Other Metal dppe Complexes

The Ag(I) complex (AgN03)2 (dppe), although toxic to mice (MTD 8 pmol/kg) was inactive as an antitumour agent. However, some bis-chelated Ag(I) diphosphine complexes do have in vivo anitumour activity. 

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Other metal hydrides which lose after protonation at the H ligand include TpM(CO)H(P Pr3) (M=Ru, Os) (Tp = tris(pyrazolyl)borate) [61] and TpmRuH(PPh3)2 (Tpm = tris(pyrazolyl)methane) [62]. Protonation of Os(dppe)2 H(CH3CN) gives a stable complex, but transient loss is implied... 

Analogous reaction of Pt(Me)(OMe)(dppe) with CF2=CF2 in THF to give 6-methoxytetrafluoroethyl complex was proposed to involve migratory insertion step, without dissociation of OMe ion, though no direct stereochemical evidence has been provided [51], Apparent migratory insertion of alkenes to metal-hydroxo bond has also been observed in other metal complexes such as those of Ir [52]. 

This unusual reactivity was subsequently extended to a broad variety of allylic and propargylic amines, in combination with other ruthenium(II) metal fragments, allowing the isolation of aminoaUenylidene complexes 33-35 [47 9] (Fig. 6). In addition, the S3mthesis of the thio-allenylidene [44] and seleno-aUenylidene [50] derivatives 36 from the in situ generated butatrienylidene tra s-[RuCl (=C=C=C=CH2)(L2)2] (L2 = dppm, dppe) and the corresponding aUyl sulfides... 

In our initial studies on the [5+2] cycloaddition, several metal catalysts were screened. Rhodium(I) systems were found to provide the optimum yields and generality [26]. Since the introduction of this new reaction in 1995, our group and others have reported other catalyst systems that can effect the cycloaddition of tethered VCPs and systems. These new catalysts thus far include chlororhodium dicarbonyl dimer ( [RhCl(CO)2]2 ) [27], bidentate phosphine chlororhodium dimers such as [RhCl(dppb)]2 [28] and [RhCl(dppe)]2 [29], and arene-rhodium complexes [(arene)Rh(cod)] SbFs [30]. [Cp Ru(NCCH3)3] PFg has also been demonstrated to be effective in the case of tethered alkyne-VCPs [31], but has not yet been extended to intermolecular systems or other 2n -components. 

Mo(r75-C5H5)2H2] and [MoH dppe ]. Our studies of the di- and trihydride complexes of ruthenium and iridium, described above and published previously (27,35), and those of other workers (discussed at the beginning of this chapter), indicate that photoinduced elimination of molecular hydrogen is a common reaction pathway for di- and polyhydride complexes. To demonstrate the photoreaction s generality and its utility for generating otherwise unattainable, extremely reactive metal complexes, we have begun to study the photochemistry of polyhydride complexes of the early transition metals. We focused initially... 

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