Dimeric pentacoordinate trivalent iron complexes of benzoyl hydrazones

Synthesis and structural characterization of diorganotin(IV) esters with pyruvic acid isonicotinyl hydrazone and pyruvic acid salicylhydrazone Schiff bases

“…The structures are very similar to that of derivatives reported previously [11]. The bond distances of Sn1-O7 and Sn2-O8 are 2.288(6) and 2.274(6) Å , respectively, for 1, Sn1-O4 and Sn2-O8 are 2.291(5) and 2.327(4) Å for 2, which are relatively longer than those in the analogous [5,9,18,25], due to the formation of intradimeric hydrogen bonds, O7Á Á ÁO5 (2.619 Å ) and O8Á Á ÁO2 (2.643 Å ) for 1, O4Á Á ÁO6 (2.583 Å ) and O8Á Á ÁO2 (2.652 Å ) for 2, and interdimeric hydrogen bonds, O7Á Á ÁN3#1 [Àx + 1, y + 1/2, Àz + 3/2] (2.808 Å ) and O8Á Á ÁN6#2 [x À 1/2, Ày + 3/2, Àz + 2] (2.785 Å ) for 1, O4Á Á ÁN6#1 [x, Ày + 2, z + 1/2] (2.651 Å ) and O8Á Á ÁN3#2 [x, Ày + 1, z À 1/2] (2.804 Å ) for 2. Neighboring molecules are held together by hydrogen bonds O7Á Á ÁN3#1 and O8Á Á ÁN6#2 for 1, O4Á Á ÁN6#1 and O8Á Á ÁN3#2 for 2.…”

“…The disappearance of the bands assigned to carbonyls unambiguously confirms that the ligands coordinated with the tin are in the enol form. The characteristic absorptions at 1614-1633 and 1598-1609 cm À1 in the spectra of these compounds indicate the presence of C@N and C@N-N@C groups [18]. The stretching frequencies of interest are those associated with the COO, Sn-O and Sn-N groups.…”

Polynuclear diorganotin(IV) complexes with arylhydroxamates: Syntheses, structures and in vitro cytotoxic activities

“…Probably, the weaker H bonding of available NH protons in the two compounds induces changes of the N-H bond properties. The IR spectra of the 1:1 complexes [R 2 SnL] n a indicate the complete disappearance of the stretching vibration bands of N-H (and O-H) of their free ligands and show characteristic absorptions at 1661-1610 cm À1 assigned to m(C@N) [24][25][26][27][28]. These features are consistent with the double deprotonated hydroximic form of the hydroxamate ligands.…”

Synthesis, crystal structures and spectral characterization of diorganotin compounds with phenylglyoxylic acid isonicotinyl hydrazone

“…The Dm[mas(CO À 2 )-ms(CO À 2 )] values (230-282 cm À1 ) for compounds 1-3, indicate that the carboxylate groups adopt the monodentate coordination mode [27]. The characteristic absorption at 1630-1665 cm À1 can indicate the presence of C@N group [28]. The characteristic absorption at 1600-1620 cm À1 in the spectra of these compounds indicate the presence of the C@NAN@C group [29], thus indicating the ligand coordinate to the tin centre in an enolic form, which is in accordance with the X-ray structure analysis and their corresponding reaction mechanism.…”

“…The distance of Sn1AO1#1 is 2.561(2) Å, close to the sum of the covalent radii of Sn and O (2.56 Å), indicating the strong tin-oxygen interaction. The Sn1AN1 is 2.315(3) Å, which is greater longer than the sum of the covalent radii of Sn and N 2.15 Å, but is considerably less than the sum of the Van der Waals radii (3.75 Å) [28], and should be considered as the bonding interactions. The intermolecular chains O4AH4AÁ Á ÁO1#1 (#1 À x, Ày + 2, Àz), O4AH4AÁ Á ÁO2#1 (#1 À x, Ày + 2, Àz), C22AH22Á Á ÁO3#3 (#3x + 1, y, z) and O4AH4BÁ Á ÁN3#2 (#2 À x À 1/2, y + 1/2, Àz + 1/2) hydrogen bonds to generate three-dimensional network (Fig.…”