Problems with MS SQL Server and ruby on rails

I have a problem when I save data in the database. The problem is
because I send some characters with accent or any other latin character
like ñ, I have changed some configuration like the encoding in the
application controller I have changed it to ISO-8859-1 adding at the top
of the file the next:

before_filter :set_charset

     def set_charset
       @headers['Content-Type'] = 'text/html; charset=ISO-8859-1'

     end

, also I have add "encoding :ISO-8859-1" to the file database.yml in the
database conecction parameters, and I have changed the stream <meta
http-equiv="content-type" content="text/html;charset=utf-8" /> to <meta
http-equiv="content-type" content="text/html;charset=ISO-8859-1" /> in
the file app/views/layout/idiomas.rhtml. But It works just in some cases
for example I don't have any problem when I try to save or update the
word "españool" or the word "estánn" but if I try to save or update the
word "español" or the word "está" the application shows an error like
this:

DBI::DatabaseError: Execute
    OLE error code:80040E14 in Microsoft OLE DB Provider for SQL Server
      Unclosed quotation mark before the character string ' WHERE [id] =
29'.
    HRESULT error code:0x80020009
      Ocurrió una excepción.: UPDATE idiomas SET [idioma] = 'está' WHERE
[id] = 29

What I want is that if I save whit the aplications words with latin
characters they apear in the databes like I worte them, for example if i
write the word "español" or "está" they appear in the database like
"español" or "está". I don't want that the application change the
characters and pust something like "está" instead of "está".

I don't know what to do, if someone knows how to solve this problem tell
me please.