Phosphole transition metal complexes

When the sodium or bromomagnesium salts of these anions are treated with transition metal halides (FeCU) (78JOM(156)C33, 81IC3252) or carbonyls, e.g. Mn2(CO)10, very interesting 175 67r-phosphole transition metal complexes (89) and (90) are formed (equations 51 and 52) <79JCS(D)1552, 80JA994). 

Figure 3 Recently reported single crystal X-ray structures of phosphole systems with three and four heteroatoms (transition metal complexes are not included).

It is noteworthy that the P atoms of these phosphole oligomers retain the versatile reactivity observed with monophospholes [7]. In particular, biphosphole 9 exhibits a rich coordination chemistry, which allows for the preparation of a variety of neutral and cationic transition metal complexes (Scheme 4.5) [18a,b, 22]. These have been used as precursors for homogeneous catalysts [22] however, their photophysical properties have not been studied. 

Phospholes and Their Transition Metal Complexes as Therapeutic Agents... 

It is noteworthy that phosphole derivatives with CN 4 (oxo-, thiooxo-phospholes, phospholium salts, etc.) as well as transition metal complexes are generally air stable and can be purified by crystallization or column chromatography. 

Table 2. Transition metal complexes of phospholes as two electron donors ...

A theoretical study of the Diels-Alder reactions between 1,3-butadiene and, respectively, cyclopentadiene and 2H-phosphole, has revealed a remarkable similarity between the two reactions. Further studies of photocycloaddition reactions of phosphole moieties have also been reported. Transition metal complexes of phospholide anions continue to attract attention, and in particular the chemistry of phosphaferrocene systems remains a major interest . The past year has also seen significant activity in the chemistry of di- and tri-phospholes, related polyphospholide anions, and also heterodiphosphole systems. Routes have been developed to the diphosphonio-l,2-diphospholes 356,... 

An interesting new development in aromatic phosphole chemistry has been the preparation and subsequent study of the electrophilic substitution reactions of transition-metal complexes of phospholyl anions, e.g. the phosphaferrocenes (165), which are obtained by the reaction of the appropriate P-phenylphosphole with transition-metal cyclopentadienyls or carbonyls, - and which undergo acetylation at... 

Phosphine ligands, including P-heterocyclic entities, are often used in transition metal complexes. The phosphole derivatives are the most widely used heterocyclic P-ligands. In this part the less known transition metal complexes with 6-ring phosphines are summarized. 

Other instances of the uses in synthesis of perfluoroalkyne-containing transition-metal complexes are the preparation of tetrakis(triiluoromethyl)-phosphole (147) and the IV-anilinoquinolone (148), both from perfluoro-but-2-yne. 

Aromatic groups on the ring carbons stabilize strongly the C-phenylated group 14 metalloles, as in the case with phospholes , but the reactivity of the dienic system (i.e. Diels-Alder cycloadditions, formation of transition metal complexes) decreases . ... 

Matano Y, Nakabuchi T, Fujishige S, Nakano H, Imahori H (2008) Syntheses, structures, and coordination chemistry of phosphole-containing hybrid calixphyrins promising macrocyclic P,N-2,X-mixed donor ligands for designing reactive transition-metal complexes. J Am Chem Soc 130 990... 

Scheme 12.63 Synthesis of phosphole-containing hybrid calixpyrroles 177 and their transition metal complexes-178-179...

Scheme 12.67 Synthesis of phosphole based cyclophanes 193-197 and their transition metal complexes 198-200...

Phospholes can behave as simple two electron donors, in the same way as tertiary phosphines, and most of the transition metals have been complexed to phospholes. For example, ruthenium(II) forms a series of complexes [(Phole)2 Ru(CO)2C12] and [(Phole)3 Ru(CO)C12]. The formation of the tris phosphole complex attests to their small size. Because of the ring structure an unusual isomerism has been observed, with the rings either in the basal plane of the square pyramidal complex or normal to the basal plane (Figure 23). 

A rich and diverse chemistry has developed based on the phosphorus ring system complexed to transition metals analogous to the metallocenes. Phospholes and phosphametallocenes have recent-... 

Phosphinimato complexes transition metals, 122,125 bonding, 124 IR spectroscopy, 124 reactions, 125 structure, 124 synthesis, 123 Phosphini mines imido metal complexes synthesis from, 167 Phosphoglucomutase zinc complexes, 965 Phospholes... 

Compared with organic molecules, metal complexes offer a larger variety of molecular structures and a diversity of electronic properties [13]. Since it is well known that phospholes and pyridines behave as classical two-electron donors toward transition metals [13, 14], we have explored the coordination behavior of 2-pyridyl-substituted phospholes with the aim of obtaining complexes exhibiting interesting physical properties. Moreover, original structures can be expected since these heteroditopic P,N-ligands possess two coordination centers with different stereo-electronic properties. The performances of such complexes have been evaluated as catalysts as well as new materials for optoelectronics. 

Finally, phosphole sulfides can behave as 77 4-electron or Tj -CjTj -Y-b-electron donors toward transition metals. For example, derivative 106 reacts with CpCo(CO)2 to afford the [7] -(phosphole sulphide)]cobalt(I) complex 107 (Scheme 31), which was characterized by X-ray diffraction <2006HAC344>. The chromium complex 109 was obtained in high yield from thioxophosphole 108 and its molecular structure determined crystallographically (Scheme 31). 

Figure 3.92 Synthesis of a transition metal phosphino functionalised carbene complex starting from a coordinated phosphole.

A rich and diverse chemistry has developed based on the phosphorus ring system complexed to transition metals analogous to the metallocenes. Phospholes and phosphametallocenes have recently been reviewed by Mathey et al The phosphacymantrenes and phosphaferrocenes will be used here as representative examples (equation 76). UV photoelectron spectroscopy has shown that the HOMO is not localized on phosphorus, but is mainly on the ring carbons the lone pair orbital is only the fourth highest occupied orbital. The LUMO is mainly localized on phosphorus in phos-phacymantrene, whereas in cymantrene it is on the manganese. 

H, R = R" = Me) and 154. The first of them corresponds to the composition LM(C0)5, while complexes 154 are formulated as L2M(CO)4 (M = Cr, R = Ph M = Mo, R = Me, Bu, Ph M = W, R = Ph) and represent the derivatives of Diels-Alder dimers with an unusual exo configuration. They have a cis arrangement around the metal atom. The first step of transition-metal-assisted dimerization includes formation of 155 (M = Cr, W) where two phosphole units are quite close to each other. The second stage, intramolecular dimerization, is promoted by... 

---