Metal complexes that have unpaired electrons are magnetic . Considering only monometallic complexes, unpaired electrons arise because the complex has an odd number of electrons or because electron pairing is destabilized. Thus, monomeric Ti(III) species have one "d-electron" and must be (para)magnetic , regardless of the geometry or the nature of the ligands. Ti(II), with two d-electrons, forms some complexes that have two unpaired electrons and others with none. This effect is illustrated by the compounds TiX 2 [(CH 3 ) 2 PCH 2 CH 2 P(CH 3 ) 2 ] 2 : when X = Cl , the complex is paramagnetic ( high-spin configuration), whereas when X = CH 3 , it is diamagnetic ( low-spin configuration). It is important to realize that ligands provide an important means of adjusting the ground state properties.