Rhenium and molybdenum oxo-complexes containing ligands related to N-hydroxyiminodipropionic acid

Abstract

The reaction of N-hydroxy-2,2′-iminodipropionic acid with [PPh 4 ][ReOBr 4 ], [ReOCl 3 (PPh 3 ) 2 ], [ReOCl 2 (OEt)(PPh 3 ) 2 ] or [PPh 4 ][MoOCl 4 (H 2 O)] has produced four novel complexes: [ReOBr 3 (C 6 H 8 NO 5 )] - , [ReOBr 3 (C 3 H 3 NO 2 )] - , [ReOCl 2 (R,S-idpa)] - (H 3 idpa = 2,2′-iminodipropionic acid) and [MoO 2 Cl 2 (C 3 H 4 NO 3 )] - . All have been successfully crystallised as their [PPh 4 ] + salts which have been characterised by single-crystal X-ray diffraction. The anions [ReOBr 3 (C 6 H 8 NO 5 )] - and [ReOBr 3 (C 3 H 3 NO 2 )] - involve tetragonally distorted octahedral Re V OBr 3 (N,O) centres with the bromides cis to the oxo-group; [ReOCl 2 (R,S-idpa)] - involves a tetragonally distorted octahedral Re V OCl 2 (O,N,O) centre with the 2Cl cis and O trans to the oxo-group; [MoO 2 Cl 2 (C 3 H 4 NO 3 )] - involves a skew-trapezoidal Mo VI O 2 Cl 2 (N,O) centre with essentially mutual cis oxo-groups and trans chloro-groups. The dimensions of each of these co-ordination spheres are generally typical of related complexes; however, [ReOBr 3 (C 3 H 3 NO 2 )] - involves an unusually short Re–O oxo bond of 1.45(4) A. The organic moieties are considered to arise from rearrangement and/or fragmentation of N-hydroxy-2,2′-iminodipropionic acid, presumably under the influence of the metal centre.