at calculated positions and refined isotropically. ~ Othe : 12 520 collected reflections for form I1 of 4.Etz0 Anal. Found: C, 64.7; H, 6.1. Calcd for ( C ~ ~ H ~ ~ C U P S ~ ) ~ - HOf C, 64.6; H, 5.8. Reaction of CuMe(PPh&O.SEt20) (490 mg, 11 980 were unique (R,,t = 0.039). Over the data collection, 0.76 mmol) with HCzCSiMe3 (110 mg, 1.13 mmol) for 48 h in the standards decreased by 1.3%. A linear correction factor toluene at 0 "C also gave 4 (66 mg, 20%). was applied to the data to account for this phenomenon. An Reactions of Cu(OCHPhz)(PPh3)3with 1.2 equiv of HCrCPh empirical absorption correction based on azimuthal scans of and with 1.2 equiv of HC=CC6H4-p-Me gave 5 (87%)and 6 several reflections was applied, which resulted in transmission (83%),respectively. Spectroscopicdata for 5: IR (KBr) v(C=C) factors ranging from 0.89 to 1.00. The data were corrected 2018 cm-l; lH NMR (CD2C12) b 6.0 (d, 2H,Cd.15, J = 8 Hz), for Lorentz and polarization effects. The structure was solved 6.7 (d, 2H, Cd.15, J = 8 Hz), 6.8-7.7 (m, 16H, Cd.15). Anal. by direct methods and expanded using Fourier technique. The Found: C, 73.6; H, 4.8. Calcd for (C2&&uP)4: C, 73.1; H, non-hydrogen atoms were refined anisotropically, while the 4.7. Spectroscopic data for 6: IR (KBr) v(C=C) 2014 cm-l; hydrogen atoms were refined isotropically. 'H NMR (CD2C12) b 2.1 (s,3H,CH3), 5.9 (d, 2H, Cd.14, J = 8 Reaction of 5 with HCSCCOOEt in the Presence of Hz), 6.4 (d, 2H,Cd.14, J = 8 Hz), 6.9-7.8 (m, 15H, Cd.15); 13CPPb. To a toluene (9 mL) suspension of 5 (130 mg, 0.30 mmol {'H} NMR (CsD6)2.12 (s, CH3), 77.1 and 97.5 (s, C=C), 124of Cu) and PPh3 (80 mg, 0.31 mmol) was added HCWCOOEt 136 (C6H5 and C6H4). Anal. Found: C, 73.7; H, 5.1. Calcd (59 mg, 0.60 mmol). When the reaction mixture was stirred for ( C ~ ~ H ~ Z C U C,P73.5; ) ~ : H, 5.0. at room temperature, 5 gradually dissolved to give a red Crystal Structure Determination of 4.Et20. Single solution. After the reaction had proceeded for 16 h a small crystals of 4.Et20 were grown from Et20 solutions of 4 at -30 amount of insoluble solid was removed by filtration. Evaporation of the solvent of the filtrate and ensuing addition of Et20 (3 mL) gave 2 as a colorless solid (140 mg, 84%). Anal. (46)Final D-map of the structure calculation of crystal form I of 4.Etz0 shows a clear peak due to oxygen surrounded by several weaker O~ 69.4; P ~ H, : Found: C, 69.4; H, 5.3. Calcd for C M H ~ ~ C U ~ C, peaks whose position are not reasonable as the carbon atoms of Et20. 5.0. Although we initially assigned the crystal to the formula 4.H20,we Reaction of 5 with HCICCOOMe. To a toluene (6 mL) later improved the formula to 4.Et20 according to the comments by suspension of 5 (290 mg, 0.68 mmol of Cu) was added the reviewer who suggested the following points. The crystal (form I) has a larger volume of crystal cell than form I1 and has too large a HCWCOOMe (120 mg, 1.4 mmol) at room temperature. vacancy to be filled by H20 molecules around the 0 atom. We could Stirring the reaction mixture for 8 h caused the color of the not obtain further analytical or NMR results of the single crystal that mixture to change from colorless to yellow brown. After the was analyzed by X-ray crystallography to compare the two formulas for the crystal. reaction mixture was diluted by addition of toluene (14 mL),
;pq
Osakada et al.
