Color of Bi(dmg)2 complex
The Bi(dmg)2 complex has a yellow color. To understand why this complex exhibits a yellow color, let's break down the components and the electronic transitions involved.

Components of the complex:
- Bi: This refers to the central metal atom, which in this case is bismuth (Bi). Bismuth is a heavy metal with several d orbitals available for bonding.
- dmg: This stands for dimethylglyoxime, which is a chelating ligand. It has the formula C4H8N2O2 and can form coordination bonds with metal ions.

Electronic transitions involved:
When light interacts with a complex, it can be absorbed by the electrons present in the metal's d orbitals. This absorption of light causes the complex to appear colored. The color observed is determined by the energy difference between the metal's d orbitals.

In the case of the Bi(dmg)2 complex, the yellow color arises due to a specific electronic transition. The d orbitals of bismuth are split into different energy levels in the presence of ligands. This splitting is known as crystal field splitting.

Explanation of the yellow color:
The yellow color of the Bi(dmg)2 complex can be attributed to the specific electronic transition between the split d orbitals. The transition responsible for the yellow color is typically referred to as a d-d transition.

During a d-d transition, an electron in one of the lower energy d orbitals is excited to a higher energy d orbital by absorbing a specific wavelength of light. The absorbed light falls in the blue or violet region of the electromagnetic spectrum, while the complementary color observed is yellow.

In summary, the Bi(dmg)2 complex appears yellow because of the specific d-d electronic transition that occurs when the complex absorbs light. The energy difference between the split d orbitals in the presence of ligands determines the color observed, with the absorbed light falling in the blue or violet region of the spectrum and the complementary color being yellow.