  We present Spitzer high-resolution spectra of off-nuclear regions in the
central cluster galaxies NGC 1275 and NGC 4696 in the Perseus and Centaurus
clusters, respectively. Both objects are surrounded by extensive optical
emission-line filamentary nebulae, bright outer parts of which are the targets
of our observations. The 10-37um spectra show strong pure rotational lines from
molecular hydrogen revealing a molecular component to the filaments which has
an excitation temperature of ~300-400K. The flux in the 0-0S(1) molecular
hydrogen line correlates well with the strength of the optical lines, having
about 3 per cent of the Halpha+[NII] emission. The 11.3um PAH feature is seen
in some spectra. Emission is also seen from both low and high ionization fine
structure lines. Molecular hydrogen cooler than ~400K dominates the mass of the
outer filaments; the nebulae are predominantly molecular.
