GeII and SnII Complexes of [2.2.2]Paracyclophane with Threefold Internal η6 Coordination

2
191 X-ray structure analysis of the [22]coproporphyrin I1 Zb space group P2,/n. a = 828.1(5), b = 2619.5(6), c = 1028.7(6) pm, fl = 100.30(2)'. Z = 2, four-circle diffractometer CAD4 (Enraf-Nonius) (Cu,,, L = 154.178 pm, graphite monochromator), 3561 measured reflections. Fur- ther details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich- technische Information mbH. W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-54603, the names of the authors, and the journal citation. (lo] H. Konig, C. Eickmeier, M. Moller, U. Rodewald, B. Franck. Angex'. Chmi. 102 (1990) 1437; Angew. Chem. Znf. Ed. Engl. 29 (1990) 1393. (1 11 R. Scheidt in D. Dolphin (Ed.): The Porphyrins, Vol. 1110, Academic Press, New York 1978, p. 500. 1121 Other [22]porphyrins are also described in this issue: E. Vogel, N. Jux, E. Rodriguez-Val, J. Lex, H. Schmickler, Angew. Chem. 102 (1990) 1431; Aii@w. Chem. In[. Ed. Engl. 29 (1990) 1387. Ge" and Sn" Complexes of [2.2.2]Paracyclophane with Threefold Internal q6 Coordination ** By Thonzus Probst, Oliver Steigelmunn, Jiirgen Riede, and Hubert Schmidbaur * During the last few years K complexes of main-group p- block elements have been ordered in a system which now covers the complete triads (Ga,In,Tl), (Ge,Sn,Pb), and (As,Sb,Bi).[' -31 Though the interactions of these metals with neutral aromatic hydrocarbons are relatively weak, the structural features are amazingly consistent. They include the strong centroid (q6) coordination above the aromatic rings, which is observed for all nine metals in oxidation states corresponding to an nd"(n + 1)s' electronic configuration. Only for antimony(iI1) is this mode of coordination avoided by a displacement of the metal away from the central posi- ti o n . E41 At first only rnono(arene) complexes were found, but later on a series of bis(arene) complexes with interplanar angles of about 60" were also discovered.['* -71 The [n.n]paracy- clophanes (n = 2, 3), in particular, have shown high donor capacities. However, the metal ions in the resulting systems are coordinated to the benzene rings from the Attempts to introduce Ga@ into the cavity were finally suc- cessful when [2.2.2]paracyclophane with its larger interstice was allowed to react with gallium subhalides, Ga[GaX, J (X = CI, Br)."'] We now report the synthesis and structural characteriza- tion of the analogous germanium(r1) and tin(Ir) compounds. They are obtained by allowing the cyclophane (p- C,H,CH,CH,), (= C,,H,,) to react in benzene with one equivalent of GeCI, and SnCI,, respectively, and two to three equivalents of AICI, . Upon standing, the resulting yel- low to red solutions afford colorless crystals. In the case of the Sn" compound, depending on the molar ratios employed, these crystals contain the expected 1 :1:2 adduct (1, m.p. 63 "C), with two AlCIf anions, or a 1 : 1 :3 adduct (2, m.p. 225 T). with one of the anions extended to the Al,Cl$ spe- cies [Eqs. (a) and (a'), respectively]. Similarities in the IR and H NMR spectra suggest the presence of the same cationic species in both cases. [*] Prof. Dr. H. Schmidbaur, DipLChem. T. Probst, DipLChem. 