She tried to talk to him and persuade him not to buy a car.
没有语法错误啊
tried to 后要接动词原型 I try to talk to him,在这里to是不定式
tried to 'talk to him' and tried to 'persuade' him
这里的tried to也是指要尝试说服他,所以persuade也是动词原型
persuade sb not to do sth,所以 persuade him not to buy a car 是对的,不是 doesn't buy a car.
to通常都是接动词原型,除非是一些固定的动词短语,像是Look forward to,这里的to是介词,I look forward to buying a car.look 已经是个动词,接下来的动词就做伴随分词状语,故用ing