Solid-State Photochemical [2+2] Cycloaddition Reaction of Mn^II Complexes

Area of Science:

• Coordination Chemistry
• Materials Science
• Crystallography

Background:

• Manganese(II) complexes with paddlewheel and dinuclear structures were synthesized.
• Ligand alignment influences crystal packing and photoreactivity.

Purpose of the Study:

• To synthesize and characterize novel manganese(II) complexes.
• To investigate their photoreactivity and compare with zinc analogues.
• To explore the relationship between crystal structure and photobehavior.

Main Methods:

• Single-crystal X-ray diffraction to determine structures and space groups.
• UV light irradiation to induce photoreactions.
• Density measurements to determine volume expansion.

Main Results:

• Three Mn(II) complexes, [Mn2(benzoate)4(4spy)2] (1), [Mn2(benzoate)4(2F-4spy)2] (2), and [Mn2(benzoate)4(3F-4spy)4] (4), were synthesized.
• Complexes 1-3 exhibit 1D aggregates facilitating [2+2] cycloaddition, while complex 4 shows face-to-face ligand alignment.
• All complexes are photoreactive, but 2 and 3 lack photosalient behavior due to minimal volume expansion (<5%).

Conclusions:

• The synthesized Mn(II) complexes display diverse structural motifs and photoreactivity.
• Ligand arrangement and crystal packing are crucial for photoreaction pathways.
• The absence of photosalient behavior in complexes 2 and 3 highlights the importance of significant volume changes during photoreactions.