Synthesis and reactivity of novel molecules and solids derived from heavier group 15 cyanate analogues

金属化合物(含氮、磷、砷、锑和/或铋的化合物)是一类具有多种结构和化学计量的固体。[1，2]在它们的许多应用中，它们被用作熏蒸剂、杀虫剂、照明弹，也许最值得注意的是作为半导体。[3]它们的物理和化学性质的多样性使这类化合物在一系列技术应用中引起了兴趣。然而，虽然许多这样的物种可以很容易地用各种方法来合成，但这些方法往往需要很高的能量成本。此外，我们获得定义明确的纳米材料的能力仍然受到现有技术方法的严重限制。这就是我们提出要解决的挑战。我们的目标是研究使用替代的含尼古丁原试剂来合成新的分子、簇、纳米颗粒和结构固体。考虑到这一点，我们将探索更重的含镍原的氰酸盐阴离子类似物PnCO-(Pn=P-Bi)与过渡金属盐和过渡后金属盐的反应性。初步研究表明，这类物种很容易发生脱碳反应，充当电子来源。2-磷酰乙醇盐离子(PCO-)是由Becker和他的同事在1992年首次报道的，直到最近才成为有限研究的对象。[8，9]2012年，Grutzmacher和Cummins的两份独立报告重新唤起了人们对这种非凡的阴离子物种的兴趣。[10，11]最近，我们观察到K3P7的溶液以中等到很好的产率直接羰化也可以获得PCO-。[12]2014年报道了一种新的最先进的这种阴离子的合成方法，允许以多克的量分离钠盐(&GT；100 GRS)。从廉价的前体开始(方案1)。[13]我们最近扩展了这项研究，以提供更重的含砷类似物(ASCO-)，这种类似物也可以从元素砷和钠金属中高产率分离。[14]这些合成突破将这些阴离子从单纯的化学稀有物质转变为可行的合成原料，用于合成新的含磷和含砷的分子物种。尽管如此，由于它们的相对新颖性，这些化合物在合成固体和分子簇方面的应用在很大程度上还没有被探索。我们的目标是在较重的15族氰酸酯类似物(PnCO-)和各种金属盐(在存在和不存在强配位配体和/或表面活性分子的情况下)之间进行溶液相歧化反应，目的是开发一种新的自下而上的金属多肽的合成方法。我们的第一个目标是在PnCO-(Pn=P，As)的碱金属盐与第13族元素的低卤化物(如GaI)之间进行概念验证反应，目的是确定一条通往III/V半导体材料(如GaP)的新途径。III-V半导体如GaAs、Ga1-xInxP和InP因其最佳带隙和高吸收系数而被认为是有吸引力的光电子器件候选材料。除了光伏应用，它们还被广泛应用于固态激光器、LED和光波导中。[16-19]目前两种更重的氰酸盐类似物的出现也为合成混合化合物提供了可能性，如GaAs1-xPx，这是一种具有巨大工业兴趣的化合物，用于字母数字和图形显示。该项目属于EPSRC物理科学研究主题(特别是化学合成方法学领域)。

Metal pnictides (compounds containing nitrogen, phosphorus, arsenic, antimony and/or bismuth) are a varied family of solids that adopt a wealth of structures and stoichiometries.[1,2] Amongst their many applications they have been employed as fumigants, pesticides, flares and, perhaps most notably, as semiconductors.[3] The diversity of their physical and chemical properties makes such compounds interesting for a range of technological applications. However, while many such species can be readily synthesised using a variety of methods, these often come at a high energetic cost. Moreover, our ability to access well defined nanoscale materials is still significantly limited by existing technological methods. This is the challenge we propose to address.Our goal is to study the use of alternative pnictogen-containing reagents for the synthesis of novel molecules, clusters, nanoparticles and structured solids. With this in mind, we will explore the reactivity of heavier pnictogen-containing analogues of the cyanate anion, PnCO- (Pn = P-Bi), with transition- and post-transition metal salts. Preliminary studies have shown that such species readily undergo decarbonylation reactions acting as E- sources. The 2-phosphaethynolate ion (PCO-) was first reported by Becker and co-workers in 1992 and was the subject of limited study until very recently.[8,9] In 2012, two separate reports by Grutzmacher and Cummins revived the interest in this remarkable anionic species.[10,11] More recently, we observed that PCO- can also be obtained by direct carbonylation of solutions of K3P7 in moderate to good yields.[12] A novel state-of-the-art synthesis of this anion was reported in 2014 allowing for the isolation of sodium salts in multi-gram quantities (> 100 grs.) starting from inexpensive precursors (Scheme 1).[13] We recently extended this research to afford the heavier arsenic-containing analogue (AsCO-) which can also be isolated in high yields from elemental arsenic and sodium metal.[14] These synthetic breakthroughs have transformed these anions from mere chemical curiosities to viable synthetic feedstocks for the synthesis of novel phosphorus- and arsenic-containing molecular species. That being said, due to their relative novelty, the use of these compounds for the synthesis of solids and molecular clusters remains largely unexplored.Our goal is to carry out solution-phase metathesis reactions between heavier group 15 cyanate analogues (PnCO-) with a variety of metal salts (in the presence and absence of strongly coordinating ligands and/or surfactant molecules), with the aim of developing a novel bottom-up approach to metal pnictides. Our first objective is to carry out proof-of-concept reactions between alkali metal salts of PnCO- (Pn = P, As) with the lower halides of the group 13 elements (e.g. GaI) with the objective of identifying a novel route towards III/V semiconductor materials (such as GaP). III-V semiconductors such as GaAs, Ga1-xInxP, and InP are considered attractive candidates for optoelectronic devices due to their optimal band gaps and high absorption coefficients. In addition to photovoltaic applications,[15] they have been widely utilized in solid state lasers, LEDs, and optical waveguides.[16-19] The current availability of two heavier cyanate analogues also opens up the possibility of synthesising mixed pnictide species such as GaAs1-xPx, which is a compound of enormous industrial interest for alpha-numeric and graphical displays.This project falls within the EPSRC Physical Sciences research theme (specifically the Chemical Synthetic Methodology area).