Treatment of the ditopic phenylene-bridged bis(pyrazol-1-yl)borate K2[m-C6H4(B(tBu)pz2)2] (m-1) with [Mn(CO)5Br] results in ligand degradation with formation of the pyrazabole-bridged macrocyclic dimer {m-C6H4(B(tBu)pz)2}2 (2) and the triply pyrazolide-bridged dinuclear complex K[(OC)3Mn(μ-pz)3Mn(CO)3] (3). Even though the Ph-substituted scorpionate ligands Li2[m-C6H4(B(Ph)pz2)2] and Li2[p-C6H4(B(Ph)pz2)2] (m-5, p-5) possess a significantly higher hydrolytic stability than m-1, their reaction with [Mn(CO)5Br] also leads to B−N bond cleavage and gives the 3-type complex Li[(OC)3Mn(μ-pz)2(μ-Br)Mn(CO)3] (6). When, however, the corresponding tris(pyrazol-1-yl)borate ligands Li2[m-C6H4(Bpz3)2] and Li2[p-C6H4(Bpz3)2] (m-8, p-8) are employed, the clean formation of dinuclear Mn(CO)3 complexes Li2[m-C6H4(Bpz3Mn(CO)3)2] and Li2[p-C6H4(Bpz3Mn(CO)3)2] (m-11, p-11) is observed. The same is true for the novel tritopic scorpionate Li3[1,3,5-C6H3(Bpz3)3] (10), which gives ready access to the trinuclear Mn(CO)3 complex [1,3,5-C6H3(Bpz3Mn(CO)3)3] (12).

Rare examples of heteroditopic scorpionate ligands [m-(pz(HO)BtBu)(pz2BtBu)C6H4]2- ([m]2-) and [p-(pz(HO)BtBu)(pz2BtBu)C6H4]2- ([p]2-) are reported. As a unique feature, both ligands possess a chiral boron centre. Treatment of [m]2- and [p]2- with FeII and CoII ions, respectively, gives the dinuclear metallomacrocycles [FeII2(micro-m)2] and [CoII2(micro-p)2]. The molecular structures of the colourless complex [FeII2(micro-m)2] and the red-purple complex [CoII2(micro-p)2] have been determined by X-ray crystallography. To meet the geometric requirements of macrocycle formation, the two asymmetric boron centres have opposite absolute configurations in the case of [FeII2(micro-m)2] and the same configuration in [CoII2(micro-p)2].

The synthesis and characterization of the ditopic bis(pyrazol‐1‐yl)borate ligand Li2[p‐C6H4(B(C6F5)pz2)2] is reported (pz = pyrazol‐1‐yl). Compared to the corresponding t‐butyl derivative Li2[p‐C6H4(B(t‐Bu)pz2)2], the C6F5‐substituted scorpionate is significantly more stable towards hydrolysis. Reaction of Li2[p‐C6H4(B(C6F5)pz2)2] with two equivalents of MnCl2 leads to the formation of coordination polymers {(MnCl2)2(Li(THF)3)2[p‐C6H4(B(C6F5)pz2)2]}∞ featuring penta‐coordinate MnII ions chelated by one bis(pyrazol‐1‐yl)borate fragment and further bonded to three chloride ions. Two of the three chloride ions are also coordinated to a neighbouring MnII ion; the third chloro ligand is shared between the MnII centre and a Li(THF)3 moiety.

The synthesis and full characterization of the sterically demanding ditopic lithium bis(pyrazol‐1‐yl)borates Li2[p‐C6H4(B(Ph)pzR2)2] is reported (pzR = 3‐phenylpyrazol‐1‐yl (3Ph), 3‐t‐butylpyrazol‐1‐yl (3tBu)). Compound 3Ph crystallizes from THF as THF‐adduct 3Ph(THF)4 which features a straight conformation with a long Li···Li distance of 12.68(1) Å. Compound 3tBu was found to function as efficient and selective scavenger of chloride ions. In the presence of LiCl it forms anionic complexes [3tBuCl]− with a central Li‐Cl‐Li core (Li···Li = 3.75(1) Å).

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