Organometallics 1986,5,1171-1178
1171
Reaction of Diazomethane with Platinum(I I ) Chloride Complexes of Chelating Olefins. Crystal Structure Analyses of a -Chloro-b -(chloromethyl)-cd(2,2, N ,N-tetrameth y l-3-buten- 1-amine)platinum( I I ), a -Chloro-b -(chloromethy1)-dc-(2,2,N ,N-tetramethyl-3-buten- 1amine)platinum( I I), a -Chloro-b-(chloromethy1)-dc(2,2-dlmethyl-3-buten-l-yl methyl sulfide)platinum( I I), and Dlchloro[ (2,2-dimethyl-4-penten-l-yl)methylsulfonium methylide-C ,C,C]platinum( I I ) Robert McCrindle,' George Ferguson, Gllles J. Arsenault, Alan J. McAlees, Barbara L. Ruhl, and David W. Sneddon Gueiph-Waterloo Centre for Graduate Work in Chemism, Guelph Campus, Department of Chemistry and Biochemistry, Univers@ of ooelph, Gueiph, Ontario, Canada N1G 2W1 Received August 16, 1985
Reaction of dichloro(2,2JVJV-tetramethy1-3-buten-l-amine)platinum(II) (11, dichloro(2,2-dimethy1-3buten-1-yl methyl sulfide)platinum(II) (2), or dichloro(2,2-dimethyl-2-silabut-3-enyl methyl sulfide)platinum(I1) (4), with diazomethane leads to the carbene insertion products a-chloro-b-(chloromethy1)cd-(2,2JVJV-tetramethyl-3-buten-l-amine)platinum(II) (8), a-chloro-b-(chloromethyl)-dc-(2,2-dimethyl3-buten-1-ylmethyl sulfide)platinm(II) (lo), and a-chloro-b-(chloromethy1)-dc(2,2-dimethyl-2-silabut-3-enyl methyl sulfide)platinum(II) (ll),respectively. Similar treatment of dichloro(2,2-dimethyl-4-penten-l-y1 methyl suKde)platinum(II) (7) gives an unstable chloromethyl complex which decomposes to a sulfur ylide methylidelplatinum(I1) (13). In solution, complex, dichloro[(2,2-dimethyl-4-penten-l-yl)methylsulfonium 8 isomerizes at ambient temperature to a-chloro-b-(chloromethyl)-dc-(2,2JVJV-tetramethyl-3-buten-lamine)platinum(II) (9). X-ray crystal structure analyses have been completed on 8, two forms of 9,10, and 13. Crystals of 8,CgHlgC12NPt,are monoclinic, space group R 1 / c , with a = 8.464 (2)A, b = 9.563 (2)A, c = 15.112 (3)A, p = 94.68 (2)O,and 2 = 4. Crystals of both forms of 9, CgHl9Cl2NPt,are monoclinic, space group P2'/n. Form 1 has a = 6.575 (2)A, b = 12.141 (2)A,c = 16.129 (3) A, B = 101.10 (2)O,and 2 = 4. Form 2 has a = 7.578 (1)A, b = 15.950(3)A, c = 10.885 (2)A, 0 = 107.26 (2)O,and 2 = 4. Crystals of 10,C8H16C12PtS,are monoclinic, space group R1/c, with a = 6.775 (1)A, b = 16.345 (2)A, c = 11.469 (1)A,0 = 105.51 (1)O, and 2 = 4. Crystals of 13, CgH18C12PtS,are monoclinic, space group R , / c , with a = 12.851 (2)A, b = 12.950 (1)A, c = 16.206 (2)A, 0 = 108.14 (1)O,and 2 = 8.
Introduction We have carried out an extensive series of studied on the reactions of palladium(I1) complexes of chelating methyl olefinic ligands including 2,2-dimethyl-3-buten-l-y1 sulfide and 2,2,N&-tetramethyl-3-buten-l-amine. Our interest has centered particularly on reactions involving the olefin. The ligands used were chosen' because (i) 'H NMR spectra of the original complexes, and of products derived from them, are readily interpretable and (ii) the structures of the ligands restrict the reaction pathways available. Both amine and sulfide ligands were examined to determine the influence of the nature of the accompanying ligand atom on the course of reaction. Indeed, contrary to what one might have anticipated, the nature of the products obtained changes on substituting amine for sulfide and/or six-membered chelate ring for fivemembered ring. Recently we reportedlb the results of the reaction of diazomethane with the PdCI2complexes of the two ligands mentioned above. We were interested in generating either the cyclopropane analogues (in the expectation that these might give characterizable, chelated complexes) or related complexes, for example, ?r-allyl or palladiocyclobutane species. Indeed in the case of the sulfide ligand, products (1) For leading references see: (a) McCrindle, R.; McAlees, A. J. J. Chem. SOC.,Dalton Trans. 1983,127-131. (b) McCrindle, R.; Sneddon, D. W. J . Organomet. Chem. 1985,282,413-419.
containing cyclopropyllb and ?r-ally12moieties have been obtained. However, the major products from the complexes of both ligands derive from methylene insertion into a Pd-Cl bond. This type of insertion, although well-known for main-group halides, is rather rare for the transitionmetal analogues? a-Haloalkyl complexes have attracted recent interest4 as potential sources of carbenes and as precursors to a wide range of functionalized alkyl derivatives of transition metals. We have now turned to an investigation of the reaction of diazomethane with the platinum(I1) analogues for several reasons. First, products of insertion, if formed, were expected to be more stable than the corresponding palladium derivatives. Second, it was hoped that the lower kinetic reactivity of platinum(I1) might provide information about steps in the insertion process. Third, any (halomethy1)platinumolefin products might serve as precursor to platinacyclobutanes. (2) Araenault, G. J., unpublished result.
