Structures of [M(2)(dimen)(4)](Y)(2)(M=Rh,Ir;dimen=1,8-diisocyanomenthane;Y=PF6,tetrakis[3,5-bis(trifluoromethyl)phenyl]borate,B(C6H5)(4)) crystals featuring an exceptionally wide range of metal-metal distances and dihedral twist angles

The binuclear complexes [M(2)(dimen)(4)](Y)(2) (M = Rh, Ir; dimen = 1,8-diisocyanomenthane; Y = PF6, tetrakis[3,5-bis(trifluoromethyl)phenyl] borate), and B(C6H5)(4)) have face-to-face structures with M-M distances between 3.60 and 4.48 Angstrom, and square-planar unit twist angles between 0 and 17.2 degrees. Ligand flexing and out-of-plane bending of the metal centers accommodate M-M distances longer than 3.9 Angstrom; addition of a torsional deformation produces a twisted conformation for shorter M-M distances (<3.9 Angstrom). Spectroscopic data indicate that there are two or more deformational isomers of Ir-2(dimen)(4)(2+) in solution.