A Magnetic Study of the Effect of Bond Angle Distortion

Abstract

THE prediction1 that diamagnetic nickel complexes would prove to be square co-ordinated has been verified in a number of different ways. The discovery of isomeric nickel glyoximes2, the crystal structure of potassium nickel dithioxalate3 and investigations of crystal optics4 and isomorphism5 of other diamagnetic nickel compounds have all borne out the existence of this correlation between structure and magnetic properties. All internal nickel complexes in which four nitrogen atoms are bonded to the metal atom have proved, on investigation, to be diamagnetic, and they may therefore be presumed to be square bonded. The nickel derivatives of various glyoximes2, phthalocyanine6 and proto-porphyrin7 afford examples of this type of complex. In these circumstances it becomes possible to investigate magnetically the question as to whether distortion from a square configuration gives nickel-nitrogen bonds sufficient ionic character to make a complex paramagnetic.