Open frame works, self-assembled on graphite represent an important current area of science. These frameworks which overcome the usual close packing forces of molecular systems, have potential applications in a number of areas including catalysis and guest -host chemistry. In this work we aim to use the unique capability of 2D neutron diffraction to characterize the in-plane crystal structure of self assembled layers with very high precision as part of a programme to understand the origin of very distinctive Moire patterns of these overlayers observed by STM.