Co-Gd phosphonate complexes as magnetic refrigerants.

Three 3d-4f phosphonate complexes, [(Co8Gd8III)-Gd-II(mu(3)-OH)(4)(NO3)(4)((O3PBu)-Bu-t)(8)((O2CBu)-Bu-t)(16)], [(Co8Gd4III)-Gd-II((O3PBu)-Bu-t)(6)((O2CBu)-Bu-t)(16)] and [(Co4Gd6III)-Gd-II(O3PCH2Ph)(6)((O2CBu)-Bu-t)(14)(MeCN)(2)], have been synthesized and have structures that can be related to molecular grids. Magnetic studies show they have promise as low temperature magnetic refrigerants.