Complexes and Ligands

A compound of Formula (IIIf):

• or a pharmaceutically acceptable salt thereof, wherein:
• Y is selected from C1-6 alkylene, C2-6 alkenylene, and C2-6 alkynylene;
• x is an integer from 0 to 100;
• wherein if x is 0 then L is a bond;
• each L is independently selected from C1-3 alkylene, C2-4 alkenylene, C2-4 alkynylene, C1-3 alkylene-O—, —O—C1-3 alkylene, phenylene, —C(O)NH—, —NHC(O)—, —C(O)O—, and —OC(O)—;
• each X1 is independently selected from halo, NO2, CN, N3, C1-6 alkyl, C1-6 alkoxy, C2-6 alkenyl, C2-6 alkynyl, C6-10 aryl, and 5-14 membered heteroaryl, wherein said C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C6-10 aryl, and 5-14 membered heteroaryl are each optionally substituted with 1, 2, or 3 substituents independently selected from halo, OH, SH, NH2, C1-3 alkylamino, di(C1-3 alkyl)amino, NO2, CN, C(O)OH, C1-3 alkoxy, C1-3 haloalkoxy, and N3;
• and
• each R1 is independently selected from H, C1-6 alkyl, C2-6 alkenyl, and C2-6 alkynyl, each of which is optionally substituted with 1, 2, or 3 substituents independently selected from halo, OH, SH, NH2, C1-3 alkylamino, di(C1-3 alkyl)amino, NO2, CN, C(O)OH, C1-3 alkoxy, C1-3 haloalkoxy, and N3.