Heterobimetallic Complexes Featuring Fe(CO)₅ as a Ligand on Gold

Abstract

Iron(0) pentacarbonyl complexes of gold(I), [Mes PAu-Fe(CO) ][SbF ] (1) and [(IPr*)Au-Fe(CO) ][SbF ] (2) (Mes=2,4,6-trimethylphenyl; IPr*=1,3-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene) have been synthesized using Mes PAuCl and (IPr*)AuCl as the gold(I) precursor, AgSbF halide ion abstractor, and the Lewis base Fe(CO) . The Au-Fe bond lengths of these metal-only Lewis pair complexes are significantly shorter than the sum of the experimentally derived covalent radii of Au and Fe. The v̄(CO) bands of the molecules show a notable blueshift relative to those observed for free Fe(CO) , indicating a substantial reduction in Fe→CO backbonding upon its coordination to gold(I) with either Mes P or IPr* supporting ligands (L). The analysis of the electronic structure with quantum chemical method suggests that the Au-Fe bond consists mainly of [LAu] ←Fe(CO) σ-donation and weaker [LAu] →Fe(CO) π-backdonation. The donor strength of Fe(CO) is similar to that of CO.

Synthesis and Characterization of Heterobimetallic Carbonyl Clusters with Direct Au‐Fe and Au···Au Interactions Supported byN‐Heterocyclic Carbene and Phosphine Ligands

“…The Au‐Fe distances [2.50–2.52 Å] found in these monoanionic complexes were very similar to those previously reported for the neutral complexes Fe(CO) 4 (AuNHC) 2 [2.51–2.53 Å] (Table ) . Conversely, a slight elongation of the Au‐Fe contact [2.56–2.57 Å] was observed in the cationic complexes [Fe(CO) 5 (AuNHC)] + and [Fe(CO) 5 (AuPR 3 )] + that contained a Fe(CO) 5 rather than a Fe(CO) 4 fragment …”

Chemical Bonding in Homoleptic Carbonyl Cations [M{Fe(CO)5}2]+(M=Cu, Ag, Au)

“…The [Cu{Fe(CO) 5 } 2 ][SbF 6 ] is the first copper(I)‐Fe(CO) 5 complex to our knowledge, and shows that copper(I) can also form adducts with Fe(CO) 5 . We have observed an analogy between Fe(CO) 5 and CO in their interaction with gold or coinage metal ions [16b] . In that regards, it is noteworthy that although three and four‐coordinate copper‐carbonyls are known, [26] there are no structurally characterized, two‐coordinate [Cu(CO) 2 ] + complexes to our knowledge.…”

“…The reaction of AuCl with Na[B{3,5‐(CF 3 ) 2 C 6 H 3 } 4 ] in the presence of ethylene to generate [Au(C 2 H 4 ) 3 ] + , followed by the addition of Fe(CO) 5 produced a mixture that shows relatively less decomposition, but still not very stable above −20 °C. Again, despite several attempts, we could not obtain crystalline [Au{Fe(CO) 5 } 2 ][B{3,5‐(CF 3 ) 2 C 6 H 3 } 4 ], although the resulting white solid indicated the presence of product that contains metal carbonyl bands as in [Mes 3 PAu‐Fe(CO) 5 ][SbF 6 ] [16b] and [(NHC)Au‐Fe(CO) 5 ][SbF 6 ] [16b, 14c] systems. After several days at −20 °C, we obtained a crystalline product in low yield from this solution, which upon analysis by X‐ray diffraction indicated to be [Au{Fe(CO) 5 } 2 ][HOB{3,5‐(CF 3 ) 2 C 6 H 3 } 3 ].…”

“…For example, during late 1920s, Hock and Stuhlmann investigated the chemistry of Fe(CO) 5 with several mercury(II) salts and managed to isolate products with mixed metallic compositions [12] . Structurally well‐characterized molecules involving the Fe(CO) 5 ligand appeared only recently [14a, 16a,b, 19b] . They include a homoleptic [20] silver(I) complex synthesized by Krossing et al.…”

Syntheses and Reactivity of New Zwitterionic Imidazolium Trihydridoborate and Triphenylborate Species

“…By tuning the steric and electronic properties around the carbene center, several carbenes featuring various σ-donating and π-accepting properties have been developed to date [ 15 , 16 , 17 ]. Their chemical versatility not only implies a wide variety of structural diversity and coordination modes, but also a capability to form stable complexes with a large number of transition metals with different oxidation states [ 6 , 7 , 18 , 19 , 20 ] and labile ligands [ 21 , 22 , 23 , 24 , 25 , 26 ]. Metal-NHCs complexes gained considerable interest in recent years because of their application in material chemistry [ 27 ], in catalysis [ 19 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], in carbene transfer reactions [ 38 , 39 ], and in medicinal inorganic chemistry [ 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ].…”