1 Supporting Information Rational Assembly of Soluble Copper(II)Phosphonates. Synthesis, Structure and Magnetism of Molecular Tetranuclear Copper(II)Phosphonates Vadapalli Chandrasekhar a* , Tapas Senapati, a Atanu Dey a and E. Carolina Sañudo b* a Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur-208016, India, and b Departament de Química Inorgànica and Institute for Nanoscience and Nanotechnology, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain AUTHOR EMAIL ADDRESS: vc@iitk.ac.in