What is the correct way to write a complex sentence?

Question

I was writing an email in German;

Ich habe für meine Klausur, die voraussichtlich ca. 60 Studentinnen und Studenten schreiben werden, zwei Räume gebucht.

I always use an automatic translation to check whether my sentence makes sense. After translating this sentence to English and then back to German, it becomes;

Ich habe zwei Räume für meine Prüfung gebucht, die voraussichtlich von etwa 60 Studenten geschrieben wird.

My question here is not about passive and active forms but rather whether the description of the object should be in the middle of the main clause as I did or after it?

1. Ich habe für meine Klausur, die voraussichtlich ca. 60 Studentinnen und Studenten schreiben werden, zwei Räume gebucht.

2. Ich habe für meine Klausur zwei Räume gebucht, die voraussichtlich ca. 60 Studentinnen und Studenten schreiben werden.

Answer 1

Word and sentence order is relatively flexible in German, but some rules need to be obeyed - In your case, it's the relationship between relative clause and associated substantive.

Generally, the relative clause should be positioned directly after the related noun in the sentence. Your example #2 breaks this rule. (Note the sentence #2 would be unclear in English as well. It's clear from the context the students will write the exam and not the rooms, but it still makes you trip up when reading the sentence.)

That's the grammatical issue with the sentence. Then, there are stylistic rules advising you to avoid large parts of the sentence going between subject and object(s) (the brain tends to loose track of where we are, so your very first example somewhat breaks this [soft] rule). Thus

Ich habe zwei Räume für meine Prüfung gebucht, die voraussichtlich von etwa 60 Studenten geschrieben wird.

is probably the best way to express the matter.

Answer 2

Extraposition (distancing a dependent clause from its referent word) is perfectly acceptable with relative clauses.

The underlying reason why we recommend keeping related items together is short-term memory. All other things equal, it is easier to understand that "die" refers to "Klausur" if it follows sooner rather than later. However, in your case there is also the pair "habe" + "gebucht". Decreasing the distance between this pair increases the distance between the other, and vice versa. Thus there is a trade-off between following one principle and another very similar one.

Now, German split verbs are used to being far from each other and in general, they can deal with a lot of complements intervening between them. An entire relative clause is a boundary case; the full verb often degenerates to a short remote appendix that seems a bit lonely, almost to the point that I'd prefer version 2.

(A good indicator that the two principles are both of similar strength is that in informal speech, people often invert the sentence to

Ich habe zwei Räume gebucht für meine Klausur, die voraussichtlich ca. 60 Studentinnen und Studenten schreiben werden.

even though this contradicts another, theoretically even stronger principle that complements should not follow the split verb at all.)