  (abridged) We present a study based on XMM data of RX J0256.5+0006, a medium
distant (z=0.36) galaxy cluster found in the Bright SHARC catalog. The
intracluster medium shows a bimodal structure: one main cluster component and a
substructure in the west. Despite the indication of interaction we do not find
any sign of temperature gradients. Due to the non-symmetric form of the main
cluster we extract surface brightness profiles in different sectors around its
centre. We see large variations between the profiles, which we quantify by
beta-model fitting. The corresponding r_c's vary between 0.1-0.5Mpc and the
beta's between 0.5-1.2. The variations of the beta-model parameters indicate
that the main cluster is not entirely relaxed. This hypothesis is strengthened
by the fact that the cluster is over-luminous with respect to the (z-evolving)
L_x-T relation found for nearby clusters. Comparing our profiles to the
reference emission measure profile of Arnaud et al., we find that only the
profile extracted north-east (NE) of the main cluster centre is similar to this
reference profile. This indicates that only the NE profile is representative
for the relaxed part of this cluster component. Using this profile and the
spectroscopically fitted temperature of T=4.9^+0.5_-0.4keV we find M_500~4
10^14 solar masses. This value is in agreement with the value obtained using
the z-evolving M_500-T relation from the HIFLUGCS sample. For the gas mass
fraction we find f_g~18-20% which is in good agreement with other work. We also
develop a simple on-axis merger model for the cluster. Together with a simple
ram pressure model we find that the most likely physical distance of the
subcluster to the main cluster lies between 0.6<d<1.0Mpc. We find for the ratio
of subcluster to main cluster mass values between 20-30%.
