A Prelude to Biogermylene Chemistry*.

The biological applications of germylenes remain unrealised owing to their unstable nature. We report the isolation of air-, water-, and culture-medium-stable germylene DPMGeOH (3; DPM=dipyrromethene ligand) and its potential biological application. Compound 3 exhibits antiproliferative effects comparable to that of cisplatin in human cancer cells. The cytotoxicity of compound 3 on normal epithelial cells is minimal and is similar to that of the currently used anticancer drugs. These findings provide a framework for a plethora of biological studies using germylenes and have important implications for low-valent main-group chemistry.

Germylene stabilized group 12 metal complexes and their reactivity with chalcogens.

This manuscript reports the first examples of germylene stabilized cadmium complexes {[{(i-Bu)2ATIGe(i-Pr)}2(CdI2)] (3, monomeric), [{(i-Bu)2ATIGe(i-Pr)(CdCl2)}2] (6, dimeric), [{(i-Bu)2ATIGe(i-Pr)(CdI2)}2] (7, dimeric)} and novel germylene zinc complexes {[{(i-Bu)2ATIGe(i-Pr)}2(ZnCl2)] (2, monomeric), [{(i-Bu)2ATIGe(i-Pr)(ZnI2)}2] (5, dimeric)} (ATI = aminotroponiminate). The reactions of germylene zinc complex [{(i-Bu)2ATIGe(i-Pr)(ZnCl2)}2] (4) with elemental sulphur and selenium resulted in the first examples of germathione and germaselenone stabilized ZnCl2 complexes [{(i-Bu)2ATIGe(i-Pr)(S)(ZnCl2)}2] (8) and [{(i-Bu)2ATIGe(i-Pr)(Se)(ZnCl2)}2] (9), respectively. Compound 4 was obtained through the reaction of compound 2 with ZnCl2. Interconversions between the monomeric and dimeric zinc/cadmium complexes (2 ↔ 4/3 ↔ 7) are shown. Compounds 2-3 and 5-9 are characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction studies are performed on compounds 2-3, 5-7, and 9. To understand the nature of bonding in the first examples of germylene cadmium complexes, ab initio calculations are also carried out on compounds 3 and 7.

Donor-acceptor-stabilised germanium analogues of acid chloride, ester, and acyl pyrrole compounds: synthesis and reactivity.

Germaacid chloride, germaester, and N-germaacyl pyrrole compounds were not known previously. Therefore, donor-acceptor-stabilised germaacid chloride (i-Bu)2ATIGe(O)(Cl) → B(C6F5)3 (1), germaester (i-Bu)2ATIGe(O)(OSiPh3) → B(C6F5)3 (2), and N-germaacyl pyrrole (i-Bu)2ATIGe(O)(NC4H4) → B(C6F5)3 (3) compounds, with Cl-Ge[double bond, length as m-dash]O, Ph3SiO-Ge[double bond, length as m-dash]O, and C4H4N-Ge[double bond, length as m-dash]O moieties, respectively, are reported here. Germaacid chloride 1 reacts with PhCCLi, KOt-Bu, and RLi (R = Ph, Me) to afford donor-acceptor-stabilised germaynone (i-Bu)2ATIGe(O)(CCPh) → B(C6F5)3 (4), germaester (i-Bu)2ATIGe(O)(Ot-Bu) → B(C6F5)3 (5), and germanone (i-Bu)2ATIGe(O)(R) → B(C6F5)3 (R = Ph 6, Me 7) compounds, respectively. Interconversion between a germaester and a germaacid chloride is achieved; reaction of germaesters 2 and 5 with TMSCl gave germaacid chloride 1, and 1 reacted with Ph3SiOLi and KOt-Bu to produce germaesters 2 and 5. Reaction of N-germaacyl pyrrole 3 with thiophenol produced a donor-acceptor-stabilised germaacyl thioester (i-Bu)2ATIGe(O)(SPh) → B(C6F5)3 (10). Furthermore, the attempted syntheses of germaamides and germacarboxylic acids are also discussed.

Ge(ii) cation catalyzed hydroboration of aldehydes and ketones.

Well-defined germylene cations [(i-Bu)2ATI]GeOTf (4) and [(i-Bu)2ATIGe][GaCl4] (5) are isolated, and the catalytic utility of compound 4 for the hydroboration of a variety of aldehydes and ketones is reported (ATI = aminotroponiminate).

Expanding the limits of catalysts with low-valent main-group elements for the hydroboration of aldehydes and ketones using [L†Sn(ii)][OTf] (L† = aminotroponate; OTf = triflate).

A triflatostannylene [L†Sn(ii)][OTf] (2) is reported here as an efficient catalyst with low-valent main-group element for the hydroboration of aldehydes and ketones (L† = aminotroponate). Using 0.025-0.25 mol% of compound 2, hydroboration of various aldehydes and ketones is accomplished in 0.13-1.25 h at room temperature; the aliphatic aldehydes show an impressive TOF of around 30 000 h-1. DFT calculations are performed to explore the mechanistic aspects of this reaction suggesting that the reaction proceeds via a stepwise pathway with hydridostannylene [L†Sn(ii)H] (2a) as the active catalyst and the H atom transfer from the Sn-H bond to the carbonyl carbon being the rate determining step.

