▁in ▁V ancouver ▁in ▁ 2 0 0 0 . ▁Ar M X ▁with ▁M ▁= ▁Cu , ▁Ag ▁or ▁Au ▁and ▁X ▁= ▁F , ▁Cl ▁or ▁Br ▁have ▁been ▁prepared . ▁The ▁mole cules ▁are ▁linear . ▁In ▁Ar A u Cl ▁the ▁Ar − A u ▁bond ▁is ▁ 2 . 4 7   Å , ▁the ▁stretch ing ▁frequency ▁is ▁ 1 9 8   cm − 1 ▁and ▁the ▁dis soci ation ▁energy ▁is ▁ 4 7   k J / m ol . ▁Ar Ag Br ▁also ▁has ▁been ▁made . ▁Ar Ag F ▁has ▁a ▁dis soci ation ▁energy ▁of ▁ 2 1   k J / m ol . ▁The ▁Ar − Ag ▁bond - length ▁in ▁these ▁mole cules ▁is ▁ 2 . 6   Å . ▁Ar Ag Cl ▁is ▁is oe lect ron ic ▁with ▁ ▁which ▁is ▁better ▁known . ▁The ▁Ar − C u ▁bond ▁length ▁in ▁these ▁mole cules ▁is ▁ 2 . 2 5   Å . ▁ ▁Trans ition ▁metal ▁ox ides ▁In ▁a ▁solid ▁arg on ▁matrix ▁V O 2 ▁forms ▁V O 2 Ar 2 , ▁and ▁V O 4 ▁forms ▁V O 4 · Ar ▁with ▁binding ▁energy ▁calculated ▁to ▁be ▁ 1 2 . 8 ▁and ▁ 5 . 0   k cal / m ol ▁( 5 3 ▁and ▁ 2 1   k J / m ol ). ▁Sc and ium ▁in ▁the ▁form ▁of ▁Sc O + ▁coordinates ▁five ▁arg