The reaction of [Ni(terpy)Cl-2] with similar to 2 equiv of 2,4,6-(Me)(3)C6H2Se- in 3:1 acetonitrile/ethanol affords [Ni(terpy)(2,4,6-(Me)3C(6)H(2)Se)(2)] (7), while [Ni(DAPA)Cl-2] (DAPA = 2,6-bis[1-(phenylimino)ethyl]pyridine) reacts with similar to 2 equiv of PhSe(-) and PhSe(-) in neat ethanol or acetonitrile to yield [Ni(DAPA)(SPh)(2)] (8) and [Ni(DAPA)-(SePh)(2)] (9), respectively. All three complexes contain the distorted trigonal bipyramidal (TBP) NiN(3)E(2) (E = S, Se) chromophore. Previous X-ray absorption spectroscopic data have indicated a distorted TBP NiN3S2 coordination for the nickel site of the hydrogenase (H(2)ase) from Thiocapsa roseopersicina. Complex 7 crystallizes in the monoclinic space group P2(1)/n with a = 13.170(6) Angstrom, b = 16.091(5) A, c = 15.111(8) Angstrom, beta = 114.42(2)degrees, V = 2916(2) Angstrom(3), and Z = 4. The structure of 7 was refined to R = 4.78% on the basis of 2730 reflections (I > 4 sigma(I). Complex 8.CH3-CN crystallizes in the monoclinic space group P2(1)/c with a = 23.012(7) Angstrom, b = 17.814(5) Angstrom, c = 15.698(4) Angstrom, beta = 108.52(2)degrees, V = 6099(5) Angstrom(3), and Z = 8. The structure of 8.CH3CN was refined to R = 6.46% on the basis of 6133 reflections (I > 4 sigma(I)). Complex 9.CH3CN also crystallizes in the monoclinic space group P(2)1/c with a = 23.209(2) Angstrom, b = 17.960(1) Angstrom, c = 15.749(1) Angstrom, beta = 108.482(6)degrees, V = 6225 Angstrom(3) and Z = 8, The structure of 9.CH3CN was refined to 3.90% on the basis of 5808 reflections (I > 4 sigma(I)). Reduction of the terpy analogue 7 with aqueous dithionite gives rise to the corresponding Ni(I) complex which binds CO (reversibly) and H-. The EPR parameters of the CO and hydride adducts resemble the Ni-CO and Ni-C signal of the H(2)ases. Much like the other terpy analogues reported previously by this group, oxidation of 7 affords unstable Ni(III) products in low yields.