title: New organic-inorganic frameworks incorporating iso- and heteropolymolybdate units and a 3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium multiple hydrogen-bond donor.
abstract: Poly[bis(3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium) γ-octamolybdate(VI) dihydrate], {(C(10)H(16)N(4))(2)[Mo(8)O(26)]·2H(2)O}(n), (I), and bis(3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium) α-dodecamolybdo(VI)silicate tetrahydrate, (C(10)H(16)N(4))(2)[SiMo(12)O(40)]·4H(2)O, (II), display intense hydrogen bonding between the cationic pyrazolium species and the metal oxide anions. In (I), the asymmetric unit contains half a centrosymmetric γ-type [Mo(8)O(26)](4-) anion, which produces a one-dimensional polymeric chain by corner-sharing, one cation and one water molecule. Three-centre bonding with 3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium, denoted [H(2)Me(4)bpz](2+) [N···O = 2.770 (4)-3.146 (4) Å], generates two-dimensional layers that are further linked by hydrogen bonds involving water molecules [O...O = 2.902 (4) and 3.010 (4) Å]. In (II), each of the four independent [H(2)Me(4)bpz](2+) cations lies across a twofold axis. They link layers of [SiMo(12)O(40)](4-) anions into a three-dimensional framework, and the preferred sites for pyrazolium/anion hydrogen bonding are the terminal oxide atoms [N···O = 2.866 (6)-2.999 (6) Å], while anion/aqua interactions occur preferentially via μ(2)-O sites [O···O = 2.910 (6)-3.151 (6) Å].
authors.affiliation: Inorganic Chemistry Department, National Taras Shevchenko University of Kyiv, Volodimirska Street 64, Kyiv 01033, Ukraine.
authors.forename: Liliana V
authors.initials: LV
authors.lastname: Lukashuk
authors.forename: Andrey B
authors.initials: AB
authors.lastname: Lysenko
authors.forename: Harald
authors.initials: H
authors.lastname: Krautscheid
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Domasevitch