Novel bis(phosphine) pincer complexes of iridium based on ferrocene and ruthenocene have been synthesized. The reaction of 1,3-bis((di-tert-butylphosphino)methyl)metallocenes [t-BuP,CH,PM] (M = Fe, 10; M = Ru, 13) with [Ir(COE)2Cl]2 in refluxing toluene leads to the corresponding chloro-hydrido pincer complexes as a mixture of H-endo- (M = Fe, 11; M = Ru, 14) and H-exo-IrH(Cl)[t-BuP,C,PM] (M = Fe, 12; M = Ru, 15) isomers. Treatment of compounds 11, 12 and 14, 15 with NaH in hot cyclooctane generates corresponding dihydrido complexes IrH2[t-BuP,C,PM] (M = Fe, 6; M = Ru, 7). Reactivity of the chelated iridium atom in hydrido-iridium pincer complexes and oxidation centered at the iron atom of ferrocene-based pincer complexes were studied. Complexes H-exo-IrH(Cl)(CO)[t-BuP,C,PFe] (20), Ir(CO)[t-BuP,C,PFe] (21), and Ir(CO)[2,6-(tBu2PO)2C6H3] (30) were characterized by X-ray crystallography. On the basis of νCO values for carbonyl iridium derivatives, electronic characteristics of the corresponding fragments {Ir[t-BuP,C,PM]} n (n = 0, +1) were elucidated. Complexes 6 and 7 reveal unprecedented catalytic activity in cyclooctane dehydrogenation in the presence of tert-butylethylene as a hydrogen acceptor:  turnover numbers 3300, 2571, and 1843 were obtained for 6, 7, and the known complex IrH2[2,6-(tBu2PO)2C6H3] (4c), respectively, at 180 °C for 8 h. The high catalytic activity for 6 and 7 and the difference in the catalytic activity of these “isostructural” complexes are discussed in terms of steric and electronic effects.

Several palladium(II) complexes with 1,1‘-bis(diphenylphosphino)octamethylferrocene (dppomf) and its oxidized form 1,1‘-bis(diphenylphosphino)octamethylferrocenium (dppomf+) have been synthesized and characterized by spectroscopic and electrochemical methods. For comparative purposes, analogous Pd(II) derivatives with 1,1‘-bis(diphenylphosphino)ferrocene (dppf) have been also prepared. Single-crystal X-ray analyses have been carried out for the square-planar mononuclear compounds [Pd(H2O)2(dppf)](OTf)2 and [Pd(H2O)2(dppomf)](OTf)2 and for the binuclear complex [Pd(μ-OPF2O)(dppomf+)]2(BF4)4·6CH2Cl2 in which two [Pd(dppomf+)]3+ moieties are held together by the oxygen atoms of two bridging PO2F2 - groups derived from the oxidative degradation of PF6 - ions. Selected dppf and dppomf Pd(II) complexes have been employed as catalyst precursors for the methoxycarbonylation of ethene (600 psi, 1:1 CO/C2H4, 85 °C). It has been found that dppomf generates selective catalysts for the production of methyl propanoate, while dppf leads to a variety of low-molecular-weight oxygenates spanning from methyl propanoate to alternating oligoketones.

Tetramethylcyclobutadiene(cyclopentadienyl)cobalt complexes Cb*Co(C 5 H 4 R) (Cb* ) η 4 -C 4 Me 4 ; R ) H (5a), Me (5b), SiMe 3 (5d), C(O)H (5f), and C(O)Me (5g)) were obtained by reaction of cyclopentadienide anions either with the (carbonyl)iodide complex Cb*Co(CO) 2 I (1) (method A) or with the more reactive acetonitrile complex [Cb*Co(MeCN) 3 ] + (2) (method B). Analogous compounds Cb*CoCp* (5c), Cb*Co(1,3-C 5 H 3 (SiMe 3 ) 2 ) (5e), and Cb*Co(η 5indenyl) (6) can be prepared only by method B. Treatment of 5f,g with NaBH 4 /AlCl 3 or LiAlH 4 affords the alkyl derivatives 5b and 5h (R ) Et) or the alcohols 5i (R ) CH 2 OH) and 5j (R ) CH(OH)Me), respectively. The reaction of 1 with fluorene/AlCl 3 yields complex [Cb*Co-(η 6 -fluorene)] + (8), which was deprotonated by KOBu t to give Cb*Co(η 6 -fluorenyl) (9). Visible light irradiation of 9 induces η 6 fη 5 haptotropic rearrangement to afford Cb*Co(η 5 -fluorenyl) (7). The pyrrolyl and phospholyl complexes Cb*Co(C 4 R 4 N) (R ) H (10a), Me (10c)) and Cb*Co-(C 4 R 4 P) (R ) H ( 11a), Me (11c); R 4 ) H 2 Me 2 (11b)) were obtained by reaction of 2 with the corresponding pyrrolide or phospholide anions. Improved procedures for the preparation of the starting materials 1 and 2 were developed. Using a one-pot procedure, the iodide 1 was obtained in high yield from 2-butyne and Co 2 (CO) 8 . Complex 2 was prepared by heating or irradiation of the toluene complex [Cb*Co(C 6 H 5 Me)] + (4b) in acetonitrile. Structures of 5g, 6, and 11c were investigated by X-ray diffraction. Electrochemistry and joint UV-visible and EPR spectroelectrochemistry of complexes prepared were studied. Scheme 3Scheme 4

The syntheses and characterization of series of new metallocene-bridged diphosphines and the structures of complexes of some of them with Pd(II) are reported. These complexes were examined as the catalysts in amination reactions of halogenoarenes and in the Suzuki reaction. The complexes based on ruthenocene (2) and osmocene (3) showed lower activities then the palladium complex with dppf in amination reactions and the same activities in the Suzuki reaction. New palladium complexes with the bidentate bulky and electron-rich ligands Fe(η 5-C5H4P(o-Pr i C6H4)2)2 (6) and Fe(η 5-C5H4P(o-MeOC6H4)2)2 (5) showed a very high catalytic activity in amination and Suzuki coupling of aryl bromides. A complex with ligand 6 was used in the amination of 4-bromotoluene by primary and secondary amines and showed excellent activity.