Puzzle 693 Prime Chemical Compounds

Jeff Heleen sent the following nice puzzle

There are millions of chemical compounds in existence, each made
up of different elements. Each element has its own atomic number, Z number. I.e., hydrogen is 1, helium is 2, carbon is 6, gold is 79, etc.

If all the Z numbers of the elements of a compound are added up, sometimes a prime is obtained. Some examples are:

ammonium - NH4
    N = 7; 7 * 1 = 7
    H = 1; 1 * 4 = 4
                    __
                    11 = prime

aluminum diboride - AlB2
    Al = 13; 13 * 1 = 13
     B = 5; 5 * 2 = 10
                    ___
                        23 = prime

barium manganate - BaMnO4
    Ba = 56; 56 * 1 = 56
    Mn = 25; 25 * 1 = 25
     O = 8; 8 * 4 = 32
                    ___
                    113 = prime

arsenic diiodide - AsI2
    As = 33; 33 * 1 = 33
     I = 53; 53 * 2 = 106
                     ___
                     139 = prime

Q. What is the largest prime chemical compound you can find?

Notes
1) For your largest solution please send the prime number, the chemical formula, the chemical name and a link to these.

2) Perhaps you will find useful in your search the following links.

http://chemistry.about.com/od/elementfacts/a/elementlist.htm

http://www.convertunits.com/compounds/

http://formulas.tutorvista.com/chemistry/chemical-compound-formulas.html

http://en.wikipedia.org/wiki/Dictionary_of_chemical_formulas

http://en.wikipedia.org/wiki/List_of_biomolecules