Abstracts Book - IMRC 2018

• SD7-P033
SYNTHESIS, STRUCTURE AND MAGNETIC PROPERTIES OF NOVEL
COPPER(II) CLUSTERS BRIDGED BY SCHIFF BASE AND AZIDE.
Cándida Pastor 1
1 Benemerita Universidad Autonoma de Puebla, Instituto de Química, Mexico.
In this work we present the synthesis, electronic, magnetic and spatial
characterization of three new compounds [Cu II 4-m-N 3 (H 2 L -2 ) 2 (HL -
3 )(H 2 O)] 2 ∠CH 3 CH 2 OHâˆÂÂnH 2 O (1), [Cu II 4(H 2 L -
2 ) 4 (H 2 O)]âˆÂÂCH 3 OH (2) and [Cu II 3(H 2 L -2 ) 2 (m-N 3 ) 2 (H 2 O) 2 ] (3). Using the
starting materials 2-((2-hydroxy-benzylidene)-amino)-2-hydroxymethylpropane-1,3-diol
(H 4 L), sodium azide (NaN 3 ) and Cu(II). Crystallographic analysis
of 1-3 revealed that 1 has two units of pseudo-cubans built by four Cu(II) each,
2 is a pseudo-cuban of four Cu(II) belonging to the spatial group P-1 and 3 is a
polymeric structure with three units of Cu(II) belonging to the spatial group
P2 1 /n. In 1-3 the m-alkoxo bridges were observed since the H 4 L ligand is not only
acting as a chelate but also bypasses another neighbor metal ion forming a
polynuclear compound. The IR and absorption spectra of 1-3 showed the bands
coming the H 4 L ligand, new vibrational bands n Cu-O , n Cu-N and the bridge ligand
N 3
-
in the case of 1 and 3. Additionally LMCT bands (~27000 cm -1 ) and wide bands
assigned to the d-d transitions (~15000 cm -1 ), informed that the local geometry
around the Cu(II) ions are: square-pyramidal and square plane in 3, octahedral
and square-pyramidal in 1 and 2, which confirmed formation of the coordination
compounds. Temperature-dependent (2.9-300K) magnetic measurements
indicate the coexistence of ferromagnetic-antiferromagnetic spin interactions in
1 and 2 with J 1 =102cm -1 , J 2 =-117cm -1 , g = 2, J 1 = 205cm -1 , J 2 = -235cm -1 , g = 2.
Meanwhile there are antiferromagnetic interactions among the metal centres in
3. The EPR spectrum of 1-3 presents axial symmetry with hyperfine split at g //
with the copper nuclei (I = 3/2). The EPR parameters (g // = 2.24, 2.27, 2.3, A // =
161, 178, 188 x10 -4 cm -1 respectively and g^ = 2.06) indicate a d x
2 -y
2
ground state.
The IR, absorption spectra and magnetic studies of 1-3 were analysed and
compared to related complexes of known geometries and the data is in accord
with the structural data obtained herein.
Acknowledgment:
CONACyT por la beca otorgada Plan de Trabajo, Cuerpo Académico 261-BUAP-
2015. Proyectos VIEP: REOY-NAT16-G, REOY-NAT17-G y HEAS NAT-17. Red