From Heptacoordinated Cr III Complexes with Cyanide or Isothiocyanate Apical Groups to 1D Heterometallic Assemblages with All‐Pentagonal‐Bipyramid Coordination Geometries

A series of heptacoordinated Cr III complexes with either cyano or thiocyanato ligands in the apical positions are described and their ability to act as metallo‐ligands is illustrated. These compounds contain a pentadentate ligand, H 2 L N3O2R [H 2 L N3O2R = 2,6‐diacetylpyridinebis(benzoylhydrazone) for R = Ph, 2,6‐diacetylpyridinebis(4‐biphenylylcarbonylhydrazone) for R = biPh], chelated in the equatorial positions of the Cr metal center, thus imposing a bipyramidal‐pentagonal geometry on the complexes. The two axial water molecules of the precursor complexes [Cr(HL N3O2Ph )(H 2 O) 2 ](NO 3 ) 2 ( 1 ) and [Cr(HL N3O2biPh )(H 2 O) 2 ](NO 3 ) 2 ( 2 ) were easily exchanged with coordinating substituents such as CN – or NCS – to yield K[Cr(L N3O2Ph )(CN) 2 ] ( 3 ), K[Cr(L N3O2biPh )(CN) 2 ] ( 4 ), and [Cr(HL N3O2Ph )(NCS) 2 ] ( 5 ). The reaction of 3 with Mn II complexes [Mn(L N5 )(H 2 O) 2 ]Cl 2 and [Mn(L N5 R , R )Cl 2 ] (L N5 and L N5 RR represent macrocyclic pentadentate ligands: L N5 = 2,13‐dimethyl‐3,6,9,12,18‐pentaazabicyclo[12.3.1]octadeca‐1(18),2,12,14,16‐pentaene, and L N5RR = 2,21‐dimethyl‐(4 R ,9 R ,14 R ,‐19 R )‐3,10,13,20,26‐pentaazatetracyclo[20.3.1.0 4,9 .0 14,19 ]hexacosa‐1(26),22(23),24‐triene) yielded the 1D coordination polymers [Cr(L N3O2Ph )(CN) 2 Mn(L N5 )](PF 6 ) ( 6a,b ) and the chiral chain [Cr(L N3O2Ph )(CN) 2 Mn(L N5 R , R )](PF 6 ) 0.75 Cl 0.25 ( 7 ), which are constructed of only heptacoordinated metal centers. The assembly of 4 with [Mn(L N5 )(H 2 O) 2 ]Cl 2 gave the neutral trinuclear complex [{Cr(L N3O2biPh )(CN) 2 } 2 Mn(L N5 )] ( 8 ), whereas the association of 3 with the Ni II Schiff‐base complex [Ni(valpn)] [H 2 (valpn) = 1,3‐propanediylbis(2‐iminomethylene‐6‐methoxyphenol] led to the discrete compound K[Ni(valpn)Cr(L N3O2Ph )(CN) 2 ] ( 9 ). The crystal structures and magnetic properties of all the compounds are reported.