Absorption of dietary phosphorus plays a critical role in the development of metabolic bone diseases in patients with chronic renal failure. However, phosphorus absorption is difficult to quantitate in dialysis patients because the dialysis treatments complicate metabolic balance studies. Utilizing a recently developed technique which permits measurement of net absorption of dietary constituents after a single meal, we measured phosphorus absorption in dialysis patients. The following observations were made: A.) Following a meal containing approximately 300 mg phosphorus, mean phosphorus absorption in five hemodialysis patients (with severe vitamin D deficiency) was only slightly less than in matched controls (186 +/- 35 vs. 242 +/- 30). B.) After dialysis patients were treated with 1,25(OH)2-D3, phosphorus absorption increased from 186 +/- 35 to 272 +/- 16 mg (P less than 0.025). C.) The effect of three aluminum containing antacids on phosphorus absorption was studied; each slightly reduced the absorption of phosphorus compared to placebo (P less than 0.01), but there was no significant difference between them. D.) Aluminum hydroxide and calcium carbonate each reduced dietary phosphorus absorption to approximately the same extent. Calcium carbonate ingestion was associated with sharply increased calcium absorption. The absorption of dietary phosphorus is influenced only modestly by 1,25(OH)2-D3 and is inhibited to an equal but only modest degree by various aluminum antacids and by calcium carbonate.

The reaction of [SnMe2Cl2] with the bidentate ligand 4,7‐phenanthroline (4,7‐phen) resulted in the formation of [SnMe2Cl2 (4,7‐phen)]n (1a) which is probably a polymeric chain in solution. On the other hand, the reaction of [SnEt2Cl2] with 4,7‐phen afforded the complex [Sn2Et4Cl4 (κ1‐N‐4,7‐phen)2(μ‐κ2‐N,N‐4,7‐phen)] (1b) which dissociates in dimethylsulfoxide solution. The reaction of [SnR2Cl2] (R = Me, Et) with 2,2′‐biquinoline (biq) yielded the complexes [SnMe2Cl2 (κ2‐N,N‐biq)] (2a) and [SnEt2Cl2 (κ1‐N‐biq)2] (2b) in the solid state. Moreover, the reaction of [SnR2Cl2] (R = Me, Et) with the tridentate ligand 4′‐(2‐furyl)‐2,2′:6′,2″‐terpyridine (ftpy) resulted in the formation of ionic penta‐ and hexa‐coordinated tin complexes [SnMe2Cl (ftpy)][SnMe2Cl3] (3a) and [SnEt2Cl (ftpy)]Cl (3b). The reaction of [SnMe2 (NCS)2] with ftpy afforded the hepta‐coordinated complex [SnMe2 (NCS)2(ftpy)] (4a). The products were fully characterized using elemental analysis, and infrared, UV–visible, multinuclear (1H, 13C, 119Sn) NMR, DEPT‐135°, HH‐COSY and HSQC NMR spectroscopies. The crystal structure of complex 3a reveals that it contains the simultaneous presence of penta‐ and hexa‐coordinated tin (IV) atoms. Notably, the crystal structure of complex 4a shows that tin (IV) is hepta‐coordinated in a pentagonal bipyramidal geometry SnC2N5 by three nitrogen atoms of ftpy, two nitrogen atoms of NCS− and two Me groups with trans‐[SnMe2] configuration. These data indicate the influence of halide or pseudo‐halide group on the coordination number and geometry of tin. Hirshfeld surface analysis and two‐dimensional fingerprint plots were calculated for 3a and 4a which show the π–π interaction between molecules in the solid is relatively weak.

No abstract

No abstract

Diorganotin (IV) complexes SnR 2 X 2 (R = Me, Ph; X = Cl, NCS) form a series of versatile complexes when react with bidentate substituted pyridyl ligands. The reaction of dimethyltin dichloride with 5,5′-dimethyl-2,2′-bipyridine (5,5′-Me 2 bpy) resulted in the formation of [SnMe 2 Cl 2 (5,5′-Me 2 bpy)] (1). Moreover, the reaction of SnMe 2 (NSC) 2 with 4,4′-di-tert-butyl-2,2′-bipyridine (bu 2 bpy), 1,10-phenanthroline (phen) and 4,7-diphenyl-1,10-phenanthroline (bphen) affords the hexa-coordinated complexes [SnMe 2 (NCS) 2 (bu 2 bpy)] (2), [SnMe 2 (NCS) 2 (phen)] (3) and [SnMe 2 (NCS) 2 (bphen)] (4), respectively. The resulting complexes have been characterized using elemental analysis, IR, multinuclear NMR ( 1 H, 13 C, 119 Sn) and DEPT-135°NMR spectroscopy. On the other hand, the reaction of diphenyltin dichloride with 2,2′-biquinoline (biq) and 4,7-phenantroline (4,7-phen) led to the formation of polymeric complexes of [SnPh 2 Cl 2 (4,7-phen)] n (5) and [SnPh 2 Cl 2 (biq)] n (6). The NMR spectra, however, reveal the ligand lability in solution and suggest a coordination number of 5. The X-ray crystal structures of complexes [SnMe 2 Cl 2 (5,5′-Me 2 bpy)] (1), [SnMe 2 (NCS) 2 (bu 2 bpy)] (2) and [SnMe 2 (NCS) 2 (bphen)] (4) have been determined which reveal that the geometry around the tin atom is distorted octahedral with trans-[SnMe 2 ] configuration. Interestingly, the crystal structure of (H 2 biq) 2 [SnPh 2 Cl 4 ]•2CHCl 3 (7) was characterized by X-ray crystallography from a chloroform solution of [SnPh 2 Cl 2 (biq)] n (6) indicating the formation of doubly protonated [H 2 biq] + and [Ph 2 SnCl 4 ] 2− which are stabilized by a network of hydrogen bonds with a feature of trans-[SnPh 2 ]. The 3D Hirshfeld surface analysis and 2D fingerprint maps were used for quantitative mapping out of the intermolecular interactions for 1, 2, 4 and 7 which show the presence of π-π and hydrogen bonding interactions which are associated between donor and acceptor atoms (N, S, Cl) in the solid state.