0 Steigel- mann['], J. Riedel'] Anorganisch-chemisches Institut der Technischen Universitat Miinchen Lichtenbergstrasse 4, W-8046 Garching (FRG) [ '1 X-ray structure analyses [**I This work has been supported by the Deutsche Forschungsgemeinschaft (Leibniz-Programm) and the Fonds der Chemischen Industrie. C,,H2, + SnCI, + 2 AICI, --f [((C,,H,,)Sn}(AICI,)]eAICl~ 1 (a) C,,H,, + SnCI, + 3 AICI, -+ [((C,,H,,)Sn)(AIC1,)JeA1,CI~ 2 (a') Crystallization of the Ge" compound is much slower. Sin- gle crystals of a product are obtained only over a longer period accompanied by unavoidable slow diffusion of water into the solution. The germanium atoms of the cations are still bound to one chlorine ligand and are associated-in the molar ratio 2: 1-with the anions A140,C1:F formed by par- tial hydrolysis [Eq. (b)]. 1 : 1 : 1 complexes were not obtained. (b) 2 C,,H,, + 2 GeCI, + 4 AICI, + 2H,O- 4HC1 + [(C,,H,,)GeCI],(Al,O,C1,,) 3 'H NMR spectra of solutions of the three complexes in [D,]acetone (1, 2) or [D,]dimethyl sulfoxide (3) show only two signals in each case, indicating the preservation of the maximum symmetry of the ligand ($-D3,J through unper- turbed centroid metal coordination in solution. This obser- vation may however be the result of a shift in anion coordi- nation from one side to the other (see below), which is fast on the NMR time scale, or of solvation by the strongly donating solvents. The tin(rr) bis(tetrachloroa1uminate) 1 crystallizes with 1.5 equivalents of benzene (m.p. 63 "C). X-ray analysis" 'I re- vealed that the Sn" ion in 1 is indeed located in the interior of the arene "fence" (Fig. 1). The contact to one of the coun- Fig. 1. Structure of 1 (ORTEP, thermal ellipsoids at 50% probability; H atoms omitted). terions causes a displacement of the metal away from the center of the cavity. This is accompanied by a tilting of the three benzene rings in such a manner that the positioning of the metal ions above the ring centers is largely retained. The distances of the tin atom from the 38 carbon atoms of the rings span a relatively narrow range (2.817(5)-3.075(6) A). The AICIF counterion, which shows metal contact, is coordi- nated only via one chlorine atom (Sn-C12 = 3.073(2) A); the second counterion is not engaged in metal bonding. The distances of the tin atom from the centers of the ben- zene rings are not exactly the same, but their values (Sn- Z1 = 2.623, Sn-Z2 = 2.666, Sn-Z3 = 2.534 A) indicate a comparable bonding situation. The sum of the angles Z1-Sn-Z2 = 115.52", ZI-Sn-Z3 = 119.08", and Z2-Sn-Z3 = 118.53' is 358.13'. The small deviation from the standard value of 360" for a local trigonal-planar symmetry reflects the only moderate distortional influence of the anion con- tact. The germanium(r1) compound 3 crystallizes with four mol- ecules of benzene.[' l] The anions AI,O,CI:F do not need any further description, since they are already known as compo- Angew. Chem. Inl. Ed. Engl. 29 (1990) No. 12 CC ) VCH Verlagsgesellschaft mbH, W-6940 Wernheim, 1990 0570-0833~Y0j1212-1~Y7 3 3.50+.25/0 1397

