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Acetato-bis(pyrazole) complexes [Mo(η 3 -methallyl)(O 2 CMe)(CO) 2 (pz ∗ H) 2 ], (methallyl = CH 2 C(CH 3 )CH 2 ) and fac -[M(O 2 CMe)(CO) 3 (pz ∗ H) 2 ], (pz ∗ H = pyrazole or 3,5-dimethylpyrazole, dmpzH; M = Mn, Re) are obtained from [Mo(η 3 -methallyl)Cl(CO) 2 (NCMe) 2 ] or fac -[MBr(CO) 3 (NCMe) 2 ] [M = Mn (synthesized in situ ), Re], 2 equiv. of pyrazole, and 1 equiv. of sodium acetate for Mo complexes, or silver acetate for Mn or Re complexes. The chlorido-complexes [Mo(η 3 -methallyl)Cl(CO) 2 L 2 ] (L = pzH, dmpzH), obtained from the same starting material by substitution of MeCN by pzH or dmpzH, are also described. The crystal structures of the fac -acetato-bis(dimethylpyrazole) complexes present the same pattern of intramolecular hydrogen bonds between the acetate and the dimetylpyrazole ligands, whereas the crystal structures of the fac -acetato-bis(pyrazole) complexes show different hydrogen bonds patterns, with intermolecular interactions. NMR data indicate that these interactions are not maintained in solution.

The reactions of fac-[MnBr(CO)3(NH C(CH3)pz∗-κ2N,N)] (pz∗ = pz, dmpz; pzH = pyrazole; dmpzH = 3,5-dimethylpyrazole) with wet AgBF4 in a 1:1 ratio lead to the cationic pyrazolylamidino complexes fac-[Mn(OH2)(CO)3(NH C(CH3)pz∗-κ2N,N)]BF4. The aquo ligand is readily substituted by 2,6-xylylisocyanide (CNXyl) to give fac-[Mn(CNXyl)(CO)3(NH C(CH3)pz∗-κ2N,N)]BF4. The pyrazole complexes fac-[Mn(pz∗H)(CO)3(NH C(CH3)pz∗-κ2N,N)]BF4 are obtained by treating fac-[MnBr(CO)3(NCMe)2] with AgBF4 and then with pyrazole (pzH or dmpzH), in a 1:1:2 ratio. A similar reaction using 1:1:1 ratio and AgClO4 leads to the acetonitrile complexes fac-[Mn(NCMe)(CO)3(NH C(CH3)pz∗-κ2N,N)]ClO4. The X-ray structures of the complexes show moderate hydrogen bonds interactions between the N-bond hydrogen of the pyrazolylamidino ligand and the anion. In the aquo complex, one of the hydrogens of the coordinated water molecule is also involved in a hydrogen bond.

An alternative synthesis of (±)-4-ethynyl[2.2]paracyclophane (PCP C CH) (5) and 4,16-diethynyl[2.2]paracyclophane (6) via the Corey–Fuchs reaction has been developed. The olefinic intermediate 4-dibromovinyl[2.2]paracyclophane (3) has been isolated and structurally characterized. The racemic terminal alkyne 5 was employed as starting material for assembling of a luminescent extended π-conjugated system containing a thiophene unit and for a catalytic bis-silylation reaction yielding the olefinic dithioether Z-PhSCH2Me2SiC(H) C(PCP)SiMe2CH2SPh (9). The dimetallatetrahedran [Co2(CO)6(μ-η2–PCP–CCH)] (10) has been prepared and its crystal structure determined by an X-ray diffraction analysis. Alkyne 5 has also been used for the preparation of the Pt(0) complex [Pt(PPh3)2(PCP C CH)] (11) and the heterodinuclear dimetallacyclopentenone [(OC)2Fe{μ C( O)C(PCP) C(H)}(μ-dppm)Pt(PPh3)] (12). The synthesis and reactivity of 4-isocyano[2.2]paracyclophane (15) towards heterobimetallic iron–platinum and palladium–platinum complexes is also presented. Opening of the dative iron → platinum bond of [(OC)4Fe(μ-dppm)PtCl2] (16) occurred upon addition of 15 to a CH2Cl2 solution of 16 leading to [(OC)4Fe{μ-dppm}PtCl2(C N PCP)] (17). Treatment of [ClPd(μ-dppm)2PtCl] (18) with isocyanide 15 in a 1:1 ratio affords the A-frame compound [ClPd(μ-dppm)2(μ-C N PCP)PtCl] (19), resulting from formal insertion of 15 into the Pd–Pt bond. Addition of 2 equiv. of 15–18 leads to the ionic A-frame compound [ClPd(μ-dppm)2(μ-C N PCP)Pt(C N PCP)]Cl (20).

The reactions of [Mo(CO)4(NBD)] with two equivalents of Hpz (pyrazole) or Hdmpz (3,5-dimethylpyrazole) in hexane lead to the precipitation of cis-[Mo(CO)4(Hpz)2] or cis-[Mo(CO)4(Hdmpz)2], which are the first pyrazole complexes of molybdenum(0). In the solid state structure of cis-[Mo(CO)4(Hdmpz)2], two molecules are self-assembled by intermolecular hydrogen bonds between the N-bound hydrogen of one Hdmpz ligand and a oxygen atom of a carbonyl group. This explains the lack of planarity observed for the nitrogen donor atom of the Hdmpz involved in the intermolecular interaction. The complexes are unstable in solution and as solids.