(3) (a) Seyferth, D. Chem. Reu. 1966,55,1155-1177. (b) Mataumoto, K.; Odaira, Y.; Tautaumi, S. Chem. Commun..1968,832-833. (c) H e m ann, W. A. Adu. Organomet. Chem. 1982,20, 159-263. (d) Hill, A. F.; Roper, W. R.; Water, J. M.; Wright, A. H. J . Am. Chem. SOC.1983,105, 6939-5940. (e) Clark, G. R.; Roper, W. R.; Wright, A. H. J. Organomet. Chem. 1984,273, C17-Cl9. (0Jennings, P. W.; Ekeland, R. E.; Waddington, M. D.; Hanks, T. W. J. Organomet. Chem. 1985,285,429-436. (4) For leading references see: (a) Kennode, N. J.; Lappert, M. F.; Skelton, B. W.; White, A. H. J. Chem. SOC.,Dalton Trans. 1981,698-699. (b) Botha, C.; Moas, J. R.; Pelling, S.J. Organomet. Chem. 1981, 220, C21X24. (c) Engelter, C.; Moss, J. R.; Niven, M. L.; Nassimbeni, L. R.; Reid, G . J. Organomet. Chem. 1982,232, C7&CSO.
0276-733318612305-1171$01.50/0 0 1986 American Chemical Society
1172 Organometallics, Vol. 5, No. 6, 1986 Table 1. Analytical and Physical Data for the Complexes anal. found (calcd) comdex mD, 'C C H N 1 2200 24.41 (24.44) 4.29 (4.36) 3.50 (3.56) 199-200 21.15 (21.22) 3.56 (3.56) 2 151-153' 17.42 (17.48) 3.55 (3.42) 4 130-132 23.56 (23.42) 3.80 (3.93) 7 8b 158-160 26.67 (26.54) 4.68 (4.70) 3.38 (3.44) 154-155 9b 79-81 23.90 (23.42) 3.86 (3.93) 1O b 158-165 13b Decomposition. bX-raystructure determination done on single crystal.
Experimental Section Melting points were determined on the Kofler block and are uncorrected. 'H NMR and '% NMR spectra were recorded on Bruker WH-400 (Southwestern Ontario N M R Centre) or AM-250 spectrometers for solutions in deuteriochloroform with tetramethylsilane as internal standard. Elemental analyses were performed by Galbraith Laboratories, Inc., Knoxville, TN. TLC plates were spread with Kieselgel G (Merck) and run in dichloromethane/methanol (49:l or 99:l). Diazomethane was prepared by reacting N-methyl-N-nitroso-p-toluenesulfonamide with potassium hydroxide in aqueous 2-(2-ethoxyethoxy)ethanol and was distilled and then trapped in diethyl ether (at 0 "C). Table I contains physical and analytical data for the complexes while Tables 11and III contain relevant 'H N M R data and Table IV contains I3C NMR data. S y n t h e s i s of t h e Dichloroplatinum(I1) Complexes. Platinum dichloride was stirred with a slight excess of the appropriate free ligand in dichloromethane (30 mL) at room temperature. When the reaction was complete (no further dissolution of PtCl,), the solution was filtered and the resulting product crystallized, in some cases after chromatography. Dichloro(2,2,N ,N-tetramethyl-3-buten-1-amine)platinum(I1) (1). Platinum dichloride (399 mg, 1.50 mmol) and 2,2,iV,iV-tetramethyl-3-buten-l-amine5 were allowed to react for 7 days, and then the products were chromatographed to give 1 (200 mg, 34%). Crystallization from chloroform/hexane afforded pale yellow needles. Dichloro(2,2-dimethyl-3-buten1-yl methyl su1fide)platinum(I1) (2). Platinum dichloride (532 mg, 2.00 mmol) and 2,2-dimethyl-3-buten-l-yl methyl sulfide (3)5were stirred together for 4 days to give 2. Crystallization from dichloromethane/hexane afforded pale yellow rods (720 mg, 9070). Dichloro(2,2-dimethyl-2-silabut-3-enyl methyl sulfide)platinum(I1) (4). Platinum dichloride (441mg,1.66 m o l ) and 2,2-dimethyl-2-silabut-3-enyl methyl sulfide (5)5upon reaction for 3 days gave 4 (470 mg, 73%) as pale yellow prisms when crystallized from dichloromethane. Dichloro(2,2-dimethy1-4-penten-l-y1 methyl sulfide)platinum(I1) (7). Platinum dichloride (381 mg, 1.43 mmol) and 2,2-dimethyl-4penten-l-yl methyl sulfide (6)6 (225 mg,1.56 mmol) were stirred together for 4 days to give 7 (434 mg, 74%) as rosettes of fine yellow needles when crystallized from acetone/hexane. Reaction of t h e Dichloroplatinum(I1) Complexes w i t h Diazomethane. Unleas otherwise stated, the dichloroplatinum(II) complexes were dissolved in dichloromethane (25 mL) and were treated at 0 OC under an atmosphere of air with aliquots of ethereal diazomethane until analytical "LC showed that all of the substrate had reacted. Reaction of 1with Diazomethane. (i) Reaction of 1 (80mg, 0.203 mmol) gave essentially one less polar product (on TLC evidence). The resulting solution was evaporated, giving a-
chloro-b-(chloromethyl)-cd-(2,2,N,N-tetramethyl-3-buten-lamine)platinum(II) (8) as a residual oil (88 mg), which upon crystalkation from dichloromethane/ hexane yielded air-stable, near colorless needles (62 mg, 75%). (ii) When the above ex(5)McCrindle, R.; Alyea, E. C.; Dias, S. A.; McAlees, A. J. J. Chem. SOC.,Dalton Trans. 1979, 640-647. (6) McCrindle, R.; Alyea, E. C.; Feguaon, G.; Dias, S. A.; McAlees, A. J.; Parvez, M. J. Chem. SOC.,Dalton Trans. 1980, 137-144.
