A Distinct Tetradentate N₂O₂‐type Ligand: (o‐Carboranyl)bis(2‐hydroxymethyl)pyridine

Abstract

A new chiral racemic ligand (o‐carboranyl)bis(2‐hydroxymethyl)pyridine oCB(hmpH)2, that is composed of a central o‐carborane unit where two arms radiate out of the cluster carbons each one containing a 2‐pyridylmethylalcohol chelating arms, provides two potentially bidentate {NO} or one tetradentate {N2O2} binding pockets. An unprecedented octahedral CoII complex [CoCl2(anti‐oCB(hmpH)2] was obtained under aerobic conditions and characterized by X‐ray crystallography as well as IR and NMR spectroscopy. anti‐oCB(hmpH)2 acts as a tetradentate N2O2‐ligand affording the complex as a racemic mixture of cis‐α Δ‐[CoCl2(RRanti‐oCB(hmpH)2)] and Λ‐[CoCl2(SSanti‐oCB(hmpH)2)]. The new ligand oCB(hmpH)2 appears to be suitable for producing a variety of new chiral‐at‐metal complexes.

Carborane Bis-pyridylalcohols as Linkers for Coordination Polymers: Synthesis, Crystal Structures, and Guest-Framework Dependent Mechanical Properties

“…In addition to that, the high thermal and chemical stability, acceptor character and 3D nature of the icosahedral carborane clusters make them valuable ligands in coordination chemistry. [18][19][20][21][22][23] For example, Mirkin and co-workers explored the use of di-, tri-and tetra-carboxylic acid derivatives of para-carborane (I to IV in Scheme 1) for CP synthesis, providing a series of CPs exhibiting unprecedented stabilities with respect to thermal degradation, inherited from the carborane moiety. [24][25][26][27][28][29][30] Some of the CPs including these polycarboxylato p-carborane-based linkers showed gas uptake properties and excellent selectivity for CO 2 /CH 4 mixtures.…”

“…The spherical feature of these molecules, with slightly polarized hydrogen atoms, and the presence of the hydride-like hydrogens at the B–H vertexes make the carboranes very hydrophobic. In addition to that, the high thermal and chemical stability, acceptor character, and 3D aromatic nature of the icosahedral carborane clusters make them valuable ligands in coordination chemistry. − For example, some of us have reported the synthesis and electronic and magnetic properties of purely inorganic CPs based on the dicarboxylic acid of ortho -carborane. − Mirkin and co-workers explored the use of di-, tri-, and tetra-carboxylic acid derivatives of para -carborane ( I – IV in Scheme ) for CPs synthesis, providing a series of CPs exhibiting unprecedented stabilities with respect to thermal degradation, inherited from the carborane moiety. − Some of the CPs including these polycarboxylato p- carborane-based linkers showed gas uptake properties and excellent selectivity for CO 2 /CH 4 mixtures. Jin and co-workers also constructed CPs based on the dicarboxylic acid derivatives of para -, but also of meta -carborane linker ( V in Scheme ), and studied their adsorption and luminescence properties. , More recently, dicarboxylic and tricarboxylic derivatives of the smaller carborane closo -1,10-C 2 B 8 H 10 were also incorporated into porous CPs. , …”

N,O-Type Carborane-Based Materials

“…Racemic anti-5a (see Scheme 2 for nomenclature) formed the octahedral cobalt II complex 30 upon reaction with CoCl2 (Scheme 11) [71]. The X-ray structure of 30 revealed a distorted geometry where each cobalt II center is coordinated by all nitrogen and oxygen atoms of an anti-diastereomer of 5a that is acting as a tetradentate N2O2-ligand.…”

Nickel(II) and Palladium(II) Complexes with η5:κ1(N)-Coordinated Dicarbollide Ligands Containing Pendant Pyridine Group

“…To date, the synthesis of many ortho-carborane derivatives with a pyridyl group as a substituent has been described [26][27][28][29][30][31][32][33][34][35][36][37][38], most of which were obtained by the reaction of lithium derivatives of carboranes with pyridylaldehydes [33][34][35][36][37][38]. A number of transition 2 of 17 metal complexes of various structures with pyridyl ortho-carborane ligands were synthesized as well [28,29,31,[38][39][40][41][42][43][44][45][46][47][48]. However, only a few examples of nido-carborane derivatives with a pyridyl group have been described [39,[49][50][51], and a few transition metal complexes (metallacarboranes) based on them [50].…”