Inorg. Chem. 2008, 47, 3468-3470
Synthesis and Characterization of Linear and Square-Planar Nickel
Complexes with Primary Amido Ligands
Jianfeng Li, Haibin Song, Chunming Cui,* and Jin-Pei Cheng
State Key Laboratory of Elemento-organic Chemistry, Nankai UniVersity,
Tianjin 300071, People’s Republic of China
Received February 14, 2008
The synthesis and characterization of the two homoleptic mono-
nuclear nickel complexes (2,6-Dipp2C6H3NH)2Ni (1) and [2-C(H)-
NDippC6H4NH]2Ni (2) (Dipp ) 2,6-Pri2C6H3) are described. 1 is
formally two-coordinate and adopts a strictly linear geometry, while
2 features a slightly distorted square-planar geometry. Electro-
chemistry of 1 and 2 shows that they can be reduced to the
corresponding nickel(I) species and oxidized to the corresponding
nickel(III) species reversibly or quasi-reversibly. A solid-state
magnetic measurement (µeff ) 2.79 µB) for paramagnetic 1
indicates the presence of two unpaired electrons on the nickel
center.
phosphines or chelating π-type ligands. In contrast, homo-
leptic mononuclear nickel amido complexes remain ex-
tremely rare. The paucity may be related to the incompat-
ibility of “hard” amido groups bonded to “soft” late transition
metals7 and the propensity for amido groups to form
intermetallic bridges.8 Nonetheless, the use of multiple
dentate and bulky amido ligands has allowed the isolation
and structural characterization of several homoleptic mono-
nuclear amido species.9 In particular, Power and co-workers
have shown that two-coordinate, homoleptic nickel amides
can be obtained by employing arylamido ligands with an
electronically unsaturated boryl substituent to accept the lone
pair of electrons on the nitrogen and prevent nitrogen
bridging.10
Late-transition-metal amido complexes have been pro-
posed as important intermediates in many catalytic and
organic reactions because of their relatively labile M-N
bonds.1 In order to understand the factors that control the
nature of M-N bonds, a number of monomeric nickel
complexes with amido functionalities have been synthesized
and structurally authenticated.2–6 These nickel amides are
mostly stabilized by employing either a soft donor such as
Given the unique reactivity of nickel imides,11 we are
interested in the investigation of nickel complexes with
primary amido ligands as imido precursors via oxidation
followed by abstraction of the hydrogen atom from the amido
moieties.3 Several nickel primary amido complexes supported
by phosphine and ꢀ-diketiminato ligands and the Cp family
of ligands are known.3–6,11 However, to the best of our
* To whom correspondence should be addressed. E-mail: cmcui@
nankai.edu.cn (C.C.).
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3468 Inorganic Chemistry, Vol. 47, No. 9, 2008
10.1021/ic800288x CCC: $40.75 2008 American Chemical Society
Published on Web 04/01/2008