Inorg. Chem. 1983, 22, 1339-1344
1339
Contribution from the Department of Chemistry, California State University, Northridge, California 9 1330, and the Istituto di Chimica Generale ed Inorganica, Universita di Parma, Centro di Studio per la Strutturistica Diffrattometrica del CNR, 43100 Parma, Italy
Synthesis and Crystal Structure of Mercury-Bridged Transition-Metal Clusters: H ~ [ R U ~ ( C O ) ~-Bu)], ( C ~ -and ~ [(C2-t-BU)RU~(CO)~H~MO(&H~)(CO)~] SUSAN ERMER, KEVIN KING, KENNETH I. HARDCASTLE,; EDWARD ROSENBERG,* ANNA MARIA MANOTTI LANFREDI, ANTONIO TIRIPICCHIO,* and MARISA TIRIPICCHIO CAMELLINI Received July 17, 1982
The synthesis and crystal structure of Hg[Ru3(CO)g(C2-t-Bu)1,(11) and [(C2-t-Bu)Ru3(CO)9HgMo(~-C5H5)(CO)3] (111) are reported. Both compounds are prepared from [(C2-t-Bu)Ru3(CO),HgX](X = Br (I) or I) by reaction with [AsPh.,] [Ru,(CO)~(C,-~-BU)] or Na[Mo(&,H,)(CO),]. Crystals of I1 are monoclinic, space group P2,/c, with Z = 4 in a unit cell of dimensions a = 13.522 (8) A, b = 17.105 (10) A, c = 18.159 (12) A, and 0 = 104.79 ( 7 ) O , while those of 111 are monoclinic, nonstandard space group P2,/n, with Z = 4 in a unit cell of dimensions a = 15.377 (1 1) A, b = 12.714 (8) A, c = 15.917 (10) A, and 0 = 104.12 (9)'. Each structure was solved from diffractometer data by combined direct and Patterson methods and refined by full-matrix least squares to R = 0.052 for 2322 observed reflections for I1 and R = 0.064, R , = 0.059 for 3135 observed reflections for 111. In 11, the mercury atom, bridging one side of two triangular Ru clusters, is surrounded by four Ru atoms (the Ru-Hg bond distances range from 2.808 to 2.840 A) where the dihedral angle between the two Ru2Hg planes is 45O, intermediate between square-planar and tetrahedral geometry. In 111 the mercury atom is in a nearly trigonal arrangement bridging one side of a triangular Ru cluster and being bonded also to the Mo atom of the [Mo(&H,)(CO)~] group (the Hg atom lies only 0.05 A above the Ru2Moplane; the two Ru-Hg bond distances are 2.811 (2) and 2.812 (2) A and the Hg-Mo bond is 2.743 (2) A).
Introduction We recently reported the synthesis and the crystal structure of [(C2-t-Bu)Ru3(C0)9HgBr]2 (I)' (Figure 1). There are two unique features about this transition-metal mercuric halide. First, the mercury is involved in a three-center-two-electron bond, and second, the compound exists as a bromine-bridged dimer in the solid state with the mercury having a distortedtetrahedral arrangement, in contrast to other transition-metal mercuric compounds, which are monomeric with mercury linearly coordinated.2 The compound I, however, is monomeric in solution. There are now several other cases that have recently appeared in the literature where mercury has undergone an expansion of its coordination number by delocalized bonding to transition metak3s4 In the compound [MOH~MO(~-C~H~)(CO)~]~,~ which has a metallacubane structure, the mercury is tetrahedrally coordinated to four molybdenum atoms (three Mo atoms at neighboring corners of the cube and one [Mo(~-C,H,)(CO)~]group). In the anionic [G~(CO~(CO),)((CO~CO)~)(H~CO(CO),)]complex3the mercury bridges two cobalt atoms in a three-center-twoelectron bond and is bound to a third cobalt atom to give a trigonal-planar geometry