I fixed this error following this link:
http://jermdemo.blogspot.com.es/2011/08/installing-rstudio-server-on-scientific.html
You have to install some dependencies:
yum install libcrypto.so.6 -y
yum install libgfortran.so.1 -y
yum install libssl.so.6 -y
yum install openssl098e-0.9.8e -y
yum install gcc41-libgfortran-4.1.2 -y
yum install pango-1.28.1 -y
and the tricky one:
wget ftp.scientificlinux.org/linux/scientific/6.0/x86_64/os/Packages/compat-
libgfortran-41-4.1.2-39.el6.x86_64.rpm
rpm -Uvh compat-libgfortran-41-4.1.2-39.el6.x86_64.rpm
and install Rstudio with no-deps flag:
rpm -Uvh --nodeps rstudio-server-0.97.336-x86_64.rpm
rstudio-server verify-installation