Bimetallic Complexes of Ytterbium and Europium Stabilized by Sterically Demanding Dipyridylamides

Deprotonation of Ap*pyH {Ap*pyH = (6‐methylpyridin‐2‐yl)‐[6‐(2,4,6‐triisopropylphenyl)‐pyridin‐2‐yl]‐amine} using KH leads to Ap*pyK which undergoes a clean salt metathesis reaction with [YbI 2 (thf) 4 ] and [EuI 2 (thf) 4 ] in THF forming[Yb 2 (Ap*py) 3 I(thf)] and [Eu 2 (Ap*py) 3 I(thf)], respectively. The two Yb II centers in [Yb 2 (Ap*py) 3 I(thf)] are in close proximity and chemically different. Thus, an f‐block‐element–f‐block‐element coupling pattern was observed. The low‐field 171 Yb signal consists of a central singlet and two satellites with integral intensities of about 7 % each. This 14 % approximately corresponds to the natural abundance of the 171 Yb isotope and was assigned as a doublet arising from 1 J ( 171 Yb, 171 Yb) spin‐spin coupling with a magnitude of 76.1 Hz. The 151 Eu Mössbauer spectrum of [Eu 2 (Ap*py) 3 I(thf)] recorded at 77 K shows an isomer shift ( δ ) of –11.9(1) mm/s with an experimental line width ( Γ ) of 6.9(1) mm/s. This line width is extremely large and results from an overlap of the signals from both crystallographically independent europium sites. The reaction of [Yb 2 (Ap*py) 3 I(thf)] with Ap*pyK leads to [Yb 2 (Ap*py) 4 (thf) 2 ]. In the reactions of [Yb 2 (Ap*py) 3 I(thf)] with azidotrimethylsilane and sulfur the rearrangement products [Yb 2 (Ap*py) 3 I 2 ] and [Yb 2 (Ap*py) 3 I 3 ] were obtained, respectively. Treating [Yb 2 (Ap*py) 3 I(thf)] with NaN(SiMe 3 ) 2 afforded homoleptic “ate” complex Na 2 [Yb(Ap*py) 4 ]. A mixed silylamide dipyridylamide complex was obtained in the reaction of NaYb[N(SiMe 3 ) 2 ] 3 with Ap*pyH. All complexes – three of which are paramagnetic – were characterized by X‐ray crystal structure analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)