The crystal and molecular structures of some nickel(ll)bis(O-alkyldithiocarbonate)s and nickel(II)bis(N,N-dialkyldithiocarbamate)s: an evaluation of the coordination potential of 1,1-dithiolate ligands in their nickel(II) complexes

Abstract

AbstractThe crystal and molecular structures of four complexes of the general formula Ni(S2COR)2and two with the general formula Ni(S2CNR2)2have been determined. The brown crystals of [Ni(S2COMe)2], investigated at 293 K, are monoclinic, space groupP21/cwith unit cell dimensionsa= 6.357(4) Å,b= 13.755(10) Å,c= 10.566(3) Å,β= 97.20(3)°,Z= 4 andDx= 1.979 Mg m−3. The brown crystals of [Ni(S2COiBu)2], (293 K) are triclinic, space groupP{unk] with unit cell dimensionsa= 8.224(7) Å,b= 8.722(3) Å,c= 6.139(4) Å,α= 98.99(4)°,β= 105.36(5)°,γ= 109.10(4)°,Z= 1 andDx= 1.534 Mg m−3. Crystals of brown [Ni(S2COHex)2], (200 K) are triclinic, space groupP[unk] with unit cell dimensionsa= 7.566(2) Å,b= 10.713(4) Å,c= 6.779(2) Å,α= 97.73(3)°,β= 111.22(2)°,γ= 103.19(2)°,Z= 1 andDx= 1.417 Mg m−3. Crystals of brown [Ni(S2COCy)2], (200 K) are triclinic, space groupP[unk] with unit cell dimensionsa= 9.89(1) Å,b= 10.102(7) Å,c= 9.850(7) Å,α= 110.83(5)°, β= 107.19(7)°,γ= 87.28(9)°,Z= 2 andDx= 1.550 Mg m−3. Crystals of brown [Ni(S2CNCy2)2], (200 K) are triclinic, space groupP[unk] with unit cell dimensionsa= 11.551(5) Å,b= 14.651 (7) Å,c= 9.872(5) Å,α= 102.46(5)°,β= 114.78(3)°,γ= 89.65(4)°,Z= 2 andDx= 1.287 Mg m−3. The colorless crystals of [Ni(S2CN(Et)Cy)2] (200 K) are monoclinic, space groupP21/cwith unit cell dimensionsa= 8.534(4) Å,b= 12.087(4) Å,c= 11.109(4) Å,β= 95.54(3)°,Z= 2 andDx= 1.349 Mg m−3. The structures were solved by direct methods and each refined by a full-matrix least-squares procedure to finalR= 0.047 using 1149 reflections for [Ni(S2COMe)2]; toR= 0.040 using 1239 reflections for [Ni(S2COiBu)2]; toR= 0.050 using 1664 reflections for [Ni(S2COHex)2]; to finalR= 0.035 for 2956 reflections for [Ni(S2COCy)2]; to finalR= 0.055 for 3468 reflections for [Ni(S2CNCy2)2]; and to finalR= 0.031 for 1827 reflections for [Ni(S2CN(Et)Cy)2]. A systematic evaluation of the coordination geometries in these and related complexes indicate that there is little variation in the Ni-atom geometries which are invariably square planar, defined by a S4donor set. Further, there is no apparent systematic variation in the Ni–S bond distances that can be correlated with the nature of the individual xanthate (−S2COR) and dithiocarbamate C(−S2CNR2) ligands as moderated by the electronic/steric profiles of R. Rather, variations in the Ni–S bond distances are ascribed to i) intramolecular interactions between the sulfur atoms and the R substituents and, ii) intermolecular forces.