send Dictionary with socket Programming from Server to Client

Dictionary rates = new Dictionary<string,>(); 
        rates.Add("usd", 47.5); 
        rates.Add("eur", 60.4);
        rates.Add("ukp", 78.8);

public void GetListn()
    {
        var dataToSend = new DataToSend { Rates = new Dictionary<string,>() };

        dataToSend.Rates.Add("asd", decimal.Parse("12.23"));
        dataToSend.Rates.Add("asd", decimal.Parse("41.11"));
        dataToSend.Rates.Add("asd", decimal.Parse("25.23"));

        var stream = new MemoryStream();
        var formatter = new BinaryFormatter();
        formatter.Serialize(stream, dataToSend.Rates);

        client.Send(stream.ToArray());
    }


public class DataToSend
{
    public Dictionary<string,> Rates { get; set; }
}

private void WindowLoaded(object sender, RoutedEventArgs e)
    {
        try
        {
            _server = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

            _server.Connect(_ipep);

            _server.Send(Encoding.Unicode.GetBytes("GetList"));

            _data = new byte[BufferSize];

            _recv = _server.Receive(_data);

            var stream = new MemoryStream(_server.Receive(_data));
            var formatter = new BinaryFormatter();
            var dataToSend = (DataToSend)formatter.Deserialize(stream);

        }
        catch (Exception exception)
        {
            MessageBox.Show(exception.Message, "Error", MessageBoxButton.OK,
                                MessageBoxImage.Error);
        }

    public class DataToSend
    {
        public Dictionary<string,> Rates { get; set; }
    }