[Er(NH₃)(Cp₃)]

Formula Unicode styled: 
[Er(NH₃)(Cp₃)]
Compound name(s): 
Ammine-tris(η⁵-cyclopentadienyl)-erbium
Central atom: 
Charge on formula unit (QN): 
0
Compound type: 
Notes: 

The three cyclopentadienyl groups as a set contribute 13 electrons rather than 15 (five for each cyclopentadienyl) to the metal. This is because one of the ligand orbitals set associated with the three cyclopentadienyl groups has no symmetry match with relevant metal atomic orbitals. This reduces the formal metal electron count by two. See:

Valence Number (VN) = 𝘹 + 2𝘻 : 
Coordination Number (CN, sum of attached group denticities): 
Oxidation Number (ON) (Roman numerals): 
Electron Number (EN) = 𝘮 + 𝘹 +2𝘭: 
Bond number (BN) = 𝘹 + 𝘭 + 𝘻: 
9
[MLXZ]𝘲 class: 
[MX3L6]
MLXZ class (ENC, equivalent neutral class): 
MX3L6
Summary of calculated classifications: 
Er«V3C10OIIIE29B9Z0X3L6»
𝘥-electron configuration = 𝘮 – VN: 
𝘥-electron configuration = 𝘮 – ON: 
𝘥-electron configuration = 𝘮 – VN – 𝘲 from [MLXZ]𝘲: 
Attached atoms: 
C15N1
Phase: 
InChIKey (see www.inchi-trust.org): 
ZGUNAZJPAOOQSY-UHFFFAOYSA-N