doi:10.1021/acs.organomet.1c00621engBuil, María L.Esteruelas, Miguel A.Oñate, EnriquePicazo, Nieves R.Dissimilarity in the Chemical Behavior of Osmaoxazolium Salts and Osmaoxazoles: Two Different Aromatic MetalladiheterocyclesART-2021-125997The preparation of aromatic hydride-osmaoxazolium and hydrideoxazole compounds is reported and their reactivity toward phenylacetylene investigated. Complex [OsH(OH)( CPh)(IPr)((PPr3)-Pr-i)]OTf (1; IPr = 1, 3-bis(2, 6-diisopropylphenyl)imidazolylidene, OTf = CF3SO3) reacts with acetonitrile and benzonitrile to give [OsH{kappa(2)-C, O-[C(Ph)NHC(R)O]}(NCR)(IPr)((PPr3)-Pr-i)]OTf (R = Me (2), Ph (3)) via amidate intermediates, which are generated by addition of the hydroxide ligand to the nitrile. In agreement with this, the addition of 2-phenylacetamide to acetonitrile solutions of 1 gives [OsH{kappa(2)-C, O-[C(Ph)NHC(CH2Ph)O]}(NCCH3)(IPr)((PPr3)-Pr-i)]OTf (4). The deprotonation of the osmaoxazolium ring of 2 and 4 leads to the oxazole derivatives OsH{kappa(2)-C, O-[C(Ph)NC-(R)O]}(IPr)((PPr3)-Pr-i) (R = Me (5), CH2Ph (6)). Complexes 2 and 4 add their Os-H and Os-C bonds to the C-C triple bond of phenylacetylene to afford [Os{eta(3)-C-3, kappa(1)-O-[CH2C(Ph)C(Ph)NHC(R)O]}(NCCH3)(2)(IPr)]OTf (R = Me (7), CH2Ph (8)), bearing a tridentate amide-N-functionalized allyl ligand, while complexes 5 and 6 undergo a vicarious nucleophilic substitution of the hydride at the metal center with the alkyne, via the compressed dihydride adduct intermediates OsH2(C CPh){kappa(2)-C, O[C(Ph)NC(R)O]}(IPr)((PPr3)-Pr-i) (R = Me (9), CH2Ph (10)), which reductively eliminate H-2 to yield the acetylide-osmaoxazoles Os(C CPh){kappa(2)-C, O-[C(Ph)NC(R)O]}(IPr)((PPr3)-Pr-i) (R = Me (11), CH2Ph (12)).2021http://zaguan.unizar.es/record/15129210.1021/acs.organomet.1c00621http://zaguan.unizar.es/record/151292oai:zaguan.unizar.es:151292info:eu-repo/grantAgreement/ES/DGA/FEDER E06-20Rinfo:eu-repo/grantAgreement/ES/MICINN/PID2020-115286GB-I00/AEI/10.13039/501100011033info:eu-repo/grantAgreement/ES/MICINN/RED2018-102387-TOrganometallics 40, 24 (2021), 4150-4162byhttps://creativecommons.org/licenses/by/4.0/deed.esinfo:eu-repo/semantics/openAccess