Pseudohalogenogermylenes versus Halogenogermylenes: Difference in their Complexation Behavior towards Group 6 Metal Carbonyls.

Pseudohalogenogermylenes [(iBu)2 ATI]GeY (Y=NCO 4, NCS 5) show different coordination behavior towards group 6 metal carbonyls in comparison to the corresponding halogenogermylenes [(iBu)2 ATI]GeX (X=F 1, Cl 2, Br 3) (ATI=aminotroponiminate). The reactions of compounds 4-5 and 1-3 with cis-[M(CO)4 (COD)] (M=Mo, W, COD=cyclooctadiene) gave trans-germylene metal complexes {[(iBu)2 ATI]GeY}2 M(CO)4 (Y=NCO, M=Mo 6, W 11; Y=NCS, M=Mo 7) and cis-germylene metal complexes {[(iBu)2 ATI]GeX}2 M(CO)4 (M=Mo, X=F 8, Cl 9, Br 10; M=W, X=Cl 12), respectively. Theoretical studies on compounds 7 and 9 reveal that donor-acceptor interactions from Mo to Ge atoms are better stabilized in the observed trans and cis geometries than in the hypothetical cis and trans structures, respectively.

Catalytic cyanosilylation using germylene stabilized platinum(ii) dicyanide.

The ability of a platinum compound to act as a catalyst for the cyanosilylation of carbonyl compounds is demonstrated through a well-defined germylene stabilized Pt(ii) dicyanide, trans-{(iBu)2ATIGe(iPr)}2Pt(CN)2.

A cationic aluminium complex: an efficient mononuclear main-group catalyst for the cyanosilylation of carbonyl compounds.

A structurally characterized cationic aluminium complex [(AT)Al(DMAP)]+[OTf]- (3) stabilized through a relatively nonbulky aminotroponate (AT) ligand is reported (DMAP = 4-(dimethylamino)pyridine). This compound was found to work as an excellent mononuclear main-group catalyst of the cyanosilylation of a variety of aldehydes and ketones. Loadings of 1 to 2 mol% of this catalyst consumed these substrates in just 5 to 30 min at room temperature.

The Preparation of Complexes of Germanone from a Germanium µ-Oxo Dimer.

Complexes of germanone containing formal Ge=O→M bonds (M=Zn, B, Ge, Sn) were isolated and characterized. The compounds were prepared through a novel synthetic route using a germanium µ-oxo dimer 3 as the starting material. This method circumvents the need to employ germanones to prepare complexes of germanones.

Crystal structure of (Z)-3-[5-chloro-2-(prop-2-yn-yloxy)phen-yl]-3-hy-droxy-1-[4-(tri-fluoro-meth-yl)phen-yl]-prop-2-en-1-one.

The title compound, C19H12ClF3O3, obtained by the photochemical transformation of 2-[5-chloro-2-(prop-2-yn-yloxy)benzo-yl]-3-[4-(tri-fluoro-meth-yl)phen-yl]oxirane adopts a Z conformation with respect to the enolic C=C double bond. The dihedral angle between the benzene rings is 12.25 (16)° and an intra-molecular O-H⋯O hydrogen bond closes an S(6) ring. An intra-molecular C-H⋯O inter-action also leads to an S(6) ring. In the crystal, very weak C-H⋯O inter-actions and short Cl⋯Cl contacts [3.3221 (16) Å] are seen, as well as weak aromatic π-π stacking inter-actions [centroid-centroid separation = 3.879 (2) Å].

Endoscopic evaluation of therapeutic effects of "Anuloma-Viloma Pranayama" in Pratishyaya w.s.r. to mucociliary clearance mechanism and Bernoulli's principle.

The current endeavor intended to evaluate the effectiveness and mode of action of Anuloma-Viloma Pranayama (AVP), i.e., alternate nasal breathing exercise, in resolving clinical features of Pratishyaya, i.e., rhinosinusitis. The present study was directed to validate the use of classical "saccharin test" in measuring the nasal health by measuring mucociliary clearance time. This study also highlights the effects of AVP by application of Bernoulli principle in ventilation of paranasal sinuses and surface oxygenation of nasal and paranasal sinuses ciliary epithelium. Clinically, endoscopically and radiologically diagnosed patients of Pratishyaya, i.e., rhinosinusitis, satisfying the inclusion criteria were selected to perform AVP as a breathing exercise regularly for 30 min every day in order to evaluate the effectiveness of AVP in resolving features of rhinosinusitis. Saccharin test was performed before and after completion of 40 days trial to assess the nasal ciliary activity, which has been proved to be directly related to the health of ciliary epithelium and nasal health overall as well. AVP may be regarded as a catalyst to conspicuously enhance ventilation and oxygenation of the paranasal sinuses and the positively effect the nasal respiratory epithelium by increasing better surface availability of oxygen and negative pressure in the nasal cavity itself.