title: Electrospray ionization mass spectrometry of palladium(II) quinolinylaminophosphonate complexes.
abstract: The mass spectrometric behavior of palladium(II) halide complexes of three types of quinolinylaminophosphonates, diethyl and dibutyl esters of [α-anilino-(quinolin-2-yl)methyl]phosphonic (L1, L2), [α-anilino-(quinolin-3-yl)methyl]phosphonic (L3, L4), and [α-(quinolin-3-ylamino)-N-benzyl]phosphonic acid (L5, L6), was investigated under positive ion electrospray ionization conditions. Each type of ligand forms complexes with different metal-ligand interactions. Mononuclear dihalide adducts cis-[Pd(L1/L2)X(2)] (1-4) and trans-[Pd(L3/L4)(2)X(2)] (5-8) as well as dinuclear tetrahalide complexes [Pd(2)(L5/L6)(3)X(4)] (9-12) (X=Cl, Br) are formed by metal bonding either through the quinoline or both the quinoline and amino nitrogen atoms. The sodiated molecule [M + Na](+) is observed in the mass spectra of all the complexes, and its abundance as well as the fragmentation pathway depend on the type of the complex. In the cis complexes (1-4) the initial decomposition goes under two fragmentation routes: those in which the sodium molecular adduct sequentially loses halides HX/NaX and those in which this loss is in the competition with the loss of dialkyl phosphite. The predominant pathways for decomposition of trans dihalide (5-8) and tetrahalide (9-12) complexes include three competitive reactions; the loss of halides, dialkyl phosphites and the intact phosphonate ligand molecule and its fragments formed by ester dissociation or complete loss of the phosphonate ester moiety. A series of acetonitrile adducts and cluster ions derived from dimolecular clusters [2M + Na](+) were also detected. The most important fragmentation patterns are rationalized and supported by the MS(n) studies.
authors.affiliation: Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička cesta 54, HR-10002 Zagreb, Croatia. marina.juribasic@irb.hr
authors.forename: Marina
authors.initials: M
authors.lastname: Juribašić
authors.forename: Lisa
authors.initials: L
authors.lastname: Bellotto
authors.forename: Pietro
authors.initials: P
authors.lastname: Traldi
authors.forename: Ljerka
authors.initials: L
authors.lastname: Tušek-Božić
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D063065:Organophosphonates / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D011806:Quinolinium Compounds / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry
chemical_list: D000097:Acetonitriles; D056831:Coordination Complexes; D063065:Organophosphonates; D011806:Quinolinium Compounds; D010165:Palladium; C032159:acetonitrile