Tungsten pentacarbonyl complexes of 1,3-benzoxaphospholes

Abstract 2-R-1,3-Benzoxaphospholes (R-BOPs) are examples of fluorescent conjugated materials possessing low coordinate phosphorus centers. A series of 2-( p -XC 6 H 4 )-BOPs (X = H, Cl, Br, Me, OMe) react with [W(CO) 5 (NCMe)] to produce the crystalline complexes [W(CO) 5 (2-Ar-BOP)] ( 2a - e ). All complexes were characterized by NMR spectroscopy and by single crystal X-ray diffraction. The crystal structures all displayed extensive π-stacking of the BOP ligands and gear locking of the CO groups. Addition of the protecting [W(CO) 5 ] group to the BOPs was discovered to significantly diminish fluorescence of the BOP moiety.