(CO)₄ (tetracarbonyl, (C≡O)₄ tetrahedral Ⓢ)

[Fe(CO)₄]²⊖

Formula Unicode styled: 
[Fe(CO)₄]²⊖
Compound name(s): 
tetracarbonyl-iron(2-)
Central atom: 
Iron
Attached groups: 
(CO)₄ (tetracarbonyl, (C≡O)₄ tetrahedral Ⓢ)
Charge on central atom: 
-2
Compound type: 
Molecular
Valence Number (VN) = 𝘹 + 2𝘻 : 
VN: 2
Oxidation Number (ON) (Roman numerals): 
ON: (-II)
Coordination Number (CN, sum of attached group denticities): 
CN: 4
Electron Number (EN) = 𝘮 + 𝘹 +2𝘭: 
EN: 18
Summary of calculated classifications: 
Fe«V2C4O-IIE18B6X0L4Z2»2⊖
[MLXZ]𝘲 class: 
[ML4Z2]2-
MLXZ class (ENC, equivalent neutral class): 
MX2L4

[Co(CO)₄]⊖

Formula Unicode styled: 
[Co(CO)₄]⊖
Compound name(s): 
tetracarbonylcobalt(1-)
Central atom: 
Cobalt
Attached groups: 
(CO)₄ (tetracarbonyl, (C≡O)₄ tetrahedral Ⓢ)
Charge on central atom: 
-1
Compound type: 
Molecular
Valence Number (VN) = 𝘹 + 2𝘻 : 
VN: 3
Oxidation Number (ON) (Roman numerals): 
ON: (-I)
Coordination Number (CN, sum of attached group denticities): 
CN: 4
Electron Number (EN) = 𝘮 + 𝘹 +2𝘭: 
EN: 18
Summary of calculated classifications: 
Co«V3C4O-IE18B6X0L4Z2»⊖
[MLXZ]𝘲 class: 
[ML4Z2]-
MLXZ class (ENC, equivalent neutral class): 
MX3L3