Heterodi- and Heterotrinuclear Complexes Containing Highly Polar Metal−Metal Bonds

Abstract

Reaction of the dichlorozirconium complex [CH2(CH2NSiMe3)2ZrCl2(thf)2] (1), containing a chelating amido ligand and having a trans disposition of the chloro ligands established by an X-ray diffraction study, with the carbonylmetalate derivatives K[MCp(CO)2] (Cp = C5H5) and Na[Co(CO)3(PPh3)] gave the heterotrinuclear complexes [CH2(CH2NSiMe3)2Zr{MCp(CO)2}2] (M = Fe (2), Ru (3)) and [CH2(CH2NSiMe3)2Zr{Co(CO)3(PPh3)}2] (4), respectively. Of these, 2 and 3 were structurally characterized by X-ray crystallography, establishing two unsupported metal−metal bonds in each of the compounds [2, d(Zr−Fe) = 2.665(2), 2.664(2) Å; 3, d(Zr−Ru) = 2.7372(7), 2.7452(7) Å]. Reaction of 2 and 3 with 1 in a 1:1 molar ratio led to a quantitative redistribution of complex fragments, yielding the dinuclear complexes [CH2(CH2NSiMe3)2(Cl)Zr−MCp(CO)2] (M = Fe (5), Ru (6). Both products as well as the Zr−Co complex [CH2(CH2NSiMe3)2(Cl)Zr−Co(CO)3(PPh3)] (7) were also obtained in moderate yields by reacting 1 with 1 molar equiv of the carbonylmetalate. Reacting 5−7 with NaCp gave the corresponding CpZr complexes [CH2(CH2NSiMe3)2(Cp)Zr−MCp(CO)2] (M = Fe (8), Ru (9)) and [CH2(CH2NSiMe3)2(Cp)Zr−Co(CO)3(PPh3)] (10), of which 9 was characterized by a single-crystal X-ray structure analysis [d(Zr−Ru) = 2.8297(14) Å]. Compounds 5, 6, 8, and 9 insert methyl isonitrile to give the heterobimetallic metallaiminoacylzirconium complexes [CH2(CH2NSiMe3)2(Cl)Zr{η2-C(NCH3)MCp(CO)2}] (M = Fe (11), Ru (12)) and [CH2(CH2NSiMe3)2(Cp)Zr{η2-C(NCH3)MCp(CO)2}] (M = Fe (13), Ru (14)), respectively. Reaction of the heterotrinuclear compounds 2 and 3 with isonitriles exclusively gave the products of the insertion into one of the unsupported metal−metal bonds, [CH2(CH2NSiMe3)2Zr{η2-C(NCH3)MCp(CO)2}{MCp(CO)2}] (M = Fe, R = Me, n Bu, Cy, Tol (15a−d); M = Ru, R = Me, n Bu, Cy, Tol (16a−d)). A crystal structure analysis of 16a established the insertion into one of the metal−metal bonds while the intact Zr−Ru bond was elongated in comparison to that of 3 [d(Zr−Ru) = 2.8639(6) Å]. Cleavage of both metal−metal bonds in 2 and 3 was observed in reactions with sulfoxides. Transfer of the S-bound oxygen atom to a carbonyl ligand led to CO2-linked trinuclear complexes in which the thioether thus generated was coordinated to the late transition metal center. The reaction at the two metal−metal bonds occurred cooperatively, precluding the isolation of intermediates.

[Me2Al(THF)2]+[{Me2Si(NDipp)2}2Zr2Cl5]- (Dipp = 2,6-Diisopropylphenyl), an Unusual Zirconium/Aluminum Ion Pair Containing a THF-Stabilized Dimethylaluminum Cation

“…However, reaction of 2 with 1 equiv of ZrCl 4 in THF provided, upon crystallization from toluene, the colorless zirconium dichloride complex 3 in high (80%) yield. Like the previously reported [{Me 2 Si( t -BuN) 2 }ZrCl 2 (THF) 2 ] and [CH 2 (CH 2 NSiMe 3 ) 2 ZrCl 2 (THF) 2 ], complex 3 contains two molecules of THF per zirconium center. 3 is robust in solution, and 1 H NMR studies undertaken in C 6 D 6 or d 8 -toluene indicate none of the partial loss or exchange of THF reported for [{Me 2 Si( t -BuN) 2 }ZrCl 2 (THF) 2 ] .…”

Preparation and physical properties of early-late heterobimetallic compounds featuring Ir–M bonds (M = Ti, Zr, Hf)

“…Such an assignment implies that Ir has a formal oxidation state of +1 and donates two electrons that form a polarized metal-metal bond. [66][67][68][69] This view of the bonding in 2-M is consistent with the reactivity of such species that typically behave as a nucleophilic Ir center acting cooperatively with a proximal Lewis acid. 35…”

Propargylic Substitution Reaction Catalyzed by Group IV (Ti, Zr, Hf)–Ru Heterobimetallic Complexes

“…As shown in Figures and , the configuration around the Ru center in both 6a and 7a adopts a three-legged piano stool coordination geometry, typical of coordinatively saturated cyclopentadienyl Ru(II) bis(phosphine) complexes . As for 6a , the interatomic distance between Zr and Ru atoms (3.9745(9) Å) is too long to draw a metal–metal single bond, where the chloride ligand bridges Zr and Ru atoms. The interatomic distance between Zr and Ru (4.9464(8) Å) in 7a is comparable to that of 1a (5.0017(4) Å), suggesting that there is also no metal–metal bond.…”