Structural Diversity in Manganese(II) Complexes with Multidentate N‐Donor Imino Pyridyl Ligands

Abstract

Four Mn(NCS)2 based compounds of the types [Mn(SCN)2(L1)]·EtOH (1), [Mn(SCN)2(L2)]·½EtOH (2), [Mn(SCN)2(L3)] (3), and [Mn(SCN)2(L4)2]n·3nMeCN (4) [L1 = benzilbis((pyridin‐2‐yl)methylidenehydrazone), L2 = benzilbis((acetylpyridin‐2‐yl)methylidenehydrazone, L3 = benzilbis((phenylpyridin‐2‐yl)methylidenehydrazone, and L4 = benzilbis((pyridin‐3‐yl)methylidenehydrazone)] were synthesized and characterized by single‐crystal X‐ray diffraction studies, elemental analysis, and IR spectroscopy. The first three complexes of general formula Mn(SCN)2(L1–3) consist of discrete units, whereas the fourth one consists of one‐dimensional coordination polymer. The central metal atoms in 1–4 exhibit a distorted octahedral arrangement.

Benzyl Dihydrazone versus Thiosemicarbazone Schiff Base: Effects on the Supramolecular Arrangement of Cobalt Thiocyanate Complexes and the Generation of CoN6 and CoN4S2 Coordination Spheres

“…Materials and Measurements: The Schiff bases were prepared by the previously reported methods and used without further purification . All other reagents and solvents for the synthesis and analysis were commercially available and used as received.…”

“…The ligands (Scheme ) were selected to enable the fine analysis of (1) the steric effects of the substituents and (2) chelation modes; additionally, a common feature of all of the structures is the presence of the thiocyanate anion, which is connected to the cobalt(II) or cobalt(III) centers or present in free form between the complex molecules. Specifically, the first investigated group consists of cobalt thiocyanate complexes 1 – 3 with a tailored set of benzyl dihydrazone based Schiff bases {constructed from (1 E ,2 E )‐1,2‐diphenyl‐1,2‐bis[( E )‐(pyridin‐2‐ylmethylene)hydrazono]ethane ( L1 ) and its methyl ( L2 ) and phenyl ( L3 ) analogues, respectively; see Scheme a} featuring CoN 6 coordination spheres.…”

Structural versatility of the quasi-aromatic Möbius type zinc(ii)-pseudohalide complexes – experimental and theoretical investigations

“…It is worthy to note, that 1 is isostructural to its Mn II and Co II analogues. 22,31 Complex 1 has a neutral discrete heteroleptic mononuclear structure, where the Zn II metal center is coordinated by one ligand L I via its two pyridyl-imine chelate functions as well as two N-bound NCS À anions giving rise to the ZnN 6 chromophore with a distorted trigonal-prismatic coordination environment around the cation (Fig. 1, Table S1 in the ESI †), which has been proven by the SHAPE 2.1 soware.…”

“…The C]N stretching vibration is at a lower energy by 40 cm À1 for complexes 1 and 2 compared to the free ligand L I , whilst a similar 20 cm À1 difference is observed in this vibration between compound 3 and L II . 22 This rmly conrms the participation of the azomethine nitrogen atoms in chelate formation. The FTIR spectra of 2 and 3 further contain a broad band for the methanol at 3353 to 3443 cm À1 , respectively.…”

“…[18][19][20] Recently, we have also directed our attention to Schiff bases comprising two pyridyl-imine functions obtained from benzyldihydrazone. [21][22][23][24][25][26][27] These ligands were found to be efficient for helical structures upon coordination to metal centers. Particularly our comprehensive efforts were directed to various Cd II salts as complexing agents.…”