Bi- and oligometallic early and late transition metal complexes based on alkynyl-titanocenes and related species spanned by carbon rich π-systems

doi:10.1016/S0022-328X(01)01288-8

Journal of Organometallic Chemistry

Volume 641, Issues 1–2, 4 January 2002, Pages 41-52

https://doi.org/10.1016/S0022-328X(01)01288-8 Get rights and content

Abstract

The synthesis and reaction chemistry of bi- and oligometallic transition metal complexes containing Groups 4, 8, 10 as well as 11 metal atoms are presented. The respective metals are thereby linked by carbon rich π-conjugated organic units, mainly σ- and π-bonded alkynyls. The structural aspects and electrochemical properties of the corresponding complexes will be discussed.

The synthesis and reaction chemistry of oligometallic transition metal species, featuring early and late metal atoms which are bridged by organic as well as inorganic π-systems is discussed. The electrochemical behavior of such species is presented.

Introduction

Since the early work of Creutz and Taube [1], there is a rapidly growing interest in the synthesis, chemical and physical properties of homo- and heterodinuclear species in which a π-conjugated organic ligand spans the two transition metal atoms [2], [3], [4].

Meanwhile, a series of redox-active model compounds have been synthesized, such as (η⁵-C₅Me₅)(dppe)FeCCCCFe(η⁵-C₅Me₅)(dppe) [5] and [(η⁵-C₅Me₅)(NO)(Ph₃P)ReCCCCCMn(η⁵-C₅H₅)(CO)₂]⁺ [6] in which a molecular wire consisting of an all-carbon C₄- or C₅-chain, bridges two metal centers giving rise to an electron coupling through five or six bonds.

Next to these late–late transition metal complexes, also a number of early–late species, e.g. (η⁵-C₅H₅)(Me₃P)₂RuCCZr(η⁵-C₅H₅)₂(Cl) [7] are known [8].

Extending the idea of connecting early and late transition metal building blocks from all-carbon units to other carbon-rich π-conjugated organic groups enables the synthesis of molecules of type (Me₃SiCH₂)[Ti]CCC₆H₄CN→[Ru]-1,4 {[Ti]=(η⁵-C₅H₅)₂Ti, (η⁵-C₅H₄SiMe₃)₂Ti, …, [Ru]=RuCl₂[C₆H₃N(CH₂NMe₂)₂-2,6]} [9]. Beside linear organic bridges based on σ-bonded alkynyls, also organometallic π-tweezers of type [Ti](CCR)₂ (R=singly bonded organic or organometallic unit) allow the synthesis of early–late transition metal complexes in which the respective metal atoms are linked by σ- and π-bound alkynyl groups [10], [10](a), [10](b), [10](c), [10](d), [10](e).

Thus, in this article we focus on the synthesis as well as the electrochemical behavior of early–late (Ti–M) and late–late (M–M′; M, M′=Groups 8, 10 and/or 11 transition metal atoms of the periodic table of elements) complexes, since such species are well-suited to study electronic communication between the corresponding metal centers. Despite the many homo- and heterometallic redox active (model) complexes known [2], [3], [4], [11], [12], [12](a), [12](b), [12](c), [12](d) we focus here on species which are mainly based on titanium–alkynyl fragments.

Section snippets

Synthesis and reaction chemistry

The heterobimetallic tweezer molecules {[Ti](CCR)₂}MX {[Ti]=(η⁵-C₅H₅)₂Ti, (η⁵-C₅H₄SiMe₃)₂Ti, …; M=Cu, Ag; R=SiMe₃, ^tBu, Ph, Fc, …; X=organic or inorganic ligand; Fc=(η⁵-C₅H₄)Fe(η⁵-C₅H₅)} can be successfully used as suitable starting materials for the preparation of diverse hetero-oligonuclear transition metal complexes [10], [10](a), [10](b), [10](c), [10](d), [10](e). In this respect, {[Ti](CCR)₂}CuCH₃ (1) (1a, R=SiMe₃; 1b, R=^tBu) [13], [13](a), [13](b) affords on its reaction with acidic

Acknowledgements

The creative contributions of Drs S. Back, R.A. Gossage, I. del Rio and K. Köhler as well as Dipl.-Chem. Wolfgang Frosch and Stefan Köcher are gratefully acknowledged. The financial support from the Deutsche Forschungsgemeinschaft, the Volkswagenstiftung, the Fonds der Chemischen Industrie and the Degussa-Hüls AG/Hanau has been essential throughout. For many fruitful discussions we are grateful to Professor Dr R. Holze (Chemnitt Technische Universität) and Professor Dr G. van Koten (University

References (44)

