| abstract |
A compound of formula (I), in which M is a transition metal ion; A is a counter-ion if required; r, s and t are independently 0 to 3 such that r+s+t is in the range of 1 to 3; Ra, Rb, Rc are each independently hydrogen or CH2OR' where R' is hydrogen or an organic group; B and E are independently oxygen, CH2, NRd in which Rd is alkyl, hydrogen, alkylcarbonyl, or arylcarbonyl or SOn where n is 0 or an integer 1 or 2, with the proviso that B and E are not simultaneously CH2 and that when B is oxygen, NRd or SOn, then r cannot be 0, and when E is oxygen, NRd or SOn, then t cannot be 0; R1, R2, R3, R4, R5, R6, R7, R8, R9 and R10 are independently hydrogen, alkyl or alkoxy. |