The co-ordination chemistry of bis(2,2′-bipyrid-6′-yl)ketone with first row transition metals: The reversible interconversion of a mononuclear complex and a dinuclear hemiketal containing species

Abstract

Bis(2,2'-bipyrid-6'-yl)ketone has been shown to co-ordinate to Zn(II) to form either a dinuclear hemiketal complex in methanol solutions or mononuclear complexes in acetonitrile. The ligand readily complexes to the late transition metals in acetonitrile to yield mononuclear complexes (Mn(II), Co(II), Ni(II),Zn(II) and Cd(II)) however for Fe(II) only dinuclear complexes [Fe(2){(2-bipy)(2)C(OMe)O(-)}(2)][ClO(4)](2) could be isolated. The solid state structures of the mononuclear complexes exhibit varying degrees of distortion compared to an anticipated planar array of bipyridyl donors.

A compressed octahedral cobalt(II) complex in the crystal structure of diaqua[6,6′-sulfanediylbis(2,2′-bipyridine)]cobalt(II) dinitrate

“…The corresponding Co-O bond lengths are 2.0444 (18) Å and 2.0821 (17) Å , which are obviously shorter than the equatorial Co-N bond lengths [2.1213 (18) À2.1574 (18) Å ]. These coordination bond lengths indicate that the Co II cation is in a high-spin state at 123 K, comparable with other high-spin Co II complexes (Li et al, 2016;Knight et al, 2010;Suckert et al, 2017;Zhong et al, 2008;Hathwar et al, 2017). The O-Co-O angle is almost linear at 178.59 (7) .…”

“…For example, bidentate 2,2 0 -bipyridine or its derivatives are common ligands that can be employed to assemble functional compounds (Zhang et al, 2014;Kamdar et al, 2016;Pal et al, 2014). Linking two 2,2 0 -bipyridine units through a suitable atom leads to a tetradentate ligand (Knight et al, 2010) and, more importantly, the distance of the two 2,2 0 -bipyridine moieties can then be controlled by the type and size of the bridging atom. As a consequence, the coordination geometry of the metal cation can be affected.…”

Structure–Activity and Stability Relationships for Cobalt Polypyridyl‐Based Hydrogen‐Evolving Catalysts in Water

“…The latter was converted into (MeO) 4 appy ( L2 b ) by repeated reaction with lithiated (MeO) 2 bpyBr. Tetradentate bpy 2 CO ( L5 ) and hexadentate hpy ( L4 ) have been synthesized by Singh and co‐workers . We present herein a simpler pathway: Reaction of lithiated bpyBr with 0.5 equivalents of ethyl chloroformate (ClCOOEt) gave bpy 2 CO ( L5 ).…”

“…The interconversion of the mono‐ to the dinuclear complex in protic solvents was reported for zinc and iron. The dimerization was shown to be reversible by NMR spectroscopy for Zn 2+ . The electron‐donating effect of the methoxy substitution in ligand (MeO) 2 tpy ( L1 b ) and its complex 1 b becomes evident, when comparing to six‐coordinate 1 a .…”

A Family of Immobilizable Chiral Bis(pinenebipyridine) Ligands

“…In fact L1 17 , and its phenanthroline homologue L2 18 (Figure 1), as well as some of their derivatives, 19 have attracted considerable interest in the past few years. They have been shown to have an excellent ability to form complexes with structural distortions from the ideal octahedral geometry, high reactivity, and thus an improved catalytic activity.…”