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,, (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,, (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,, (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).