Transcript of GeII and SnII Complexes of [2.2.2]Paracyclophane with Threefold Internal η6 Coordination

Page 1: GeII and SnII Complexes of [2.2.2]Paracyclophane with Threefold Internal η6 Coordination

191 X-ray structure analysis of the [22]coproporphyrin I1 Zb space group P2,/n. a = 828.1(5), b = 2619.5(6), c = 1028.7(6) pm, f l = 100.30(2)'. Z = 2, four-circle diffractometer CAD4 (Enraf-Nonius) (Cu,,, L = 154.178 pm, graphite monochromator), 3561 measured reflections. Fur- ther details of the crystal structure investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich- technische Information mbH. W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD-54603, the names of the authors, and the journal citation.

(lo] H. Konig, C. Eickmeier, M. Moller, U. Rodewald, B. Franck. Angex'. Chmi. 102 (1990) 1437; Angew. Chem. Znf. Ed. Engl. 29 (1990) 1393.

(1 11 R. Scheidt in D. Dolphin (Ed.): The Porphyrins, Vol. 1110, Academic Press, New York 1978, p. 500.

1121 Other [22]porphyrins are also described in this issue: E. Vogel, N. Jux, E. Rodriguez-Val, J. Lex, H. Schmickler, Angew. Chem. 102 (1990) 1431; Ai i@w. Chem. In[. Ed. Engl. 29 (1990) 1387.

Ge" and Sn" Complexes of [2.2.2]Paracyclophane with Threefold Internal q6 Coordination ** By Thonzus Probst, Oliver Steigelmunn, Jiirgen Riede, and Hubert Schmidbaur *

During the last few years K complexes of main-group p- block elements have been ordered in a system which now covers the complete triads (Ga,In,Tl), (Ge,Sn,Pb), and (As,Sb,Bi).[' - 3 1 Though the interactions of these metals with neutral aromatic hydrocarbons are relatively weak, the structural features are amazingly consistent. They include the strong centroid (q6) coordination above the aromatic rings, which is observed for all nine metals in oxidation states corresponding to an nd"(n + 1)s' electronic configuration. Only for antimony(iI1) is this mode of coordination avoided by a displacement of the metal away from the central posi- ti o n . E41

At first only rnono(arene) complexes were found, but later on a series of bis(arene) complexes with interplanar angles of about 60" were also discovered.['* -71 The [n.n]paracy- clophanes (n = 2, 3), in particular, have shown high donor capacities. However, the metal ions in the resulting systems are coordinated to the benzene rings from the Attempts to introduce Ga@ into the cavity were finally suc- cessful when [2.2.2]paracyclophane with its larger interstice was allowed to react with gallium subhalides, Ga[GaX, J (X = CI, Br)."']

We now report the synthesis and structural characteriza- tion of the analogous germanium(r1) and tin(Ir) compounds. They are obtained by allowing the cyclophane (p- C,H,CH,CH,), (= C,,H,,) to react in benzene with one equivalent of GeCI, and SnCI,, respectively, and two to three equivalents of AICI, . Upon standing, the resulting yel- low to red solutions afford colorless crystals. In the case of the Sn" compound, depending on the molar ratios employed, these crystals contain the expected 1 :1:2 adduct (1, m.p. 63 "C), with two AlCIf anions, or a 1 : 1 : 3 adduct (2, m.p. 225 T). with one of the anions extended to the Al,Cl$ spe- cies [Eqs. (a) and (a'), respectively]. Similarities in the IR and H NMR spectra suggest the presence of the same cationic

species in both cases.

[*] Prof. Dr. H. Schmidbaur, DipLChem. T. Probst, DipLChem. 0 Steigel- mann['], J. Riedel'] Anorganisch-chemisches Institut der Technischen Universitat Miinchen Lichtenbergstrasse 4, W-8046 Garching (FRG)

[ '1 X-ray structure analyses [**I This work has been supported by the Deutsche Forschungsgemeinschaft

(Leibniz-Programm) and the Fonds der Chemischen Industrie.

C,,H2, + SnCI, + 2 AICI, --f [((C,,H,,)Sn}(AICI,)]eAICl~ 1 (a)

C,,H,, + SnCI, + 3 AICI, -+ [((C,,H,,)Sn)(AIC1,)JeA1,CI~ 2 (a')

Crystallization of the Ge" compound is much slower. Sin- gle crystals of a product are obtained only over a longer period accompanied by unavoidable slow diffusion of water into the solution. The germanium atoms of the cations are still bound to one chlorine ligand and are associated-in the molar ratio 2: 1-with the anions A140,C1:F formed by par- tial hydrolysis [Eq. (b)]. 1 : 1 : 1 complexes were not obtained.

