Answer
Au (gold).
Coordination number 2: $Au(CN)_{2}^{-}$; oxidation number = +1
Coordination number 4:$Au(Cl)_{4}^{-}$; oxidation number = +3
Coordination number 5: $Au(DMP)Cl_{3}$; oxidation number = +3
(DMP: 2,9-dimethyl-1,10-phenanthroline)
Work Step by Step
Coordination number 2: $Au(CN)_{2}^{-}$; oxidation number = +1
CN- has -1 charge; complex charge is -1. So, Au is in +1
Coordination number 4:$Au(Cl)_{4}^{-}$; oxidation number = +3
Cl- has -1 charge; 4Cl- ligands;
complex charge is -1. So, Au is in +3
Coordination number 5: $Au(DMP)Cl_{3}$; oxidation number = +3
(DMP: 2,9-dimethyl-1,10-phenanthroline); DMP has neutral charge. 2Cl- ligands. So, oxidation number =+3
