Synthesis and Crystal Structure of Manganese(II) Bipyridine Carboxylato Complexes: [(bipy)2MnII(μ-C2H5CO2)2MnII(bipy)2](ClO4)2 and [MnII(ClCH2CO2)(H2O)(bipy)2]ClO4 · H2O (bipy = 2,2′-bipyridine)

Abstract

Two manganese(II) bipyridine carboxylate complexes, [(bipy) 2 Mn II (l-C 2 H 5 CO 2 ) 2 Mn II (bipy) 2 } 2 ](ClO 4 ) 2 (1), and [Mn II (ClCH 2 CO 2 )(H 2 O)(bipy) 2 ]ClO 4´H2 O (2) were prepared. 1 crystallizes in the triclinic space group P 1 with a = 8.604 (3), b = 12.062(3), c = 13.471(3) A Ê , a = 112.47(2), b = 93.86(2), c = 92.87(3)°, V = 1211.1(6) A Ê 3 and Z = 1. In the dimeric, cationic complex with a crystallographic center of symmetry two 2,2'-bipyridine molecules chelate each manganese atom. These two metal fragments are then bridged by two propionato groups in a syn-anti conformation. The Mn´´´Mn distance is 4.653 A Ê . 2 crystallizes in the mono-clinic space group P2 1 /c with a = 9.042(1), b = 13.891(1), c = 21.022(3) A Ê , b = 102.00(1)°, V = 2569.3(5) A Ê 3 and Z = 4.2 is a monomeric cationic complex in which two bipyridine ligands chelate the manganese atom in a cis fashion. A chloroacetato and an aqua ligand complete the six-coordination. Only in 2 is the intermolecular packing controlled by weak p-stacking besides C±H´´´p contacts between the bipyridine ligands.

Preparation of Highly Efficient Manganese Catalase Mimics

“…They are bridged by two acetato groups in a syn−anti fashion resulting in an intermetal distance of 4.128(1) Å. This is considerably shorter than the distances found in the syn−anti dicarboxylato bridged complexes [Mn 2 (bipy) 4 (μ-C 2 H 5 CO 2 ) 2 ] 2+ (4.653 Å), [Mn 2 (bipy) 4 (μ-C 6 H 5 CO 2 ) 2 ] 2+ (4.509 Å), and [Mn(bipy) 4 (μ-CH 3 O 2 ) 2 ] 2+ (4.583 Å). − Mn−Mn distances similar to that in 1 can be found in two syn−anti diacetato bridged complexes that contain tetradentate nitrogen donor ligands: [Mn 2 (μ-CH 3 CO 2 ) 2 (bispicMe 2 en) 2 ](ClO 4 ) 2 (4.298 Å) (bispicMe 2 en = N , N ‘-dimethyl- N , N ‘-bis(2-pyridylmethyl)ethane-1,2-diamine) and [Mn 2 (μ-CH 3 CO 2 ) 2 (tpa) 2 ](TCNQ) 2 ·2CH 3 CN (4.145 Å) ( tpa = tris(2-pyridylmethyl)amine, TCNQ = tetracyanoquinodimethane). , The coordination environment around the manganese center in 1 is best described as distorted octahedral where four coordination sites are occupied by nitrogen atoms from bpia. It is completed by two oxygen atoms from the bridging acetates.…”