What are metal carbonyls? Give examples.

(N/A) Metal carbonyls are coordination complexes of transition metals with carbon monoxide $(CO)$ as the ligand.
Examples include: $[Ni(CO)_{4}]$,$[Fe(CO)_{5}]$,$[Mn_{2}(CO)_{10}]$,and $[Cr(CO)_{6}]$.
These are homoleptic compounds,meaning they contain only carbonyl groups as ligands and possess simple,well-defined structures:
$1$. $[Ni(CO)_{4}]$ is tetrahedral.
$2$. $[Fe(CO)_{5}]$ is trigonal bipyramidal.
$3$. $[Cr(CO)_{6}]$ is octahedral.
$4$. Decacarbonyldimanganese $(0)$ $[Mn_{2}(CO)_{10}]$ consists of two square pyramidal $[Mn(CO)_{5}]$ units joined by a $Mn-Mn$ bond.
$5$. Octacarbonyldicobalt $(0)$ $[Co_{2}(CO)_{8}]$ features a $Co-Co$ bond bridged by two $CO$ groups.