using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var customer = new Customer();

​

        customer.properties["wow-123:test"] =

            new JArray(JToken.FromObject(new { 

                name = "Mark", 

                company = new  { 

                        name = "LLC",

                        address = new  {

                            city= "London" } } }));

        Console.WriteLine(JsonConvert.SerializeObject(customer));

    }

}

​

public class Customer{

  public string name {get;set;}

  public JObject properties {get;set;} = new JObject();

}

​

​