Nickel as a Lewis Base in a T‐Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand

Abstract

Flexible, chelating bis(NHC) ligand 2, able to accommodate both cis-and trans-coordination modes, was used to synthesize (2)Ni(η 2-cod), 3. In reaction with GeCl2, this produced (2)NiGeCl2, 4, featuring a T-shaped Ni(0) and a pyramidal Ge center. Complex 4 could also be prepared from [(2)GeCl]Cl, 5, and Ni(cod)2, in a reaction that formally involved Ni-Ge transmetalation, followed by coordination of the extruded GeCl2 moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ-donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)2Ni(cod) complexes 9 and 10, as well as (NHC)2GeCl2 derivative 11, incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni-Ge complexes. The isolation of (2)Ni(η 2-Py), 12, provides further evidence for the reluctance of the (2)Ni(0) fragment to act as a σ-Lewis acid.

Coordinating Ability of Anions, Solvents, Amino Acids, and Gases towards Alkaline and Alkaline‐Earth Elements, Transition Metals, and Lanthanides

“…After the isonitriles there are two families of solvents with some ever‐coordinated members, the N‐heterocycles and the thioethers, even if other members of those two families cover a wide range of coordination abilities, with a TM eventually reaching values close to 0.0 (i.e., 50 % of coordinated structures). Among the N‐heterocycles, a remarkable case is that of pyridine, which is commonly bound to transition metals through the N atom, but can alternatively be π‐coordinated in a η 2 mode, in a triply bridging η 2 , η 2 , η 2 mode or fully η 6 coordinated . More striking is the fact that pyridinium cations, disregarded for the study of the coordinating ability of pyridine, can also be found in π‐coordinated modes .…”

“…[128][129][130] After the isonitriles there are two families of solvents with some ever-coordinated members, the N-heterocycles andt he thioethers, even if other members of those two families cover aw ide range of coordination abilities, with a TM eventually reachingv alues close to 0.0 (i.e.,5 0% of coordinated structures). Among the N-heterocycles, ar emarkable case is that of pyridine, which is commonly boundt ot ransitionm etals through the Na tom, but can alternatively be p-coordinated in a h 2 mode, [131,132] in at riply bridging h 2 , h 2 , h 2 mode [133] or fully Table 5. Coordinating ability of gases towards transition metals:c oordinating ability index a TM ,p ercentage of structures in which the anion is found coordinatedo rs emi-coordinated to at ransition metal, and number of structures analysed.D ata for some non gaseous neutral ligands also given for comparison.…”

A Nickel Complex Containing a Pyramidalized, Ambiphilic Pincer Germylene Ligand

“…The Ge center of germylene complexes generally takes a trigonal‐planar geometry, but pyramidalized base‐free germylene complexes have recently been reported for the first time by Braunschweig et al., that is, dichlorogermylene platinum complexes L(Cy 3 P)Pt=GeCl 2 (L=PCy 3 , IMes) (IMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene) . This type of pyramidalized germylene ligand can also be seen in a very recently reported nickel germylene complex, but is still very rare. Moreover, reactivity of the pyramidalized germylene centers have never been reported.…”

“…Hydrogen atoms are omitted for clarity except for the Ha toms on the Ba tom. Selectedb ond lengths ()and angles (8): NiÀGe 2.3370(8), NiÀP1 2.2117(15), NiÀP2 2.2325(16), NiÀC1 1.986(5), GeÀC2 1.981(5),Ge ÀC8 1.972(6), GeÀB2 .109(7),Ge-Ni-C1151.81(16), P1-Ni-P2 142.90(6), Ni-Ge-C2 108.90(16), Ni-Ge-C8 108.27(15), Ni-Ge-B 108.27(15), C2-Ge-C8 109.0(2).…”

Side‐on Coordination in Isostructural Nitrous Oxide and Carbon Dioxide Complexes of Nickel

“…Solution 1 H NMR analysis of 2 revealed a broad, complex spectrum denoting C 1 symmetry, reflected in the 13 C NMR spectrum by the presence of two resonances for the coordinated carbene carbons (200.4 and 208.4 ppm). Reduced conformational fluxionality in complexes containing bis(NHC)Ni fragments was shown to lead to broad, poorly resolved resonances in the solution NMR spectra, as well as lowering of the expected time‐averaged symmetry [27] . An X‐ray diffraction experiment on 2 confirmed chelation of the ligand to Ni in a bent geometry (C1‐Ni1‐C8 107.9(1)°) (Figure S28) and the η 2 ‐coordination of 1,5‐cyclooctadiene.…”