Diosmium(III) Compounds Supported by 2-Anilinopyridinate and Novel Alkynyl Derivatives

The reaction between Os2(OAc)4Cl2 and Hap (Hap is 2-anilinopyridine) under prolonged refluxing conditions resulted
in an OsIII2 compound, Os2(ap)4Cl2 (1), that can be crystallized as either the cis-(2,2) isomer from a CH3OH−CH2Cl2 solution or the (3,1) isomer from a hexanes−CH2Cl2 solution. Compound 1 undergoes facile reactions with
LiC2Y to yield a series of Os2(ap)4(C2Y)2 compounds with Y as Ph (2), ferrocenyl (3), SiMe3 (4), and C2SiMe3 (5).
X-ray diffraction study of compound 2 reveals solvent-dependent isomerism similar to that of the parent compound
1. Compound 1 has Os−Os distances of 2.3937(8) and 2.3913(8) Å for the cis-(2,2) and (3,1) isomers, respectively,
and is paramagnetic (S = 1). Both the ethynyl derivatives 2−4 and butadiynyl derivative 5 are diamagnetic and
have Os−Os distances of 2.456(1), 2.471(1), and 2.481(1) Å for the cis-(2,2) and (3,1) isomers of 2 and (3,1)
isomer of 4, respectively. Compounds 1−5 exhibit multiple one-electron redox couples in their cyclic voltammograms,
including a reversible Os2(8+/7+) couple for 2. Resonance Raman spectra of both compounds 1 and 2 are reported.