Changing data frame column headings

I am not sure why ?rename() is not working.
?a <- list(a = 1, b = 2, c = 3)
?? ? rename(a, c(b = "a", c = "b", a="c"))

I have the reshape2 library loaded and ?rename did not find the help page.
Are the parentheses required in the command?

Thanks,

Rich