Metal Carbonyl Anions:  from [Fe(CO)₄]^2-to [Hf(CO)₆]^2-and Beyond

Abstract

A chronological survey of the syntheses and characterizations of homoleptic mononuclear metal carbonyl anions is presented, from the first isolated example, [Fe(CO)4]2-, to the most recently reported species, [Hf(CO)6]2-. These materials are of historical interest, since they are the first compounds to contain transition metals in formal negative oxidation states, but remain important reagents in all areas of chemical synthesis and often closely resemble electron-rich nonmetallic compounds in their ability to function as Lewis and Brønsted bases, nucleophiles, and/or reducing agents. Prospects for the syntheses of new carbonyl anions for the very early and late transition metals and the lanthanides and actinides are also discussed.

From Storable Sources of Atomic Nb− and Ta− Ions to Isolable Anionic Tris(1,3‐butadiene)metal Complexes: [M(η4‐C4H6)3]−, M=Nb, Ta

“…As such, it qualitatively resembles carbon monoxide, and like the latter, [27] should be capable of providing anionic homoleptic complexes for most d-block elements. For this reason, it is astonishing that only three well-defined anions of this type have been previously reported, all for later 3d-block metals: [Co(h 4 -C 4 H 6 ) 2 ] À , [28,29] [Co(h 4 -1,4-tBu 2 C 4 H 4 ) 2 ] À , [9] and [Fe(h 4 -C 4 H 6 ) 2 ] À .…”

Thallium(I) as a Coordination Site Protection Agent: Preparation of an Isolable Zero‐Valent Nickel Tris‐Isocyanide

“…Low-coordinate, zero-valent metal isocyanide complexes [M(CNR) n ] are of interest as potentially isolable analogues to the unsaturated metal carbonyls studied by Burdett [1] and Turner [2] ([Cr(CO) 3 3 ]). Indeed, the electronic structure combination of coordinative unsaturation, coupled with strongly p-acidic ligands has, outside of gas-phase matrix isolation studies and the highly reduced carbonyl metalates championed by Ellis, [3] received limited attention.…”

“…Indeed, the electronic structure combination of coordinative unsaturation, coupled with strongly p-acidic ligands has, outside of gas-phase matrix isolation studies and the highly reduced carbonyl metalates championed by Ellis, [3] received limited attention. For neutral d 10 [Ni(CO) 3 ], analogues possessing strongly s-donating phosphines, such as [Ni-(PR 3 ) 3 ], have been widely investigated, [4] whereas recent attention has been given to three-coordinate species featuring NHC ligands. [5,6] With respect to strongly p-acidic isocyanide ligands, studies by Otsuka [7] on [Ni(CNtBu) 4 ] are noteworthy in that homoleptic [Ni(CNtBu) 3 ] is proposed to be the reactive entity in solution.…”

“…For neutral d 10 [Ni(CO) 3 ], analogues possessing strongly s-donating phosphines, such as [Ni-(PR 3 ) 3 ], have been widely investigated, [4] whereas recent attention has been given to three-coordinate species featuring NHC ligands. [5,6] With respect to strongly p-acidic isocyanide ligands, studies by Otsuka [7] on [Ni(CNtBu) 4 ] are noteworthy in that homoleptic [Ni(CNtBu) 3 ] is proposed to be the reactive entity in solution. However, isolation or experimental verification of this species have not been achieved.…”

Сучасні Отруйні Речовини Як Терористична Загроза Суспільству

“…При потраплянні в легені рицин так само токсич-ний, як і зарин, а симптоми отруєння нагадують сильний бронхіт або пневмонію. Тим часом перші ознаки отруєння іноді приймають за симптоми ін-фекційного захворювання [17,30].…”