Group 12 Metal–Metal Bonds

Wu, Xian; Harder, Sjoerd

doi:10.1002/9783527673353.ch12

Cited by 6 publications

(6 citation statements)

References 93 publications

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“…Group 12 metal−metal bonds have been reviewed by Wu and Harder. 547 Zinc is known to form Zn−Zn covalently bonded molecules, mostly in its Zn + oxidation state, while the Zn(0) oxidation state is present in the Zn 2 dimer. A rough idea of the possible length for a Zn−Zn single bond may be obtained from twice the covalent radius of 1.22 Å assigned to zinc 41 (i.e., a value of about 2.44 Å).…”

Section: Zinc−zinc Bondsmentioning

confidence: 99%

Metal–Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc

2018

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This survey of metal–metal (MM) bond distances in binuclear complexes of the first row 3d-block elements reviews experimental and computational research on a wide range of such systems. The metals surveyed are titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc, representing the only comprehensive presentation of such results to date. Factors impacting MM bond lengths that are discussed here include (a) the formal MM bond order, (b) size of the metal ion present in the bimetallic core (M2) n+, (c) the metal oxidation state, (d) effects of ligand basicity, coordination mode and number, and (e) steric effects of bulky ligands. Correlations between experimental and computational findings are examined wherever possible, often yielding good agreement for MM bond lengths. The formal bond order provides a key basis for assessing experimental and computationally derived MM bond lengths. The effects of change in the metal upon MM bond length ranges in binuclear complexes suggest trends for single, double, triple, and quadruple MM bonds which are related to the available information on metal atomic radii. It emerges that while specific factors for a limited range of complexes are found to have their expected impact in many cases, the assessment of the net effect of these factors is challenging. The combination of experimental and computational results leads us to propose for the first time the ranges and “best” estimates for MM bond distances of all types (Ti–Ti through Zn–Zn, single through quintuple).

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Section: Zinc−zinc Bondsmentioning

confidence: 99%

Metal–Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc

2018

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“…The creation of new reactivities by metal mixing also entered the field of metal–metal bonding. [ 19 , 20 , 21 , 22 ] The unique reactivity of homometallic, low‐valent main group metal complexes can be further enriched by heterobimetallic metal–metal bound complexes. A most recent example represents the introduction of R 2 Al‐K reagents[ 23 , 24 , 25 , 26 , 27 , 28 , 29 ] which based on the metal's electronegativity differences should be classified as R 2 Al − K + reagents with nucleophilic aluminyl units (e.g.…”

Section: Introductionmentioning

confidence: 99%

Cationic Heterobimetallic Mg(Zn)/Al(Ga) Combinations for Cooperative C–F Bond Cleavage

et al. 2021

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Low-valent ( Me BDI)Al and ( Me BDI)Ga and highly Lewis acidic cations in [( tBu BDI)M + •C 6 H 6 ][(B(C 6 F 5 ) 4 À ]( M= Mg or Zn, Me BDI = HC[C(Me)N-DIPP] 2 , tBu BDI = HC[C-(tBu)N-DIPP] 2 ,D IPP = 2,6-diisopropylphenyl) react to heterobimetallic cations [( tBu BDI)Mg-Al( Me BDI) + ], [( tBu BDI)Mg-Ga( Me BDI) + ]a nd [( tBu BDI)Zn-Ga( Me BDI) + ]. These cations feature long Mg-Al (or Ga) bonds while the Zn-Ga bond is short. The [( tBu BDI)Zn-Al( Me BDI) + ]c ation was not formed. Combined AIM and charge calculations suggest that the metal-metal bonds to Zn are considerably more covalent, whereas those to Mg should be described as weak Al I (or Ga I )!Mg 2+ donor bonds.F ailure to isolate the Zn-Al combination originates from cleavage of the C À Fb ond in the solvent fluorobenzene to give ( tBu BDI)ZnPh and ( Me BDI)AlF + which is extremely Lewis acidic and was not observed, but ( Me BDI)Al(F)-(m-F)-(F)Al( Me BDI) + was verified by X-ray diffraction. DFT calculations show that the remarkably facile C-F bond cleavage follows adearomatization/rearomatization route.

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“…The 18electron rule has been used for assigning plausible metal−metal bond order (BO) values to hundreds of binuclear complexes studied using DFT. 3 The problem here lies in that, all too often, the ideal (18,18) population for the electrons around each metal center is not attained, with populations like (17,17), (18,16), or even (14,14) appearing in many cases. Application of the 18-electron rule to the paddlewheel type complexes studied here often leads to Co−Co BO values which are clearly not possible.…”

Section: Methodology and Approachmentioning

confidence: 99%

“…4 Metal−metal bonds of multiple order are less common for first row transition metals except chromium and vanadium. Among the 3d-block metals, homobinuclear complexes with metal−metal bonds are known for titanium, 5−8 chromium, 9,10 manganese, 11 iron, 12,13 cobalt, 12,14 nickel, 15,16 copper, 17 and zinc, 18,19 with formal metal−metal bond orders from 1 to 5, as described in a recent review. 3 The term "lantern" or "paddlewheel-type" refers to complexes having an array of two, three, or four bridging bidentate ligands around a bimetallic core with each ligand binding atom being bonded to one of the atoms of the bimetallic core.…”

Section: Introductionmentioning

confidence: 99%

“…Metal–metal bonds of multiple order are less common for first row transition metals except chromium and vanadium. Among the 3d-block metals, homobinuclear complexes with metal–metal bonds are known for titanium, − chromium, , manganese, iron, , cobalt, , nickel, , copper, and zinc, , with formal metal–metal bond orders from 1 to 5, as described in a recent review…”

Section: Introductionmentioning

confidence: 99%

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Binuclear Cobalt Paddlewheel-Type Complexes: Relating Metal–Metal Bond Lengths to Formal Bond Orders

et al. 2020

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Paddlewheel-type complexes are prominent among experimentally known binuclear cobalt complexes and incorporate substituted formamidinate, guanidinate, and carboxylate ligands in digonal, trigonal, and tetragonal arrays around the bimetallic core. Such complexes are modeled here by density functional theory using unsubstituted ligands, extending the whole set to incorporate a variety of metal oxidation states and spin multiplicities. The DFT results for ground state cobalt–cobalt bond lengths and ground state spin multiplicity of the model complexes are often quite close to the experimental results for the corresponding substituted complexes. The three series of complexes often exhibit parallel trends with regard to effects of change in the metal oxidation state and spin multiplicity. The formamidinate and guanidinate series show marked resemblances. The lowered symmetry in many model trigonal complexes implies that such deviations in the experimentally known congeners arise from the inherent electronic structure. For ground state species, the DFT results provide Co–Co bond orders (BOs) from MO occupancy considerations. Further, using a revised electron bookkeeping method, Co–Co formal bond order (fBO) values from 0.0 to 2.0 are assigned to all of the 85 complexes studied. The computed Co–Co bond lengths fall into distinct ranges according to the formal bond order values (from 0.5 to 2)

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Group 12 Metal–Metal Bonds

Cited by 6 publications

References 93 publications

Metal–Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc

Metal–Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc

Cationic Heterobimetallic Mg(Zn)/Al(Ga) Combinations for Cooperative C–F Bond Cleavage

Binuclear Cobalt Paddlewheel-Type Complexes: Relating Metal–Metal Bond Lengths to Formal Bond Orders

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