Metamagic Rod Clarification

I'm slightly confused about using a metamagic rod to cast a spell that you wouldn't be able to cast otherwise. For example lets say your level 3 wizard with a rod of silent spell. Could you cast a 2nd level spell with it? The spell slot would be fine, but you wouldn't be able to cast it normally...

This doesn't seem odd except when I think about a maximized level 9 spell or something else. I can't find a rule otherwise in the book.

The exact question is can you use a metamagic rod to cast a spell you wouldn't normally be able to cast at all, or a spell who's value would be a slot over level 9.

Metamagic rods have different levels of spells they can effect based on thier value (lesser to greater) and they dont give you extra spell slots. The way they work is that you cast a spell from your wizard spell list as normal but have it modified by the silent rod. If it is a lesser silent rod it can only effect up to level 3 spells. Using a metamagic rod to modify a spell with a metamagic feat in this way does not increase the level of the spell slot you must expend to modify it. You still can't cast spells you didn't memorize that morning, and can only use the rod three times per day.