“…25 Recently, the free cyclopentadienyl/scorpionate hybrid ligands [(C 5 Me 4 H)B(pz prepared, but their ligand properties are still largely unexplored. 26,27 The purpose of this paper is to describe the synthesis and molecular structure of B-type Mn(CO) 2 complexes that are readily available from cymantrenylpoly(pyrazol-1-yl)borates (cf. A3, M ) K + ) by replacement of one CO ligand with a pyrazolyl nitrogen atom.…”
Section: Introductionmentioning
confidence: 99%
“…These are the multiple-decker sandwich complexes B1 (M = Li + −Cs + ) 21 and the samarium complex B2 , which forms in a unique rearrangement reaction upon thermolysis of the precursor compound Sm[HB(pz 3,5-Me ) 3 ] 2 (Cp) at 165 °C in the solid state , 1 Bridging ( A ) and chelating ( B ) coordination mode of cyclopentadienyl/poly(pyrazol-1-yl)borate hybrid ligands; representative examples A1 − B2 for which these coordination modes have been realized. B2 : CH 3 groups in the 3 and 5 positions of all pyrazolyl rings are omitted for clarity. …”
Rare examples of complexes featuring a chelating cyclopentadienyl/scorpionate hybrid ligand are reported. The compounds are obtained by photolytic decarbonylation of K[(OC) 3 Mn(C 5 H 4 -B(pz)(R)R′)] (1: R ) R′ ) Me; 2: R ) Me, R′ ) pz; 3: R ) R′ ) pz; pz ) pyrazol-1-yl), which leads to the constrained-geometry complexes K[(OC) 2 Mn(C 5 H 4 -B(µ-pz)(R)R′)] (4-6) in quantitative yields. In 4-6, the Mn-coordinating pyrazolyl ring is tethered to the cyclopentadienyl ligand via a borate bridge. According to X-ray crystallography, the molecular frameworks of 4-6 are largely unstrained. The ligand scaffold is thus well adapted to the coordination requirements of the Mn(I) ion. The crystal lattices of 2, 3, and Li[(OC) 3 Mn(C 5 H 4 -BPh 3 )] ( 7) contain dimeric aggregates held together by K + -OC σ adducts, K + -pz σ adducts, and K + -pz π interactions (2, 3) as well as Li + -OC σ adducts and Li + -phenyl π interactions (7). In none of these cases does the π-electron cloud of the cymantrenyl substituent take part in alkali metal ion complexation.
“…25 Recently, the free cyclopentadienyl/scorpionate hybrid ligands [(C 5 Me 4 H)B(pz prepared, but their ligand properties are still largely unexplored. 26,27 The purpose of this paper is to describe the synthesis and molecular structure of B-type Mn(CO) 2 complexes that are readily available from cymantrenylpoly(pyrazol-1-yl)borates (cf. A3, M ) K + ) by replacement of one CO ligand with a pyrazolyl nitrogen atom.…”
Section: Introductionmentioning
confidence: 99%
“…These are the multiple-decker sandwich complexes B1 (M = Li + −Cs + ) 21 and the samarium complex B2 , which forms in a unique rearrangement reaction upon thermolysis of the precursor compound Sm[HB(pz 3,5-Me ) 3 ] 2 (Cp) at 165 °C in the solid state , 1 Bridging ( A ) and chelating ( B ) coordination mode of cyclopentadienyl/poly(pyrazol-1-yl)borate hybrid ligands; representative examples A1 − B2 for which these coordination modes have been realized. B2 : CH 3 groups in the 3 and 5 positions of all pyrazolyl rings are omitted for clarity. …”
Rare examples of complexes featuring a chelating cyclopentadienyl/scorpionate hybrid ligand are reported. The compounds are obtained by photolytic decarbonylation of K[(OC) 3 Mn(C 5 H 4 -B(pz)(R)R′)] (1: R ) R′ ) Me; 2: R ) Me, R′ ) pz; 3: R ) R′ ) pz; pz ) pyrazol-1-yl), which leads to the constrained-geometry complexes K[(OC) 2 Mn(C 5 H 4 -B(µ-pz)(R)R′)] (4-6) in quantitative yields. In 4-6, the Mn-coordinating pyrazolyl ring is tethered to the cyclopentadienyl ligand via a borate bridge. According to X-ray crystallography, the molecular frameworks of 4-6 are largely unstrained. The ligand scaffold is thus well adapted to the coordination requirements of the Mn(I) ion. The crystal lattices of 2, 3, and Li[(OC) 3 Mn(C 5 H 4 -BPh 3 )] ( 7) contain dimeric aggregates held together by K + -OC σ adducts, K + -pz σ adducts, and K + -pz π interactions (2, 3) as well as Li + -OC σ adducts and Li + -phenyl π interactions (7). In none of these cases does the π-electron cloud of the cymantrenyl substituent take part in alkali metal ion complexation.
