Preparations and characterization of five-coordinate zinc(II) complexes ofH(2)tmtaa, (Zn(tmtaa)L [L= PPh3, OPPh3 and CH3CN]) and crystal structure of Zn(tmtaa)OPPh3

When Zn(tmtaa) (H(2)tmtaa = tetramethyldibenzotetraaza[14]annulene) reacted with PPh3 (PPh3 = triphenylphosphine) in benzene in air atmosphere, Zn(tmt aa)OPPh3 (OPPh3 = triphenylphosphine oxide) was obtained. Under argon atmos phere, Zn(tmtaa) reacted with PPh3 in benzene, and then Zn(tmtaa)PPh3 was o btained. When Zn(tmtaa)PPh3 was recrystallized in benzene-acetonitrile (1:2 v/v), Zn(tmtaa)CH3CN was produced. Zn(tmtaa)L (L = PPh3, OPPh3 and CH3CN) was characterized by IR, UV, mass and NMR spectra as well as DSC (different ial scanning calorimetry) measurements. C-13 NMR and P-31 NMR spectra show that the phosphorus atom in PPh3 and the oxygen atom in OPPh3 coordinate to the zinc atom. The stability of Zn(tmtaa)L complexes in solution has been studied. The crystal structure of Zn(tmtaa)OPPh3 was determined by X-ray si ngle crystal diffraction. The zinc(II) is coordinated by four nitrogen atom s of tmtaa and an oxygen atom of triphenylphosphine oxide to form a five-co ordinate, square-pyramidal geometry. The average bond length of Zn to the f our nitrogens of tmtaa is 2.024(3) Angstrom and for the oxygen of triphenyl phosphine oxide it is 2.040(3) Angstrom. The displacement of Zn from the pl ane of four nitrogens in tmtaa is 0.48 1(4) Angstrom.