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

Triosmium dodecacarbonyl catalyzes a very efficient oxidation of alkanes by H(2)O(2) in MeCN to afford alkyl hydroperoxides (primary products) as well as alcohols and ketones (aldehydes) at 60 degrees C if pyridine is added in a low concentration. Turnover numbers attain 60,000, and turnover frequencies are up to 24,000 h(-1).

Triple-decker complexes with a bridging diborolyl ligand CpCo(µ-1,3-C 3 B 2 Me 5 )M(ring) (M(ring) ) RuCp, 4; RuCp*, 5; Co(C 4 Me 4 ), 6) were synthesized by electrophilic stacking of the sandwich anion [CpCo(1,3-C 3 B 2 Me 5 )]with the [(ring)M(MeCN) 3 ] + cations. Structures of 4-6 were confirmed by X-ray diffraction. The electrochemical and spectroelectrochemical behavior of the complexes prepared was studied. DFT calculations of the redox potentials were also performed. Similar bonding properties of anions [CpCo(1,3-C 3 B 2 R 5 )]and [C 5 R 5 ] -(R ) H, Me) toward [M(ring)] + cations were established both experimentally (synthesis, electrochemistry, and X-ray diffraction) and theoretically (energy decomposition and Mulliken population analysis).