around mercury. Both the molybdenum and the cobalt compounds were obtained as minor side products from reactions involving sodium amalgam and metal carbonyls. The reaction of I with various carbonyl metalates represents a possible specific route to mercury-bridged metal clusters which presents an opportunity to study systematically the relationship between structure and bonding in this class of molecules. We report here the initial results of these studies, specifically, the reaction of I with [Ru3(CO),(C2-t-Bu)]- and [ M O ( ~ - C ~ H ~ ) ( C Oand ) ~ the ] - crystal structures of the products obtained. Results and Discussion Synthesis of Hg[Ru3(CO)9(C2-t-Bu)lz and [(C2-t -Bu)Ru3(CO),H~MO(~~-C,H,)(CO)~]. In our initial investigations of the synthesis of the complex I and its iodo analogue we reported 30-40% yields of these compounds from the reaction of PhHgX with H R U ~ ( C O ) ~ ( C ~ - ~or - Bfrom U ) reaction of HgX2 with [AsPh4][Ru~(CO),(C,-~-BU)].~ In order to study the reaction chemistry of [(C2-t-Bu)Ru,(CO),HgX] (X = Br, *To whom correspondence should be addressed: K.I.H. and E.R., California State University; A.T., Universita di Parma. 0020-1669/83/1322-1339$01.50/0
I), we wanted to develop a high-yield synthesis of these compounds. We now report a one-pot synthesis of [(C2-t-Bu)Ru3(C0),HgX] (X = Br, I) from [ R U ~ ( C O )where ~ ~ ] much higher yields of these compounds are realized (eq 1). reflux (1) KOH
room temp
[(C2-t-Bu)Ru3(CO)gHgXI (11 80% overall (X = I) 45% overall (X = Br) The reaction of [(C2-r-Bu)Ru3(C0)9HgX](X = Br, I) with 1 equiv of [AsPh4][ R U ~ ( C O ) ~ ( C , - ~ - B yields U ) ] Hg[Ru3(C0)9(C2-t-Br)]2(11) quantitatively (eq 2). [(C ~ - ~ - B U ) R U ~ ( C O ) ~ +H ~ X ] (X = Br or I) H ~ [ R u ~ ( C O ) , ( C ~ - ~ - B(2) U)]~ 11, 100%
It should be pointed out that I1 is also obtained in varying amounts from the reaction of [AsPh4][Ru3(CO),(C2-t-Bu)] with HgX2 (X = Br, C1, CN, CH3CO0, SCN) and from the thermolysis of [(C,-~-BU)RU,(CO)~H~X]. Presumably, the formation of I1 occurs via a redistribution reaction whose equilibrium constant is dependent on X. We are currently investigating this process, and the results of these studies will be reported separately., The reaction of N ~ [ M o ( ~ ~ - C , H , ) ( C O generated )~], from [ M o ( ~ - C , H , ) ( C O ) ~and ] ~ sodium amalgam, with [(C2-t(1) (2) (3) (4)
E. Rosenberg, R. Fahmy, K. King, A. Tiripicchio,and M. T. Camellini, J . Am. Chem. Soc., 102, 3626 (1980). M. J. Mays, MTP Int. Rev. Sci.: Inorg. Chem., Ser. One, 6 (1972)
(Part 2). D. N. Duffy, K. M. MacKay, and B. K. Nicholson, J . Chem. Soc.,
Dalton Trans., 381 (1981). S.Fadel, J. Deutcher, and M. L. Ziegler, Angew. Chem., Int. Ed. Engl.,
16, 704 (1977). ( 5 ) It should be noted here that I1 was erroneously reported in ref 1 as
Hg,[(C,-r-Bu)Ru?(CO),],. This formulation was based on metal analysis by atomic absorption spectroscopy, which was shown to be incorrect due to mutual interferences between Hg and Ru absorptions.
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1340 Inorganic Chemistry, Vol. 22, No. 9, 1983
Table I. Selected Bond Distances ( A ) and Angles (deg) with Their lstimated Standard Deviations for Complex I1
Figure 1. Solid-state structure of [(C2-r-Bu)Ru3(CO)9HgBr]2 (I). '?
