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Structural Variations in Copper(II) Complexes of a Bitopic Bis(pyrazolyl)methane Ligand
Author(s) -
Reger Daniel L.,
Pascui Andrea E.,
Smith Mark D.
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200118
Subject(s) - chemistry , ligand (biochemistry) , copper , methanol , medicinal chemistry , square pyramidal molecular geometry , solvent , crystallography , stereochemistry , organic chemistry , biochemistry , receptor
The equal molar reaction of Cu(BF 4 ) 2 · 3H 2 O with the ditopic, bis(pyrazolyl)methane ligand p ‐[CH(pz) 2 ] 2 C 6 H 4 ( L p ) where pz is a pyrazolyl ring, in methanol produces [Cu(μ‐ L p )(CH 3 OH)](BF 4 ) 2 · (CH 3 OH) 0.62 ( 1 ) and a similar reaction in water/methanol yields [Cu(μ‐ L p )(CH 3 OH)] 2 (SiF 6 )(BF 4 ) 2 · (CH 3 OH) 2 ( 2 ). The water/ethanol solvent system yields both [Cu 2 (μ‐ L p )(H 2 O) 6 ](SiF 6 ) 2 · (H 2 O) 4 ( 3 ) and [Cu(μ‐ L p )(H 2 O)](BF 4 ) 2 · (CH 3 CH 2 OH) 2 ( 4 ), and if the ratio of Cu(BF 4 ) 2 · 3H 2 O and L p is changed to 2:1, only 3 forms. Recrystallization of the solid formed from the reaction of THF solutions of Cu(BF 4 ) 2 · 3H 2 O with L p from DMSO yields [Cu 2 (μ‐ L p )(DMSO) 6 ](BF 4 ) 4 · (DMSO) 2 · C 6 H 6 · (H 2 O) 0.5 ( 5 ) and a recrystallization of compound 1 from DMSO yields [Cu 2 (μ‐ L p )(DMSO) 6 ](BF 4 ) 4 · (DMSO) 2 · C 6 H 6 ( 6 ). Complexes 1 , 2 , and 4 are coordination polymers in which the N 4 O‐coordinated, square‐pyramidal copper(II) ions are oriented in an anti conformation withrespect to the phenylene spacer of L p . Complexes 3 , 5 and 6 are dinuclear with N 2 O 3 ‐coordinated, square‐pyramidal copper(II) ions again oriented in an anti configuration with respect to the bridging L p . The square pyramidal geometries show axial elongation, a result of pseudo Jahn–Teller electronic effects. In the cases of the coordination polymers, the axially coordinated solvent molecule is lost at low temperatures upon heating of the crystals. The three compounds in each structural type have nearly the same overall configurations. Cooperative effects of O–H ··· F, O–H ··· O and C–H ··· F hydrogen bonding interactions organize the supramolecular structures and influence the crystal packing of complexes 1 – 4 . The C–H ··· F interactions have metrics that indicate they are unusually strong, due to the enhanced polarization of the C–H bond and charge assistance from the anionic fluorine atom.