Hydrothermal synthesis and characterization of mixed-valence hexatungstates: crystal structures of [(C2H5)4N]3[WVW5VIO19]·0.5H2O and [H3N(CH2)2NH3]2 [WVW5VIO19]·[H2N(CH2)2NH2]Cl·8H2O

ELSEVIER Inorganica Chimica Acta 277 (1998) 69-75 Hydrothermal synthesis and characterization of mixed-valence hexatungstates: crystal structures of [ (C2H5) 4N] 3 [WVW~IO]9] 0.5H20 and [H3N(CH2)2NH3]2 [wVwWO 9] • [H2N(CH2)2NH2]CI-8H20 M. Ishaque Khan '*, Sabri Cevik , Robert J. Doedens b, Qin Chen ¢, Sichu Li d, Charles J. O'Connor d Department of Bioh~gical. Chemical and Physical Sciences. Illinois Institute of Technology. Chicago. IL 60616. USA b Department of Chemistn.'. University of California. In, inc. CA 92697. USA Department of Chemistr3'. Emon' Universio; Atlanta. GA 30322. USA d Department of Chemisto'. University of New Orh, ans. New Orleans. LA 70148. USA Received 20 May 1997: revised 25 June 1997; accepted 15 September 1997 Abstract The hydrothermal reaction of a mixture of Na.,WO4.2H.,O. MoO a. Mo, Et4NCI, and H.,O at 160°C gives bluish-purple crystals of I (C.,H~).~Nlal. WvW~V~O~,~I.0.5H.,O (1) in 60% yield. Under analogous reaction conditions, a mixture of Na,WO4.2H:O.. V. . (CH,) . . . ~NH,' 2HCI, and H,,O yields brown crystals of [ H~N ( CH.,),NH ~ J 2 IW v W~ v. O~,~I.[H,.N(CH2),NH, . ICI.8H,O H,N . (2). I and2are the first one.electron reduced mixed valence hexatungstates to be crystallized and fully characterized. The crystal structures of I and 2 consist of discrete [W,Ot,~l ~ anions, cations, and water molecules of crystallization. Crystal data. I: Orthorhombic space group Pbcn (No. 60). a ~ I tL(~3(4), b'~ 22,257(5 ), c' = 19.631 (4)/~, V = 8329(3) A ~, Z = 8. A total of 6617 reflections ( 2#,,,, '~ 45 °) were collected, of which 4434 unique reflections with F,, > 4 tr(F,,) were used for structural elucidation. The structure was solved by direct metht~ls and least.squares relinement converged at R~1).0834. 2: Monoclinic, space group C2/m (No. 12), a-15.7339(10), b ~ 11.4970(9). c~9.0934(5) /~, ~ - 1(10.855 (4) °, V~ 1fil5.5(2) A ~, Z ~ 2. A total of 2473 reflections (2#..,,,,- 30 °) were collected. The structure was solved by direct methods anti least-squares refinement converged at R ~ 1).(~(~). (t~) I(J98 Elsevier Science S.A. All rights reserved. Keywonls: Crystal structures: Hexatungslate clusters; Hydrothernlal synthesis 1. Introduction Polyoxometalates exhibit fascinating electron acceptor properties whereby these systems can take, often in steps, a multiple number of electrons to form reduced and mixed valence compounds without any significant change in their molecular structures 11-3]. Partially reduced and mixed valence metal oxide clusters are of current interest due to their unusual electronic and magnetic properties [2-8] and their direct relevance to several geochemical and biochemical processes, catalysis, and materials science 12,7- ! 01. Hexatungstate, [W~,O~,,] 2- [ !1] is a prominent member of the hexametalate series ! M~,OI,~I - (M = Mo, W; n - 2: M -- Nb, Ta; n - 8) I ! I of polyoxoanions with a Lindquist type structure 1121 that has attracted considerable attention II31 in recent years. Thus, functionalized hexatungstate * Corresponding author. 0020-1693/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved. Pli S0020-1693 ( 97 ) 06124-0 clusters have been prepared and structurally character- ized. Namely, those incorporating metal-nitrosyl moieties ({M'(NO)}: (n-Bu4N)3IW.~OI,{M'(NO)}] ( M ' - W , Mo) [14]) and organoimido derivatives ([Bu4N].~- [W6OIs(NAr)] ( A r - 2 , 6 - (i-Pr),.Cc, H.~) [13]), mixed- metal compounds ([Bu4N],,[MW.~OI,~] ( M - V , Nb. Ta: n=3; M=Mo; n = 2 ) [ llb,15,16], [Bu4N].~[MoVW.~Oj,,] [17], [Bu4N].~[Nb:W4OI,~] [18], and [V2W~OI,~]'*- [ 15,16a. 19 ] ) and their organometallic analogs ( [ Bu.~N ] 2- I(OR)NbW.~O~s] (R-methyl, ethyl, isopropyl, phenyl. cholesteryl group) 120] and [(C~H~)TiW.,O~,] ~- [211). dimeric species, [ { MW.~O~, }2014 - (M - Nb, Ta) [ 201, and those containing {Nb2W40~,,} cores bridged by organo- rhodium and organoiridium moieties 1221. Novel organic- inorganic hybrid conducting materials ( I TTFi ~! W¢,O~,,i and I TMTSF131W¢,O191 ' 2DMF (TTF = tetrathiafulvalene; TMTSF = tetramethyltetraselenafulvalene) ) which contain