Syntheses of Group 4 ansa‐Trovacene Complexes and Conversion of [1]Silatrovacenophanes into Paramagnetic Metallopolymers by Ring‐Opening Polymerization

Abstract

An improved protocol for the selective dilithiation of [V(η(5)-C(5)H(5))(η(7)-C(7)H(7))] has been developed, which afforded [V(η(5)-C(5)H(4)Li)(η(7)-C(7)H(6)Li)]·PMDTA (5; PMDTA=N,N,N',N'',N''-pentamethyldiethylenetriamine) in almost quantitative yield (98%). In the solid state, the species features a dimeric structure with two terminal and two bridging lithium atoms, with the latter connecting both sandwich subunits. Reaction with suitable Group 4 dihalide compounds enabled the isolation of highly strained silicon- and germanium-bridged [1]trovacenophanes 6 and 7. Similarly, reaction of 5 with Cl(2)Sn(2)tBu(4) afforded the rather unstrained complex [V(η(5)-C(5)H(4))(η(7)-C(7)H(6))Sn(2)tBu(4)] (8), which together with 7 represent the first trovacenophanes to incorporate heavier analogues of silicon in the ansa-bridge. Ring-opening polymerization reactions of [V(η(5)-C(5)H(4))(η(7)-C(7)H(6))SiRR'] (2a: R=R'=Me; 6: R=Me, R'=iPr) were performed by heating in a solution of toluene in the presence of the Karstedt catalyst, which resulted in the formation of the corresponding soluble poly(trovacenylsilanes) in yields of 41 and 33%, respectively. As estimated by gel permeation chromatography (GPC), the macromolecules possess molecular weights of M(n)=10,010 and 5580 g mol(-1) with polydispersity indices of 2.31 and 1.64 for 9 and 10, respectively. ESR spectroscopic studies on 9 and 10 revealed only a single broad resonance in each case without any identifiable (51)V hyperfine coupling.

Ansa‐Complexes of [Mn(η5‐C5H5)(η6‐C6H6)]: Preparation, Characterization, and Reactivity of [n]Manganoarenophanes (n=1, 2, 3)

“…After workup, 1 was obtained as an analytically pure, highly oxygen-and moisturesensitives olid in modest yields (56 %, Scheme 1). The 1 HNMR resonances of the Cp and benzene ligands appear as characteristic multipletsa td = 4.27 and 4.34 ppm and d = 4.86, 5.03, and 5.24 ppm, respectively.T wo different resonances were obtained for the chemically inequivalent 11 Bc enters,a sw ell as for the tBu and SiMe 3 groups in the 1 HNMR spectrum,i na greement with the 1,1'-disubstitution pattern. Moreover,t he data indicatet hat only one of the possible B=Nd ouble-bondi somers is formed.…”

“…[34] However, the non-selective Pt 0 insertion contrasts the oxidative addition mechanism of other heteroleptic sandwich systems with larger differences in the size of their ring systems, such as the ansa derivatives of [Ti(h 5 -C 5 H 5 )(h 7 -C 7 H 7 )] or [V(h 5 -C 5 H 5 )(h 7 -C 7 H 7 )]. [4,11,12] In this case, the insertion of the platinum moiety occursr egioselectively into the C ipso -element (E) bond of the larger hydrocarbon ring.…”

“…[1][2][3] Typically,t he incorporation of the bridge to give such ansa-complexesi sa chievedb y salt elimination of dilithiated sandwich compounds with appropriate element dihalides. Examples include the preparation of metalloarenophanes derived from [M(h 5 -C 5 H 5 )(h 7 -C 7 H 7 )],t hat is, troticene (M = Ti), [3][4][5][6][7][8] trovacene( M= V), [9][10][11][12] and trochrocene (M = Cr), [13][14][15][16] [Ti(h 5 -C 5 H 5 )(h 8 -C 8 H 8 )] [17] or [Co(h 4 -C 4 Me 4 )(h 5 -C 5 H 5 )]. [18] Reactivity studies on these metalloarenophanes revealed their potential for further transformations, such as ringopeningp olymerization [7,[10][11][12] to produce metallopolymers or the functionalization of unsaturated organic substrates.…”

“…Examples include the preparation of metalloarenophanes derived from [M(h 5 -C 5 H 5 )(h 7 -C 7 H 7 )],t hat is, troticene (M = Ti), [3][4][5][6][7][8] trovacene( M= V), [9][10][11][12] and trochrocene (M = Cr), [13][14][15][16] [Ti(h 5 -C 5 H 5 )(h 8 -C 8 H 8 )] [17] or [Co(h 4 -C 4 Me 4 )(h 5 -C 5 H 5 )]. [18] Reactivity studies on these metalloarenophanes revealed their potential for further transformations, such as ringopeningp olymerization [7,[10][11][12] to produce metallopolymers or the functionalization of unsaturated organic substrates. [19][20][21][22][23][24][25][26][27][28] Herein, we focus on the manganese-containing complex [Mn(h 5 -C 5 H 5 )(h 6 -C 6 H 6 )],w hichi si soelectronic to ferrocene.…”

Sandwich Complex‐Containing Macromolecules: Property Tunability Through Versatile Synthesis

“…Over the decades, advances in synthetic chemistry resulted in the preparation of various polymerizable sandwich complexes in addition to ferrocene. Indeed, polymers containing sandwich complexes of hafnium, zirconium, vanadium, chromium, cobalt, titanium, and ruthenium have been reported.…”