High Yielding, One-Pot Synthesis of Bis(1 H -indazol-1-yl)methane Catalyzed by 3 d -Metal Salts.

Synthetic access to poly(indazolyl)methanes has limited their study despite their structural similarity to the highly investigated chelating poly(pyrazolyl)methanes and their potentially important indazole moiety. Herein is presented a high yielding, one-pot synthesis for the 3 d -metal catalyzed formation of bis(1 H -indazol-1-yl)methane from 1 H -indazole utilizing dimethylsulfoxide as the methylene source. Complete characterization of bis(1 H -indazol-1-yl)methane is given with 1 H and 13 C NMR, UV/Vis, FTIR, high resolution mass spectrometry and for the first time, single crystal X-ray diffraction. This simple, inexpensive pathway to yield exclusively bis(1 H -indazol-1-yl)methane provides synthetic access to further investigate the coordination and potential applications of the family of bis(indazolyl)methanes.