Oncollisionenter and time,OnCollisonEnter and time.

I'm making a cube collision game. If the cubes are the same, they collide and turn into another cube with 2. My goal is for the cubes to transform after a certain amount of time after colliding. I couldn't do what I did. Can you help me? thanks

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 public class CubeCollision : MonoBehaviour
 {
     Cube cube ;
   // public AudioSource audio;
 
     private void Awake() {
         cube = GetComponent<Cube>();
        // audio = GetComponent<AudioSource>();
     }
            IEnumerator WaitOneSecToDeactivateTrash(Collision collision)
       {
           Debug.Log("hello before time");
           yield return new WaitForSeconds (1f);
           Debug.Log("hello after time");
       }
     public void  OnCollisionEnter(Collision collision) {
         Cube otherCube = collision.gameObject.GetComponent<Cube>();     
         // check if contacted with other cube
         if(otherCube != null && cube.CubeID > otherCube.CubeID){
             //check if both cubes have same number
             if(cube.CubeNumber == otherCube.CubeNumber){
                 //Debug.Log("HIT: "+cube.CubeNumber);
                 Score.score +=cube.CubeNumber*2;
                Vector3 contactPoint = collision.contacts[0].point; 
                //check if cubes number less than max number in cubespawner:
                 if(otherCube.CubeNumber < CubeSpawner.Instance.maxCubeNumber){
                      //spawn a new cube as a result.
                      Cube newCube = CubeSpawner.Instance.Spawn(cube.CubeNumber*2, contactPoint+Vector3.up*.3f); //2 4 8 16 32 64 128 256 512 1024 2048 4096                           
                     //push the new cube up and forward.
                      float pushForce = 2.5f;
                      newCube.CubeRigidbody.AddForce(new Vector3(0, .3f, 1f)*pushForce,ForceMode.Impulse);
                      //add some torque
                      float randomValue = Random.Range(-20f,20f);
                      Vector3 randomDirection = Vector3.one * randomValue;
                      newCube.CubeRigidbody.AddTorque(randomDirection);            
                 }
                 //the expolison should effect sorrounded cubes too.
                 Collider[] surroundedCubes = Physics.OverlapSphere ( contactPoint,1f);
                 float expolisonForce = 400f;
                 float expolisonRadius = 1.5f;
                 foreach(Collider coll in surroundedCubes){
                     if(coll.attachedRigidbody!= null){
                         coll.attachedRigidbody.AddExplosionForce(expolisonForce,contactPoint,expolisonRadius);
                     }
                 }
                 FX.Instance.PlayCubeExplosionFX(contactPoint,cube.CubeColor);
                 //Destrory the two cubes: 
                 CubeSpawner.Instance.DestroyCube(cube,3f); //sonradan incele ---------!!!
                 CubeSpawner.Instance.DestroyCube(otherCube,3f);
                  
             }
         }
 
     }
 }
 

, I'm making a cube collision game. If the cubes are the same, they collide and turn into another cube with 2 times. My goal is for the cubes to transform after a certain time after they collide. I couldn't do it no matter what I did. can you help me? thanks

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 public class CubeCollision : MonoBehaviour
 {
     Cube cube ;
   // public AudioSource audio;
 
     private void Awake() {
         cube = GetComponent<Cube>();
        // audio = GetComponent<AudioSource>();
     }
            IEnumerator WaitOneSecToDeactivateTrash(Collision collision)
       {
           Debug.Log("hello before time");
           yield return new WaitForSeconds (1f);
           Debug.Log("hello after time");
       }
     public void  OnCollisionEnter(Collision collision) {
         Cube otherCube = collision.gameObject.GetComponent<Cube>();     
         // check if contacted with other cube
         if(otherCube != null && cube.CubeID > otherCube.CubeID){
             //check if both cubes have same number
             if(cube.CubeNumber == otherCube.CubeNumber){
                 //Debug.Log("HIT: "+cube.CubeNumber);
                 Score.score +=cube.CubeNumber*2;
                Vector3 contactPoint = collision.contacts[0].point; 
                //check if cubes number less than max number in cubespawner:
                 if(otherCube.CubeNumber < CubeSpawner.Instance.maxCubeNumber){
                      //spawn a new cube as a result.
                      Cube newCube = CubeSpawner.Instance.Spawn(cube.CubeNumber*2, contactPoint+Vector3.up*.3f); //2 4 8 16 32 64 128 256 512 1024 2048 4096                           
                     //push the new cube up and forward.
                      float pushForce = 2.5f;
                      newCube.CubeRigidbody.AddForce(new Vector3(0, .3f, 1f)*pushForce,ForceMode.Impulse);
                      //add some torque
                      float randomValue = Random.Range(-20f,20f);
                      Vector3 randomDirection = Vector3.one * randomValue;
                      newCube.CubeRigidbody.AddTorque(randomDirection);            
                 }
                 //the expolison should effect sorrounded cubes too.
                 Collider[] surroundedCubes = Physics.OverlapSphere ( contactPoint,1f);
                 float expolisonForce = 400f;
                 float expolisonRadius = 1.5f;
                 foreach(Collider coll in surroundedCubes){
                     if(coll.attachedRigidbody!= null){
                         coll.attachedRigidbody.AddExplosionForce(expolisonForce,contactPoint,expolisonRadius);
                     }
                 }
                 FX.Instance.PlayCubeExplosionFX(contactPoint,cube.CubeColor);
                 //Destrory the two cubes: 
                 CubeSpawner.Instance.DestroyCube(cube,3f); //sonradan incele ---------!!!
                 CubeSpawner.Instance.DestroyCube(otherCube,3f);
                  
             }
         }
 
     }
 }