(b) 2 C,,H,, + 2 GeCI, + 4 AICI, + 2H,O-

4HC1 + [(C,,H,,)GeCI],(Al,O,C1,,) 3

'H NMR spectra of solutions of the three complexes in [D,]acetone (1, 2) or [D,]dimethyl sulfoxide (3) show only two signals in each case, indicating the preservation of the maximum symmetry of the ligand ($-D3,J through unper- turbed centroid metal coordination in solution. This obser- vation may however be the result of a shift in anion coordi- nation from one side to the other (see below), which is fast on the NMR time scale, or of solvation by the strongly donating solvents.

The tin(rr) bis(tetrachloroa1uminate) 1 crystallizes with 1.5 equivalents of benzene (m.p. 63 "C). X-ray analysis" 'I re- vealed that the Sn" ion in 1 is indeed located in the interior of the arene "fence" (Fig. 1) . The contact to one of the coun-

Fig. 1. Structure of 1 (ORTEP, thermal ellipsoids at 50% probability; H atoms omitted).

terions causes a displacement of the metal away from the center of the cavity. This is accompanied by a tilting of the three benzene rings in such a manner that the positioning of the metal ions above the ring centers is largely retained. The distances of the tin atom from the 38 carbon atoms of the rings span a relatively narrow range (2.81 7(5)-3.075(6) A). The AICIF counterion, which shows metal contact, is coordi- nated only via one chlorine atom (Sn-C12 = 3.073(2) A); the second counterion is not engaged in metal bonding.

The distances of the tin atom from the centers of the ben- zene rings are not exactly the same, but their values (Sn- Z1 = 2.623, Sn-Z2 = 2.666, Sn-Z3 = 2.534 A) indicate a comparable bonding situation. The sum of the angles Z1-Sn-Z2 = 115.52", ZI-Sn-Z3 = 119.08", and Z2-Sn-Z3 =

118.53' is 358.13'. The small deviation from the standard value of 360" for a local trigonal-planar symmetry reflects the only moderate distortional influence of the anion con- tact.

The germanium(r1) compound 3 crystallizes with four mol- ecules of benzene.[' l ] The anions AI,O,CI:F do not need any further description, since they are already known as compo-

Angew. Chem. Inl. Ed. Engl. 29 (1990) N o . 12 CC) VCH Verlagsgesellschaft mbH, W-6940 Wernheim, 1990 0570-0833~Y0j1212-1~Y7 3 3.50+.25/0 1397

Page 2: GeII and SnII Complexes of [2.2.2]Paracyclophane with Threefold Internal η6 Coordination

nents of other salts.[t21 As a consequence of the crystallo- graphic center of symmetry, pairs of cations (CZ4HZ4)- GeCl@ are structurally equivalent. The geometrical situation in the cations of 1 (Fig. 1) and 3 (Fig. 2) seems to be similar only at first glance. The most important difference is the strong binding of the germanium atom to one chlorine atom, as revealed by the short distance of 2.224(1) A. Accordingly, a C(Ge-CI) vibrational band is found in the IR spectrum at 429 cm-*.

Fig. 2. Structure of the cation in 3 (ORTEP, thermal ellipsoids at 50% proba- bility; arbitrary radii for C atoms, H atoms omitted).

The environment of the germanium atom in 3 can best be described as tetrahedral, consisting of three arene rings and one chlorine atom. The Ge-Z distances (Ge-Z1 = 2.797, Ge-Z2 = 2.722, Ge-Z3 = 2.715 A) are slightly longer than the Sn-Z distances in 1, and the Ge-C distances (2.724(7)- 3.408(7) ,&)are scattered over a broader range than the Sn-C distances in 1. Tin is thus more strongly coordinated to the arene rings than germanium, which is consistent with the situation met with arsenic and antimony. Stereochemical ac- tivity of the lone pair at the metal center is not obvious.