C124)
I-
0116)
2 4)
(a) In the Coordination Sphere of the Metal Atoms Ru(2)-C(20) 2.27 (4) 2.808 (6) Hg-Ru(1) Ru(3)-C(7) 1.85 (4) 2.840 (6) Hg-Ru(2) Ru(3)-C(8) 1.89 (4) 2.840 (7) Ilg- R u ( 4) Ru(3)-C(9) 1.83 ( 5 ) 2.819 (6) Hg-Ru(5) R~(3)-C(19) 1.98 (3) 2.855 (3) Ru(l)-Ru (2) Ru(4)-C(10) 1.84 (4) 2.799 ( 5 ) Ru(l)-Ru(3) Ru(4)-C(ll) 1.90 (4) 2.798 ( 5 ) Ru(2)-Ru(3 Ru(4)-C(12) 1.95 (4) 2.847 (3) Ru(~ ) - R u5() Ru(4)-C(25) 2.17 (3) 2.812 (4) Ru(4)-Ru(6) Ru(4)-C(26) 2.24 (3) 2.807 ( 5 ) Ru(5)-Ru(6) Ru(5)-C(13) 1.84 ( 5 ) Ru(1)-C(l) 1.83 (4) Ru(5)-C(14) 1.88 (4) 1.90 (3) Ru( 1)-C(2) Ru(5)-C(15) 1.90 (3) 1.89 ( 5 ) Ru(1 )-C(3) Ru(5)-C(25) 2.14 (3) 2.20 (3) Ru(l)-C(19) 2.31 (4) Ru(5)-C(26) 2.21 (3) Ru(l)-C(20) Ru(6)-C(16) 1.83 ( 5 ) Ru(2)-C(4) 1.88 (3) Ru(6)-C(17) 1.83 (4) Ru(2)-C(5) 1.87 (4) Ru(6)-C(18) 1.82 ( 5 ) Ru(2)-C(6) 1.87 (4) Ru(6)-C(25) 1.96 (3) Ru(2)-C(19) 2.16 (3) Ru(1 )-Hg-Ru(2) Ru(l)-Hg-R~(4) Ru(l)-Hg-Ru(S) Ru(2)-Hg-RU(4) Ru(2)-Hg-Ru(S) Ru(4)-Hg-R~(5) Ru(Z)-Ru(l ) - R u ( ~ ) Ru(Z)-Ru(l )-Hg Ru(3)-Ru(l )-Hg Ru(~)-Ru(~)-H~
60.7 (1) 126.6 (1) 156.2 (1) 159.4 (1) 122.1 (1) 60.4 (1) 59.3 (1) 60.2 (1) 99.7 (1) 98.9 (1)
R u ( ~ ) - R u ( ~ ) - R u ( ~ ) 59.4 (1) H ~ - R u ( ~ ) - R u1)( 59.1 (1) Ru(l)-Ru(3)-Ru(2) 61.3 (1) R u ( ~ ) - R u ( ~ ) - R u ( ~ )59.5 (1) Ru(S)-Ru(4)-Hg 59.4 (1) Ru(6)-Ru(4)-Hg 100.7 (1) Ru(6)-Ru(S)-Hg 101.3 (1) R u ( ~ ) - R u ( ~ ) - R u ( ~ )59.6 (1) Hg-Ru(S)-Ru(4) 60.1 (1) R u ( ~ ) - R u ( ~ ) - R u ( ~ )60.9 (1)
(b) In the Carbonyl Groups
Figure 2. Solid-state structure of [ ( C , - ~ - B U ) R U ~ ( C O ) ~ (11). ],H~
B U ) R U , ( C O ) ~ H ~ X(X ] = Br, I)] gives [(C,-t-Bu)Ru,(C0)9HgMo($-C5H5)(C0)3]in moderate yield (eq 3). The Na[Mo(v5-C5H5)(Co),1 + [(C,-t-Bu)Ru,(CO)gHgXI
THF
[(C,-t-Bu)Ru,(CO)9HgMo(~5-C5H5)(Co),l(3) reaction is accompanied by nonspecific decomposition and by the formation of significant amounts of I1 and Hg[Mo($C5H5)(CO),],. Lowering the reaction temperature to 0 'C or reversing the order of addition of reactants did not significantly change the yield of 111. Crystal Structure of Hg[Ru,(CO),(C,-t-Bu)~. The structure of the complex H ~ [ R U , ( C O ) ~ ( C ~ - ~ -(11) B ~ with ) ] , the atomic numbering system is represented in Figure 2; selected bond distances and angles are given in Table I. The complex can be described as a dimer of two butterfly clusters with the mercury atom sharing a common wingtip. The dihedral angles between the two triangular wings in each butterfly are 124.4 and 126.7'; these values are comparable with those found (127') in the starting complex I.' The coordination geometry around mercury can be described as intermediate between a tetrahedral and a square-planar arrangement. The distortion from these idealized geometries is manifested in the mercury-ruthenium bond angles, which range from 60.4 to 159.4', and by the dihedral angle between the two Ru,Hg planes, which is 44.6'. There is a slight asymmetry in the