ClientContext clientContext = new ClientContext("http://MyServer/sites/MySiteCollection");
GroupCollection collGroup = clientContext.Web.SiteGroups;
Group oGroup = collGroup.GetById(7);
UserCollection collUser = oGroup.Users;
clientContext.Load(collUser);
clientContext.ExecuteQuery();
foreach (User oUser in collUser)
{
Console.WriteLine("User: {0} ID: {1} Email: {2} Login Name: {3}",
oUser.Title, oUser.Id, oUser.Email, oUser.LoginName);
}