title: Structural and spectroscopic properties of trans-difluoro(1,4,8,12-tetraazacyclopentadecane)chromium(III) perchlorate hydrate.
abstract: The structure of [CrF(2)([15]aneN(4))]ClO(4).H(2)O ([15]aneN(4)=1,4,8,12-tetraazacyclopentadecane) has been determined by a single-crystal X-ray diffraction study at 173 K. The complex crystallizes in the space group P1- of the triclinic system with two mononuclear formula units in a cell of dimensions a=9.6117(7) A, b=10.2882(7) A, c=11.0001(7) A and alpha=99.7570(10) degrees, beta=105.6080(10) degrees and gamma=113.7130(10) degrees. The complex cation unit has its central Cr atom in an octahedral coordination with four nitrogen atoms and two fluorine atoms in a trans position. Three six-membered and one five-membered chelate rings of the [15]aneN(4) ligand are in a chair-twist(skew)-chair-gauche conformation sequence. The gauche five-membered ring is disordered with the twist six-membered ring opposite. The four H atoms in the chiral N atoms have the trans-II (CTCg) type configuration. The mean Cr-N and Cr-F bonds are 2.095(2) and 1.8752(13) A, respectively. The IR and visible spectral properties are consistent with the result of X-ray crystallography. The resolved band maxima of the electronic d-d spectrum are fitted with secular determinant for quartet state energy of d(3) configuration in tetragonal field including configurational but neglecting spin-orbit coupling. It is confirmed that the fluoride has strong sigma- and pi-donor properties toward the chromium(III) ion and the nitrogen atoms of the [15]aneN(4) ligand also have a strong sigma-donor character.
authors.affiliation: Department of Chemistry, Andong National University, Andong 760-749, South Korea. jhchoi@andong.ac.kr
authors.forename: Jong-Ha
authors.initials: JH
authors.lastname: Choi
authors.forename: In-Gyung
authors.initials: IG
authors.lastname: Oh
authors.forename: Keon Sang
authors.initials: KS
authors.lastname: Ryoo
authors.forename: Woo-Taik
authors.initials: WT
authors.lastname: Lim
authors.forename: Yu Chul
authors.initials: YC
authors.lastname: Park
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Habibi
mesh_terms: D002857:Chromium / Q000737:chemistry*; D017608:Chromium Compounds / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008954:Models, Biological; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D010472:Perchlorates / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D017608:Chromium Compounds; D009942:Organometallic Compounds; D010472:Perchlorates; C518757:difluoro(1,4,8,12-tetraazacyclopentadecane)chromium(III); D002857:Chromium; C494474:perchlorate