“…In summary, our results reveal that the bottom-up synthesis of ditopic cyclopentadienyl/scorpionate hybrid ligands [Cp R -Bpz R ′ 3 ] 2− via (substituted) cyclopentadienyl boranes , currently remains unrivaled and that the protective group approach using Mn(CO) 3 is not a superior option.…”
Section: Resultsmentioning
confidence: 94%
“…In order to overcome these limitations, facile routes to free cyclopentadienyl/scorpionate hybrids are required. Up to now, three examples are known in the literature: the tetramethylcyclopentadienyl derivative [C 5 Me 4 -Bpz Me 3 ] 2− and the fluorenyl derivatives [C 13 H 8 -Bpz R ′ 3 ] 2− (pz R ′ = pyrazolyl, 3- tert -butylpyrazolyl). , Here, the use of methylated and benzannulated cyclopentadienyl rings helped to circumvent the notorious problems associated with the propensity of C 5 H 5 -BX 2 intermediates to dimerize via Diels−Alder reactions …”
The ditopic 1,3-cymantrenediyl-bridged scorpionate K2[(OC)3Mn(C5H3(Bpz3)2)] (3) is available in three steps and good yields starting from cymantrene. Its THF adduct [3(THF)2]2 crystallizes in the form of macrocyclic dimers. Reaction of 3 with BrMn(CO)5 gives access to the trinuclear MnI complex [(OC)3Mn(C5H3(Bpz3Mn(CO)3)2)] (4). Irradiation of 3 in CD3CN for 30 min with a high-pressure mercury lamp (λmax = 510 nm) results in the liberation of one CO molecule and intramolecular Mn-pyrazolyl coordination (mono-ansa-complex K2[(OC)2Mn(C5H3(B(μ-pz)pz2)(Bpz3)]; 5). Upon further irradiation, 5 undergoes demetalation, and the free cyclopentadienyl/scorpionate hybrid ligand K2[C5H4(Bpz3)2] (7) can be isolated from the reaction mixture. 7 has been structurally characterized both as a THF adduct (coordination polymer [7a(THF)2]∞) and as a THF/18-crown-6 adduct (dimer [7a(18-c-6)(THF)2]2).
“…Tp Nt [243,244] [241,245] R' = t Bu, R =H: Tp BuPy [203] [88,252] [138] [268] [271] [189] [196] R = 4-Pyridyl: pz°Tp 4Py [196] 298 Tp Mementh [179] B N N N N N H N [183] B N N N N 300 (BBN)Bp +menth [183] B N N N N 301…”
This review is intended to cover the developments in the chemistry of poly(azolyl)borates through the years 2000-2008, based on the main synthetic methods, coordination properties, spectroscopic and structural features of this important class of ligands. The subject matter is the chemistry of substituted bis-, tris-and tetrakis-(pyrazolyl)borate ligands. In this review we provide essential information to allow the reader to probe more deeply into the main aspects of the chemistry of these fascinating and flexible ligands. This review would also demonstrate the enormous potential of poly(pyrazolyl)borates chemistry, as also the future perspectives in this field.
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