The role of the 16-electron [(.eta.5-C5Me5)Ru(NO)] transient in the formation of dinuclear complexes and in oxidative addition reactions

Synthesis of Hydride and Alkyl Compounds Containing the Cp*Os(NO) Fragment. Crystal Structure of [Cp*Os(μ-NO)]2

“…The latter complexes were prepared from [Cp*OsBr 2 ] 2 , a molecule that we described in 1994; treatment of this dinuclear complex with nitric oxide gives the mononuclear nitrosyl complex Cp*Os(NO)Br 2 . This latter nitrosyl compound is analogous to the widely used starting material Cp*Ru(NO)Cl 2 , ,,, and we now show that it serves as an excellent entry point for the exploration of Cp*Os(NO) chemistry. We describe the synthesis of several Cp*Os(NO)BrR and Cp*Os(NO)R 2 alkyl and hydride compounds as well as the synthesis and structure of the dinuclear nitrosyl complex [Cp*Os(NO)] 2 .…”

“…Thermolysis of the iron bis(benzyl) complex Cp*Fe(NO)(CH 2 C 6 H 5 ) 2 affords dibenzyl and the dinuclear complex [Cp*Fe(NO)] 2 . The analogous ruthenium bis(aryl) complexes Cp*Ru(NO)R 2 , where R is phenyl or p -tolyl, react similarly in ethanol, acetonitrile, or 1,2-dichloroethane to produce diaryl and [Cp*Ru(NO)] 2 . , Interestingly, carrying out the thermolysis of Cp*Ru(NO)R 2 in hexane generates a different product, [Cp*Ru(NO)R] 2 , − and in CH 2 Cl 2 the haloalkyl complex Cp*Ru(NO)Cl(CH 2 Cl) is formed . Carbon−carbon bond formation of a different kind is exhibited by the chloromethyl complex Cp*Ru(NO)(CH 2 Cl) 2 .…”

Synthesis and Characterization of Osmium(II) Compounds of Stoichiometry (C5Me5)OsL2Br, (C5Me5)OsL2H, and (C5Me5)Os(NO)Br2

“…The reaction of (C 5 Me 5 ) 2 Os 2 Br 4 with 8 atm of nitric oxide in dichloromethane at room temperature yields the osmium(II) nitrosyl complex (C 5 Me 5 )Os(NO)Br 2 ( 15 ) in 81% yield . The purple color of (C 5 Me 5 )Os(NO)Br 2 contrasts with the green color of the analogous ruthenium compound. , The 1 H NMR spectrum of the complex in CD 2 Cl 2 features a sharp singlet at δ 2.03, and the IR spectrum of the complex exhibits a strong ν NO band whose frequency, 1766 cm -1 , is indicative of a linear nitrosyl ligand.…”

Structure and Reactivity of (η-C5R5)Mo(NO)2−Halide, −Halomethyl, and −Alkyl Complexes: Consecutive Aerobic Methylene and Nitrosyl Ligand Oxidation

“…This trend together with a comparable torsion angle of 80° Cp*Mo(NO) 2 (CH 2 Cl) is consistent with increasing steric demands of the halides and the Cp* ligand. The equivalence of the methylene protons in the 1 H NMR spectrum down to −90 °C does not argue for a strongly locked gauche solution conformation observed for Cp*Ru(NO)(CH 2 Cl) 2 by NOE 1 H NMR spectroscopy . While the anti orientation ( B ) in the Cp*Cr(NO) 2 (CH 2 I) and [CpCr(NO) 2 (CH 2 PPh 3 )] + complexes was presumed to be reasonable on steric grounds, it is possible that the longer metal−carbon bond lengths in the Mo complexes (both Mo−Cp and Mo−CH 2 ) make the gauche conformation more stable for the Mo complexes.…”

“…The study of metal−methylene stabilization and methylene transfer to organic substrates is an area of considerable importance . We have reported on a variety of new α-halomethyl complexes, focusing primarily on the study of intramolecular methylene insertion processes to give C−C bond formation. − …”