  The twistor space of the sphere S^{2n} is an isotropic Grassmannian that
fibers over S^{2n}. An orthogonal complex structure on a subdomain of S^{2n} (a
complex structure compatible with the round metric) determines a section of
this fibration with holomorphic image. In this paper, we use this
correspondence to prove that any finite energy orthogonal complex structure on
R^6 must be of a special warped product form, and we also prove that any
orthogonal complex structure on R^{2n} that is asymptotically constant must
itself be constant. We will also give examples defined on R^{2n} which have
infinite energy, and examples of non-standard orthogonal complex structures on
flat tori in complex dimension three and greater.
