Bending in the CH2OR radical trapped in crystals of methyl α-D-mannopyranoside as measured by ENDOR

A CH2OR radical trapped in single crystals of methyl α-D-mannopyranoside has been characterized by ENDOR measurements at 77 K. The highly accurate α-hydrogen tensors are used to calculate the geometry about the free-radical center. The CH2OR radical is bent with theta = 5.8 +- 0.40, where theta is the angle between the nodal plane of the lone electron orbital and the three σ bonds (O-C, H-C, H'-C). The three angles H-C-H', O-C-H, and O-C-H' are 127.0 +- 0.40, 108.0 +- 0.20, and 122.1 +- 0.20, respectively. The unpaired electron densities are rho/sub c/ ≅ 0.83 and rho/sub o/ ≅ 0.17