Crystal structures and Se-77 NMR spectra of molybdenum(IV) areneselenolates having intramolecular NH center dot center dot center dot Se hydrogen bonds

Okamura TA; Taniuchi K; Lee K; Yamamoto H; Ueyama N; Nakamura A

Inorganic Chemistry, Vol.45, No.23, 9374-9380, 2006

Okamura TA, Taniuchi K, Lee K, Yamamoto H, Ueyama N, Nakamura A

Salts of the monooxomolybdenum(IV, V) areneselenolates having intramolecular NH center dot center dot center dot Se hydrogen bonds, [(MoO)-O-IV(Se-2-RCONHC6H4)(4)](2-) (R = t-Bu, CH3, CF3) and [(MoO)-O-V(Se-2-t-BuCONHC6H4)(4)](-), were synthesized and characterized by H-1 nuclear magnetic resonance (NMR), Se-77 NMR, electron spin resonance (ESR), UV-visible spectra, X-ray analysis, and electrochemical measurements. Se-77-H-1 correlated spectroscopy (COSY) indicated a significant correlation between amide H-1 and selenolate Se-77 atoms through an NH center dot center dot center dot Se hydrogen bond with (1)J(Se-77-H-1) = 5.4 Hz coupling. The hydrogen bonds contribute to the positive shift in the Mo(V)/Mo(IV) redox potential. In the crystal structure of (PPh4)(2)[(MoO)-O-IV(Se-2-CH3CONHC6H4)(4)], an NH center dot center dot center dot O=Mo hydrogen bond was found. Ab inito calculations support the presence of intramolecular NH center dot center dot center dot O=Mo and NH center dot center dot center dot Se hydrogen bonds.