Crystal Structure of a Lantern-Type Dirhodium(II) Complex with a <i>cis</i>-(2:2) Arrangement of Two Formamidinato and Two Trifluoroacetato Bridges

Abstract

There has been much interest directed to lantern-type diuclear metal complexes with direct metal–metal bonds due to their unique properties based on their metal–metal bonds.1,2 Formamidinate ions as well as carboxylate ions are known to work as a dinuclearting ligand to give a lantern-type dinuclear structure.1,2 Dinuclear complexes with the mixing of carboxylato and formamidinato bridges are intriguing, because the chemistry would be newly developed based on the different bridging groups within the dinuclear core. We have reported on the crystal structure rhodium(II) dinuclear complexes with two formamidinatao and two carboxylato bridging ligands in a cis(2:2) arrangement around the dinuclear core, cis-[Rh2(4-Etpf)2(O2CCF3)2(H2O)(MeOH)] (1) and cis-[Rh2(4-Etpf)2(O2CCF3)2(MeOH)2] (2), where 4-Et-pf= N,N¢-bis(4ethylphenyl)formamidinate anion.3,4 They have the same dinuclear structure with similar dimensions other than the difference in the axial ligand between H2O and MeOH (Rh–Rh = 2.4487(7)A, Rh–N(4-Et-pf) = 2.008(4) – 2.012(3)A, Rh–O(O2CCF3) = 2.078(3) – 2.100(3)A, Rh–O(H2O) = 2.453(5) A, and Rh–O(MeOH) = 2.321(3)A for 1; Rh–Rh = 2.4484(6)A, Rh–N(4Et-pf) = 2.005(3) – 2.016(3)A, Rh–O(O2CCF3) = 2.079(2) – 2.115(2)A, and Rh–O(MeOH) = 2.314(2) and Crystal Structure of a Lantern-Type Dirhodium(II) Complex with a cis-(2:2) Arrangement of Two Formamidinato and Two Trifluoroacetato Bridges