This paper describes the generation and properties of nonchelated d(0) zirconocene-aryl-alkene and alkyne adducts that are stabilized by the presence of beta-SiMe3 substituents on the substrates and the weak nucleophilicity of the -C6F5 ligand. The cationic complexes [(C5H4R)(2)Zr(C6F5)][B(C6F5)(4)] (4a: R) H, 4b: R) Me) were generated by methide abstraction from (C5H4R)(2)Zr(C6F5) Me by Ph3C+. NMR studies show that 4a,b contain an o-CF center dot center dot center dot Zr dative interaction and probably coordinate a PhCl molecule in PhCl solution. Addition of allyltrimethylsilane (ATMS) to 4a, b in C6D5Cl solution at low temperature produces an equilibrium mixture of (C5H4R)(2)Zr(C6F5)(H2CdCHCH2SiMe3)(+) (7a, b), 4a, b, and free ATMS. Similarly, addition of propargyltrimethylsilane (PTMS) to 4a produces an equilibrium mixture of Cp2Zr(C6F5)( HCtCCH(2)SiMe(3))(+) (8a), 4a, and free PTMS. The NMR data for 7a, b, and 8a are consistent with highly unsymmetrical substrate coordination and substantial polarization of the substrate multiple bond with significant positive charge buildup at C-int and negative charge buildup at C-term. PTMS binds to 4a more strongly than ATMS does. The ATMS adducts undergo nondissociative alkene face exchange ("alkene flipping"), i. e., exchange of the (C5H4R)(2)Zr(C6F5)(+) unit between the two alkene enantiofaces without decomplexation of the alkene, on the NMR time scale.