Saved Bookmarks
| 1. |
Explain about the classification of metal carbonyls with suitable examples. |
|
Answer» Solution :`(i)` BASED on the number of metal atoms present. Depending upon the number of metal atoms present in a metalic carbonyl , they are classified as follows. `(a)` Mono nuclear carbonyls :- These compounds contain only one metal atom and have simple structure. for e.g.,`[Ni(CO)_(4)]` Nickel tetra carbonyl is tetrahedral, `[Fe(CO)_(5)]` Iron pentacarbonyl is trigonalbipyramidal. `[Cr(CO)_(6)]` Chromium hexacarbonyl is octahedral. `(b)` Poly nuclear carbonyls- Metallic carbonyls containing two or more metal atoms are called poly nuclear carbonyls. Poly nuclear metal carbonyls may be Homenuclear `-([Co_(2)(CO)_(6)]`, `[Mn_(2)(CO)_(10)])`, `[Fe_(3)(CO)_(12)])` Hetero nuclear - `([MnCo(CO)_(9)]`, `[MnRe(Co)_(10)])` `(II)` based on structure The structures of binuclear metal carbonyls in involve either metal-metal bonds or bridging`Co` groups or both. The carbonyls ligands that are attached to only one metal atom are referred to as terminal carbonyl groups, WHEREAS those attached to two metal atoms simultaneously are called bridging carbonyls. Depending upon the structures of metalmetal carbonyls they are classified as follows : `(a)` Non bridges metal carbonyls These metal carbonyls do not contain any bridgingcarbonyl ligand. They may be of two types `(i)` Non-bridged metal carbonyle which contain only terminal carbonyls. Example : `[Ni(CO)_(4)]`  `(ii)` Non-bridged metal carbonyls which contain terminal carbonyls as well as Metal- Metal bonds. For examples, The structure of `Mn_(2)(CO)_(10)`. Contains one metal -metal bond, so the formula is more correctly represented as `(CO)_(5)Mn-Mn(CO)_(3)`.  `(b)` Bridged carbonlys : These metal carbonyl contain one or more bridging carbonyl ligands ALONG with terminal carbonyl ligands and one or more metal -metal bonds . For example : `Fe(CO)_(9)` Di -iron ennea carbonyl molecule consists of three `CO` ligands , six terminal `CO` groups and single `Fe-Fe Delta` bond formed by weak coupling of the unpaired electrons present in two `3d` orbitals of `2 Fe` atoms. The bond represented by dotted line is called fractional single bond. 
|
|