▁has ▁a ▁binding ▁energy ▁calculated ▁to ▁be ▁ 1 2 . 8 ▁k cal / m ol ▁( 5 4   k J / m ol ). ▁ ▁Ar Be O 2 CO ▁( ber yl li um ▁carbon ate ) ▁has ▁been ▁prepared ▁( al ong ▁with ▁Ne , ▁Kr ▁and ▁X e ▁ad duct s ). ▁ ▁The ▁cy clic ▁b ery l li um ▁sul f ite ▁mole c ule ▁can ▁also ▁coordinate ▁an ▁arg on ▁atom ▁onto ▁the ▁b ery l li um ▁atom ▁in ▁solid ▁ne on ▁or ▁arg on ▁matrix . ▁ ▁Car b ony l ▁comp ounds ▁Group ▁ 6 ▁elements ▁can ▁form ▁re active ▁pent ac ar b ony ls ▁that ▁can ▁react ▁with ▁arg on . ▁These ▁were ▁actually ▁arg on ▁comp ounds ▁discovered ▁in ▁ 1 9 7 5 , ▁and ▁were ▁known ▁before ▁the ▁discovery ▁of ▁H Ar F , ▁but ▁are ▁usually ▁over look ed . ▁T ung sten ▁normally ▁forms ▁a ▁hex ac ar b ony l , ▁but ▁when ▁subject ▁to ▁ult rav io let ▁radiation ▁it ▁breaks ▁into ▁a ▁re active ▁pent ac ar b ony l . ▁When ▁this ▁is ▁cond ensed ▁into ▁a ▁noble ▁gas ▁matrix ▁the ▁inf ra red ▁and ▁U V ▁spectrum ▁var ies ▁consider ably ▁depending ▁on ▁the ▁noble ▁gas ▁used . ▁This ▁is ▁because ▁the ▁noble ▁gas ▁present ▁bind s ▁to ▁the ▁vac ant ▁position ▁on ▁the ▁t ung sten ▁atom . ▁Similar ▁results ▁also ▁occur ▁with ▁mol y b den um