Consider the [CoCl₆]^4- ion. Determine which responses are true statements.
I. The oxidation number of Co is -4.
II. The coordination number of cobalt is 6.
III. It is paramagnetic.
IV. It is a low-spin complex.

Question

Quizplus · Accepted Answer

II, III. The coordination number of cobalt in this complex is 6, given by the coordination of 4 Cl- ions and 2 H2O molecules (not explicitly shown but implied by the typical composition of such complexes). Cobalt complexes are often paramagnetic due to unpaired electrons in the d orbitals. The oxidation state of Co is not -4; it's typically +2 or +3 in such complexes, making statement I incorrect. Whether it's a high-spin or low-spin complex depends on the ligands and the metal's oxidation state, which isn't clearly defined by the information given, making IV uncertain without more context.

Consider the [CoCl6]4- Ion

Consider the [CoCl₆]^4- Ion