POST запрос Яндекс.Облако

HttpClient client = new HttpClient();
var values = new Dictionary<string, string>
{
{ "yandexPassportOauthToken", "OAuth-токен" }
};
var content = new FormUrlEncodedContent(values);
var response = await client.PostAsync("https://iam.api.cloud.yandex.net/iam/v1/tokens", content);
Console.WriteLine(response);
var responseBytes = await response.Content.ReadAsByteArrayAsync();
 File.WriteAllBytes("token.txt", responseBytes);

async Task getiamNewTokenAsy()
{
 
    string yandexPassportOauthToken = "Ваш токен";
 
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
    HttpClient client = new HttpClient();
 
    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "https://iam.api.cloud.yandex.net/iam/v1/tokens");
    request.Content = new StringContent("{\"yandexPassportOauthToken\":\"" + yandexPassportOauthToken + "\"}");
    request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
 
    HttpResponseMessage response = await client.SendAsync(request);
    response.EnsureSuccessStatusCode();
    string responseBody = await response.Content.ReadAsStringAsync();
 
    iamToken = responseBody.Split('"')[3]; //готовый токен
 
 
}