An unprecedented 1,4-diphospha-2,3-disila butadiene (-P[double bond, length as m-dash]Si-Si[double bond, length as m-dash]P-) derivative and a 1,3-diphospha-2-silaallyl anion, each stabilized by the amidinate ligand.

The first acyclic 4π-electron -P[double bond, length as m-dash]Si-Si[double bond, length as m-dash]P- motif with two four coordinate silicon substituents supported by the amidinate ligand and two coordinate phosphorus has been synthesized from the reaction of heteroleptic chlorosilylene LSiCl (1), TripPCl2 (Trip = 2,4,6-iPr3C6H2) and KC8 in a 1 : 1 : 3 ratio. The same reaction in a 1 : 2 : 6 ratio in the presence of one equivalent of 18-crown-6 ether affords the 1,3-diphospha-2-silaallyl anion.

Transformations of molecules and secondary building units to materials: a bottom-up approach.

A variety of complex inorganic solids with open-framework and other fascinating architectures, involving silicate, phosphate, and other anions, have been synthesized under hydrothermal conditions. The past few years have also seen the successful synthesis and characterization of several molecular compounds that can act as precursors to form open-framework and other materials, some of them resembling secondary building units (SBUs). Transformations of rationally synthesized molecular compounds to materials constitute an important new direction in both structural inorganic chemistry and materials chemistry and enable possible pathways for the rational design of materials. In this article, we indicate the potential of such a bottom-up approach, by briefly examining the transformations of molecular silicates and phosphates. We discuss stable organosilanols and silicate secondary building units, phosphorous acids and phosphate secondary building units, di- and triesters of phosphoric acids, and molecular phosphate clusters and polymers. We also examine the transformations of metal dialkyl phosphates and molecular metal phosphates.

Is water a friend or foe in organometallic chemistry? The case of group 13 organometallic compounds.

This Account summarizes the recent developments in the hydrolysis chemistry of Group 13 trialkyl and triaryl compounds. Emphasis has been placed on the results obtained by us on (a) 1H NMR investigations of controlled hydrolyses of AlMes3 and GaMes3, (b) low-temperature isolation of water adducts of triaryl compounds of aluminum and gallium, (c) synthesis and structural characterization of new polyhedral alumoxanes and galloxanes, and (d) the search for an easy way to synthesize well-defined crystalline methylalumoxanes by deprotonation of the hydroxides with alkyllithium reagents. The systematic studies on the hydrolysis of tBu3Al carried out by Barron et al. are also discussed in order to elucidate the roles of (i) reaction temperature, (ii) solvent medium, and (iii) source of water molecules, in building up hitherto unknown alumoxane clusters. The role of water impurity in organometallic reactions involving a Group 13 alkyl and other ligands (such as silanetriols and phosphorus acids) to build molecular clusters has also been discussed.

Di-tert-butyl phosphate complexes of cobalt(II) and zinc(II) as precursors for ceramic M(PO3)2 and M2P2O7 materials: synthesis, spectral characterization, structural studies, and role of auxiliary ligands.