3538 Organometallics, Vol. 14, No. 7, 1995 a small amount of insoluble product was removed by filtration. Evaporation of the solvent of the filtrate under vacuum followed by addition of Et20 (5 mL) gave a yellow brown solid (270 mg). The spectroscopic results indicate that the product is a mixture of copper complexes having Cu-CEC-COOMe bonds. IR (KBr)v(C=C) 2050, 2010, and 1904 cm-', v(C=O) 1671 cm-'; 'H NMR (CD2C12, -80 "C) 6 2.8-3.6 (br, 3H, CHd, 7.7-7.0 (m, 15H, C6H.5). Reaction of 3 with HCECCOOMe and with HC= CCOOEt. To an Et20 (10 mL) solution of 3 (110 mg, 0.095 mmol) was added HCECCOOMe (18 mg, 0.21 mmol) at room temperature. Stirring the yellow solution for 20 h caused the color of the solution to change from pale yellow to colorless, which was accompanied by formation of a white solid precipitated. The solid was filtered, washed with EtzO, and dried in vacuo (68 mg, 63%). The IR and the 'H NMR spectra of the product were identical with 1. Anal. Found: C, 68.5; H, 4.9. Calcd for C ~ ~ H ~ I C U C, ~ O68.9; ~ P H, ~ : 4.8. Similar reaction with 4 equiv of HCWCOOEt gave 2 in 73%. Anal. Found: C, 70.2; H, 5.0. Calcd for C64H55C U ~ O ~ C, P ~69.4; : H, 5.0. Reactions of 1-3 with PdC12(PEt&. A mixture of 1 (160 mg, 0.30 mmol of Cu), PPh3 (65 mg, 0.24 mmol) and PdC12(PEt3)z (60 mg, 0.15 mmol) was dissolved in toluene (2 mL). Stirring the reaction mixture caused gradual precipitation of a white solid from the initially colorless solution. After the reaction had proceeded for 4 h, the deposited white solid (CuC1(PPh3)3, 190 mg, 88%)was removed by filtration. The filtrate and Et20 washings of the solid were condensed to give the colorless residue. Recrystallization of the product from hexane (7a) (64 mg, at -30 "C gave trans-Pd(C~CCOOMe)2(PEt3)2 80%). IR (KBr disk) v(C=C) 2112 cm-', v(C=O) 1683 cm-'; lH NMR (CD2C12) b 1.2 (m, 18H, P(CHzCH3)3),1.9 (m, 12H, P(CH2CH&) 3.6 (s,6H, ocH3);13C{'H} NMR (CD2C12) b 8.6 (s,P(CHzCH3)3),17.2 (t,J 15 Hz, P(CHzCH3)3),51.9 (s,OCH3), 103.7 (t, J = 3 Hz, Pd-CZC), 117.8 (t, J = 16 Hz, Pd-C), 154.5 (s, C=O); 31P{1H}NMR (CD2C12) 19.4 ppm (s). Anal. Found: C, 47.5; H, 7.1. Calcd for C20H3604P2Pd: C, 47.2; H, 7.1. Similar reactions of 2 and 3 with PdC12(PEt3)2gave trunsPd(C=CCOOEt)2(PEt& (8a)(84%) and truns-Pd(CZCCO0'Bu)~(PEt3)2(9a)(loo%), respectively. Spectroscopic data for 8a: IR (KBr disk) v(C=C) 2094 cm-', v(Cp.0) 1673 cm-'; 'H NMR (CD2Clz) 8 1.2 (m, 18H, P(CHzCH&), 1.2 (t, 6H, CHd, 1.9 (m, 12H, P(CH2CH3)3),4.1 (q, 4H, OCH2); 13C{'H} NMR (CDzClz) b 8.6 (s, P(CHzCH3)3), 14.4 (s,CHd, 17.2 (t, J = 15 Hz, P(CHzCH3)3),60.8 (s,OCH2), 104.2 (t, J = 3 Hz, Pd-C=C), 117.4 (t,J = 16 Hz, Pd-C), 154.5 (s,C-0); 31P{1H}NMR (CD2Cl2) 19.8 ppm (s). Anal. Found: C, 49.5; H, 7.5. Calcd for CzzH4004PzPd: C, 49.2; H, 7.5. Spectroscopic data for 9a: IR (KBr disk) v ( C W ) 2090 cm-', v(C-0) 1669 cm-'; 'H NMR (CD2C12) b 1.2 (m, 18H, P(CH2CH3)3), 1.4 (s, 18H, CH3), 1.9 (m, 12H, P(CH2CHdd; 13C{'H} NMR (CD2C12) b 8.6 (s, P(CHzCH&), 14.4 (s,CH3), 17.3 (t,J = 14 Hz, P(CH2CH3)3), 28.3 (s,C(CH3)),80.5 (s, OC(CH3)3),105.8 (t,J = 3 Hz, PdCEC), 114.1 (t, J = 17 Hz, Pd-C), 153.5 (s,C-0); 31P{1H} NMR (CD2C12) 19.7 ppm (s). Anal. Found: C, 53.2; H, 8.9. Calcd for C26H48OzPzPd: C, 52.7; H, 8.2. Reaction of 4 with PdC12(PEt3)2. A mixture of 4 (150 mg, 0.35 mmol of Cu), PPh3 (180 mg, 0.68 mmol) and PdC12(PEtd2 (85 mg, 0.21 mmol) was stirred in Et20 ( 3 mL) under Ar for 6 h. The starting materials dissolved at once to give a pale yellow solution which gradually affords a white solid precipitate. After the mixture had been stirred for 6 h at room temperature the resulting white solid (CuCl(PPh3)3, 250 mg, 81%) was removed by filtration. The filtrate was evaporated to dryness to give a white residue, which was extracted with hexane several times. Cooling the hexane extract at -78 "C
gave trun~-PdCl(C~CSiMe3)(PEt3)~ (lob)as colorless crystals (82 mg, 82%). IR (KBr)v(C=C) 2048 cm-I; lH NMR (CD2C12) b 0.07 (s, 9H, Si(CH3)3),1.2 (m, 18H, P(CHzCH3)3),1.9 (m, 12H, P(CHzCH3)3);13C{lH} NMR (CD2C12) b 0.8 (5, Si(CH3)3),8.5 (s,P(CHzCH&), 15.7 (t, J = 14 Hz, P(CHzCH&), 112.1 (t, J = 4 Hz, Pd-CEC), 116.0 (t,J = 16 Hz, Pd-C). 31P{1H}NMR (CD2C12) 17.3 ppm (s). Anal. Found: C, 43.3; H, 8.3. Calcd for C17H39ClP2PdSi: C, 43.0; H, 8.3. Reactions of 5 and 6 with PdCl~(PEt3)z.A mixture of 5 (530 mg, 1.2 mmol of Cu),PPh3 (650 mg, 2.5 mmol), and PdC12(PEt& (310 mg, 0.75 mmol) was stirred in toluene (12 mL) under Ar for 4 h. Evaporation of the solvent followed by addition of Et20 caused precipitation of CuCl(PPh3)3, which was separated by filtration. Cooling the filtrate at -30 "C gave l l a as a yellow crystalline solid (160 mg, 39%). Complex l l b (200 mg, 56%) was obtained by addition of hexane to the filtrate after removal of l l a . Spectroscopic data for l l a : IR (KBr disk) v(C=C) 2098 cm-l; IH NMR (90 MHz, CD2C12) b 1.2 (m, 