Syntheses, structures, and properties of two binuclear cadmium(II) iodides containing a bis(tridentate) Schiff base/tetradentate tripodal amine: control of coordination numbers by varying ligand matrices

Abstract

Two binuclear cadmium(II) iodide compounds of the types [Cd 2 (L1)(I) 4 ] (1) and [(L2)Cd(l-I)CdI 3 ] (2) [L1 = N,N 0 -(bis(pyridine-2-yl)formylidene)triethylenetetramine and L2 = tris(2-aminoethyl)amine] are synthesized and characterized. X-ray structural study shows that each cadmium(II) in 1 has a distorted square pyramidal geometry with a CdN 3 I 2 chromophore and that L1 behaves as a binucleating bis(tridentate) ligand bridging the metal centers with iodides remaining as terminals. In 2, one cadmium(II) adopts a distorted tetrahedral geometry with a CdI 4 chromophore surrounded by four iodides, while the other has a distorted trigonal bipyramidal environment with CdN 4 I chromophore bound by four N atoms of L2 and one bridging iodide. Weak C-HÁÁÁp interactions in 1 result in an infinite 1D chain; however, such weak non-covalent interactions are absent in 2. The Schiff base complex, 1, shows high-energy intraligand 1 (p-p*) fluorescence in DMF solution at room temperature, whereas compound 2 containing tripodal amine is fluorescent-inactive.Keywords Cadmium(II) iodide Á Schiff base bridge Á Tripodal amine Á X-ray structure Á Luminescence

Synthesis, structure and characterization of a new cadmium(II) iodide containing a tetradentate tripodal amine

“…They connect the cationic complexes [Cd(L)I] + to form layers parallel to the (a, c) plane. The number of 13 C CP-MAS NMR lines is in full agreement with the crystallographic data. The vibrational absorption bands are identified by infrared spectroscopy and theoretical calculations.…”

“…The degree of distortion from a regular trigonal bipyramid can be quantified by the structural index , namely the Addison parameter  = ( -)/60 with  and  being the two largest angles, which assumes the value of zero for an ideal square pyramidal and becomes equal to one for an ideal trigonal bipyramid [21]; the calculated  values of the title compound is (Cd) = 0.97 (where  and  values are 176.1(1) and 117.9(2)°, respectively), indicating a quite small distortion from the regular polyhedron. For the sake of comparison, nine pentacoordinated Cd complexes containing the L ligand have been retrieved from CSD [13,[22][23][24][25][26][27]; for them, the (Cd) values are in the range 0.64-0.95. The geometrical parameters of the CdN4I chromophore (Table 2) are in agreement with those of the literature compounds, being their mean Cd-N distances 2.419 Å (for Cd-N1) and 2.292 Å (for the other Cd-N bonds).…”

“…In our present work, we have chosen a tetradentate tripodal amine, tris(2-aminoethyl)amine (L), to isolate a mononuclear cadmium(II) iodide material which contains a pentacoordinated metal ion. It is worth noticing that Satapathi et al [13] have reported a binuclear cadmium(II) iodide with the same ligand comprising two cadmium(II) centers, with one trigonal bipyramidal geomerty and the other with Td environment, whereas one iodide ion bridges the two metal centers.…”

Some novel hexa‐coordinated cadmium Schiff base complexes: X‐ray structure, Hirshfeld surface analysis, antimicrobial and thermal analysis

“…The observed metal–ligand bond distances follow the order Cd–N azidic < Cd–N iminic = Cd–N aminic . However, the investigation of literature indicates that in other cadmium complexes with Schiff base ligands based on triethylenetetramine, the distances of the Cd–N iminic bond is smaller than that of the Cd–N aminic bond . Two azido groups in the complex are quasi‐linear with an N–N–N angle of 178.2(2) ° and coordinated in a bending way (N—N—Cd = 120.95(17)°) to the metal, which is common for terminal‐azide cadmium complexes …”

Interplay of thermochemistry and Structural Chemistry, the Journal (volume 22, 2011, issues 1–3) and the discipline

“…Satapathi et al [164] synthesized and characterized two neutral binuclear Cd(II) compounds with hexadentate Schiff bases/tetradentate tripodal amine [Cd 2 (L1)(I) 4 ] and [(L2) Cd(l-I)CdI 3 ] (L1 = N,N 0 -(bis(pyridine-2-yl)formylidene) triethylenetetramine, L2 = tris(2-aminoethyl)amine). The X-ray single crystal structure of both compounds has been determined and showed distorted square pyramidal geometry of the former and distorted tetrahedral geometry of the later compound.…”