Can syntax be part of semantics?

The definition of parts of speech is an uneasy mixture of semantic and formal properties. So nouns and verbs can be identified largely semantically with some important reference to formal properties whereas things like prepositions are defined purely formally. That's why they are not a very good foundational category.

Of course, you cannot just say something like 'nouns' are things and 'verbs' are actions, but it's actually not a bad place to start. They also have different formal properties (more in some languages than others) but when you try to look at a language to see which formal properties map to which part of speech, you start with the semantics.

So if I have a pattern like 'X(N) Verbed a Y(N) with a Z(N)', I can make certain assumptions about the meanings of the blanks knowing what part of speech they are as well as how they are typically used in a pattern like this.

Hope this helps. It would be useful if you could clarify a bit more what you're trying to achieve by your question.