DIPHOSPHINE BIFUNCTIONAL CHELATORS FOR LOW-VALENT METAL-IONS - CRYSTAL-STRUCTURES OF THE COPPER(I) COMPLEXES [CUCLL(2)(1)] AND [CUL(2)(1)][PF6] [L(1) EQUALS 2,3-BIS(DIPHENYLPHOSPHINO)MALEIC ANHYDRIDE]

The chelating diphosphine 2,3-bis(diphenylphosphino)maleic anhydride ( L(1)) reacted with CuCl to give [CuClL(2)(1)] 1a in which the copper i s bound to three phosphorus atoms and one chlorine in a pseudo-tetrahe dral structure, as demonstrated by X-ray crystallography. Compound L(1 ) reacted with [Cu(MeCN)(4)][PF6] to give the red salt [CuL(2)(1)][PF6 ] 1b in which the copper is bound by four phosphorus atoms of two chel ating bidentate ligands, as demonstrated by X-ray crystallography. Add ition of chloride ions to 1b quantitatively affords 1a. Complex 1a can be converted quantitatively into [CuL(2)(1)][NO3] 1c by treatment wit h AgNO3. These complexes reacted quantitatively with water, benzylamin e and methanol to give the corresponding [CuL(2)(2)](+) 2, [CuL(2)(3)] (+) 3 and [CuL(2)(4)](+) 4 where L(2) = 2,3-bis(diphenylphosphino)male ic acid and L(3) and L(4) are the monobenzylamide and monomethyl ester derivatives, respectively, of L(2). Uncomplexed L(1) can also be hydr olysed to L(2) or derivatised with benzylamine or methanol to give L(3 ) and L(4) respectively. Compounds L(2), L(3) and L(4) reacted with co pper-(I) or -(II) salts to yield salts of 2, 3 and 4. This chemistry p rovides versatile routes to the synthesis of stable bioconjugates cont aining copper or radiocopper and of derivatised solids containing pend ant diphosphine ligands.