Answer:
a Lewis acidic metal center with Lewis basic ligands surrounding it.
Step-by-step explanation:
A lewis acid is a chemical specie capable of accepting a lone pair of electrons while a lewis base is a chemical specie capable of donating a lone pair of electrons.
In a coordination compound, a lewis acid(central metal atom/ion) accepts electron pairs from lewis bases (ligands). Any chemical specie called a ligand must possess at least one electron pair available for coordinate covalent bonding.
Coordination compounds are usually formed between transition metal atoms/ions and neutral molecules having lone pairs of electrons or anionc species .