Counting different words in one column (Excel 2013 / 365)

Hello Forum,

hopefully anybody can help us!!

i need to count the amount of different words (not effected by any dots, semicolons etc...) in one column.

I've got a huge amount of rows. In every row some sentences. Now i need to know how many different words are in the table in total.

I've got it to work so far with: "=SUMME(WENN(B2:B300<>"";1/ZÄHLENWENN(B2:B300;B2:B300)))"
But it makes failures with dots etc... for example: "some statement and other statement." -> this counts the word statement as two different ones because of the "." ....

any ideas???

Thanks for your help!!!

greetings

SWu