C. Scott Eschbach

A 13C nuclear magnetic resonance study of cyclobutadieneirontricarbonyl-substituted carbonium ions

Abstract The 13 C NMR spectra of (hydroxymethyl)-, (α-hydroxyethyl)- and (α-hydroxybenzyl)cyclobutadieneiron tricarbonyl (in CDCl 3 ) and of their derived carbonium ions (in concentrated H 2 SO 4 ) are reported. The data suggest extensive donation of electron density from the metal, via the cyclobutadiene unit, to the exocyclic, electron-deficient carbon atom, thus giving highly stabilized carbonium ions.

The diphenylmethylbis(π-chromium tricarbonyl) carbonium ion. Isolation of a stable hexafluorophosphate salt

Abstract Reaction of diphenylmercurybis(π-chromium tricarbonyl) with dicobalt octacarbonyl in THF gave benzophenonebis(π-chromium tricarbonyl). Reduction of the latter with NaBH 4 in methanol resulted in formation of the expected alcohol which was treated with hexafluorophosphoric acid in propionic anhydride to give the title carbonium ion salt as a blue solid. This salt was found to alkylate ethanol, diethylamine and pyrrole.

Organocobalt cluster complexes: XXII. α,β-Unsaturated methylidynetricobalt nonacarbonyl complexes☆

Abstract The reaction of the appropriate RCCl 3 compound with dicobalt octacarbonyl has been used to prepare CH 2 CHCCo 3 (CO) 9 , CH 2 C(CH 3 )CCo 3 (CO) 9 , Me 3 SiCHCHCCo 3 (CO) 9 and CH 3 C(O)CHCHCCo 3 (CO) 9 . A similar reaction with CH 2 CHCH 2 CCl 3 gave a mixture of CH 2 CHCH 2 CCo 3 (CO) 9 , CH 3 CH CHCCo 3 (CO) 9 and CH 3 CH 2 CH 2 CCo 3 (CO) 9 . Protonation of these α,β-unsaturated methylidynetricobalt nonacarbonyl complexes resulted in formation of the αcluster carbonium ions (e.g., CH 2 =C(CH 3 )CCo 3 (CO) 9 + HPF 6 → (OC) 9 Co 3 CC(CH 3 ) 2 + PF6 6 − ), with desilylation occurring during the protonation of Me 3 SiCH CHCCo 3 (CO) 9 . The CH 3 C(O)Cl/AlCl 3 reagent was used to acetylate the first two listed complexes in the β position, and methoxymercuration of CH 2  CHCCo 3 (CO) 9 with Hg(O 2 CCF 3 ) 2 , followed by anion exchange with NaCl, gave ClHgCH 2 CH(OCH 3 )CCo 3 (CO) 9 .

Organocobalt cluster complexes : XVI. Vinyl derivatives of methylidynetricobalt nonacarbonyl: useful precursors to (OC)9 Co3 c-substituted carbonium ions and functionally substituted derivatives☆

Abstract Vinyl-substituted of methylidynetricobalt nonacarbonyl of the type RR′CC(R″)CCo3(CO)9 have been prepared, with vinylic groups CH2 CH, CH2 C(CH)3, Me3SiCHCH and CH3 C(O)CHCH. Reaction of the first two with HPF6 produced the carbonium ions via β-proton addtions to the CC bonds. Acetylium ion addition also could be achieved. Proton addition to the Me3Si compound resulted in desilylation.

Organocobalt Cluster Complexes. XXIII. Clemmenszn and Borane Reductions of Acyl-and Vinylic Methylidynetri-Cobalt Nonacarbonyl Complexes

Abstract The Clemmensen reduction is an effective means of converting acyl- and vinylic methylidynetricobalt nona-carbonyl complexes to the corresponding saturated alkylidynetricobalt nonacarbonyl when it is carried out in nonaqueous medium. Diborane in tetrahydrofuran reacts with acyl-substituted cobalt clusters to give a mixture of the corresponding alcohol and alkyl complexes in which the latter predominates.