The crystal structure of tedhadleyite, Hg2+Hg101+O4I2(Cl,Br)2, from the Clear Creek Claim, San Benito County, California

The crystal structure of tedhadleyite, ideally Hg2+Hg10+O4I2(Cl,Br)(2), triclinic, A (1) over bar, a 7.0147(5). b 11.8508(7), c 12.5985(8) angstrom, alpha 115.583(5), beta 82.575(2), gamma 100.619(2)degrees, V 927.0(2) angstrom(3), Z = 2, was solved by direct methods and refined to an R-1 index of 4.5% for 2677 unique reflections. There are six symmetrically distinct Hg sites in tedhadleyite: Hg(1) is occupied by Hg2+ and Hg(2-6) are occupied by Hg+ that forms three [Hg-Hg](2+) dimers with Hg-Hg separations between 2.527 and 2.556 angstrom. These [Hg-Hg](2+) dimers have strong covalent bonds to 0 atoms, forming pseudo-linear O-Hg-Hg-O arrangements, and weak bonds to halogen and 0 atoms at high angles to the dimer axis. The [O-Hg-Hg-O] groups share anions to form four-membered square rings of composition [Hg8O4] that link along [100] via [O-Hg-Hg-O] groups and along [001] via [O-Hg-O] groups, forming rectangular rings of composition [Hg14O8]. The rings form a corrugated layer that interweaves with a symmetrically related layer whereby the [O-Hg(6)-Hg(6)-O] linking groups of one layer pass through the centres of the square [Hg8O4] rings of the other layer to form [Hg11O4] complex slabs parallel to (010) that link through Hg-I and Hg-Br,Cl bonds.