Synthesis, characterization and magnetic studies on mono-, di-, and tri-nuclear Cu(ii) complexes of a new versatile diazine ligand.
The synthesis and coordination chemistry of a new open-chain diazine ligand (L4H2) containing bipyridine, oxime and hydrazone functionalities is reported. Reaction of L4H2with CuCl2·2H2O affords the mononuclear complex [Cu(L4H2)Cl2] (1) in which the ligand acts as a neutral tridentate N,N',N'' donor, whereas treatment with a large excess of CuCl2·2H2O affords the dinuclear complex [Cu2(L4H)Cl3(CH3OH)(H2O)] (2) in which the ligand is singly-deprotonated at the diazine, offering N,N',N'' and N,N' donor sets to two Cu(ii) ions. Reaction with Cu(NO3)2·3H2O yields the trinuclear complex, [Cu3(L4H)2(CH3OH)4(NO3)4] (3) in which the ligand is again singly deprotonated, but now presents a tetradentate N,N',N'',N'''-donor set to the first Cu(ii) and behaves as an N,O-chelate to a second Cu(ii), with a conformational change from cis to trans at the diazine moiety. When the latter reaction is repeated in the presence of a mild base, a second trinuclear complex is isolated, [Cu3(L4)2(CH3CH2OH)](NO3)2(4) in which both the diazine and oxime functionalities of the ligand are deprotonated which subsequently bridges all three Cu(ii) ions, acting as an N,N',N'' donor to the first Cu(ii), a N,N' donor to a second Cu(ii) (similar to 2) and as a terminal O-donor to a third Cu(ii) ion. The Cu(ii) ions are linked mutually cis via the two-atom diazine bridge in the case of 2 and 4 and trans in the case of 3. Magnetic studies reveal the presence of weak ferromagnetic interactions in 2 (g = 2.2, J/k = +12.8 K) and strong antiferromagnetic interactions in both 3 and 4 (g = 2.093 J/k = -140 K and g = 2.24 J/k = -300 K respectively).
University of Nizwa, Chair of Oman's Medicinal Plants and Marine Natural Products, P O Box 33, PC 616, Birkat Almouz, Nizwa, Oman. usman.anwar@unizwa.edu.om and Department of Chemistry and Biochemsitry, University of Windsor, 401 Sunset ave, Windsor, ON N9B3P4, Canada. jmrawson@uwindsor.ca.
Muhammad U
http://orcid.org/0000-0003-4740-5737
MU
Anwar
Department of Chemistry and Biochemsitry, University of Windsor, 401 Sunset ave, Windsor, ON N9B3P4, Canada. jmrawson@uwindsor.ca.
Jeremy M
JM
Rawson
Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Cathaerines, ON L2S3A1, Canada.
Emma L
EL
Gavey
Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Cathaerines, ON L2S3A1, Canada.
Melanie
M
Pilkington
University of Nizwa, Chair of Oman's Medicinal Plants and Marine Natural Products, P O Box 33, PC 616, Birkat Almouz, Nizwa, Oman. usman.anwar@unizwa.edu.om.
Ahmed
A
Al-Harrasi
Deptartment of Chemistry, Memorial University, St. John's, Newfoundland A1B 3X7, Canada.
Laurence K
LK
Thompson