Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes

Abstract

In order to synthesize new iron (II) complexes of 1,5-diaza-3,7-diphosphacyclooctanes with a wider variety of the substituents on ligands heteroatoms (including functionalized ones, namely, pyridyl groups) and co-ligands, it was found that these ligands with relatively small phenyl, benzyl, and pyridin-2-yl substituents on phosphorus atoms in acetonitrile formed bis-P,P-chelate cis-complexes [L2Fe(CH3CN)2]2+ (BF4)2−, whereas P-mesityl-substituted ligand formed only monoligand P,P-complex [LFe(CH3CN)4]2+ (BF4)2−. 3,7-dibenzyl-1,5-di(1′-(R)-phenylethyl)-1,5-diaza-3,7-diphosphacyclooctane reacted with hexahydrate of iron (II) tetrafluoroborate in acetone to give an unusual bis-ligand cationic complex of the composition [L2Fe(BF4)]+ BF4−, where two fluorine atoms of the tetrafluoroborate unit occupied two pseudo-equatorial positions at roughly octahedral iron ion, according to X-ray diffraction data. 1,5-diaza-3,7-diphosphacyclooctanes replaced tetrahydrofurane and one of the carbonyl ligands of cyclopentadienyldicarbonyl(tetrahydrofuran)iron (II) tetrafluoroborate to form heteroligand complexes [CpFeL(CO)]+BF4−. The structural studies in the solid phase and in solutions showed that diazadiphosphacyclooctane ligands of all complexes adopted chair-boat conformations so that their nitrogen atoms were in close proximity to the central iron ion. The redox properties of the obtained complexes were performed by the cyclic voltammetry method.

Synthesis of Cu(II) complexes by N,O‐donor ligand transformation and their catalytic role in visible‐light‐driven alcohol oxidation

“…The combined organic layers were dried over anhydrous Na 2 SO 4 , and the solvent was removed in vacuo to give a light orange oil (2.11 g, 7.6 mmol, yield 73%). 1 S2). ESI-MS in HPLC MeOH (m/z): 303.3 (100%) (in negative mode) (Figure S5a).…”

“…In this report, we present two copper complexes derived from ligand H 2 L. Upon reaction with copper (II) acetate in methanol, an unprecedented piperizinyl ring cleavage has been observed with further organic transformation to yield [Cu (HL 1 )]…”

“…A flexible ring or open structure as ligand with one or more than one donor centers can induce structural preferences in formation of metal complexes in various ways. [1][2][3][4][5][6] It has been also noticed that in a sterically demanding situation or for the sake of less strainer chelating environment, certain ligands can decyclise or ring-opening of the ligands can happen. [7][8][9][10][11][12][13][14][15] In point of view of the catalytic properties, in-built flexibility of the associated ligands in terms of denticity, ability to engage in different noncovalent interactions with substrate, and providing an efficient and robust platform remain very crucial as per earlier reports.…”

Phospha-Mannich reactions of RPH2, R2PH, and R3P

“…Entry R R' Yield, % d P , ppm 66 [25] -53.8 (DMF-d 7 ) 74 [25] -53.5 (DMF-d 7 ) 62 [84] -44.4 (CDCl 3 ) 67 [36] -36.8 (DMF) 59 [64] -40.0 (DMSO-d 6 ) 68 [36] -43.1 (DMF) 78 [64] -44.1 (DMSO-d 6 ), -43.6 (DMFd 7 ) (-)*** [70] -(-)*** [70] -37 [24] -77.1 (DMSO-d 6 ) 45 [24] -Entry R R' Yield, % d P , ppm 83 [64] -42.5 (DMF-d 7 ) Me 46 [50] -Et 43 [50] i-Pr 42 [85] -37.1 (CDCl 3 ) n-Bu 45 [86] -50.0 (CDCl 3 ) t-Bu 63 [87] -18.2 and -27.8 (acetone-d 6 ) t-Bu t-Bu 34, [88] 76 [89] -9.9 and -14.3 (CDCl 3 ) t-Bu 95 [87] -37.5 and -62.3 (THF-d 8 ) CH 2 CH=CH 2 48 [50] -52, [86] (-)* [53,90] -46.0 (CDCl 3 ), -47.4 (CD 2 Cl 2 )…”

“…76 [91] -47.8 (CHCl 3 ) (-)* [53] -63.6 (CD 2 Cl 2 ) 58 [84] -67.5 (CDCl 3 ) 30 [86] -49.0 (CDCl 3 ) 48, [92] 67 [93] -45.7 (CDCl 3 ) 36 [92] -50.9 (CDCl 3 ) 58 [86] -53.0 (CDCl 3 )…”