Solution Self-Assembly, Spontaneous Deprotonation, and Crystal Structures of Bipyrazolate-Bridged Metallomacrocycles with Dimetal Centers^†

A series of nanosized cavity-containing bipyrazolate-bridged metallomacrocycles with dimetal centers, namely, {[(bpy)M]8L4}(NO3)8 [L = 3,3‘,5,5‘-tetramethyl-4,4‘-bipyrazolyl, Pd 1, Pt 2; 1,4-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene), Pd 5; and 1,4-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbiphenyl, Pd 9], {[(phen)M]8L4}(NO3)8 [L = 3,3‘,5,5‘-tetramethyl-4,4‘-bipyrazolyl, Pd 3, Pt 4; 1,4-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, Pd 7; and 1,4-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbiphenyl, Pd 11], {[(bpy)Pd]6L3}(NO3)6 [L = 1,4-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, 6, 10], {[(phen)Pd]6L3}(NO3)6 [L = 1,4-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, 8, 12], {[(bpy)Pd]4L2}(NO3)4 [L = 1,3-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, 13, and 1,2-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, 15], and {[(phen)Pd]4L2}(NO3)4 [L = 1,3-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, 14, and 1,2-bis-4‘-(3‘,5‘-dimethyl)-pyrazolylbenzene, 16] (where bpy = 2,2‘-bipyridine and phen = 1,10-phenanthroline) have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the 1H-bipyrazolyl ligands in aqueous solution. These complexes, with weak Pd(II)···Pd(II) or Pt(II)···Pt(II) interactions, have been characterized by elemental analysis, 1H and 13C NMR, cold-spray ionization or electrospray ionization mass spectrometry, UV−visible spectroscopy, and luminescence spectroscopy. Complexes 1, 3, 5, 6, 14, and 15 have also been characterized by single-crystal X-ray diffraction analysis.