Inorganica Chimica Acta, 198-200 (1992) 557-564 557 zyxwvut Metal insertion into a CH bond as a route to the heterobimetallic p-methylidene complex C,H,(CO),Re(p-CH,)Pt(PPh,), Charles P. Casey*, Yan Wang, Lori M. Petrovich, Todd L. Underiner, Paulette N. Hazin and John M. Desper Department of Chemktry, University of Wuconsin, Mad&on, WZ 53706 (USA) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJ Abstract zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA The reaction of C,H,(CO),Re(CH,)-Li+ -THF (5) with (Ph,P),Pt[(E)-C(CH,)=CHCH,]+CF,SO,- (3E) in an attempt to prepare the heterobimetallic complex C,H,(CO),(CH,)RePt[(E)-C(CH,)=CHCH,](PPh,), (B) led to the formation of the new heterobimetallic p-methylene complex C,H,(CO),Re(@ZHz)Pt(PPh,), (4), which was characterized by X-ray crystallography. A mechanism involving initial generation of intermediate B followed by insertion of Pt into a C-H bond and reductive elimination is suggested. The related substituted alkylidene complexes C,H,(CO),Re[~-CH(E-CH~C=CHCH3)]Pt(PPh3)2 (9) and CsH,(C0)2Re(~-CHCH,)Pt(PPh,), (11) were prepared from Pt(C&)(PPh,), and the appropriate rhenium alkylidene complexes GH,(CO),Re=CHR. We have been exploring the synthesis and reactions of heterobimetallic compounds in an effort to find new types of reactions and catalysts. We found that the rhenium-platinum dihydride C,H,(CO),Re(p-H)- Pt(H)(PPh,), (1) [l] reduced 2-butyne to the &s-alkene rhenium complex C,H,(CO),Re(c&CH,CH=CHCH,) (2) and proposed that the reduction proceeded via platinum hydride addition across the alkyne to give the rhenium-platinum vinyl intermediate C,H,(CO),Re(p- H)Pt[(E)-C(CH,)=CHCH,](PPh,), (A) (Scheme 1) [2]. In an attempt to test this hypothesis, we reacted K+C,H,(CO),ReH- with (Ph,P),Pt[(E)-C(CH,)= CHCH,]+CF,SO,- (3E) in an effort to generate A by an independent route. The proposed intermediate A was not observed but 2 was obtained in high yield, consistent with our hypothesis [3]. We suggested that A was generated and that rapid hydride transfer led to 2. We thought that by replacing the reactive hydride of intermediate A with a methyl group we might be able to observe the related methyl intermediate C,H,(CO),(CH,)RePt[(E)-C(CH,)=CHCH,](PPh,), (B). Here we report that attempted generation of B led to formation of the new heterobimetallic I*.-methylene complex C,H,(CO),Re(p-CHz)Pt(PPh& (4), possibly via intermediate B (Scheme 2). *Author to whom correspondence should be addressed. Experimental General procedures ‘H NMR spectra were measured on a Bruker WP200, WP270, AM360 or AM500 spectrometer. 13C(1H} NMR spectra were obtained on an AM500 spectrometer operating at 125.76 MHz. 31P ‘H} { NMR spectra were obtained on an AM500 spectrometer operating at 202.46 MHz. ‘H{lH} NMR spectra were obtained on an AM360 or AM500 spectrometer operating at 55 or 76 MHz. ‘HflP} spectra were obtained on a Varian VXR 500 spectrometer. 31P chemical shifts are referenced to 85% external H,PO,. IR spectra were obtained on a Mattson Polaris (FT) spectrometer. Elemental analyses were performed by Galbraith Laboratories, Inc. (Knoxville, I-N). Air-sensitive material was manipulated in an inert- atmosphere glove box or by standard high-vacuum and Schlenk techniques. Tetrahydrofuran, hexane and di- ethyl ether were distilled prior to use from purple solutions of sodium and benzophenone. CH,Cl, was dried over CaH,. Cp(CO),Re(CH,)-Li+ - THF (5) At - 78 “C, THF (10 ml) was condensed into a flask containing CpRe(CO), (500 mg, 1.495 mmol) and LiAlI& (111 mg, 2.925 mmol) and equipped with a reversible frit. When the mixture was stirred at room temperature, gas evolved and the solution turned yellow. The mixture was then heated at 60 “C for 4 h. Solvent was evaporated under high vacuum and the resulting 0020-1693/92/$5.00 0 1992-Elsevier Sequoia. All rights reserved