Answer: [Mn(H 2 O) 6 ] 2+.
- A [Co(NH<sub>3</sub>)<sub>6</sub>]<sup>3+</sup>
- B [Fe(CN)<sub>6</sub>]<sup>4-</sup>
- C [Mn(H<sub>2</sub>O)<sub>6</sub>]<sup>2+</sup>
- D [Ni(CN)<sub>4</sub>]<sup>2-</sup>
Correct answer: C. [Mn(H<sub>2</sub>O)<sub>6</sub>]<sup>2+</sup>
Explanation: Mn<sup>2+</sup> is d<sup>5</sup>; with weak-field H<sub>2</sub>O it is high spin with 5 unpaired electrons, so mu = sqrt(5x7) = 5.92 BM. The others are low spin or diamagnetic.
The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).
Concept context
Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.