A compound according to Formula (I), or a pharmaceutically acceptable salt thereof: wherein R1 and R2 are each independently selected from optionally substituted C1-6-alkyl and optionally substituted aryl; R3, R4, R5, and R6 are each independently selected from the group consisting of H, halo, optionally substituted C1-6-alkyl, and optionally substituted C1-6 alkoxy; and R7 is a phosphorus containing moiety, wherein a phosphorus atom is bonded to Au.