how to insert content into wp_head after loop_end

Since the plugin you are using does not provide the data you need until the loop_end hook, getting information into the header is going to be tricky. I can only think of two ways to proceed:

1. Use Javascript to insert the data into the header after page load. I
   don’t know if this will work. I am not sure if the “og” headers will
   be respected.
2. Run a loop before the page loads, and get your data early. I have no
   to test that but I imagine it too look something like this:

function generateOGtag(){
  if (is_single()) {
    global $wp_query;
    if (have_posts()) {
      while (have_posts()) {
        the_post();
        // no idea if your plugin needs anything else here
      }
    }
    $jobTitle = get_jobs()->get("job_title");
    $jobDescription = get_jobs()->get("job_description");
    echo "<meta property='og:title' content="$jobTitle">\n";
    echo "<meta property='og:title' content="$jobDescription">\n";
    wp_reset_query();
    wp_reset_postdata();
  }
}
add_action("wp_head", 'generateOGtag');

This is obviously a labor intensive procedure as code will run twice.