Nitrogenous chelate complexes of transition metals. V. Binuclear hydroxybridged copper(II) complexes of 1,10-phenanthroline and 2,2'-bipyridyl

Abstract

A series of compounds of the type OH [chelate Cu ' \Cu chelate]X,,nH20 \OH/ [where chelate = 1,lO-phenanthroline; X = 01 (n = 3), Br (n = 4), I (n = 2), NCS (n = 2), C10, (n = 1); 2X = SO, (n = 5), PtCl, (n = 4), and where chelate = 22'-bipyridyl; X = C1 (n = 3), Br (n = 4), I (n = 3), NCS (n = l), PF6 (n = 2), C10, (n = 1); 2X = SO4 (n = 5) and PtC1, (n = 3)] have been prepared and their properties investigated. In dilute aqueous solution the compounds are ionized forming the solvated [chelate Cu(OH,)Cu chelateI2+ species which exhibit similar visible absorption spectra (where chelate = p,h, ,eAn, = 630 mp and 6 = 97, and where chelate = b ,i,p,Ay, = 620 mp and E = 105). In nitrobenzene solution some of these compounds have been shown from electrical conductivity and spectrophotometric measurements to involve coordination of the anion to the copper(11) atoms. This effect has also been verified in the solid state by the measurement of diffuse reflectance spectra. The compounds all exhibit room temperature magnetic moments of the order of 2.0 B.&I. per copper atom. A study of the magnetic susceptibility of the sulphate [bipy Cu(OH),Cu bipy]S04,5H,0 over the temperature range 83-293'~ showed no antiferromagnetic interaction between pairs of hydroxy-bridged copper atoms, and the results obey a Curie-Weiss law (8 -13'~). The average value of the corrected moment is 1.91 B.M. per copper atom. A value for g of 2.20 was estimated from these data, and is in agreement with the average g value of 2.19 obtained from an e.s.r. measurement.