Adventures with Substances Containing Metals in Negative Oxidation States

Abstract

A brief history of substances containing s,p- and d-block metals in negative oxidation states is described. A classification of these species and discussions of formal oxidation state assignments for low-valent transition metals in complexes are included, along with comments on the innocent and noninnocent character of ligands in metalates. Syntheses of highly reduced carbonyl complexes formally containing transition metals in their lowest known oxidation states of III- and IV- are discussed. Atmospheric-pressure syntheses of early-transition-metal carbonyls involving alkali-metal polyarene-mediated reductions of non-carbonyl precursors have been developed. In the absence of carbon monoxide, these reactions afford homoleptic polyarenemetalates, including the initial species containing three aromatic hydrocarbons bound to one metal. In several instances, these metalates function as useful synthons for "naked" spin-paired atomic anions of transition metals.

Structurally Distinct Homoleptic Anthracene Complexes, [M(C14H10)3]2−, M=Titanium, Zirconium, Hafnium: Tris(arene) Complexes for a Triad of Transition Metals

“…[1,2] For example, bis(anthracene)ferrate(1À) was recently shown to be a unique storable source of the atomic Fe À ion in its reactions with CO and 1,3-butadiene to afford [Fe 2 (CO) 8 ] 2À and the first isolable homoleptic butadiene iron complex, [Fe(C 4 H 6 ) 2 ]…”

“…[3] The first well-characterized homoleptic polyarenemetalate, tris(naphthalene)zirconate(2À) (1), [4] was reported nearly 15 years ago, and related complexes are now documented for Nb, [5] Ta, [6] Fe, [3] and Co. [7] However, little or nothing is known about the analogous metalates of other d-block elements. [2,8] We report herein the synthesis, isolation, and structural characterization of the first set of homoleptic polyarenemetalates for a triad of transition metals: the tris(anthracene)metalates(2À), [M-(C 14 H 10 ) 3 ] 2À , M = Ti (2), Zr (3), and Hf (4). In addition, the triad of Group 4 elements has been "completed" for homoleptic naphthalene complexes with access to the tris(naphthalene)metalates(2À), [M(C 10 H 8 ) 3 ] 2À , for M = Ti (5), Hf (6).…”

“…[11] Also, the naphthalenehafnate 6 has a nearly identical structure to that previously reported for 1. Because the solution NMR spectra of 2 and 5 are consistent with the presence of three equivalent h 4 -polyarene ligands, [11] it was a surprise to discover that their solid-state structures are much less symmetrical, and best formulated as [Ti(h 4 -polyarene) 2 (h 2 -polyarene)] 2À , the first tris(arene) complexes of 3d metals (the structure of 2 is shown in Figure 1). [18,19] These compounds are also of interest as they are the only homoleptic polyarene complexes to contain arenes of different hapticities within the same molecule, a feature previously observed for only one homoleptic arene sandwich complex, [Ru(h 6 -C 6 Me 6 )(h 4 -C 6 Me 6 )].…”

“…However, crystal structures of the [K( [18] [11,30] Facile chemical reactions of naphthalenehafnate 6 with CO and anthracene, mentioned above, are consistent with its characterization as a source of the to date unknown atomic Hf 2À . Because of the paucity of well-defined anionic homoleptic 1,3,5,7-cyclooctatetraene (cot) transition metal complexes, of which only [M(h-cot) 3 ] À (M = Nb, Ta) [31] and [Co(hcot) 2 …”

Влияние переноса заряда в NaAu-=SUB=-y-=/SUB=- на эмиссию ионов

“…Интерметаллические соединения золото-щелочной металл являют-ся широкозонными ионными полупроводниками, в которых золото выступает в роли аниона [1][2][3]. Валентная зона NaAu y сформирована Au 5d-и Au 6s-состояниями, а за счет перераспределения электронной плотности между остовами атомов золота и щелочного металла проис-ходит увеличение электронной плотности у атомов Au и уменьшение у атомов Na [4][5][6][7][8][9], при этом создаются соответствующие эффективные заряды атомов в решетке.…”