Just to rule this out, can you confirm that the hyphens in the command are correct. Your post shows ones which seem to be modified by e.g. Word.
wrong:"nohup esxtop –b –d 60 –n 60 > /file/location/esxtop.csv"
correct: "nohup esxtop -b -d 60 -n 60 > /file/location/esxtop.csv"
André