  We present results from a 577 ks XMM-Newton observation of SPT-CL J0459-4947,
the most distant cluster detected in the South Pole Telescope 2500 square
degree (SPT-SZ) survey, and currently the most distant cluster discovered
through its Sunyaev-Zel'dovich effect. The data confirm the cluster's high
redshift, $z=1.71 \pm 0.02$, in agreement with earlier, less precise optical/IR
photometric estimates. From the gas density profile, we estimate a
characteristic mass of $M_{500}=(1.8 \pm 0.2) \times 10^{14}M_{Sun}$; cluster
emission is detected above the background to a radius of $\sim 2.2 r_{500}$, or
approximately the virial radius. The intracluster gas is characterized by an
emission-weighted average temperature of $7.2 \pm 0.3$ keV and metallicity with
respect to Solar of $0.37 \pm 0.08$. For the first time at such high redshift,
this deep data set provides a measurement of metallicity outside the cluster
center; at radii $r > 0.3 r_{500}$, we find it to be $0.33 \pm 0.17$, in good
agreement with precise measurements at similar radii in the most nearby
clusters, supporting an early enrichment scenario in which the bulk of the
cluster gas is enriched to a universal metallicity prior to cluster formation,
with little to no evolution thereafter. The leverage provided by the high
redshift of this cluster tightens by a factor of 2 constraints on evolving
metallicity models, when combined with previous measurements at lower
redshifts.
