Color-coded summation images in the evaluation of renal artery stenosis before and after percutaneous transluminal angioplasty.

BACKGROUND: Endovascular therapy is the gold standard in patients with hemodynamic relevant renal artery stenosis (RAS) resistant to medical therapy. The severity grading of the stenosis as well as the result assessment after endovascular approach is predominantly based on visible estimations of the anatomic appearance. We aim to investigate the application of color-coded DSA parameters to gain hemodynamic information during endovascular renal artery interventions and for the assessment of the procedures´ technical success. METHODS: We retrospectively evaluated 32 patients who underwent endovascular renal artery revascularization and applied color-coded summation imaging on selected monochromatic DSA images. The differences in time to peak (dTTP) of contrast enhancement in predefined anatomical measuring points were analyzed. Furthermore, differences in systolic blood pressure values (SBP) and serum creatinine were obtained. The value of underlying diabetes mellitus as a predictor for clinical outcome was assessed. Correlation analysis between the patients´ gender as well as the presence of diabetes mellitus and dTTP was performed. RESULTS: Endovascular revascularization resulted in statistically significant improvement in 4/7 regions of interest. Highly significant improvement of perfusion in terms of shortened TTP values could be found at the segmental artery level and in the intrastenotical segment (p < 0.001), significant improvement prestenotical and in the apical renal parenchyma (p < 0.05). In the other anatomic regions, differences revealed not to be significant. Differences between SBP and serum creatinine levels before and after the procedure were significant (p = 0.004 and 0.0004). Patients´ gender as well as the presence of diabetes mellitus did not reveal to be predictors for the clinical success of the procedure. Furthermore, diabetes and gender did not show relevant correlation with dTTP in the parenchymal measuring points. CONCLUSIONS: The supplementary use of color-coding DSA and the data gained from parametric images may provide helpful information in the evaluation of the procedures´ technical success. The segmental artery might be a particularly suitable vascular territory for analyzing differences in blood flow characteristics. Further studies with larger cohorts are needed to further confirm the diagnostic value of this technique.

The Triple-Decker Complex [Cp*Fe(µ,η5:η5-P5)Mo(CO)3] as a Building Block in Coordination Chemistry.

Although the triple-decker complex [Cp*Fe(µ,η5:η5-P5)Mo(CO)3] (2) was first reported 26 years ago, its reactivity has not yet been explored. Herein, we report a new high-yielding synthesis of 2 and the isolation of its new polymorph (2'). In addition, we study its reactivity towards AgI and CuI ions. The reaction of 2 with Ag[BF4] selectively produces the coordination compound [Ag{Cp*Fe(µ,η5:η5-P5)Mo(CO)3}2][BF4] (3). Its reaction with Ag[TEF] and Cu[TEF] ([TEF]- = [Al{OC(CF3)3}4]-) leads to the selective formation of the complexes [Ag{Cp*Fe(µ,η5:η5-P5)Mo(CO)3}2][TEF] (4) and [Cu{Cp*Fe(µ,η5:η5-P5)Mo(CO)3}2][TEF] (5), respectively. The X-ray structures of compounds 3⁻5 each show an MI ion (MI = AgI, CuI) bridged by two P atoms from two triple-decker complexes (2). Additionally, four short MI···CO distances (two to each triple-decker complex 2) participate in stabilizing the coordination sphere of the MI ion. Evidently, the X-ray structure for compound 3 shows a weak interaction of the AgI ion with one fluorine atom of the counterion [BF4]-. Such an Ag···F interaction does not exist for compound 4. These findings demonstrate the possibility of using triple-decker complex 2 as a ligand in coordination chemistry and opening a new perspective in the field of supramolecular chemistry of transition metal compounds with phosphorus-rich complexes.

Organometallic-Organic Hybrid Polymers Assembled from Pentaphosphaferrocene, Bipyridyl Linkers, and CuI Ions.

A multicomponent approach of the P n ligand complex [Cp*Fe(η5-P5)] (1: Cp* = η5-C5Me5) with the ditopic organic linkers 4,4'-bipyridine (2) or trans-1,2-di(pyridine-4-yl)ethene (3) in the presence of CuI salts of the anions [BF4]- and [PF6]- or the coordinating anion Br-, leads to the formation of four novel organometallic-organic hybrid polymers: the cationic 1D polymeric compounds [Cu4{Cp*Fe(µ3,η5:1:1-P5)}2(µ,η1:1-C10H8N2)4(CH3CN)4] n [BF4]4n (4) and [Cu4{Cp*Fe(µ3,η5:1:1-P5)}2(µ,η1:1-C10H8N2)4(CH3CN)4] n [PF6]4n (5) as well as the unique neutral threefold 2D → 2D interpenetrated networks [Cu2Cl2{Cp*Fe(µ3,η5:1:1-P5)}(µ,η1:1-C12H10N2)] n (6) and [Cu2Br2{Cp*Fe(µ3,η5:1:1-P5)}(µ,η1:1-C10H8N2)] n (7).