The threefold coordination to neutral aromatic hydrocar- bons ( 3 . q6) found for the compounds 1-3 and for the analogous complex of Ga[GaBr,]r'ol has not been observed previously for transition metals. The complex (C24H24) AgC104tt31 is also significantly different, since the metal is coordinated only to one edge of each of three arenes (3 . q2). Centroid (q6) coordination of transition metals like chromi- um(o) to [2.2.2]paracyclophane occurs with different stoi- chiometries and e~terna l ly .~ '~] The larger radii of the p-block elements compared to the d-block elements seem to be an essential condition for accomplishing the excessive coordina- tion found with low-valent main-group metals.

Experimental Procedure 1: A slurry of SnCI, (0.56 g, 2.95 mmol) and [2.2.2]paracyclophane (0.98 g, 2.94mmol) in 180mL of benzene was treated with AICl, (0.81 g, 6.1 mmol), which was added slowly under reflux conditions via a Soxhlet apparatus. The color of the mixture changed to red. After 30 min the mixture was allowed to cool slowly to room temperature and then filtered. Upon standing at 20 "C, the solutionaffordedclearcolorlesscrystals(l,2.19 g, 84%),m.p. 63°C. 'H NMR ([D,]acetone): 6 =7.36 (s, 3H. C,H,), 6.71 (s, 4H, C,H,), 2.94 (s, 4H, CH,). 2. As described for 1, reaction of SnCl, (0.40 g. 2 11 mmol), paracyclophane (0.64 g, 2.05 mmol), and AICI, (0.81 g, 6.07 mmol) resulted in a yellow solution

above a red oil, which was separated. The solution was heated again, evaporat- ed in vacuo to a volume of 100 mL, and cooled to room temperature. Colorless crystals separated (2,1.59 g, 86%), m.p. 225 'C (dec.). The 'H NMR spectrum was as observed for 1

3: As described for 1, GeCI, (0.52 g, 3.62 mmol). cyclophane (0.84 g, 2.69 mmol), and AICI, (1 -50 g, 11.25 mmol) were allowed to react in 175 mL of benzene under reflux conditions. After 1 h a yellow solution was obtained, which was concentrated to a volume of 85 mL. Upon standing for several weeks, the solution turned green and small colorless crystals separated (3, 1.76 g. 44%). (Apparently, some water diffused into the solution during crystal- lization, though the reasons for this were not obvious.) 'H NMR ([D,]DMSO): 6 =7 35 (s, 8H, C,H,). 6.65 (s, 4H. C,H,), 2.85 (s, 4H, CH,).

Received: March 26, 1990; supplemented: July 5, 1990 [Z 3876 IE]

German version: Angew. Chem. 102 (1990) 1471

CAS Registry numbers:

3 . 4C,H,, 129833-13-2. C,,H,,, 283-80-7; SnCI,, 7772-99-8; GeCI,, 10060- 11-4; AICI,. 7446-70-0.

1, 129813-05-4; 1 . lfC,H,, 129833-12-1; 2. 129813-07-6; 3, 129813-10-1;

[I] H. Schmidbaur, Angew. Chem. 95 (1985) 893; Angew. Chem. lnt. Ed. Engl. 24 (1985) 893.

[2] H. Schmidbaur, T. Probst, B. Huber, G. Miiller, C. Kriiger, J. Organomet. Chem. 365 (1989) 53; H. Schmidbaur, T. Probst, 0. Steigelmann, G. Muller, 2. Natur/orsch. 844' (1989) 1175; H. Schmidbaur, T. Probst, 0. Steigelmann, G. Muller, Heteroot Chem. f(1990) 161, and referencescited therein

[3] H. Schmidbaur, W. Bublak, B. Huber, G. Miiller, Angew. Chem. 99 (1987) 248; Angew Chem. lnt. Ed. Engl. 26 (1987) 234; H. Schmidbaur, R. Nowak. B. Huber, G. Miiller, Orgonomerdhcs 6 (1987) 2266.

[4] H. Schmidbaur, R. Nowak, A. Schier, J. M. Wallis, B. Huber, G. Miiller, Chem. Ber. 120 (1987) 1829; H. Schmidbaur, R. Nowak, J. M. Wallis, B. Huber, G. Miilier, ibid. f20 (1987) 1837; H. Schmidbaur, R. Nowak, 0. Steigelmann. G. Miiller, ibid. 122 (1990) 19, and references cited therein.

