Question

2) Consider the complex ions [Ni(H2O)2Cl2(OH)2]2– and [Co(en)2(SCN)Cl]+ . For each, a) Identify the ligands and their charges b) What is the oxidation number of the metal? c) What is the formula for the sodium salt of the first ion and the sulfide salt of the second ion?

Answer 1

(a)  [Ni(H2O)2Cl2(OH)2]2– This complex has three different ligands as two water (neutral, H2O), two chloride (Cl-) and two hydroxy (OH-).

[Co(en)2(SCN)Cl]+ For this complex also three types of ligands are: two ethylene diamine (neutral, en), one thiocyanate (SCN-) and one chloride (Cl-).

(b) Oxidation number of Ni in [Ni(H2O)2Cl2(OH)2]2–

suppose oxidation state of Ni as X and charge on H2O = 0; Cl =-1 and OH = -1

then X + 2(0) + 2(-1) + 2(-1) = -2 (as complex has -2 charge)

X + (-2) + (-2) = -2

X - 4 = -2

X = +2 (so Ni as Ni2+)

Similarily, oxidation state of Co in [Co(en)2(SCN)Cl]+

Co = X, en = 0; SCN = -1 and Cl = -1

X + 0 + (-1) + (-1) = +1 (as charge on complex is +1)

X -1 -1 = +1

X = +1 (Co as Co+)

(c) Na2[Ni(H2O)2Cl2(OH)2]

[Co(en)2(SCN)Cl]2S