Influence of the Bridging Group of Cross-Conjugated Nitrogenous Bases on the Spectra and Structure of Solvatochromic Mixed-Ligand Copper(II) Chelates Containing β-Ketoenols

Abstract

The concomitant reaction of copper(II) with a heterocyclic nitrogenous cross-conjugated Lewis base (2,2′-dipyridyl ketone, dpk, or 2,2′-dipyridylamine, dpamH) and the anion of a 2-substituted 1,3-dione, β -, e.g. X-acac -(X ) H, Me, Cl, CN, NO 2 ) affords mixed-ligand chelates. The composition and structure of the chelates depend on the group linking the pyridyl rings. Chelation renders the 2,2′-dipyridyl ketone susceptible to nucleophilic attack by protic molecules. It also depends on the group attached to the β-dionato moiety since electron attracting substituents facilitate ligation of a water molecule when the 2,2′-dipyridylamine is present. Spectroscopic observations indicated square pyramidal or distorted tetragonal stereochemistries of the ensuing mixed-ligand chelates with the carbonyl oxygens and the pyridyl nitrogens forming the basal plane. Confirmation was acquired by X-ray structure determination of representative chelates. The compound [Cu(NC-acac)dpamH(H 2 O) OClO 3 ] crystallizes in the Pnma space group with Z ) 8 (i.e. four molecules per cell), a ) 17.996(1) Å, b ) 13.972(1) Å, c ) 7.801(1) Å. The copper atom is 2.401(3) Å from the oxygen of the water molecule and 2.60(2) Å from an oxygen atom of the ClO 4group. The chelate [Cu(NC-acac)dpC(OH)OCH 3 (OClO 3 ), resulting from the addition of methanol to the carbon atom bridging the pyridyl rings, crystallizes in the P2 1 /n space group with a ) 10.661-(1) Å, b ) 14.987(2) Å, c ) 13.963(1) Å, β ) 110.57(3)°, Z ) 4. An oxygen of the ClO 4group is in apical position, and it is 2.634(8) Å from the copper atom. The etheric oxygen is distanced 2.615(2) Å from the copper atom, and the O-Cu-O angle of these weak bonds is only 154.4(2)°. In these chelates the nitrogenous bases adopt the boat conformation with the pyridyl rings forming dihedral angles of approximately 33°.

Crystal structure of bis((pyridyl)amino-iodobenzeno)disulfatodicopper(II) methanol disolvate, Cu2(C16H12IN3)2(SO4)2 · 2CH3OH

“…The finalc oordination mode of each oxy-dianion is tridentate.The Cu1···Cu1adistance is 4.539(1) Å showing no interaction betweenthem. The bond distances and the bite angle of Ibdpamaswell asthe remaining coordination distances and angles are similartothose found for other analogous copper complexes [5][6][7][8][9][10][11]. The square pyramidalbase is formed from N1, N2, O1and O2atoms,while the axialposition is occupied by O3a.The atoms forming the basalplane practically present no deviation from the planarity (smaller or equalt hant he e.s.d.).…”

Crystal structure of bis((pyridyl)ammo-iodobenzeno)disulfatodicopper(II) methanol disolvate, Cu2(C16H12IN3)2(SO4)2 · 2CH3OH

“…The Cul-Cula distance is 4.539(1) Ä showing no interaction between them. The bond distances and the bite angle of Ibdpam as well as the remaining coordination distances and angles are similar to those found for other analogous copper complexes [5][6][7][8][9][10][11]. The square pyramidal base is formed from Nl, N2, Ol and 02 atoms, while the axial position is occupied by 03a.…”

Synthesis and characterization of copper(II) chelate with a new substituted bis(2-pyridyl)-amine derivative

“…One more water molecule per complex fulfils the formed unit cell. The bond distances and the band angle of Ipdpam as well as the rest coordination distances and angles are similar to those found at other analogous copper complexes [11][12][13][14][15][16][17][18][19][20][21][22][23][24]33]. Figure 1, presents the clinographic projection of title compound with displacement ellipsoids drawn at the 50% probability level, produced with the CAMERON program [34].…”