Inorganic nitrogen fixation. Nitrogen compounds of the transition metals

Comparison of Side‐On and End‐On Coordination of E2 Ligands in Complexes [W(CO)5E2] (E=N, P, As, Sb, Bi, Si−, Ge−, Sn−, Pb−)

“…Campana et al [9] reached a similar conclusion when studying the isostructural and isoelectronic [Co 2 (CO) 5 {P(C 6 H 5 ) 3 }P 2 ] complex. In this example, a bond length to valence bond order curve was available for P 2 , which was employed to determine a bond order of 2 for the diphosphorus ligand in the complex.…”

“…The bonding behavior of the heavier homologues is substantially different to that of N 2 which preferentially binds in an end-on manner to a single metal center, [3] although a number of examples of two metal fragments both coordinating end-on have been reported. [4] Side-on coordination of N 2 to a single organometallic fragment has been postulated for transition states in intramolecular N exchanges, [5] however only one example of a photoinduced metastable complex with N 2 coordinated in a side-on manner has been structurally characterized.…”

“…It was thus concluded that both processes occur synergistically, yielding no net charge-transfer. It has also been suggested [2a] that in the complex [Co 2 (CO) 6 As 2 ] the Co(CO) 3 groups can be regarded as ™electron sinks∫, removing electron density from the diarsenic fragment. The result-ing reduction in electron pair repulsions within the As 2 ligand then yield the significantly shorter AsÀAs bonds observed.…”

“…The AsÀAs s bond was also found to be weak, with a correspondingly high energy level, thus allowing bonding to the metal fragment. The Dewar ± Chatt ± Duncanson model was therefore not utilized for describing the bonding in [{W(CO) 5 } 3 As 2 ].…”

A Novel Field of Research: Bioorganometallic Chemistry, Origins, and Founding Principles

“…1.2), was a long-standing challenge for organometallic chemists. [135]. This synthetic challenge to activate molecular nitrogen by organometallic means was undertaken among others by the Russian group of Shilov, and also by Chatt and by Schrock [136][137][138][139][140].…”