S. Back et al.
J. Organomet. Chem.
(1999)
H. Lang et al.
Coord. Chem. Rev.
(2000)
H. Lang et al.
J. Prakt. Chem.
(1999)
H. Lang et al.
Synlett
(1996)
H. Lang et al.
Coord. Chem. Rev.
(1995)
(e)Th. Stein, H. Lang, Abhath Al Yarmouk J. (2001), in...
M.D. Janssen et al.
Organometallics
(1995)
M.D. Janssen et al.
J. Am. Chem. Soc.
(1996)
N.D. Jones et al.
Organometallics
(1997)
J.-G. Rodrı́guez et al.
J. Organomet. Chem.
(1996)
Z. Yuan et al.
J. Organomet. Chem.
(1993)
T.S. Abram et al.
Synth. React. Inorg. Met.-Org. Chem.
(1976)
M. Rosenblum et al.
J. Organomet. Chem.
(1966)
K. Schlögl et al.
Monatsh. Chem.
(1963)
S. Back et al.
J. Organomet. Chem.
(2000)
W. Frosch et al.
J. Organomet. Chem.
(2000)
S. Back et al.
Organometallics
(1999)
W. Frosch et al.
Organometallics
(2000)
M.D. Janssen et al.
Organometallics
(1995)
M.D. Janssen et al.
J. Am. Chem. Soc.
(1996)
S.P. Gubin et al.
J. Organomet. Chem.
(1969)
N. El Murr et al.
J. Chem. Soc. Chem. Commun.
(1980)
J. Langmaier et al.
J. Organomet. Chem.
(1999)
C. Levanda et al.
J. Org. Chem.
(1976)
M. Herres, PhD Thesis, Universität Heidelberg,...

C. Creutz et al.

J. Am. Chem. Soc.

(1969)

See for example: (a) M.D. Ward, Chem. Soc. Rev. (1995) 121;(b) S. Barlow, D. O'Hare, Chem. Rev. 97 (1997) 637;(c) I.R....

For theoretical work on ligand-bridged metal systems also see: (a) D.R. Kanis, P.G. Lacroix, M.A. Ratner, T.J. Marks,...

For electronic communications between ligand-bridged metals also see: (a) C. Creutz, Prog. Inorg. Chem. 30 (1983) 1;(b)...

F. Coat et al.

Organometallics

(1996)

W. Weng et al.

J. Am. Chem. Soc.

(1993)

M.R. Bullock et al.

J. Am. Chem. Soc.

(1990)

For examples see: (a) Ti, Fe: H. Bürger, C. Kluess, J. Organomet. Chem. 56 (1973) 269;(b) Ti, Fe: G.A. Razuvaev, G.A....

T.M. Swager

Acc. Chem. Res.

(1998)

(a)W. Beck, B. Niemer, M. Wieser, Angew. Chem. 105 (1993) 969; Angew. Chem. Int. Ed. Engl. 32 (1993)...H. Lang

Angew. Chem.

(1994)

U.H.F. Bunz

Angew. Chem.

(1996)

(d)P. Siemsen, R.C. Livingston, F. Diedrich, Angew. Chem. 112 (2000) 2740; Angew. Chem. Int. Ed. Engl. 39 (2000)...

S. Back et al.

Inorg. Chem. Commun.

(1999)

W. Frosch et al.

J. Organomet. Chem.

(2000)

(c)W. Frosch, S. Back, H. Lang, J. Organomet. Chem. (2001), in...W. Frosch et al.

J. Organomet. Chem.

(2001)

