(PYRAZOLYLBORATE)ZINC ORGANOPHOSPHATE COMPLEXES RESULTING FROM HYDROLYTIC CLEAVAGE OF PHOSPHATE-ESTERS

Five different (pyrazolylborate)zinc hydroxide complexes TpZn-OH (1) were used as hydrolytic reagents towards esters of various acids of ph osphorus. Trimethyl phosphate and trimethyl phosphite could not be cle aved. Dimethyl and diphenyl phosphite yielded Tp(tBu,Me)Zn-OPHO(OR) (2 , 3). Triphenyl phosphate reacted slowly producing moderate yields of TpZn-OPO(OPh)(2) (4). Tris(p-nitrophenyl) phosphate was cleaved rapid ly, forming TpZn-O-PO(OC6H4NO2)(2) (5) and Tp*Zn-OC6H4NO2 (6). Alkylb is(p-nitrophenyl) phosphates showed intermediate reactivity, losing p- nitrophenolate upon hydrolysis and producing Tp Zn-OPO(OR)(OC6H4NO2) (7, 8) When phosphorus acid diesters were employed, condensation betwe en the Zn-OH and P-OK functions occurred. This proved to be the conven ient way of preparing the organophosphate complexes Tp Zn-OPO(Ph)(2) (9), TpZn-OPO(OPh)(2) (4), and Tp*Zn-O-PO)OC6H4NO2)(2) (5). Six struc ture determinations showed the structural variability of the resulting complexes.