The syntheses, structural characterization, and magnetic behavior of four new copper(II) complexes derived from tert-butylphosphonic acid and di-2-pyridyl ketone with formulae [Cu{(py)₂C(OH)₂}](C₄H₉PO₃H)₂·(H₂O)₂ (1), [Cu₂(μ₂-C₄H₉PO₃H){(py)₂C(OCH₂CH₃)O}(μ₂-NO₃)(NO₃)(H₂O)]_n·(H₂O)_n (2), [Cu₄(μ₂-C₄H₉PO₃H)₂(μ₄-C₄H₉PO₃)₂{(py)₂C(OCH₃)O}₂]·2H₂O (3) and Na[Cu₆(μ₃-C₄H₉PO₃)₃{(py)₂C(OCH₃)O}₃(μ₆-NO₃)(NO₃)₃] (4) (C₄H₉PO₃H₂ = tert-butylphosphonic acid, (py)₂C(OH)₂ = bis(2-pyridyl)methanediol, {(py)₂C(OCH₂CH₃)O}⁻ = bis(2-pyridyl)ethoxymethanolato {(py)₂C(OCH₃)O}⁻ = bis(2-pyridyl)methoxymethanolato, are reported. 1 is a mononuclear compound, with tert-butylhydrogenphosphonate in the anionic form. 2 is a nitrate bridged monodimensional compound with 2.110 tert-butylhydrogenphosphonate bridging ligands. 3 is a tetranuclear compound with 2.110 tert-butylhydrogenphosphonate and 3.111 tert-butylphosphonate bridging ligands and 4 is a hexanuclear compound with 3.111 tert-butylphosphonate bridging ligands. The magnetic properties of 2-4 are reported.