Synthesis, Characterization, and Alkyne Trimerization Catalysis of a Heteroleptic Two-Coordinate Fe^IComplex

Abstract

The synthesis of the first heteroleptic, two-coordinate Fe(I) complex IPr-Fe-N(SiMe3)DIPP (1) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; DIPP = 2,6-(i)Pr2-C6H3) is reported. Protonation of the Fe(II) bis(amido) complex Fe[N(SiMe3)DIPP]2 followed by addition of IPr and reduction by potassium graphite in a one-pot reaction results in good yields of 1. The redox activity of 1 and comparison between 1 and its reduction product by (57)Fe Mössbauer spectroscopy are discussed, and the reduction was found to be metal-based rather than ligand-based. The activity of 1 toward the catalytic cyclotrimerization of terminal and internal alkynes is described.

Z‐Selective (Cross‐)Dimerization of Terminal Alkynes Catalyzed by an Iron Complex

“…Thet reatment of 2 with the same internal alkynes gave no product of alkyne insertion, nor apossible intermediate that could arise from alkyne insertion. [14] At the same time,i ts hemilability allows the coordination of the terminal alkyne for further reactivity. [13] In the first step of our proposed mechanism, the terminal alkyne coordinates to 1 to form complex A,i nw hich the acidity of the terminal alkyne CÀHa tom is enhanced.…”

Electronic Structure and Magnetic Anisotropy of an Unsaturated Cyclopentadienyl Iron(I) Complex with 15 Valence Electrons

“…Single-crystal X-ray diffraction revealed the slightly bent "pogo-stick" structure of 1 ( Figure 1) with an h 5coordinated Cp Ar ligand and Cp Ar (centroid)-Fe-C carbene angles of 162.11(8)8 8 and 171.19(8)8 8 for two crystallographically independent molecules in the unit cell. TheF e-Cp Ar -(centroid) distance [1.851(1) and 1.847(1) ]i ss horter than in 2 [2.038(1) and 2.020(1) for two crystallographically independent molecules].T he Fe À C carbene bonds (1.992(2) and 1.996(2) )a re similar in length to the Fe À C carbene bond of 2.014(2) for two-coordinate [(IPr)Fe I (N{SiMe 3 }Dipp)] (Dipp = C 6 H 3 -2,6-iPr 2 ), [21] and the FeÀC carbene bonds of 2.110(3) and 2.128(3) observed for Fe II complex 2.D arkyellow 1 is paramagnetic,thermally stable,and air-sensitive as asolid. Amagnetic moment of m eff = 5.4(1) m B was determined in C 6 D 6 solution using the Evans method.…”

Elektronische Struktur und magnetische Anisotropie eines ungesättigten Cyclopentadienyleisen(I)‐Komplexes mit 15 Valenzelektronen

“…Zuschriften lich, [17,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] allerdings sind einige Fe I -u nd Fe II -Komplexe bekannt, bei denen große,n icht gelçschte Orbitalbeiträge zum magnetischen Dipolmoment beitragen. [21-27, 29-31, 34-37] Manche dieser Komplexe weisen SMM-Eigenschaften auf.B eispielsweise zeigt der Fe II -Komplex [(C 5 iPr 5 )Fe(C 6 H 3 -2,6-iPr 2 )],mit streng linearer Struktur,k eine langsame magnetische Relaxation in Abwesenheit eines externen Magnetfelds aufgrund des schnellen Quantentunnelns der Magnetisierung.…”

“…Eine Rçntgenkristallstrukturanalyse (Abbildung 1) zeigte zwei kristallographisch unabhängige Moleküle für 1 in der Elementarzelle mit sehr ähnlichen, leicht gewinkelten Strukturen. Die Moleküle weisen h 5 -koordinierte Cp Ar -Liganden und Cp Ar (Zentroid)-Fe-C Carben -Winkel von 162.11(8)8 8 und 171.19-(8)8 8 auf.D ie Abstände Fe-Cp Ar (Zentroid) von 1.851(1) und 1.847(1) sind etwas kleiner als in 2 [2.038(1) und 2.020(1) fürd ie kristallographisch unabhängigen Moleküle].D ie Fe-C Carben -Bindungslängen (1.992(2) und 1.996(2) )s ind vergleichbar mit den Werten im zweifach koordinierten Eisen(I)-Komplex [(IPr)Fe I (N{SiMe 3 }Dipp)] (2.014(2) ;D ipp = C 6 H 3 -2,6-iPr 2 ) [21] sowie in 2 (Fe-C Carben 2.110(3) und 2.128-(3) ). Im kristallinen Zustand ist 1 dunkelgelb.D ie Verbindung ist paramagnetisch, thermisch stabil und luftempfindlich.…”