Structure and Reactivity of Coordinatively Unsaturated Half‐Sandwich Iron, Ruthenium and Osmium Complexes

Abstract

This review deals with the study of coordinatively unsaturated half-sandwich iron, ruthenium and osmium complexes, in particular those bearing bulky phosphane ligands. The synthesis, properties and structure of neutral complexes of the type [(C 5 R 5 )MX(L)] and their cationic derivatives+ , are described here. We will also refer to related compounds containing hydrotris(pyrazolyl)borate (Tp)

Peculiarities of the reaction of (SPY-5-34)-dichloro-(κ2(C,O)-2-formylbenzylidene)(1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene)ruthenium with potassium hydridotris(pyrazolyl)borate

“…Such 1,2 H shifts are well known especially for related iridium complexes [24]. Possibly an agostic interaction of a methyl hydrogen of a mesityl group precedents a C-H activation reaction [25], which then results in formation of a ruthenium(IV) species featuring two alkyl ligands and a hydride. Similar insertions of the ruthenium center into the C-H bond of one of the mesityl CH 3 groups had been observed in the past [26,27].…”

Half-sandwich iridium complexes—Synthesis and applications in catalysis

“…The 2-substitued OH group is believed to play a critical role in the hydrogen generation; the analogous 3-and 4-OH complexes were much less active. The iridium dimer has also been used as catalyst for the conversion of alcohols into amines via a process of dehydrogenation of the alcohol, condensation to form an imine, and finally hydrogenation to afford the amine ( Table 9, entries [8][9][10][11][12][13][14][15]. It is noted that this "borrowing hydrogen" strategy has also been applied to the formation of C-C bond from alcohols via alkene and aldehydes derived from dehydrogenation of the alcohols [128][129][130][131][132].…”

“…Herein we focus attention on half-sandwich iridium complexes containing the Cp* and Cp ligands, especially on those with chirality at the metal and on the advances made from 2000 onwards. Other structurally related complexes are known but fewer in numbers and will not be covered here [7][8][9][10][11][12]. Rather than a comprehensive summary of half-sandwich iridium complexes reported in the literature, we attempt to highlight the progress made in their synthesis, especially the novel approaches developed recently.…”

Quinine‐Derived Imidazolidin‐2‐imine Ligands: Synthesis, Coordination Chemistry, and Application in Catalytic Transfer Hydrogenation

“…The blue or purple color is highly characteristic of ruthenium 16-electron systems whereas complexes with filled coordination spheres tend to be yellow, orange, or red [24]. Unfortunately, single crystals of 6 suitable for X-ray diffraction analysis could not be obtained but the characteristic color, the elemental analysis and the 1 H, 13 C, and 19 F NMR spectroscopic data proved the formation of a 16-electron Ru II complex.…”