[5] M. Uson-Finkenzeller, W. Bublak, B. Huber, G. Miiller, H. Schmidbaur. Z . Naturforsch. 84f (1986) 346.

161 H. Schmidbaur, R. Nowak, B. Huber, G. Muiler, Z . Narurforsch.B43 (1988) 1447; H. Schmidbaur, R. Nowak, B. Huber, G. Miiller. Polyhedron 9 (1990) 283.

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181 H. Schmidbaur, W. Bublak, B. Hlrber, G. Miiller, OrganomefaNicsS (1986) 1647; Helo. Chim. Acta 69 (1986) 1742; Z . Naturjorsch. B42 (1987) 147.

[9] H. Schmidbaur, W. Bublak, B. Huber, J. Hofmann. G. Miiller, Chem. Ber. 122 (1989) 265.

[lo] H. Schmidbaur, R. Hager. B. Huber, G. Muller, Angew. Chem. 99 (1987) 354; Angew Chem. Int. Ed. Engl. 26 (1987) 338.

[ l l ] 1: Crystal data: C,,H,,AI,CI,Sn, M , = 885 91, monoclinic, space group P2,/n, a = 17.431(3), b = 12.738(3), c = 17.617(3) A , p = 99.86(1)", V =

3853.8 Z = 4, = 1.527 gcm-3, ~(Mo,.) = 7.8Scm-', F(OO0) = 1280 e, Syntex P2, diffractometer, Mo,, radiation, i. = 0.71069 A, T = -5O"C, 5990 independent reflections to (sinO/%)max = 0.572 k', 4520 observed with F, 2 4.00(F,). R(R,) = 0.051(0.045), w = l/u2(F,), [397 refined parameters, anisotropic, H fixed (21 located, 12 calculated)], (A.er,, = +1.10/-1 69 e k ' ) . 3: C,,H,,AI,CI,,Ge,O,, M , = 1647.92, monoclinic, space group P2,/c, a = 12.878(1), b = 12.207(1), c = 24.529(2) A, P = 96.97(1)", V = 3827.5 A3, 2 = 2, e..,.d = 1.430 gcm-', p(MoK.) = 12.84 cm- I , F(000) = 1680 e, Syntex P2, diffractometer, Mo,, radiation, 7. = 0.71069 A, T = -5O"C, 6000 independent reflections to (sin 8/j.)msx = 0.572 ki , 4665 observed with Fo t 4.00(F0). empirical ab- sorption correction (T = 0.71 -1.00). R(R,) = 0.060(0.068), w = 1/u2(F,) [415 refined parameters, anisotropic, H calculated at ideal geometrical positions (fixed with V,,, = 0.05 A')], (Aef,, = +0.59/-0.62ek3). Fur- ther information on the X-ray structure determinations can be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wis- senschaftlich-technische Information GmbH, W-7514 Eggenstein-Leo- poldshafen 2 (FRG), on quoting the dispository number CSD-54757, the names of the authors, and the journal citation.

1121 U. Thewalt, F. Stollmaier, Angew. Chem. 94(1982) 137; Angew. Chem. In[. Ed. Engl. 21 (1982) 133.

1131 C. Cohen-Addad, P. Baret, P. Cheautemps, J.-L. Pierre, Acta CrystaNogr. Sect. C 39 (1983) 1346.

[14] C. Elschenbroich, J. Schneider, M. Wiinsch, J.-L. Pierre, P. Baret, P. Cheautemps, Chem. Ber. f21 (1988) 177.

1398 VCH Verlag.~geseIlsrhaf~ mbH, W-6940 Weinheim, 1990 0570-0833/90/1212-1398 S 3.50+ .25/0 Angew. Chem. Inr. Ed. Engl. 29 (1990) No. f2