Newtonsoft.Json not serializing object as expected - error 400

I'm trying to send a post request with a json string of an object I have created. However after serializing my c# object and posting I get a 400 error (problems parsing JSON)

I'm using the Newtonsoft.Json dll to serialize my object. Here is the object I am serializing:

public class CreateRepository
{
    [JsonProperty("name")]

    public string Name { get; set; }

    [JsonProperty("description")]

    public string Description { get; set; }

    [JsonProperty("homepage")]

    public object Homepage { get; set; }

    [JsonProperty("gitignore_template")]
    public string GitIgnoreTemplate { get; set; }

    [JsonProperty("license_template")]
    public string LicenceTemplate { get; set; }

    [JsonProperty("private")]

    public bool Private { get; set; }

    [JsonProperty("has_projects")]
    public bool HasProjects { get; set; }

    [JsonProperty("has_issues")]
    public bool HasIssues { get; set; }

    [JsonProperty("has_template")]
    public bool HasTemplate { get; set; }

    [JsonProperty("has_wiki")]
    public bool HasWiki { get; set; }
}

I am then serializing an instance of the object like so:

var content = JsonConvert.SerializeObject(repository);

This then generates the json string below:

{
    \"name\": \"Test\",
    \"description\":null,
    \"homepage\":null,
    \"gitignore_template\":null,
    \"license_template\":null,
    \"private\":false,
    \"has_projects\":false,
    \"has_issues\":false,
    \"has_template\":false,
    \"has_wiki\":false}
}

I get the following back after attempting to post the request:

{
    "message": "Problems parsing JSON",
    "documentation_url": "https://developer.github.com/v3/repos/#create"
}

Does anyone know why my object has been serialized in this way?

Update:

I can deserialize the object using JSON.Net without any errors.

The url I'm posting to is as follows:

https://api.github.com/user/repos

this is how I'm sending the request:

var response = await _httpClient.PostAsJsonAsync("user/repos", content);