McCrindle et al. periment was repeated under an atmosphere of dinitrogen, only 8 was detected by TLC even after the addition of excess diazomethane. Preparative TLC of the reaction product gave 8 (91% ). (iii) Upon dissolution in deuteriochloroform (0.5 mL), 8 (44mg) slowly isomerized to a-chloro-b-(chloromethyl)-dc-(2,2,N,N(9). After 24 h at tetramethyl-3-buten-l-amine)platinum(II) ambient temperature the extent of conversion ('H NMR, TLC evidence) WBB substantial (>go%). Heating the solution a t 53 OC for a further 24 h pushed the isomerization to near completion, leaving only trace amounta of 8 (
ti CI
I
CI-R'-l JHz
It
13 -
-
JI
E -
-L
1 I
CI-Pt-CH, CI
1
\ - clr'''n ?[ -
H,C-Pt+L
HZC'd,
I
-9,10,11,12 --_
Figure 2. A proposed mechanism for the formation of compounds 8-13.
of 8 into 9 may provide an important clue as to the mechanism of the insertion process. Indeed, it may suggest that 9-12 represent thermodynamic rather than kinetic products. A possible mechanism is outlined in Figure 2. This involves a series of nucleophilic displacement processes which proceed via trigonal-bipyramidal intermed i a t e ~ . ' ~The first step is similar to that proposed3efor the reaction of diazomethane with IrI(CO)(PPh,),: nitrogen could conceivably leave at a later stage. Insertion would be expected to take place preferentially into the P t 4 l bond which is subject to the higher trans influence;'* i.e., 8 should be the kinetic product. This scheme would also rationalize the fact that we did not observe the sulfur ligand analogues of 8. Formation of five-coordinate intermediates should be less favorable with the more sterically demanding tertiary amine and a platinum-sulfur bond is expectedlg to be more labile than a platinum-nitrogen bond. This mechanism also accommodates the conversion of 12 into 13. Transformation of a thioether complex into an ylide metal complex is a well-knownmtype of reaction, and indeed the reverse process has been reported2' for a platinum(I1) derivative. Registry No. 1, 101494-50-2; 2, 101494-51-3; 3, 20025-34-7; 4, 101494-52-4; 5, 101518-24-5; 6, 73411-26-4; 7, 101494-53-5; 8,
101494-54-6; 9,101627-10-5; 10,101494-55-7; 11,101494-56-8; 12, 101494-57-9; 13, 101494-58-0; PtC12, 10025-65-7; 2,2,N,N-tetramethyl-3-buten-l-amine, 20166-72-7; diazomethane, 334-88-3. Supplementary Material Available: Lists of structure factors, thermal parameters, calculated hydrogen coordinates, torsion angles, and least-squares planes for 8 , 9 (I),9 (II), 10, and 13 (141 pages). Ordering information is given on any current masthead page. (17)Anderson, G.K.;Cross, R. J. Chem. SOC.Rev. 1980,9, 185-215. (18)See, for example: Langford, C. H.; Gray, H. B. Ligand Substitution Processes; W. A. Benjamin: New York, 1965;p 18. Huheey, J. E. "Inorganic Chemistry, Priniiplea of Structure and Reactivity", 2nd ed.; Harper and Row: New York, 1978;p 490. (19)See ref l a and Hartley, F. R. The Chemistry of Platinum and Palladium; Wiley: New York, 1973;p 220. (20)Weber, L.Angew. Chem., Int. Ed. Engl. 1983,22, 516-528. (21)Mataubayashi, G.;Kondo, Y.; Tanaka, T.; Nishigaki, S.; Nakatsu, K.Chem. Lett. 1979,375-378.
