Conformational constraints and σ–π-vinyl interchange in μ3-η3-5,6-dihydroquinoline triosmium complexes

Reactivity of [(μ-H)2Os3(CO)10] with Aminotributylstannane and Aminotrimethylstannane Derivatives

“…The coupling constant J ( 187 Os− 1 H) at natural abundance ( 187 Os = 1.64%) for compounds 1 − 4 and 5 − 8 appears as a single set with values around 30 and 33 Hz, respectively (Table ). These values are in the range previously observed for hydrides in triosmium clusters . The broad singlets in the range 2.40−2.79 are assignable to the hydrogen of the HN groups of the secondary amines coordinated to the osmium clusters 1 − 8 .…”

Bis(ferrocenylethynyl)-Substituted Digold-Tetrarhenium Cluster: Unusual Structure and Electronic Communication between Ferrocenyl Groups

“…According to the solid state structure of 2 this should not be the case because the alkynyl ligand is η 1 bound to one Re atom and η 2 bound to the other in a σ-π bonding mode. However, σ−π interchange of bridging ligands is a well-known process in this type complexes and apparently in the case of 2 this is a particularly facile process owing to the presence of two equivalent electron pairs on the μ-alkynyl ligand . On the other hand, complex 1 shows four carbonyl resonances at 198.89, 191.23, 188.74, and 185.82 ppm in a relative intensity of 1:1:2:2, entirely consistent with symmetrical structure observed in the solid state.…”

187Os subspectra in 1H and 31P{1H} spectra of triosmium carbonyl clusters

“…4 A considerable amount of information is available to the cluster chemist from 1 J(Os,H) coupling constants which, after some early interest, 5 are only now beginning to be exploited. 6 Recent developments in NMR sensitivity have made it practical to observe 1 J(Os,H) satellites for species such as [Os 3 ( -H) 2 (CO) 10 ] 4 in a single transient at 500 MHz. Similarly, it is often possible to observe the J(Os,P) satellites in a few transients at high field.…”