Inorg. Chem. 1988, 27, 1347-1353
1347
Contribution from the Department of Chemistry, Rice University, Houston, Texas 7725 1, Department of Chemistry, University of Delaware, Newark, Delaware 19716, and the INC4 Division of Los Alamos National Laboratory, Los Alamos, New Mexico 87545
A Series of Thallium-Iron Carbonyl Cluster Molecules: Structural Comparisons of [Et4N12[T12Fe4(CO)1619 [Et4N14[T14Fe8(C0)301,and [Et4N16[Tl6FelO(CO)361 Kenton H. Whitmire,*t Juanita M. Cassidy,t A. L. Rheingold,f and Robert R. Ryan5 Received September 22, 1987
Thallium salts and in situ generated K+[HFe(CO),]- react to form K+[TI(Fe(CO),),]. The [Et4N]+salt exists as a dimer in the solid state. Single-crystal X-ray analysis of [Et4N]2[T12Fe4(C0),6] ([Et4NI2[I])shows it to crystallize in the triclinic, centrosymmetric space group PT with a = 11.00 (1) A, b = 12.98 ( 1 ) A, c = 8.77 (1) A, a = 105.3 ( l ) O , = 95.7 (1)O, y = 65.30 (8)O, Z = 1 , and V = 1097 A3. The dimerization occurs through the formation of an asymmetric TI2Fe, parallelogram with TI-Fe distances of 2.632 (5) and 3.038 (4) A. The Fe atoms in the parallelogram are pseudooctahedrally coordinated by the two thallium atoms and four carbonyls. The remaining Fe(C0)4groups are trigonal bipyramids with thalliums located in axial sites = 2.553 (5) A). [Et,N],[I] is monomeric in solution and loses CO upon standing or irradiation to produce [Et4N]4[T14Fe,(CO)30] ([Et,N],[II]), which has also been characterized by single-crystal X-ray diffraction: monoclinic space group P 2 , / n , with a = 12.723 (6) A, b = 16.077 (6) A, c = 21.430 (9) A, p = 95.97 (4)O, 2 = 2, and V = 4360.2 A). It too contains a T12Fe2 parallelogram with dTI+ = 2.781 (5) and 2.786 (6) A. In addition those two thalliums bridge Fe2(Co),(~-Co)(~-T1Fe(c0),) groups. The CO loss reaction is reversible under pressures of CO. Structural comparisons are made of [Et4NI2[I]and [Et,N],[II] to the previously reported [Et4N]4[T16Felo(CO)36] ([Et,N],[III]): monoclinic space group P2,/n, with a = 12.266 (5) A, b = 20.547 (3) A, c = 22.892 (6) A, p = 93.24 (3)O, Z = 2, and V = 5759.7 AS.
Introduction Homoatomic Zintl ions of the group 13 elements are unknown. The inability to produce such complexes has been attributed to the number of electrons, which would be insufficient to stabilize cluster bonding.' It might be thought that simple addition of electrons to the clusters could overcome this deficiency; however, this approach runs into electrostatic problems when enough electrons are added to attain a stable bonding situation. Combining group 13 elements with their more electron-rich neighbors to produce heteroatomic Zintl ions, on the other hand, has been successful. Species so-produced include [ T I S ~ I ~[T1Sns]4-,2 ]~,~ and [T12Te2]2-.3 It is pertinent to compare these main-group element clusters to some mixed transition-metal/main-group clusters that have been recently characterized. The complex [SIIT~,]'~ can be compared to [Bi(Fe(C0)4)4]3-,5both of which contain a tetrahedrally coordinated central main-group atom and obey the Octet rule. More complicated structures represented by [Bi4Fe4(C0)13]2-6~7 can be compared to molecules such as [Bi4]2-8and [E7I3-(E = P, As, Sb, and mixed P4S3).9 In pursuing the ideas that electron-poor main-group elements such as T1 might be incorporated into cluster or cage structures with electron-rich transition-metal fragments, we began exploring the interaction of thallium with iron carbonyls. Some observations in the literature prompted this work. First some poorly defined thallium-iron carbonyls had been reported by Hieber and coworkers in 1959,'O which suggested such compounds should exist. Thallium-metal carbonyls have been known for some time, but only two structurally characterized examples have been previously reported. T ~ C O ( C O )consists ~ ~ ~ J of ~ discrete TI+ and CO(CO)~ions. The other compound, T I ( C P M O ( C O ) ~ )shows ~ , ' ~ a central, essentially planar thallium bonded to three molybdenum atoms in a conventional fashion. Other known but structurally uncharacterized thallium-metal carbonyl compounds are expected T1to be similar. Further examples include TI[CO(CO),]~-,'~ [Co(CO),] 3,11,14 [T~{CO(CO)~),]-,'~ TI[MII(CO)~]3,16 and TI[(C5H4CHPh2)Cr(C0)3].'7More recently we have reported the unexpected structure of [Et4N]6[T16Fe10(C0)36] obtained from the reaction of Fe(CO),/KOH/MeOH and T1C13.4H20.18 The bonding situation has relationships to both Zintl ion and transition-metal cluster chemistry. In this paper we present the structural characterization of two related cluster molecules-[ Et,"] 2[T12Fe4(CO)161 ( [Et,N] 2[ I]) 'Rice University. *University of Delaware. 8 Los Alamos National Laboratory.
