Unmasking the constitution and bonding of the proposed lithium nickelate “Li₃NiPh₃(solv)₃”: revealing the hidden C₆H₄ligand

Abstract

More than four decades ago, a complex identified as the planar homoleptic lithium nickelate “LiNiPh3(solv)3” was reported by Taube and co-workers. This and subsequent reports involving this complex have lain...

Small molecule activation with bimetallic systems: a landscape of cooperative reactivity

“…A proposed ''Li 3 NiPh 3 (solv) 3 '' structure was reported decades ago by Taube and coworkers, 83 which was described as a planar hexacoordinated compound but without authentication by X-ray crystallographic studies. The recent discovery of Pd(0) hexagonal complexes by Crimmin's group 84 85 The homobimetallic compound does not exhibit a Ni-Ni bond (NiÁ Á ÁNi distance of ca. 2.71 Å), which was characterized by NMR spectroscopic techniques as a diamagnetic complex, in agreement with the computational analysis (NBO, QTAIM and ELI techniques).…”

“…The phenyl lithium molecules are linked to the Ni atoms, forming strong Ni–C bonds with a small participation of the Li atoms in a weak σ(C–Li) → s (Ni) interaction. 85 The homobimetallic compound does not exhibit a Ni–Ni bond (Ni⋯Ni distance of ca. 2.71 Å), which was characterized by NMR spectroscopic techniques as a diamagnetic complex, in agreement with the computational analysis (NBO, QTAIM and ELI techniques).…”

Towards Hexagonal Planar Nickel: A Dispersion‐Stabilised Tri‐Lithium Nickelate

“…The overlooked tri‐lithium nickelate “Li 3 NiPh 3 (solv) 3 ” ( II , Scheme 1b), which possesses similar structural features to I , was documented by Taube in 1979 [14, 15] . Recently, however, we have reported that this proposed structure was misassigned and instead identified as an octanuclear cluster containing a bridging C 6 H 4 ligand between two nickel centres, III [16] . Although Fe 0 complexes supported solely by phenyl‐lithium ligands are known, [17] the isolation of III suggests that this is not possible for d 10 Ni 0 , leading to the in situ formation of the π‐accepting, and formally reduced, C 6 H 4 ligand in order to alleviate the extreme electron density at nickel.…”

“…1.198(2) Å for PhÀ C�CÀ Ph] [44] and bending away from linearity [C1À C2À C3 = 134.0(1)°] indicates significant backdonation from the electron-rich Ni centres, as previously observed for III (see Scheme 1b). [16] The CÀ NiÀ C angles in 2) Å] which are outside the sum of the covalent radii (2.52 Å), [27] and contracted Li•••C distances [range = 2.080(3) Å to 2.485(3) Å] including interactions with both carbon atoms of the acetylide π-system, a feature not observed in compounds 2 a-c.…”

Towards Hexagonal Planar Nickel: A Dispersion‐Stabilised Tri‐Lithium Nickelate

“…1.198(2) Å for PhÀ C�CÀ Ph] [44] and bending from linearity [C1À C2À C3 = 134.0(1)°] indicates significant backdonation from the electron-rich Ni centres, as previously observed for III (see Scheme 1b). [16] The CÀ NiÀ C angles in 2) Å] which are outside the sum of the covalent radii (2.52 Å), [27] and contracted Li•••C distances [range = 2.080(3) Å to 2.485(3) Å] including interactions with both carbon atoms of the acetylide π-system, a feature not observed in compounds 2 a-c.…”