C# dispose unmanaged object stored in managed collection

Question

In my class I have unmanaged objects in managed collection (pendingFramesBuffer). I need to implemented IDisposable interface.

My question: Where I need to clear pendingFramesBuffer collection? In the if (disposing) {...} condition or not.

public class Example : IDisposable
{
    // unmanaged pointer in managed collection
    private BlockingCollection<IntPtr> pendingFramesBuffer = new BlockingCollection<IntPtr>();

    /// SOME CODE TO FILL pendingFramesBuffer COLLECTION

    public void Dispose()
    {
        this.Dispose(true);
        GC.SuppressFinalize(this);
    }

    private bool disposed = false;

    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposed)
        {
            if (disposing)
            {
        
            }

            // CLEAR pendingFramesBuffer COLLECTION
            while (pendingFramesBuffer != null && pendingFramesBuffer.Count > 1)
            {
                var tookFrameBuffer = pendingFramesBuffer.Take();
                Marshal.FreeHGlobal(tookFrameBuffer);
            }

            this.disposed = true;
        }
    }

    ~Example()
    {
        Dispose(false);
    }
}