Müller Jochen, Weyhermüller Thomas, Bill Eckhard, Hildebrandt Peter, Ould-Moussa Linda, Glaser Thorsten, Wieghardt Karl
Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr (Germany), Fax: +(49) 208-306-3952.
Angew Chem Int Ed Engl. 1998 Mar 16;37(5):616-619. doi: 10.1002/(SICI)1521-3773(19980316)37:5<616::AID-ANIE616>3.0.CO;2-4.
The relative orientation of the two magnetic orbitals, the Cu d x 2-y 2 orbital and the half-occupied π orbital of the tyrosyl radical, is the key to answering the question in the title. The arrangement shown (Cu -O-C bond angle of about 130° and a dihedral angle of about 90° between the x,y plane of the Cu polyhedron and the tyrosyl ring plane) leads to an overlap of the orbitals, which results in a singlet ground state.
两个磁性轨道（铜的d x 2-y 2轨道和酪氨酸自由基的半占据π轨道）的相对取向是回答标题中问题的关键。所示的排列方式（铜-氧-碳键角约为130°，铜多面体的x、y平面与酪氨酸环平面之间的二面角约为90°）导致轨道重叠，从而产生单重态基态。
