'were deemed not' is correct and usable in written English.
You can use it when you wish to explain that something is not considered to be true, valid, or acceptable. For example, "The proposed project plans were deemed not feasible by the planning board."
Some, though, were deemed not qualified.
Charges of murder and rape were deemed not proved.
He claims that he was let go for wearing clothes that were deemed not appropriate for an intern.
Everolimus for breast cancer (made by Novartis as Afinitor) and ibrutinib for mantle cell lymphoma (made by Janssen as Imbruvica) were deemed not to be cost-effective.
Names such as Ryan Bertrand and Josh McEachran spring to mind as two youth players who have promised much but were deemed not up to the required standard.
Quite a few were submitted for the Booker prize, in fact, and were deemed not of high enough quality to make the long or the short list.
Before the California Supreme Court, he conceded that if Nike's statements were deemed not to be commercial speech, the First Amendment would require dismissal of his lawsuit.
The presidents whose statues ring the National Mall are those who were deemed not just wise and just, but also masters of our national destiny.
The calls come after proceedings against five of the youngest campaigners were deemed not in the public interest and withdrawn from the courts.
(All told, the test subjects came up with sixty swear words, although the paper notes that nineteen of them — including "feck," "fuckaroo," "asstaxi," "wanko," and "penis" — were "deemed not to be a recognized linguistic form of swear word").
The Taguba study noted that more than sixty per cent of the civilian inmates at Abu Ghraib were deemed not to be a threat to society, which should have enabled them to be released.