W. Frosch, S. Back, G. Rheinwald, K. Köhler, H. Pritzkow, Organometallics (2000)...

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In this respect, consecutive treatment of 29 with 1-PPh2-4-HCC–C6H4 and [Au(tht)Cl] gave 1-[(η2-dppf)(η5-C5H5)RuCC]-4-(PPh2AuCl)-C6H4 (31). The latter compound was further reacted with alkynes carrying mono- or bidentate nitrogen-containing groups such as pyridyl or 2,2′-bipyridyl (Scheme 5; synthesis of 32 [18,19]; Scheme 6, 34 [19]) similar to the synthetic methodology reported by Vicente [20], however, best results were obtained by adding catalytic amounts of [CuI] [19]. Compounds 32 and 34, respectively, facilitate the addition of the organometallic π-tweezer {[Ti](µ-σ,π-CCSiMe3)2}MX (MX = Cu(NCMe)PF6, AgOClO3: preparation of 33a,b); MX = CuOTf: synthesis of 35) (Schemes 5 and 6).
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The molecular structure of 5 in the solid state were determined by single crystal X-ray diffraction analysis. In doubly alkynyl-bridged 5 the alkynides are bridging the metals Ti and Mo as a σ-donor to one metal and as a π-donor to the other with the [Ti](CCSiMe₃)₂Mo core being planar.
Alkynyl Ti-M complexes with M = Cd and Hg: Synthesis, characterization, and reaction chemistry
2011, Journal of Organometallic Chemistry
The synthesis and properties of heterobimetallic Ti–Cd complexes of type {[Ti](μ-η¹:η²–CCR)₂}CdX₂ ([Ti] = Ti(η⁵–C₅H₄SiMe₃)₂; R = SiMe₃: 3a, X = Cl; 3b, X = Br; 3c, X = I; R = Fc: 3d, X = Br; Fc = Fe(η⁵–C₅H₄)(η⁵–C₅H₅) is reported. These compounds were accessible by treatment of [Ti](CCR)₂ (1a, R = SiMe₃; 1b, R = Fc) with the cadmium salts CdX₂ (2a, X = Cl; 2b, X = Br; 2c, X = I) in a 1:1 M ratio in diethyl ether. Dissolving, for example, 3b in tetrahydrofuran afforded coordination polymer [Cd(μ-Br)₂(thf)₂]_n (4) along with the tweezer molecule 1a. Treatment of 3b with two equiv of LiCCFc (5) gave {[Ti](μ-η¹:η²–CCSiMe₃)₂}Cd(CCFc)₂ (6) which eliminated at ambient temperature the all-carbon buta-1,3-diyne FcCC–CCFc (7) producing 1a and elemental Cd. The same reaction behavior was observed, when 2b was reacted with 5. The thus obtained bis(alkynyl) cadmium complex Cd(CCFc)₂ (8) is redox-active at low temperature producing 7 and Cd(0). When mercury halides HgX₂ (9a, X = Cl; 9b, X = Br) are used, then the titanocene dihalides [Ti]X₂ (10a, X = Cl; 10b, X = Br) together with Me₃SiCC–CCSiMe₃ (11) and Hg(0) were formed. Nevertheless, mercury acetylides were available by treatment of Hg(OAc)₂ (12) with HCCFc (13) in a 1:2 M ratio. Thus obtained Hg(CCFc)₂ (14) gave with [CuBr] (15) coordination polymer [{Hg(η²-CCFc)₂}(Cu₂(μ-Br)₂]_n (16), while with [AgPF₆] oxidation of the ferrocenyl moieties took place affording dicationic [Hg(CCFc)₂]²⁺ (18).
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The cyclic voltammogram of 14 is reported showing a single reversible redox event at E⁰ = 0.108 V with ΔE_p = 76 mV indicating that there is no communication between the Fc termini along the mercury acetylide unit.
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The synthesis of acetylene, acyl–thiol and thiol end-capped titanium–copper π-tweezer complexes of the structural type {[Ti](μ-σ,π-CCR)₂}CuSC₆H₄-4-R′ ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; 3: R = SiMe₃, R′ = CCH; 5a: R = SiMe₃, R′ = SC(O)Me; 5b: R = ^tBu, R′ = SC(O)Me), {[Ti](μ-σ,π-CCSiMe₃)₂}CuSC₆H₄–C₆H₄-4-SH (7) and ({[Ti](μ-σ,π-CCR)₂}CuSC₆H₄)₂ (8) is described. Homobimetallic 3, 5a and 5b are accessible via the reaction of {[Ti](μ-σ,π-CCR)₂}CuMe (1a: R = SiMe₃, 1b: R = ^tBu) with stoichiometric amounts of Me(O)CS-1-C₆H₄-4-CCH (2) and C₆H₄-1,4-(SC(O)Me)₂ (4), respectively. Within these reactions the copper–sulfur bond formation is accompanied by the elimination of acetone. If 1a is treated with the dithiol (HS–C₆H₄)₂ (6) in a ratio of 1:1 or 2:1 than dinuclear 7 and tetranuclear 8 are produced upon formation of methane. Both types of reaction allow in a straightforward manner the synthesis of analytically pure samples in high yield. In addition, complex 8 is also formed, when equimolar amounts of 7 are reacted with1a.
The solid state structure of 5a is reported. This complex possesses a low-valent CuSC₆H₄-4-SC(O)Me entity with copper(I) in a planar surrounding. All other geometrical features are in agreement with the expected data relevant for Ti–Cu organometallic π-tweezer complexes.
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The solid state structure of 5 is reported. The crystal structure consists of two chemical identical crystallographic independent molecules. In 5 a four-coordinated copper(I) ion is present with the P(C₆H₄CH₂NMe₂-2)₃ ligand occupying three of the coordination sites, while the 4th site is occupied by the formate anion. One of the two formic acid molecules in 5 is thereby hydrogen-bonded to the CuO₂CH entity, while the second HCO₂H molecule forms a N⋯H hydrogen bridge with the non-coordinating ortho-substituent Me₂NCH₂.

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Bi- and oligometallic early and late transition metal complexes based on alkynyl-titanocenes and related species spanned by carbon rich π-systems

Abstract

Introduction

Section snippets

Synthesis and reaction chemistry

Acknowledgements

J. Organomet. Chem.

Coord. Chem. Rev.

J. Prakt. Chem.

Synlett

Coord. Chem. Rev.

Organometallics

J. Am. Chem. Soc.

Organometallics

J. Organomet. Chem.

J. Organomet. Chem.

Synth. React. Inorg. Met.-Org. Chem.

J. Organomet. Chem.

Monatsh. Chem.

J. Organomet. Chem.

J. Organomet. Chem.

Organometallics

Organometallics

Organometallics

J. Am. Chem. Soc.

J. Organomet. Chem.

J. Chem. Soc. Chem. Commun.

J. Organomet. Chem.

J. Org. Chem.

J. Am. Chem. Soc.

Organometallics

J. Am. Chem. Soc.

J. Am. Chem. Soc.

Acc. Chem. Res.

Angew. Chem.

Angew. Chem.

Inorg. Chem. Commun.

J. Organomet. Chem.

J. Organomet. Chem.