and [Et4N]4[T14F~(CO)30] ([Et,N],[II]). These will be compared to the preViOUSly reported [ E ~ ~ N ] ~ [ T I , F ~ ~ o (([Et,N],[III]). CO)~~]
Experimental Section The thallium-iron carbonyl complexes described herein are moderately oxygen sensitive, and all manipulations were carried out under an atmosphere of oxygen-free nitrogen by using standard Schlenk and vacuum-line techniques. Organic solvents were distilled before use from standard drying agents, although the complexes are not particularly sensitive to water as evidenced by their isolation from aqueous solution. Infrared spectra were obtained on a PE 1430 spectrophotometer. Analyses were performed by Galbraith Analytical Laboratories (Knoxville, TN). The 13C NMR spectra were measured on a Nicolet 300 spectrophotometer. The reagents [Et,N]Br, Fe(CO),, TI2CO3,and T1CI3.4H20were obtained from commercial sources and used without purification. Synthesis of [Et4N]dI]. Pentacarbonyl iron (1.50 g, 7.66 mmol) was added rapidly to a solution of KOH (1.50 g, 26.7 mmol) in MeOH (50 mL) that had been previously prepared and bubbled with N,. After the mixture was stirred for about 30 min, solid T1C13.4H20(1.33 g, 3.47 mmol) was dropped in, at which time the solution color immediately changed from a clear tan to a deep yellow-brown color. Solid T12C03 (1) (a) Corbett, J. D. Chem. Rev. 1985,85, 383. (b) Corbett, J. D. Prog. Inorg. Chem. 1976, 21, 129. (2) Burns, R. C.; Corbett, J. D. J . Am. Chem. SOC.1982, 104, 2804. (3) Burns, R. C.; Corbett, J. D. J . Am. Chem. Soc. 1981, 103, 2627. (4) Huffman, J. C.; Haushalter, J. P.; Umarji, A. M.; Shenoy, G. K.; Haushalter, R. C. Inorg. Chem. 1984, 23, 2312. (5) Churchill, M. R.; Fettinger, J. C.; Whitmire, K. H.; Lagrone, C. B. J . Organomet. Chem. 1986, 303, 99. (6) Whitmire, K. H.; Churchill, M. R.; Fettinger, J. C. J . Am. Chem. SOC. 1985, 107, 1056. (7) Whitmire, K. H.; Albright, T. A.; Kang, S.-K.; Churchill, M. R.; Fettinger, J. C. Inorg. Chem. 1986, 25, 2799. (8) Cisar, A.; Corbett, J. D. Inorg. Chem. 1977, 16, 2482. (9) (a) Dahlmann, W.; v. Schnering, H. G. Naturwissenschaften 1972,59, 420; 1973, 60, 429. (b) Schmettow, W.; v. Schnering, H. G. Angew. Chem., Int. Ed. Engl. 1977, 16,857. (e) Critchlow, S. C.; Corbett, J. D. Inorg. Chem. 1984, 23,770. (d) Adolphson, D. G.; Corbett, J. D.; Merryman, D. J. J . Am. Chem. SOC.1976,98,7234. ( e ) Leung, Y. C.; Waser, J.; v. Houten, S.; Vos, A,; Wiegers, G. A.; Wiebenga, E. H. Acta Crystallogr. 1957, 10, 574. (10) Hieber, W.; Gruber, J.; Lux, F. Z . Anorg. Allg. Chem. 1959,300, 275. (11) (a) Hieber, W.; Teller, U. Z . Anorg. Allg. Chem. 1942, 249, 43. (12) Schussler, D. P.; Robinson, W. R.; Edgell, W. F . Inorg. Chem. 1974, 13, 153. (13) Rajaram, J.; Ibers, J. A. Inorg. Chem. 1973, 12, 1313. (14) Patmore, D. J.; Graham, W. A. G. Inorg. Chem. 1966, 5, 1586. (15) Robinson, W. R.; Schussler, D. P. J . Orgunomel. Chem. 1971, 30, CS. (16) Hsieh, A. T. T.; Mays, M. J . Orgonomet. Chem. 1970, 22, 29. (17) Cooper, R. L.; Fischer, E. 0.;Semmlinger, W. J. Orgonomet. Chem. 1967, 9, 333. (18) Whitmire, K.H.; Ryan, R. R.; Wasserman, H. J.; Albright, T. A,; Kang, S.-K. J . Am. Chem. SOC.1986, 108, 6831.
0020-1669/88/1327-1347$01.50/00 1988 American Chemical Society
1348 Inorganic Chemistry, Vo1. 27, No. 8,1988
Whitmire et al.
Table I. Crystallographic Data for [Et4N]+Salts of [II2-, [II]&, and [IIII6compd formula cryst syst space group a,
b, c,
A A A
a,deg
8, deg 7,deg
v,A3
g cm-3 &(MoKa), cm-I temp, K color cryst size diffractometer monochromator radiation 28 limits, deg scan type no. of reflcns collcd no. of indep reflcns no. of obsd. indep reflcns R(int), % std reflcns T * d Tmi, R,a % R,," % A ( P ) , e/A3 Dcahd,
[Et,NlZ[Il
[Et,NI,[IIl
[Et4N16[1111
C32H40Fe4N2016T12
C62H80Fe8N4030T14
C84H120Fe10N6036T16
triclinic Pi 11.00 (1) 12.98 (1) 8.77 (1) 105.3 (1) 95.7 (1) 65.30 (8) 1097 1 2.03 87.57 296 red 0.2 X 0.3 X 0.4 Rigaku AFC5S graphite Mo K n (A = 0.70930 A) 0-5 5 8/28 5330 5060 3426 (F, Z 6a(F0)) 0.4 3 stdl147 reflcns (