Dicationic E4 Chains (E=P, As, Sb, Bi) Embedded in the Coordination Sphere of Transition Metals.

The oxidation chemistry of the complexes [{CpMo(CO)2 }2 (µ,η2 :η2 -E2 )] (E=P (A), As (B), Sb (C), Bi (D)) is compared. The oxidation of A-D with [Thia]+ (=[C12 H8 S2 ]+ ) results in the selective formation of the dicationic E4 complexes [{CpMo(CO)2 }4 (µ4 ,η2 :η2 :η2 :η2 -E4 )]2+ (E=P (1), As (2), Sb (3), Bi (4)), stabilized by four [CpMo(CO)2 ] fragments. The formation of the corresponding monocations [A]+ , [C]+ , and [D]+ could not be detected by cyclic voltammetry, EPR, or NMR spectroscopy. This finding suggests that dimerization is fast and that there is no dissociation in solution, which was also predicted by DFT calculations. However, EPR measurements of 2 confirmed the presence of small amounts of the radical cation [B]+ in solution. Single-crystal X-ray diffraction revealed that the products 1 and 2 feature a zigzag E4 chain in the solid state while 3 and 4 bear a central E4 cage with a distorted "butterfly-like" geometry. Additionally, 1 can be easily and reversibly converted into a symmetric and an unsymmetric form.

Highly dynamic coordination behavior of Pn ligand complexes towards "naked" Cu(+) cations.

Reactions of Cu(+) containing the weakly coordinating anion [Al{OC(CF3 )3 }4 ](-) with the polyphosphorus complexes [{CpMo(CO)2 }2 (µ,η(2) :η(2) -P2 )] (A), [CpM(CO)2 (η(3) -P3 )] (M=Cr(B1), Mo (B2)), and [Cp*Fe(η(5) -P5 )] (C) are presented. The X-ray structures of the products revealed mononuclear (4) and dinuclear (1, 2, 3) Cu(I) complexes, as well as the one-dimensional coordination polymer (5 a) containing an unprecedented [Cu2 (C)3 ](2+) paddle-wheel building block. All products are readily soluble in CH2 Cl2 and exhibit fast dynamic coordination behavior in solution indicated by variable temperature (31) P{(1) H} NMR spectroscopy.

Complexes of monocationic Group 13 elements with pentaphospha- and pentaarsaferrocene.

Reactions of the sandwich complexes [Cp*Fe(η(5)-E5)] (Cp*=η(5)-C5Me5; E=P (1), As (2)) with the monovalent Group 13 metals Tl(+), In(+), and Ga(+) containing the weakly coordinating anion [TEF] ([TEF]=[Al{OC(CF3)3}4](-)) are described. Here, the one-dimensional coordination polymers [M(µ,η(5):η(1 -E5 FeCp*)3]n [TEF]n (E=P, M=Tl (3 a), In (3 b), Ga (3 c); E=As, M=Tl (4 a), In (4 b)) are obtained as sole products in good yields. All products were analyzed by single-crystal X-ray diffraction, revealing a similar assembly of the products with η(5)-bound E5 ligands and very weak σ-interactions between one P or As atom of the ring to the neighbored Group 13 metal cation. By exchanging the [TEF] anion of 4 a for the larger [FAl] anion ([FAl]=[FAl{OC6F10(C6F5)}3](-)), the coordination compound [Tl{(η(5)-As5)FeCp*}3][FAl] (5) without any σ-interactions of the As5-ring is obtained. All products are readily soluble in CH2 Cl2 and exhibit a dynamic coordination behavior in solution, which is supported by NMR spectroscopy and ESI-MS spectrometry as well as by osmometric molecular-weight determination. For a better understanding of the proceeding equilibrium DFT calculations of the cationic complexes were performed for the gas phase and in solution. Furthermore, the (31)P{(1)H} magic-angle spinning (MAS) NMR spectra of 3 a-c are presented and the first crystal structure of the starting material 2 was determined.

Simultaneous end-on/side-on coordination modes of a diphosphorus tetrahedral complex imposed by pre-organization of oligometallic Cu(I) acceptors.

