Cyclopentadienyl carbonyl complexes phosphines

While the majority of group 4B metal carbonyl complexes contain 7r-bonded hydrocarbon ligands, most notably 17-cyclopentadienyl, recent studies by Wreford and co-workers have led to the identification and isolation of three novel phosphine-stabilized titanium carbonyl complexes (12,13). 

A number of molecular mechanics studies of metal-cyclopentadienyl complexes have been reported recently. The systems studied include linear metallocenes (in particular ferrocene), ferrocene derivatives (such as complexes with substituted cy-clopentadienyl ligands, bis(fulvalene)diiron complexes, ferrocenophanes and mixed-ligand complexes with carbonyls and phosphines), and nonlinear cyclopentadienyl complexes 8,153,221 231]. 

Bis(amido) phosphine-donor complexes, with Zr(IV), 4, 816 Bis(amido) pyridines, with Zr(IV) and Hf(IV), 4, 790 Bis(aminoalkylidyne) complexes, diiron carbonyl complexes with cyclopentadienyl ligands, 6, 248-251 Bisaminosilylenes, in molybdenum carbonyls, 5, 406 Bis(tj-arc nc) complexes, as metal vapor synthesis milestone, 1, 236... 

Further examples include homo-, co- and terpolymers of manganese carbonyl, iron carbonyl or cyclopentadienyl, and ruthenium-phosphine complexes [31, 59, 60]. 

In addition to the release of carbon monoxide, transition metal carbonyl complexes have also found applications in anticancer chemotherapy [212], radiolabelling [213-216], and as photosensitisers. The cobalt complex shown in Fig. 14 a demonstrates a higher anticancer activity than cis-platin in certain mammary tiunor cells Hnes [217,218]. Complexes such as Tc-99m(I)(CO)3(OH2)3 along with hydroxymethyl phosphine derivatives [219] and the cyclopentadienyl complex shown in Fig. 14b have useful radiopharmaceutical applications, in diagnosis, using Tc, as the metal centre, and in therapy based on Re and Re isotopes [220]. 

Ruthenium(II), d, is known as the binary bromide and as [RuCU] ". The richer complex chemistry involves stable compounds with cyanide, amines, halides, water, nitrosyl, carbonyl, hydride, phosphine, arsine, stibine, arene, and cyclopentadienyl ligands. [RuCl2(PPh3)2] is used as a catalyst. Ruthenium(II) is a good itt-donor and... 

In both the examples given above, there is concomitant loss of one or more neutral ligands. Elimination of CO is the rule in reactions of mononuclear metal carbonyls (e.g., entry 12) and cyclopentadienyl metal carbonyls (e.g., entry 4), but not those of polynuclear carbonyls (e.g., entry 16) or carbonyl halides (e.g., entry 33). Elimination of tertiary phosphines often occurs, especially when more than two molecules are present in the initial complex however, this is not always the case (see entry 24). Clearly, steric requirements and the dictates of the 18-electron rule determine the composition of the product, and normally act in concert when they conflict, as in the case of R3SiRuH3(PR3) (n = 2 or 3 entry 22), variable stoichiometry may result. Chelating diphosphines, with somewhat reduced steric requirements, are usually retained (e.g., entry 19), while complexed olefins are invariably lost the bulky ligand P(cyclohexyl)3 is associated with unusual products (entries 47 and 48). Particular mention may be made of the 17-electron species Cl3SiVH(Cp)2 and (Cl3Si)2V(Cp)2 shown... 

In contrast to the inertness of bisalkynebisdithiocarbamate complexes, alkyne displacement from bisalkyne cyclopentadienyl derivatives is common. An extensive series of cationic [CpMo(CO)L(RC=CR)][BF4] complexes has been prepared from [CpMo(CO)(RC=CR)2][BF4] reagents by substitution of one of the coordinated alkynes [Eq. (19)] (72). Reaction of the carbonyl reagent with phosphines occurs smoothly at room temperature in methylene chloride to form monoalkyne products in high yields... 

The zerovalent cyclopentadienyl see Cymantrene) titanium carbonyl phosphine complexes [CpTi(CO)3(PR3)] and... 

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