The pair of elements which is most apt to form a molecular compound with each other would be sulfur and fluorine. In general, a nonmetal and a gas is most likely to form a molecular compound. Considering two metal molecules, most likely these metal atoms would not form a molecule since they are both positive when in ionic form and tends to donate electrons to another atom. For a situation where you have a nonmetal and a metal atom, it would not still be possible to form a molecular atoms since they are likely to form ionic bonds resulting to an ionic compound.