Crystal structure of tetrakis(5,7-dibromoquinolin-8-olato-κ2N,O)- hafnium(IV) dimethylformamide trisolvate, C45H37Br8HfN7O7
Zeitschrift für Kristallographie - New Crystal Structures
C 45 H 37 Br 8 HfN 7 O 7 , monoclinic, P2 1 /c (no. 14), a = 9.6002(5) Å, b = 38.598(2) Å, c = 13.6212(7) Å, b = 98.672(2)°, V = 4989.6 Å 3 , Z = 4, R gt (F) = 0.0333, wR ref (F 2 ) = 0.0728, T = 100 K. Source of material Chem i cals were pur chased from Sigma-Aldrich and used as received. Haf nium(IV)chlo ride (106.6 mg, 0.333 mmol) was dissolved in a min i mal amount of DMF. While stir ring this so lu tion at room tem per a ture, 5,7-dibromo-8-quinolinol (diCBrOxH) (392.7 mg, 1.297 mmol) was
... g, 1.297 mmol) was dis solved in a min i mal amount of DMF and slowly added to the HfCl 4 so lu tion, re sult ing in the forma tion of a bright yel low so lu tion. Af ter ca. a week yel low ish crys tals grow with nearly quan ti ta tive yield. UV/Vis: l DMF max = 395 nm, e = 191cm -1·M-1 . Ex per i men tal de tails All H at oms were po si tioned geo met ri cally and re fined us ing a rid ing model, with C-H methine = 0.98 Å; C-H methyl = 0.96 Å; C-H ar omatic = 0.93 Å. The H atom's iso tro pic dis place ment pa ram e ters were fixed; U iso (H) = 1.2U eq (C) for ar o matic and methine and U iso (H) = 1.5U eq (C) for methyl hy dro gen at oms. Discussion Zir co nium and haf nium co or di na tion com plexes have been a key fo cus area for many re search stud ies for sev eral de cades      . This study forms part of on-go ing re search of struc ture re ac tiv ity re la tion ships of these met als, aimed at in ves ti gat ing chelation behav iour of N-& O-do nat ing multi den tate lig ands [6-13]. The use of these and other N-& O-do nat ing lig ands find ap pli ca tion in model cat a lysts and radiopharmaceuticals synthon com plexes [12-17]. The ti tle com pound, [Hf(diBrOx) 4 ]·3(C 3 H 7 NO), (fig ure) with diBrOx = 5,7-dibromo-8-hydroxyquinoline crys tal lizes in P2 1 /c with three dimethylformamide sol vent mol e cules in the asym met ric unit. The com plex is com posed of an eight-co or dinated Hf(IV) atom with the four N,O-do nat ing bidentate lig ands (diBrOx) ar ranged around the metal atom to give a dis torted square antiprismatic ge om e try. Op po site fac ing ligand pairs lie across the metal cen tre with N1_O2, N2_O1, N3_O4 and N4_O3 in an ap prox i mate trans con fig u ra tion.. The an gle be tween ad jacent ligand planes range from 59.68(5) to 83.11(5)°. The Hf-O and Hf-N bond lengths vary from 2.081(3) Å to 2.097(3) Å and 2.384(3) Å to 2.414(3) Å, respectivily, while the O-Hf-N bite angles vary be tween 70.52(11)° and 70.95(11)°. Intramolecular C-H···O in ter ac tions are ob served be tween the DMF sol vent mol e cules and intermolecular in ter ac tions be tween the sol vent mol e cules and the com plex.