| Abstract
| - A new polynucleating ligand, 1,2,4,5-tetrakis(1,4,7-triazacyclonon-1-ylmethyl)benzene (Ldur), has been preparedand characterized as its dodecahydrobromide salt. Addition of base to an aqueous solution of this salt and 4molar equivalents (m.e.) of a Ni(II) salt produces a mixture of bi- and trinuclear complexes, which can be separatedby cation-exchange chromatography (CEC) and crystallized as [Ni2Ldur](ClO4)4·2H2O (1) and [Ni3Ldur(H2O)6](ClO4)6·9H2O (2). The “full capacity” tetranuclear complex, [Ni4Ldur(H2O)12](ClO4)8·8H2O (3), is obtained byslow addition of Ldur to a refluxing aqueous solution of excess Ni2+ ions, followed by CEC purification. Treatmentof Ldur with 4 m.e. of a copper(II) salt produces exclusively the tetranuclear complex, [Cu4Ldur(H2O)8](ClO4)8·9H2O (4), while reaction with only 2 m.e. of Cu2+ ions yields the binuclear complex, [Cu2Ldur](ClO4)4·4H2O (5).The X-ray structures of complexes 1, 2, 4, and [Cu2Ldur](ClO4)4·3H2O (5‘) have been determined; all are monoclinic,P21/c: for 1, a = 9.497(3) Å, b = 13.665(5) Å, c = 19.355(6) Å, β = 100.57(2)°, V = 2469(1) Å3, and Z = 2;for 2, a = 22.883(7) Å, b = 15.131(6) Å, c = 20.298(8) Å, β = 97.20(3)°, V = 6973(4) Å3, and Z = 4; for 4,a = 16.713(7) Å, b = 16.714(6) Å, c = 14.775(11) Å, β = 108.24(5)°, V = 3920(4) Å3, and Z = 2; and for 5‘,a = 9.5705(1) Å, b = 13.0646(1) Å, c = 20.1298(2) Å, β = 103.1618(8)°, V = 2450.81(4) Å3, and Z = 2. Themetal centers in 1 and 5‘ lie in distorted octahedral environments, each facially coordinated by two of the triaminerings of Ldur, the cation in each case being centrosymmetric. In 2, one of the nickel(II) centers is similarlysandwiched by two triamine rings, while the other two nickel(II) centers are each coordinated by a single triaminering from the ligand, with their distorted octahedral coordination spheres each being completed by three watermolecules. In 4, the four triamine rings of Ldur bind to separate copper(II) centers, with two water moleculesoccupying the remaining two sites of the distorted square pyramidal (SP) coordination spheres, the cation againbeing centrosymmetric.
- A new tetramacrocyclic ligand incorporating four 1,4,7-triazacyclononane moieties linked by a durene unit has been found to coordinate two, three, or four metal centers, thereby leading to the formation of bi-, tri-, and tetranuclear nickel(II) and copper(II) complexes.
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