18H, P(CHZCH~).J), 2.0 (m, 12H, P(CHzCH3)3),7.0-7.4 (m, 10H, C6H5); I3C{lH} NMR (125 MHz, CD2C12) b 8.8 (s, P(CH2CH3)3),17.5 (t,J = 15 Hz, P(CHzCH3)3),110.9 (t, J = 3 Hz, Pd-CZC), 111.9 (t, J = 17 Hz, Pd-C), 125-131 (CsH5). Anal. Found: C, 60.9; H, 7.7. Calcd for C28H40P2Pd: C, 61.7; H, 7.4. Spectroscopic data for llb: IR (KBr disk) v(C=C) 2114 cm-l; IH NMR (90 MHz, CD2C12) d 1.2 (m, 18H, P(CHzCH&), 1.9 (m, 12H, P(CH2CH3)3)7.0-7.4 (m, 5H, C6H5); 13C{lH}NMR (125 MHz, CD2C12) b 8.5 (s,P(CH2CH3)3), 15.8 (t, J = 14 Hz, P(CHzCH3)3),96.0 (t, J = 16 Hz, Pd-C), 106.7 (t, J = 6 Hz, Pd-CsC), 125-131 (C6H5);31P{1H}NMR (CD2C12) ppm (s). Anal. Found: C, 51.0; H, 7.7. Calcd for C20H3jClP2Pd: C, 50.1; H, 7.4. Slight disagreement of analytical values of l l a and l l b with calculated values is due to insufficient separation of the complexes from each other by fractional crystallization. Reaction of 6 with PdClz(PEt3)2was carried out analogously (12a) to give a mixture of trun~-Pd(C=CC6H4-~-Me)z(PEt3)2 and truns-PdCl(C=CCsH*-p-Me)(PEt~)2 (12b),which could not be separated from each other (yield 73%, 12a:12b = 76:24). Spectroscopic data for 12a: IR (KBr disk) v(C=C) 2098 cm-'; 'H NMR (CD2C12) d 1.2 (m, 18H, P(CH2CH&), 2.0 (m, 12H, P(CH2CH313) 2.3 (s, 6H, CH3), 7.0 (d, 4H, J = 8 Hz), 7.4 (d, 4H, J = 8 Hz). 13C{lH}NMR (CD2C12)b 8.8 (s,P(CHzCH&), 17.6 (t,J = 15 Hz, P(CH2CH3)3),21.3 (s,CH3), 110.9 (t, J = 3 Hz, Pd-C=C), 111.9 (t, J = 17 Hz, Pd-C), 126-135 (CsH4); 31P{1H}NMR (CD2Cl2) 19.0 ppm (s). Spectroscopic data for 12b: IR (KBr disk) v(C=C) 2112 cm-'; 'H NMR (CDzC12) d 1.2 (m, 18H, P(CH2CH&), 1.9 (m, 12H, P(CH2CH3)3),2.3 (s, 6H, CH3), 7.1 (d, 2H, J = 7 Hz), 7.3 (d, 2H). 13C{'H} NMR ((125 MHz, CD2Clz) b 8.5 (s,P(CH&H3)3), 15.8 (t,J = 14 Hz, P(CHzCH3)3),21.3 (s,CH3), 94.4 (t, J = 16 Hz, Pd-C), 106.6 (t, J = 6 Hz, Pd-CEC), 125-136 (CsH4);31P{1H}NMR (CD2Cl2) 18.1 ppm (s).
Acknowledgment. This work was partially supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture, Japan. Authors are grateful to Dr. Masako Tanaka of our laboratory for the crystallographic study and the reviewer who gave us helpful suggestions on the crystallographic results. Supporting Information Available: Tables of positional parameters for all atoms, anisotropic displacement parameters of non-hydrogen atoms, and bond distances and angles of crystal forms I and I1 of 4*Et20(58 pages). Ordering information is given on any current masthead page. OM950059S
