Synthesis and crystal structure of trichromium metal string complex

The synthesis, crystal structures and molecular packing of the three trichromium metal string complexes [Cr3(dpa)4Cl(OC2H5)]OH$C2- H5OC2H5$2.5H2O (1), [Cr3(dpa)4(OH)2]ClO4$3H2O (2) and [Cr3(dpa)4F2Na(H2O)BF4]BF4$CH3OH (3) (dpaKZbis(2-pyridyl)amido) have been studied. The crystal structure data for 1: C46H54ClCr3N12O5.5, monoclinic, P21/c, aZ19.9998(4) A ° , bZ15.9756(3) A ° , cZ16.9943(3) A ° , bZ114.0548(8)8, ZZ4, R1Z0.0791, wR2Z0.1927; for 2: C40H40ClCr3N12O9, orthogonal, Pna21, aZ18.3373(2) A ° , bZ16.8220(2) A° , cZ14.0268(2) A° , ZZ4, R1Z0.0683, wR2Z0.1804; for 3: C41H38B2Cr3F10N12NaO2, monoclinic, P21/n, aZ 12.3902(1) A ° , bZ16.2081(2) A ° , cZ23.4119(3) A ° , bZ98.8725(6)8, ZZ4, R1Z0.0670, wR2Z0.1568. The structure data were collected using graphite monochromated molybdenum Ka radiation and refined using full-matrix least square techniques on F2. The magnetic property of complex 1 was carried out on polycrystalline samples with a SQUID magnetometer. The IR, FAB-MS mass spectra of all complexes were also measured. In the three complexes, trichromium metal string complexes can be considered as mini-1D asymmetrically chains since the distance between the two axial ligands is around 1 nm. The types of hydrogen bonding in three complexes are C–H/O, C–H/Cl, C–H/F and O–H/O). 1 and 2 have a one-dimensional double-chain structures. 1 is a rare example of three-dimensional novel sandwich structure. In 3, one of the axial ligand, FK acts as a bridge ligand to link the sodium ion to the Cr3 axis with a bond angle of Cr(1)–F(1)–Na in 169.90(13)8. It can be considered as a metal string complex with an extra long axis. q 2004 Elsevier B.V. All rights reserved