Patent ID: 7902308

Claim:
A complex comprising the skeletal unit of Formula A wherein the ring represented by C(R 1 )-A 1 -A 2 -(A 3 ) x -C(R 2 )—C— has delocalized unsaturation and is optionally substituted via one or more of A 1 , A 2 and A 3 with atoms or groups selected from hydrogen, alkyl, aryl, halogen, or heterocyclic groups containing at least one N, S or O in a carbon ring; A 1 , A 2 and A 3 are selected from carbon, nitrogen or oxygen, R 1 and R 2 are each selected from chlorine, bromine or iodine; x is zero or 1, O is oxygen, E is nitrogen, phosphorus or arsenic, Q represents a divalent bridging group comprising one or more Group 14 atoms; M is a metal selected from Groups 3 to 7: X represents a monovalent atom or group covalently or ionically bonded to M; L is a mono- or bidentate molecule datively bound to M, y satisfies the valency of M and z is from 0 to 5.