Reaction of the metal acetates M(OAc)2xH2O with di-tert-butyl phosphate (dtbp-H) (3) in a 4:6 molar ratio in methanol or tetrahydrofuran followed by slow evaporation of the solvent results in the formation of metal phosphate clusters [M4(mu 4-O)(dtbp)6] (M = Co (4, blue); Zn (5, colorless)) in nearly quantitative yields. The same reaction, when carried out in the presence of a donor auxiliary ligand such as imidazole (imz) and ethylenediamine (en), results in the formation of octahedral complexes [M(dtbp)2(imz)4] (M = Co (6); Ni (7); Zn (8)) and [Co(dtbp)2-(en)2] (9). The tetrameric clusters 4 and 5 could also be converted into mononuclear 6 and 8; respectively, by treating them with a large excess of imidazole. The use of slightly bulkier auxiliary ligand 3,5-dimethylpyrazole (3,5-dmp) in the reaction between cobalt acetate and 3 results in the isolation of mononuclear tetrahedral complex [Co(dtbp)2(3,5-dmp)2] (10) in nearly quantitative yields. Perfectly air- and moisture-stable samples of 4-10 were characterized with the aid of analytical, thermoanalytical, and spectroscopic techniques. The molecular structures of the monomeric pale-pink compound 6, colorless 8, and deep-blue 10 were further established by single-crystal X-ray diffraction studies. Crystal data for 6: C28H52CoN8O8P2, a = 8.525(1) A, b = 9.331(3) A, c = 12.697(2) A, alpha = 86.40(2) degrees, beta = 88.12(3) degrees, gamma = 67.12(2) degrees, triclinic, P1, Z = 1. Crystal data for 8: C28H52N8O8P2Zn, a = 8.488(1) A, b = 9.333(1) A, c = 12.723(2) A, alpha = 86.55(1) degrees, beta = 88.04(1) degrees, gamma = 67.42(1) degrees, triclinic, P1, Z = 1. Crystal data for 10: C26H52CoN4O8P2, a = b = 18.114(1) A, c = 10.862(1) A, tetragonal, P4(1), Z = 4. The Co2+ ion in 6 is octahedrally coordinated by four imidazole nitrogens which occupy the equatorial positions and oxygens of two phosphate anions on the axial coordination sites. The zinc derivative 8 is isostructural to the cobalt derivative 6. The crystal structure of 10 reveals that the central cobalt atom is tetrahedrally coordinated by two phosphate and two 3,5-dmp ligands. In all structurally characterized monomeric compounds (6, 8, and 10), the dtbp ligand acts as a monodentate, terminal ligand with free P=O phosphoryl groups. Thermal studies indicate that heating the samples at 171 (for 4) or 93 degrees C (for 5) leads to the loss of twelve equivalents of isobutene gas yielding carbon-free [M4(mu 4-O)(O2P(OH)2)6], which undergoes further condensation by water elimination to yield a material of the composition Co4O19P6. This sample of 4 when heated above 500 degrees C contains the crystalline metaphosphate Co(PO3)2 along with amorphous pyrophosphate M2P2O7 in a 2:1 ratio. Similar heat treatment on samples 6-8 results in the exclusive formation of the respective metaphosphates Co(PO3)2, Ni(PO3)2, and Zn(PO3)2; the tetrahedral derivative 10 also cleanly converts into Co(PO3)2 on heating above 600 degrees C.

Synthesis, spectral characterization, and structural studies of 2-aminobenzoate complexes of divalent alkaline earth metal ions: X-ray crystal structures of [Ca(2-aba)2(OH2)3]infinity, [[Sr(2-aba)2(OH2)2].H2O]infinity, and [Ba(2-aba)2(OH2)]infinity (2-abaH = 2-NH2C6H4COOH).

Reactions of alkaline earth metal chlorides with 2-aminobenzoic acid (2-abaH) have been investigated. The treatment of MCl2.nH2O (M = Mg, Ca, Sr or Ba) with 2-abaH in a 1:2 ratio in a MeOH/H2O/NH3 mixture leads to the formation of anthranilate complexes [Mg(2-aba)2] (1), [Ca(2-aba)2(OH2)3]infinity (2), [[Sr(2-aba)2(OH2)2].H2O)]infinity (3), and [Ba(2-aba)2(OH2)]infinity (4) respectively. Alternatively, these products can also be obtained starting from the corresponding metal acetates. Anthranilate complexes 1-4 have been characterized with the aid of elemental analysis, pH measurements, thermal analysis, and infrared, ultraviolet, and NMR (1H and 13C) spectroscopic studies. All the products are found to be thermally very stable and do not melt on heating to 250 degrees C. Thermal studies of complexes 2-4, however, indicate the loss of coordinated and lattice water molecules below 200 degrees C. In the case of the magnesium complex, the analytical and thermogravimetric studies indicate the absence of any coordinated or uncoordinated water molecules. Further, the solid-state structures of metal anthranilates 2-4 have been established by single-crystal X-ray diffraction studies. While the calcium ions in 2 are heptacoordinated, the strontium and barium ions in 3 and 4 reveal a coordination number of 9 apart from an additional weak metal-metal interaction along the polymeric chains. The carboxylate groups show different chelating and bridging modes of coordination behavior in the three complexes. Interestingly, apart from the carboxylate functionality, the amino group also binds to the metal centers in the case of strontium and barium complexes 3 and 4. However, the coordination sphere of 2 contains only O donors. All three compounds form polymeric networks in the solid state with the aid of different coordinating capabilities of the carboxylate anions and O-H...O and N-H...O hydrogen bonding interactions.