Hg-Ru bonds to each Ru, cluster (2.808 (6), 2.840 (6) and 2.819 (6), 2.840 (7) A, respectively), while in I these bonds are equal and significantly shorter (2.733 (2) and 2.739 (2) A). The increase in the Hg-Ru bond distances on going from I to I1 is accompanied by a corresponding decrease in the Ru-Ru bond length at the mercury-bridged side of the Ru, cluster (2.855 (3) and 2.847 (3) A in I1 and 2.900 (3) A in I). It is difficult to assess the cause of the asymmetry in the Ru-Hg bonds and the unusual dihedral angle in 11, since both intra-
O(l)-C(l) O(l)-C(2) 0(3)-C(3) 0(4)-C(4) 0(5)-C(5) 0(6)-C(6) 0(7)-C(7) 0(8)-C(8) 0(9)-C(9)
1.21 (4) 1.14 (4) 1.11 (6) 1.18 (4) 1.16 ( 5 ) 1.16 ( 5 ) 1.15 ( 5 ) 1.17 ( 5 ) 1.18 (6)
Ru(1)-C(1)-O(1) R~(l)-C(2)-0(2) Ru(l)-C(3)-0(3) Ru(2)-C(4)-C(4) Ru(2)-C(5)-0(5) R~(2)-C(6)-0(6) Ru(3)-C(7)-0(7) Ru(3)-C(8)-0(8) Ru(3)-C(9)-0(9) C(19)-C(20) C(2O)-C(21) C(21)-C(22) C(21 )-C( 23) C(2 1)-C(24) Ru(1 )-C(19)-Ru(2) Ru(l)-C(19)-Ru(3) Ru(2)-C(19)-Ru(3) Ru(1 )-C(20)-Ru(2) C(20)-C( 19)-Ru(l) C(2O)-C(19)-Ru(2) C(2O)-C(19)-Ru(3) C(21)-C(20)-R~(l) C(21)-C(20)-R~(2) C(21)-C(2O)-C(19) Ru(1)-C(20)-C(19) Ru(2)-C(20)-C(19) C( 22)-C( 2 1)-C( 2 3) C(22)-C(21)-C(24) C(22)-C(21)-C(20) C(23)-C(21)4(24) C(23)-C(2l)-C(20) c(24)-c(21 )-C(20)
180 (3) 176 (3) 175 (4) 180 (3) 178 (3) 178 (3) 178 (3) 179 (3) 173 (4)
0(10)-C(10) O(l1)-C(l1) 0(12)-C(12) 0(13)-C(13) 0(14)-C(14) 0(15)-C(15) 0(16)-C(16) 0(17)-C(17) 0(18)-C(18)
Ru(4)-C(10)-0(10) 173 (3) R~(4)-C(11)-0(11) 175 (4) R ~ ( 4 ) 4 ( 1 2 ) - 0 ( 1 2 ) 177 (4) R~(S)-C(13)-0(13) 178 (4) R~(5)-C(14)-0(14) 178 (3) R~(5)-C(15)-0(15) 174 (3) Ru(6)-C(16)-0(16) 175 (4) Ru(6)-C(17)-0(17) 178 (4) Ru(6)-C(18)-0(18) 175 (4)
(c) In the Organic Ligands 1.32 (4) C(25)-C(26) c(26jq27) 1.51 i 5 j 1.57 (6) C(27)-C(28) C(27)-C(29) 1.59 ( 5 ) C(27)-C(30) 1.47 ( 5 )
8 2 (1) 84 (1) 85 (1) 77 (1) 77 (2) 77 (2) 156 (3) 135 (2) 136 (2) 143 (3) 6 8 (2) 6 8 (2) 112 (3) 112 (3) 106 (3) 110 (3) 105 (3) 112 (3)
1.19 ( 5 ) 1.14 ( 5 ) 1.13 ( 5 ) 1.17 ( 5 ) 1.13 ( 5 ) 1.16 (4) 1.19 (6) 1.16 ( 5 ) 1.23 (6)
1.27 (4) 1.54 ( 5 ) 1.50 (6) 1.54 (6) 1.62 (6)
Ru(5)-C(25)-RU(4) 8 3 (1) R u ( ~ ) - C ( ~ ~ ) - R U ( ~ )85 (1) Ru(5)-C(25)-Ru(6) 86 (1) Ru(4)-C(26)-Ru(5) 79 (1) C(26)-C(25)-Ru(4) 76 (2) C(26)-C(25)-Ru(5) 76 (2) C(26)-C(25)-Ru(5) 156 (3) C(27)-C(26)-Ru(4) 133 (2) C(27)-C(26)-Ru(5) 135 (2) C(27)-C(26)-C(25) 142 (3) Ru(4)-C(26)-C(25) 70 (2) Ru(S)-C(26)4(25) 70 (2) C(28)-C(27)-C(29) 112 (3) C(28)-C(27)-C(30) 107 (3) C(28)-C(27)-C(26) 114 (3) C(29)4(27) 3.0). Solution and Refmment of the Structure. With Z = 2 in the space group P2,/c, the Hg,,+ cation has crystallographic imposed inversion symmetry. The positions of the heavy atoms in the unit cell were found by inspection of the three-dimensional Patterson function. Least(4) 'XRAY 71 System of Crystallographic Programs", Technical Report TRl92; University of Maryland: College Park, MD, 197 1.
0 1983 American Chemical Societv
