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Two new supramolecular synthon induced single crystals of metal-orotato complexes of formula [Cu(Orotate)·2H 2 O] 2 ( 1 ), [Mn(Orotate) 2 ·2H 2 O]·2H 2 O] ( 2 ), have been engineered and synthesized by self-assembly of metal salts with orotic acid in presence of 25% ammonia solution. Although both complexes crystallize in similar crystal system and different coordination geometries [(square planar ( 1 ), octahedral ( 2 )] but identical synthon patterns recur after complex formation. N H⋯O, O H⋯O synthons were the only artifact for both the hydrogen bonded metal–organic architecture. X-ray structural analysis, EPR, temperature independent paramagnetism (TIP) analysis, have been discussed. DFT calculation is used to rationalize the magnetic behavior of both the complexes. These calculations underline the pathway of magnetic exchange interactions through N H⋯O, O H⋯O supramolecular synthons and confirm, that the magnetic interactions propagate through such contacts in complex 1 and 2 . [ABSTRACT FROM AUTHOR]

Hydrothermal self-assembly of orotic acid (C 5 H 4 N 2 O 4 OrH 3 ) with metal salt Cu(Ac) 2 ·H 2 O yielded a new OrH based hydrogen bonded coordination network of formula [Cu(OrH)(2NH 3 )(H 2 O)]·H 2 O ( 1 ) and [Cu(OrH) (2NH 3 )] 2 ( 2 ). Single crystal X–ray study on 1 confirms that +2 charges on the metal ions (Cu 2+ ) are balanced by OrH anion. N–H⋯O and O–H⋯O hydrogen bonding synthons are the only artifact for the resulting hydrogen bonded copper-OrH architecture. Temperature dependent measurements of magnetic susceptibility reveals the occurrence of competitive exchange interactions with a net ferromagnetic character in 1 ( J  = +0.48 cm −1 ) and strong antiferromagnetic interaction in 2 ( J  = −4.93 cm −1 ). Magnetic superexchange interaction transmitted through equatorial–axial hydrogen bridge system promotes weak ferromagnetic interactions in 1 while in 2 it is in basal-basal position, in which two d x2-y2 orbitals is involved in exchange mechanism reveals the coexistence of two antiferromagnetic exchange pathways, intramolecular much stronger than intermolecular. The natural bond orbital (NBO) analysis applied separately to α and β spin density matrices clearly shows two important magnetic superexchange pathway with shorter Cu⋯Cu contact 5.542(4) Å and 4.845(4) Å or 5.755(1) Å in ( 1 ) and inter dimer 6.665(1) Å and 4.6744(9) Å for ( 2 ). [ABSTRACT FROM AUTHOR]