What are pi-acceptors ligands give the examples?

 Examples of pi-acceptors ligands given as;

Related Questions;

(1) What type of ligands are known ?

(2) What are pi-donors ligands give the examples?

(3) What is the common formula of “Prussian blue is” and “Turn bull's blue”?  

(4) What is denticity of NO and NO+ ligands ?

(5) Why all the tetrahedral Complexes are high spin Complexes?

(6) Why Fe(CO)₅ is colourless while Fe(bipy)(CO)₃ is intensely purple in colour ?

(7) Why [Mn(H₂O)₆]⁺² is colourless although in which Mn⁺² ion had five unpaired electrons ?

(8) Why [FeF₆]^3– is colourless whereas [CoF₆]^3– is coloured? 

(9) Why [Ni(CN)₄]^-2 is colourless while [Ni(H₂O)₄]^-2 is colour although both have +2 oxidation state and 3d⁸ configuration ?