Investigation of metal-d.pi.-butadiynyl-.pi. interactions in (.eta.5-C5H5)(CO)2FeC.tplbond.CC.tplbond.CH using photoelectron spectroscopy

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

“…[199] Extension of the alkynyl ligand to butadiynyl (CϵCCϵCH) also serves to enhance the ligand character in [Fe(CϵCCϵCH)(CO) 2 Cp] by better matching of the lowerlying butadiynyl π system with the [Fe(CO) 2 Cp] metalbased orbitals. [200] The ordering of the critical metal orbitals can also be influenced by the nature of the supporting ligands, as illustrated by the rather more metal-localised frontier orbitals associated with [M(CϵCR)(dppe)(η 7 -C 7 H 7 )] n+ (n = 0, 1; M = Mo, W) complexes. [19][20][21] The C 7 H 7 ring promotes strong π and δ interactions with four of the five metal d orbitals, with d z 2 being somewhat destabilised by repulsive interactions with the C 7 H 7 a 1 -type orbital (Figure 4).…”

Spectroscopic properties and electronic structures of 17-electron half-sandwich ruthenium acetylide complexes, [Ru(CCAr)(L2)Cp′]+ (Ar=phenyl, p-tolyl, 1-naphthyl, 9-anthryl; L2=(PPh3)2, Cp′=Cp; L2=dppe; Cp′=Cp∗)

“…While much of the early work was naturally concerned with synthetic and structural issues, there is a considerable and growing body of contemporary interest concerning the electronic, optical, non-linear optical and magnetic properties of these compounds [8][9][10][11]. Comparisons of the properties of half-sandwich ruthenium acetylides [Ru(C"CR)(L 2 )(g 5 -C 5 R 5 )], where L 2 usually represents supporting phosphine ligands, with analogous iron complexes have been made, with the general conclusion being that iron gives rise to much greater metal character in the frontier orbitals, whilst the ruthenium analogues exhibit far greater Ru(d)-acetylide(p) mixing [12][13][14][15][16]. This greater delocalisation is also found to persist after one-electron oxidation of the ruthenium complexes, and has been used to rationalise the greater chemical reactivity of the 17-electron radical cations [Ru(C"C-1,4-C 6 H 4 X)-(dppe)(g 5 -C 5 Me 5 )] + [13] when considered alongside the radical cations [Fe(C"CC 6 H 4 -X)(dppe)Cp * ] + (X = CN, CF 3 , Br, F, Me, t Bu, OMe, NH 2 , NMe 2 ), which have been isolated as the [PF 6 ] À salts [16].…”

Syntheses and Structures of Buta-1,3-Diynyl Complexes from “on Complex” Cross-Coupling Reactions

“…The electronic structure of monometallic polyynyl 8,89,90 and bimetallic polyyndiyl 37-39, 87,91 complexes has been explored in detail over the last 20 years at increasingly sophisticated levels of theory.…”

“…The electronic structures of 5´ (Table 3) and 6´ (Table 4) were also examined, those of buta-1,3-diynyl complexes having been well discussed elsewhere, 8,89,90 and give features that are broadly as expected for half-sandwich alkynyl-derivatives. or four (6´) oxidation processes in these complexes.…”