Metal carboxylates. 14. Reactions of molybdenum(II) and rhenium(III) carboxylates with gaseous hydrogen halides in alcoholic media. Synthesis, characterization, and reactivity of haloanions of molybdenum and rhenium, hexabromodimolybdate(1-), undecaiodotetramolybdate(2-), and octaiododirhenate(2-)