The reaction of the [{CpMo(CO)(2)}(2)(µ,η(2):η(2)-P(2))] (Cp=cyclopentadienyl) metallo-ligand 2 with pre-organized Cu(I) bi- and trimetallic precursors afforded new coordination complexes with unprecedented coordination modes for a Mo(2)P(2) complex. Variable-temperature solution and solid-state (31)P NMR spectroscopy measurements were performed and X-ray diffraction studies revealed an η(2):η(1) coordination mode for the Mo(2)P(2) unit of 2 in the Cu(I) bimetallic complexes 3 and 4. DFT calculations were carried out to highlight the bonding situation of this unprecedented coordination mode in the Cu(I) bimetallic compound 3. It is built up from a side-on coordination of the P-P σ bond to one copper ion and from the interaction of the lone pair of one phosphorus atom with the second copper ion. The remaining available lone pair of the second phosphorus atom can be involved as well to interact with an additional metal centre, as evidenced in the Cu(I) trimetallic compound 5 in which an η(2):η(1):η(1) coordination mode of the ligand 2 is observed. Derivative 3 can be used as a molecular clip to obtain discrete π-stacked dimers through a ligand exchange reaction between acetonitrile ligands and cyano-capped π-conjugated systems, indicating the stability of the new η(2):η(1) coordination mode.

Chemistry of bridging phosphanes: a comparative study within Cu(I)-Ag(I)-Au(I) triad-based homonuclear dimers.

Bridging ligands in Ag(I) and Au(I) bimetallic complexes: The P moiety of bis(2-pyridyl)phosphole acts as a symmetrically, semi-, or non-bridging donor in Ag(I) dimers (see figure). In related Au(I) complexes, only the non-bridging mode is observed. An unsaturated Ag(I) dimer is used as an adaptive molecular clip for the synthesis of pi-stacked metallocyclophanes.Bis(2-pyridyl)phosphole C reacted with AgPF(6) and dppm giving rise to dicationic dimer 1 in which C acts as a 1kappaN:1,2kappaP:2kappaN-donor with a symmetrically bridging P-centre. This complex gives the first example of dimers based on trigonal planar metal centres bearing a bridging sigma(3),lambda(3)-phosphane ligand. The reaction of two equivalents of C with AgPF(6) and Ag{Al[OC(CF(3))(3)](4)} afforded dicationic dimers 2 and 3 of general formula Ag(2)(C)(2) (2+), respectively. X-ray diffraction studies showed that one ligand C acts as a 1kappaN:1,2kappaP:2kappaN-donor with a symmetrically bridging P-centre and one behaves as a 1kappaN:2kappaP-chelate. In complex 3, one toluene molecule interacts with an Ag centre, giving the first example of a mixed coordination dimer featuring a bridging P-donor. Ag(I)-dimers 4 a-c of the general formula Ag(2)(C)(3) (2+), 2 X(-) (X=PF(6), BF(4), Al[OC(CF(3))(3)](4)) have been prepared according to different routes and characterised by X-ray diffraction study. In these derivatives, C exhibits a variety of coordination modes depending on the nature of the counteranion and of the solvent molecules included in the asymmetric units. These complexes can feature 0, 1, or 2 bridging P-donors. These results definitively demonstrate that the P-centre of phosphane ligands can easily switch from a bridging to a semi-bridging and a non-bridging coordination mode. Dimer 2 is used as an "adaptive" molecular clip for the synthesis of pi-stacked metallocyclophanes 7 a, b and 8 upon reaction with ditopic linkers. X-ray diffraction studies revealed that these supramolecular species behave as receptors for the counteranions (PF(6), BF(4)) and that the nature of the anion impacts the stereochemistry of the supramolecular metallocyclophanes. Au(I)-Dimers 10 a, b bearing two ligands C acting as 1kappaN:2kappaP-chelates are prepared and characterised in the solid-state.

Ag(I) bimetallic molecular clips with adaptive coordination behavior for supramolecular chemistry.

An Ag (I) dimer featuring a bridging phosphane ligand acts as an adaptive molecular clip for the coordination-driven synthesis of pi-stacked metallocyclophanes.

Mono-, di- and polymetallic TlI complexes stabilized by a 2,5-bis(2-pyridyl)-1-phenyl-phosphole ligand.

Depending on the nature of the counterion and of the solvent, novel TlI complexes of different nuclearity featuring a 2,5-bis(2-pyridyl)phosphole ligand were synthesized.