Coordination Compounds Test - 6

The cation is named first and then the anion. When the anion is the complex then the -ate is added to the name of the central metal. Here there are 4 hydride ligands represented as H^{​​​​​​-} each carries a charge of -1 and hence a total of -4 charge on the ligands. Lithium ion is represented by Li⁺ and carries a +1 charge which means the charge on the complex is -1. In the complex, central metal atom/ion is written followed by the ligands in alphabetical order.
Lithium tetrahydridoaluminate(III) is Li[AlH₄].

In ionic compound, cation is named first and then the anion. If cation is the complex then ligands are named first in alphabetical order and then the central metal atom/ion with its oxidation state in paranthesis in roman numerals. Here, NH ₃ (ammine) is the neutral ligand and there are 4 NH ₃ bound to Cu (copper). Nitrate NO₃^- is the anion there are two NO ₃ ^- outside the square bracket each carries -1 charge so there is a total of -2 charge on anions and thus the complex carries a total of +2 charge. Since ammine is a neutral ligand so Cu has +2 oxidation state. So, [Cu(NH₃)₄](NO₃)₂ is tetraamminecopper(II) nitrate.

Coordination isomerism arises from the interchange of ligands between cationic and anionic entities of different metal ions present in a complex. Here interchange of CN^- and NH₃ ligands is possible between Cr and Co to give [Co(NH₃)₆][Cr(CN)₆]. So this complex can exhibit coordination isomerism.

When there is interchange of ligands between the cationic and anion species of different metal ions present in a complex, then coordination isomerism arises. Here we can find the interchange of en and Cl between Ir and Rh in the complexes.

The metal-carbon bond in metal carbonyls possesses both σ and π character. The M–C σ bond is formed by the donation of lone pair of electrons on the carbonyl carbon into a vacant orbital of the metal. The M–C π bond is formed by the donation of a pair of electrons from a filled d orbital of metal into the vacant antibonding π* orbital of carbon monoxide. The metal to ligand bonding creates a synergic effect which strengthens the bond between CO and the metal.

Ni has atomic number 28, so Ni²⁺ has electronic configuration 1s²2s²2p⁶3s²3p⁶3d⁸. NH₃ is a weak field ligand and hence two electrons are unpaired and hence this complex is paramagnetic.

Hydrate isomers differ by whether water molecules are directly bonded to the central metal atom/ion or are merely present as free water molecules in the crystal lattice. In the first complex the 6 water molecules are directly bonded to the central metal whereas in the second complex 2 water molecules are present as water of crystallisation and 4 water molecules are directly bonded to the central metal. So these exhibit hydrate isomerism.